Journal archives for March 2022

March 01, 2022

Species-coexistence in mallee-heath in Western Australia: up to 150 species of plants growing together in one type of shrubland

A familiar concept in ecology is the species-richness of any given community - technically called 'alpha-diversity' (https://en.wikipedia.org/wiki/Alpha_diversity).

Some communities of organisms contain just a few species, while others contain many species which have found a way to coexist in the same habitat. And this variation can be surprisingly great.

Eucalypts (Eucalyptus, https://en.wikipedia.org/wiki/Eucalyptus) growing naturally in the form of shrubs are the characteristic plants over large areas of southwestern Australia, under a temperate climate with rainfall mainly in winter. The climate is similar to those of southwestermost South Africa, southern California, and coastal parts of the Mediterranean Basin. However, the vegetation can be extreme in its species-richness.

This is exemplified by Fitzgerald River National Park (https://en.wikipedia.org/wiki/Fitzgerald_River_National_Park) and its environs, on the southern coast of Western Australia (see https://researchrepository.murdoch.edu.au/view/author/Newbey,_Kenneth.html).

On well-drained lithified dunes just inland from the littoral zone, the mallee vegetation consists of Eucalyptus angulosa (https://www.inaturalist.org/taxa/208143-Eucalyptus-angulosa), Eucalyptus falcata, Melaleuca pentagona (https://www.inaturalist.org/taxa/1255442-Melaleuca-pentagona) and only a few other species. The soil is calcareous sand over limestone, and the number of plant species coexisting in this community is as small as 12.

By contrast:

On the plain a few kilometers inland, a duplex soil (siliceous sand over pale clay) has developed over a siliceous sedimentary rock called spongolite (https://en.wikipedia.org/wiki/Spongolite and https://www.researchgate.net/publication/236842784_Eocene_spiculites_and_spongolites_in_southwestern_Australia_Not_deep_not_polar_but_shallow_and_warm).

Here, mallee shrubs of Eucalyptus pleurocarpa (https://en.wikipedia.org/wiki/Eucalyptus_pleurocarpa and https://apps.lucidcentral.org/euclid/text/entities/eucalyptus_pleurocarpa.htm) form an upper stratum over a knee-high heathy stratum. Here the number of plant species coexisting intimately within a single community can reach up to 150.

The typical soil-profile where species-richness is greatest is 10-15 centimeters of loamy sand (in places containing black, shiny gravel) over a monotone/slightly mottled clay between the depth of 15 centimeters and the depth of 70 centimeters, over weathering spongolite (70-80 centimeters), over spongolite rock.

Another way of describing this soil-profile is that it:

In this exceptionally species-rich vegetation, up to approximately 100 species of small-leafed, evergreen, flammable shrubs (mainly Proteaceae, Myrtaceae and Fabaceae but also Casuarinaceae, Ericaceae, Dilleniaceae, Rutaceae, etc.) share the same stand.

The shrubs in question are typically knee-high, and all have rhizal adaptations - ranging from cluster roots (https://en.wikipedia.org/wiki/Cluster_root) to ectotrophic mycorrhizae (https://mycorrhizas.info/info.html), and from rhizobial to actinorhizal (https://en.wikipedia.org/wiki/Frankia) nodules for fixation of atmospheric nitrogen.

In this exceptionally species-rich heathy stratum, it seems that every new individual plant examined adds another species to the tally.

The following show the general appearance of the community in question: https://www.inaturalist.org/observations/92880446 and https://www.inaturalist.org/observations/88921818 and https://www.inaturalist.org/observations/88491761 and https://www.inaturalist.org/observations/88400105.

The species-poverty of the first community described above, on calcareous dunes, may come as no surprise to naturalists in South Africa, California and the Mediterranean Basin, where introduced eucalypts are notorious for their suppression of other plants.

However, this connotation makes it all the more remarkable that, in the second community described above, Eucalyptus coexists with a shrubby component so species-rich as to exceed all other heathlands (in the loose sense) on Earth - including fynbos (https://www.jstor.org/stable/3235578) in South Africa with its particular reputation for beta-diversity (https://en.wikipedia.org/wiki/Fynbos and https://en.wikipedia.org/wiki/Beta_diversity and https://link.springer.com/chapter/10.1007/978-94-009-9200-9_5 and https://link.springer.com/chapter/10.1007/978-3-642-68935-2_19 and https://link.springer.com/article/10.1007/BF00121419).

Posted on March 01, 2022 23:55 by milewski milewski | 9 comments | Leave a comment

March 02, 2022

No evolutionary convergence between Australia and southern Africa in snakes and legless lizards, part 1

@herping_with_berks @hamishrobertson @ockertvs @alexanderr @bushboy @jouberth @tyroneping @ptexis @snakesrcool @halvard_midtun @sanjoaquinserpents @wolfgang_wuster @michael_jacobi @wildlife1607 @vinaygogula @ludwig_muller @asimakis_patitsas @owenlishmund @tommyh44 @adammyates @graytreefrog @zdunek_herp @chrisvankalken @alexey_katz @wyn_russell @calebcam @cr_hundermark

Fitzgerald River National Park (https://en.wikipedia.org/wiki/Fitzgerald_River_National_Park and https://www.fitzgeraldfriends.org.au/the-park) and its environs in Western Australia, and Agulhas National Park and its environs in South Africa, have similar climates.

Indeed the climates are so similar that they provide a near-ideal opportunity for testing the notion of evolutionary convergence (https://en.climate-data.org/oceania/australia/western-australia/hopetoun-982310/ and https://en.climate-data.org/africa/south-africa/western-cape/gansbaai-9058/).

The substrates too are extremely similar: nutrient-poor and mainly sandy.

In both study areas there is a littoral strip including calcareous dunes, partly fixed by vegetation.

The vegetation inland, on plains and low hills, is broadly similar between continents. Typical vegetation is mallee-heath (http://www.ecosmagazine.com/temp/EC14063_Fb.gif and https://southernforestlife.net/wa-trip-2018/2018/9/27/fitzgerald-river) in the Australian study area and proteoid fynbos (https://www.alamy.com/protea-compacta-bot-river-sugarbush-bot-river-protea-in-the-hottentots-holland-mountains-fynbos-biome-western-cape-south-africa-this-plant-is-s-image437143673.html and http://www.pofadderskloof.com/fynbos/) in the South African study area. However, there are also patches of thicket/tall shrubland, and a few small patches of woodland/forest in both study areas.

This constitutes perhaps the closest matching in overall environmental regimes that has ever been achieved in intercontinental comparisons (https://researchrepository.murdoch.edu.au/id/eprint/202/ and https://www.annualreviews.org/doi/abs/10.1146/annurev.es.14.110183.000421).

However, it is clear that any prediction of evolutionary convergence is not borne out by the faunas of either mammals (https://www.inaturalist.org/journal/milewski/62378-no-evolutionary-convergence-in-mammal-communities-in-southwestern-australia-and-the-southwestern-cape-of-south-africa-part-1#) or snakes and legless lizards.

Please see part 2 for the lists of species.

The only well-matched pair of species is Pseudonaja affinis (https://www.researchgate.net/figure/Dugite-or-Spotted-Brown-Snake-from-Red-Hill_fig15_304014934) vs Naja nivea (https://cdn.britannica.com/83/92683-050-8EE18A38.jpg).

However, this is weak confirmation of evolutionary convergence because both belong to the same family (Elapidae). Furthermore, even in this case:

Anilios australis (https://reptile-database.reptarium.cz/species?genus=Anilios&species=australis and https://en.wikipedia.org/wiki/Anilios_australis) in the Australian study area is a seeming counterpart for Rhinotyphlops lalandei (https://en.wikipedia.org/wiki/Rhinotyphlops_lalandei and https://www.jstor.org/stable/1565893) in the southern African study area. Unsurprisingly for members of the same family of snakes (https://en.wikipedia.org/wiki/Typhlopidae), these species are similar in shape, colouration, and diet (brood of ants).

However, these species are too closely related to be considered convergent. Furthermore, the Australian species is the larger-bodied.

Furthermore, there is no typhlopid counterpart in the Australian study area for Leptotyphlops nigricans (https://en.wikipedia.org/wiki/Leptotyphlops_nigricans.) - which belongs to the same family as the smallest-bodied species of snake on Earth (https://en.wikipedia.org/wiki/Leptotyphlopidae).

The elapids Acanthophis antarcticus (https://www.monaconatureencyclopedia.com/acanthophis-antarcticus/?lang=en) and Echiopsis curta (http://members.iinet.net.au/~bush/Bardick.html and https://en.wikipedia.org/wiki/Echiopsis) show considerable evolutionary convergence with the viperids, Bitis spp. However, these elapids remain less specialised than the viperids in e.g. body girth, fang mechanism, and skin-texture. Furthermore, A. antarcticus, relatively small-bodied, is rare in the study area and has neurotoxic venom, whereas Bitis arietans, relatively large-bodied, is common in the study area and has cytotoxic venom.

Beyond the above cases, the differences I form and function outweigh the similarities in the faunas compared.

There are fewer species, in the composite category of snakes and legless lizards, in the Australian than the southern African study area.

This is partly because there is far less specialisation in the Australian than in the southern African study area for staple diets of:

  • termites (Leptotyphlops nigricans, Rhinotyphlops lalandei),
  • slugs (Duberria lutrix),
  • frogs (Amplorhinus multimaculatus, Crotaphopeltis hotamboeia),
  • blind snakes and fossorial lizards (Homoroselaps lacteus),
  • arboreal vertebrates, i.e. birds and chameleons (Dispholidus typus),
  • eggs of birds (Dasypeltis scabra) and reptiles (Prosymna sundevalli, if present), and
  • rodents (Pseudaspis cana and Bitis arietans).

This is balanced by greater specialisation in the case of Australia only for:

  • large spiders (Pygopus lepidopodus), and
  • ants (Aprasia spp. and Anilios australis).

Another way of expressing the above is that the community of snakes is less differentiated in the Australian than in the southern African study area.

One aspect of this differentiation is venom.

There are virtually no snakes specialising on a diet of snakes in either study area. Closest is Homoroselaps lacteus, which eats legless skinks as well as typhlopid snakes. Its closest counterpart in the Australian study area is Suta nigriceps, which is not fossorial to the same degree but has been recorded eating typhlopids.

An approximate match for Leptotyphlops nigricans can be sought in the pygopodid (https://en.wikipedia.org/wiki/Pygopodidae) genus Aprasia, which contains up to three species in the Australian study area. However, these legless lizards:

  • are specialised on ants (eggs, larvae and pupae) instead of termites,
  • are not as slender or small-eyed as L. nigricans,
  • lay fewer eggs at a time,
  • have tails that are proportionately longer than in snakes and can be lost by autotomy, and
  • possibly spend more time at the surface, associated with ant-dominated habitats on extremely oligotrophic soils.

What this means is:
In both the Australian and the southern African study areas there are myrmecophagous (https://en.wikipedia.org/wiki/Myrmecophagy), small, legless reptiles. However, these differ in being specialised on ants in the former and termites in the latter - undermining even the similarity between typhlopids.

In both study areas there are forms specialising dietarily on lizards. However the Australian species, Lialis burtonis, is morphologically remarkably different from the southern African species in genus Psammophis, partly because the former is a lizard whereas the latter is a snake.

The elapid Rhinoplocephalus bicolor (https://calphotos.berkeley.edu/cgi/img_query?enlarge=0000+0000+0407+1885) and the lamprophiid Lamprophis fuscus (https://www.africansnakebiteinstitute.com/snake/yellow-bellied-house-snake/) are comparable in appearance, diet and habits. However, R. bicolor is smaller than L. fuscus, and live-bearing instead of oviparous. The Australian species eats mainly skinks (https://www.researchgate.net/publication/242326609_Natural_History_of_Two_Monotypic_Snake_Genera_of_Southwestern_Australia_Elapognathus_and_Rhinoplocephalus_Elapidae), whereas the southern African species eats mainly rodents.

Elapognathus coronatus and Suta nigriceps are not as specialised, in either habitat or diet, for a diet of frogs as are Amplorhinus multimaculatus and Crotaphopeltis hotamboeia.

Evolutionary convergence may remain a valid principle, conforming as it does with those most basic concepts in biology, natural selection and adaptation.

However, even the most similar climates and soils on different landmasses remain just too different in their overall environmental regimes to allow a real test. This is a particularly intractable problem because such an important aspect of the regimes is the biotic aspect itself. Even in these extremely well-matched physical environments and even when the families are the same (Elapidae and Typhlopidae), the biotic opportunities/pressures are crucial.

Hence the cobra-like snake in the Australian study area still differs from the Cape cobra in having a minimally-expressed defensive hood, and in having smaller offspring. This is explained by the Cape cobra having to contend with an intense predatory regime compared with quasi-insular Australia.

In the case of blind snakes the lesser productivity of termites in Australia (see https://www.researchgate.net/publication/271689805_Why_Are_Termite-_and_Ant-Eating_Mammals_Smaller_in_Australia_Than_in_Southern_Africa_History_or_Ecology) means that the dietary opportunities remain significantly different between continents.

Please see part 2 for the lists of species...

Posted on March 02, 2022 21:12 by milewski milewski | 41 comments | Leave a comment

March 03, 2022

No evolutionary convergence between Australia and southern Africa in snakes and legless lizards, part 2

Lists of species in the study areas:

FITZGERALD RIVER NATIONAL PARK and environs, WESTERN AUSTRALIA

Pygopodidae:

Aprasia pulchella restricted to southwest of study area if present, SV 11-12 cm TL 20.0?, https://www.inaturalist.org/taxa/36954-Aprasia-pulchella

Aprasia repens SV 11.0 - 12.6 cm T L 20.0? cm https://www.inaturalist.org/taxa/36953-Aprasia-repens

Aprasia striolata SV 12-13 cm TL 21.5? cm https://www.inaturalist.org/taxa/36950-Aprasia-striolata and https://reptile-database.reptarium.cz/species?genus=Aprasia&species=striolata

Delma fraseri fraseri SV 12-13 and up to 14 cm TL 42 cm https://www.inaturalist.org/taxa/36939-Delma-fraseri

Delma hebesa SV up to 8 cm TL 23? cm occurs in kwongan and mallee-heath, https://www.inaturalist.org/taxa/539605-Delma-hebesa and https://reptile-database.reptarium.cz/species?genus=Delma&species=hebesa

Lialis burtonis SV 29 cm uncommon https://www.inaturalist.org/observations?taxon_id=36978 and http://reptilesofaustralia.com/lizards/legless/lburton.htm#.YiF2LZZBxDM and https://www.researchgate.net/publication/272656655_Ecology_and_Behaviour_of_Burton%27s_Legless_Lizard_Lialis_burtonis_Pygopodidae_in_Tropical_Australia

Pygopus lepidopodus SV 27.4 cm https://www.inaturalist.org/taxa/36963-Pygopus-lepidopodus

Elapidae:

Acanthophis antarcticus somewhat adder-like, rare in study area, https://www.inaturalist.org/taxa/35060-Acanthophis-antarcticus and https://museum.wa.gov.au/sites/default/files/THE%20GENUS%20ACATHOPHIS%20(SERPEBTES%20ELAPIDAE)%20IN%20WESTERN%20AUSTRALIA.pdf

Echiopsis curta somewhat adder-like, https://www.inaturalist.org/taxa/35270-Echiopsis-curta

Elapognathus coronatus eats mainly skinks and frogs https://www.inaturalist.org/taxa/539637-Elapognathus-coronatus

Notechis scutatus occidentalis mixed diet including frogs, https://www.inaturalist.org/taxa/35178-Notechis-scutatus

Pseudonaja affinis affinis https://www.inaturalist.org/taxa/35148-Pseudonaja-affinis and https://australian.museum/learn/animals/reptiles/dugite/#:~:text=Wild%20caught%20females%20from%20the,ranges%20from%2012%20to%2015.

Rhinoplocephalus bicolor https://www.inaturalist.org/taxa/35137-Rhinoplocephalus-bicolor and https://arod.com.au/arod/reptilia/Squamata/Elapidae/Rhinoplocephalus/bicolor?q=author=%22M%C3%BCller%22%20yearDescribed=1885

Suta gouldii common in study area https://www.inaturalist.org/taxa/1127949-Suta-gouldii

Suta nigriceps eats mainly reptiles https://www.inaturalist.org/taxa/1127951-Suta-nigriceps

Pythonidae:

Morelia imbricata non-venomous constrictor, https://www.inaturalist.org/taxa/1224418-Morelia-imbricata

Typhlopidae:

Anilios australis certainly present in northern and eastern part of study area, 8-40 up to 42 cm, stout-bodied, https://www.inaturalist.org/taxa/539265-Anilios-australis


CAPE AGULHAS NATIONAL PARK and environs, SOUTH AFRICA

Cordylidae:

Chamaesaura anguina anguina SV 9? cm 35-40 up to 49 cm https://www.inaturalist.org/taxa/33073-Chamaesaura-anguina

Gerrhosauridae:

(Tetradactylus seps https://www.inaturalist.org/taxa/34724-Tetradactylus-seps occurs in the study area but has legs and is this disqualified from this approach. Its counterpart in the southern African study area is the skink Hemiergis peronii https://www.inaturalist.org/taxa/38366-Hemiergis-peronii.)

Tetradactylus tetradactylus tetradactylus SV 7? cm TL 18-24 up to 29 cm, occurs only marginally to study area, https://www.inaturalist.org/taxa/34725-Tetradactylus-tetradactylus

Scincidae:

Acontias meleagris meleagris SV 20 cm TL 25 up to 30 cm (tail less than 22% of TL) diet earthworms, beetle larvae and termites https://www.inaturalist.org/taxa/37301-Acontias-meleagris

Scelotes bipes only hindlegs present https://www.inaturalist.org/taxa/37694-Scelotes-bipes

Colubridae:

Crotaphopeltis hotamboeia https://www.inaturalist.org/taxa/82808-Crotaphopeltis-hotamboeia

Dasypeltis scabra specialised egg-eater, https://www.inaturalist.org/taxa/26717-Dasypeltis-scabra

Dispholidus typus typus eats perching birds and chameleons, https://www.inaturalist.org/taxa/30358-Dispholidus-typus

Elapidae:

Hemachatus haemachatus occurs only marginally, https://www.inaturalist.org/taxa/30652-Hemachatus-haemachatus

Naja nivea https://www.inaturalist.org/taxa/30487-Naja-nivea

Lamprophiidae:

Amplorhinus multimaculatus marshes and damp microsites, prefers frogs, https://www.inaturalist.org/taxa/29679-Amplorhinus-multimaculatus

Boaedon capensis constrictor, mhttps://www.inaturalist.org/taxa/539396-Boaedon-capensis and https://etd.uwc.ac.za/bitstream/handle/11394/8709/Bassier_M_Nsc_2022.pdf?sequence=1&isAllowed=y

Duberria lutrix lutrix specialised slug-eater, https://www.inaturalist.org/taxa/30326-Duberria-lutrix

Homoroselaps lacteus eats mainly Leptotyphlops, Rhinotyphlops, small burrowing lizards, and termites, https://www.inaturalist.org/taxa/116525-Homoroselaps-lacteus and https://www.tyroneping.co.za/snakes-southern-africa/homoroselaps-lacteus-spotted-harlequin-snake/ and http://www.biodiversityexplorer.info/reptiles/squamata/serpentes/elapidae/homoroselaps_lacteus.htm#:~:text=Feeds%20on%20lizards%20(particularly%20legless,snakes%20(particularly%20blind%20snakes).

Lamprophis fuscus uncommon, https://www.inaturalist.org/taxa/29763-Lamprophis-fuscus

Lycodonomorphus inornatus constrictor, diet of rodents, lizards and snakes, https://www.inaturalist.org/taxa/29758-Lycodonomorphus-inornatus

Lycodonomorphus rufulus diet mainly frogs in waterside locations, https://www.inaturalist.org/taxa/29536-Lycodonomorphus-rufulus

Lycophidion capense capense uncommon in study area, specialises on sleeping lizards, https://www.inaturalist.org/taxa/29508-Lycophidion-capense

Prosymna sundevalli sundevalli possibly present, specialist on reptile eggs (https://www.jstor.org/stable/3891967), https://www.inaturalist.org/taxa/29007-Prosymna-sundevalli and https://reptile-database.reptarium.cz/species?genus=Prosymna&species=sundevalli

Psammophis crucifer rapid-moving although less slender than congeners, mildly venomous, diet mainly small lizards (particularly geckos) but sometimes also frogs, https://www.inaturalist.org/taxa/28985-Psammophis-crucifer

Psammophis notostictus possibly present https://www.inaturalist.org/taxa/28976-Psammophis-notostictus

Psammophylax rhombeatus the most frequently observed species of snake in the study area, mixed diet with emphasis on lizards, https://www.inaturalist.org/taxa/28954-Psammophylax-rhombeatus

Pseudaspis cana specialised rodent-eater, juveniles eat mainly lizards, https://www.inaturalist.org/taxa/28948-Pseudaspis-cana

Leptotyphlopidae:

Leptotyphlops nigricans 13-17 up to 20 cm, specialised on soft parts of termites, found under graminoid tufts in sandy areas, swims rapidly through sand, clutch 1-7, https://www.inaturalist.org/taxa/32477-Leptotyphlops-nigricans

Typhlopidae:

Rhinotyphlops lalandei 25-30 up to 35 cm, slender-bodied, clutch 2-4, https://www.inaturalist.org/taxa/32735-Rhinotyphlops-lalandei

Viperidae:

Bitis arietans arietans specialised rodent-eater, https://www.inaturalist.org/taxa/30851-Bitis-arietans

Bitis armata https://www.inaturalist.org/taxa/95801-Bitis-armata

Posted on March 03, 2022 23:16 by milewski milewski | 11 comments | Leave a comment

March 05, 2022

Marlock, part 1

(writing in progress)

https://www.inaturalist.org/taxa/201389-Eucalyptus-platypus

https://en.wikipedia.org/wiki/Marlock

On the southern coastal plain of Western Australia there occurs an odd type of vegetation that deserves to be better-known. This is marlock low forest.

Marlock low forest is dominated by Eucalyptus, but in a form strange to most naturalists. This is because of the following combination:

  • the stand consists of trees, not the shrubby form of eucalypts called mallee,
  • it is as dense as the densest-known forests of eucalypts elsewhere, but only about 7 meters high,
  • there is minimal understorey,
  • the trees are as fire-prone as other eucalypts but their wildfire regime is restricted to the canopy because there is no understorey capable of carrying fire, and
  • the trees lack any basal burl and regenerate germinatively, not vegetatively.

To the naturalist familiar with mallee tall-shrublands or eucalypt open-forests, marlock low forest seems odd because it is dense, hardly taller than mallee, single-stemmed, and mortally affected by combustion of its crown..

MAMMALS

Tarsipes rostratus https://www.inaturalist.org/taxa/42788-Tarsipes-rostratus and Cercartetus concinnus https://www.inaturalist.org/taxa/42798-Cercartetus-concinnus both present in all sample sites!

Sminthopsis griseoventer https://en.wikipedia.org/wiki/Grey-bellied_dunnart

Rattus fuscipes in tall form on coastal dune https://www.inaturalist.org/taxa/44570-Rattus-fuscipes

Pseudomys albocinereus ditto https://en.wikipedia.org/wiki/Ash-grey_mouse

BIRDS

Dromaius novaehollandiae https://www.inaturalist.org/taxa/20504-Dromaius-novaehollandiae

Lophoictinia isura https://www.inaturalist.org/taxa/5286-Lophoictinia-isura

Glossopsitta porphyrocephala https://www.inaturalist.org/taxa/19245-Glossopsitta-porphyrocephala

Barnardius zonarius https://www.inaturalist.org/taxa/19265-Barnardius-zonarius

Cacomantis flabelliformis https://www.inaturalist.org/taxa/1850-Cacomantis-flabelliformis

Chrysococcus lucidus https://www.inaturalist.org/taxa/1723-Chrysococcyx-lucidus

Coracina novaehollandiae https://www.inaturalist.org/taxa/7990-Coracina-novaehollandiae

Eopsaltria griseogularis always found in this vegetation and not in other types in the study area https://www.inaturalist.org/taxa/14152-Eopsaltria-griseogularis

Pachycephala occidentalis https://www.inaturalist.org/taxa/506042-Pachycephala-occidentalis

Colluricincla harmonica https://www.inaturalist.org/taxa/8514-Colluricincla-harmonica

Rhipidura albiscapa https://www.inaturalist.org/taxa/144737-Rhipidura-albiscapa

Myiagra inquieta https://www.inaturalist.org/taxa/204547-Myiagra-inquieta

Drymodes brunneopygia https://www.inaturalist.org/taxa/14157-Drymodes-brunneopygia

Lichmera indistincta https://www.inaturalist.org/taxa/12526-Lichmera-indistincta

Melithreptus brevirostrus https://www.inaturalist.org/taxa/12254-Melithreptus-brevirostris

Melithreptus lunatus https://www.inaturalist.org/taxa/501272-Melithreptus-lunatus

Lichenostomus cratitius https://www.inaturalist.org/taxa/12164-Lichenostomus-cratitius

Where veg taller than typical:

Chrysococcyx basalis https://www.inaturalist.org/taxa/1719-Chrysococcyx-basalis

Gliciphila melanops https://www.inaturalist.org/taxa/144710-Gliciphila-melanops

Pomatostomus superciliosus https://www.inaturalist.org/taxa/144710-Gliciphila-melanops

Occurring in tall, double-storey marlock on greenstone but not in moort

Zosterops lateralis https://www.inaturalist.org/taxa/202505-Zosterops-lateralis

Sericornis frontalis https://www.inaturalist.org/taxa/13510-Sericornis-frontalis

Acanthiza apicalis https://www.inaturalist.org/taxa/72439-Acanthiza-apicalis

Phylidonyris novaehollandiae https://www.inaturalist.org/taxa/12632-Phylidonyris-novaehollandiae

Nesoptilotis leucotis https://www.inaturalist.org/taxa/508981-Nesoptilotis-leucotis

Corvus coronoides https://www.inaturalist.org/taxa/8040-Corvus-coronoides

Species notably absent

Lichenostomus virescens https://www.inaturalist.org/taxa/370319-Gavicalis-virescens

Anthochaera carunculata https://www.inaturalist.org/taxa/12622-Anthochaera-carunculata

Strepera versicolor https://www.inaturalist.org/taxa/8425-Strepera-versicolor

Smicrornis brevirostris https://www.inaturalist.org/taxa/13540-Smicrornis-brevirostris

Hylacola cauta https://www.inaturalist.org/taxa/72928-Hylacola-cauta

Pardalotus striatus https://www.inaturalist.org/taxa/13532-Pardalotus-striatus

Pardalotus punctatus https://www.inaturalist.org/taxa/13531-Pardalotus-punctatus and/or Pardalotus punctatus https://www.inaturalist.org/taxa/13531-Pardalotus-punctatus

HERPS

Pseudophryne guentheri https://www.inaturalist.org/taxa/25254-Pseudophryne-guentheri

Crinia georgiana https://www.inaturalist.org/taxa/25232-Crinia-georgiana

Underwoodisaurus milii https://www.inaturalist.org/journal/milewski/62598-marlock-part-1/edit

Diplodactylus granariensis tall marlock on greenstone only https://www.inaturalist.org/taxa/33185-Diplodactylus-granariensis

Acritoscincus trilineatus https://www.inaturalist.org/journal/milewski/62598-marlock-part-1/edit

Varanus rosenbergi https://www.inaturalist.org/taxa/39441-Varanus-rosenbergi

Ctenophorus maculatus griseus https://www.inaturalist.org/taxa/31231-Ctenophorus-maculatus

Hemiergis peronii https://www.inaturalist.org/taxa/38366-Hemiergis-peronii

Hemiergis initialis marlock on greenstone https://www.inaturalist.org/taxa/38367-Hemiergis-initialis

Ctenotus impar https://www.inaturalist.org/taxa/37089-Ctenotus-impar

Morelia imbricata tall marlock on greenstone only https://www.inaturalist.org/taxa/1224418-Morelia-imbricata

(writing in progress)

Posted on March 05, 2022 08:27 by milewski milewski | 1 comment | Leave a comment

Are birds less fecund in Australia than in southern Africa?, part 1

@ludwig_muller @alexanderr @rion_c @surfinbird @subirshakya @lukedowney @karimhaddad @colin25 @bushboy @tyroneping @calebcam @joshuagsmith @george_seagull @jadonald @gumnut @ratite @ptexis

It seems reasonable to suspect that birds in Australia are in some sense less fecund than those in southern Africa.

The main reasons are as follows:

  • the peculiar incidence of extremely adapted snakes (Dasypeltis, https://www.inaturalist.org/observations?place_id=any&taxon_id=26716&view=species) that specialise on birds' eggs in southern Africa,
  • the incidence of various, partly bird-eating, carnivorous mammals (e.g. felids, herpestids) and birds in southern Africa, with no counterparts in Australia, and
  • the generally lesser fecundity of mammals (whether metatherian or eutherian) in Australia than in southern Africa.

Reproduction and growth are generally relatively slow in marsupials. Furthermore, even in rodents the Australian forms tend to be less fecund than their southern African counterparts.

Do birds in Australia generally lay fewer eggs, or smaller eggs (or both), than those in southern Africa - given a relevant comparative basis?

To make intercontinental comparison as rigorous as possible, I chose study areas carefully matched in climates, landforms and soils: Fitzgerald River National Park and its environs in Western Australia and Agulhas National Park and its environs in South Africa (see https://www.inaturalist.org/journal/milewski/62510-no-evolutionary-convergence-between-australia-and-southern-africa-in-snakes-and-legless-lizards-part-1#).

First, let us examine those birds that nest at or below ground-level (see part 2 for faunal lists plus information on number of eggs per clutch, and size of eggs).

The ground-nesting avifaunas in the Australian study area (about 30 spp. with eggs of diameter less than 40 mm) are phylogenetically closer to those in the southern African study area (about 37 spp.) than is true for the faunas of mammals or reptiles. At least ten genera of ground-nesting birds are shared intercontinentally within this study.

The only ground-nesting birds present in the Australian study area but with no counterparts in the southern African study area are one species of parrot and one species of pardalote.

Approximate counterparts on the two continents (ducks, quails, bustards, oystercatchers, plovers, nightjars, bee-eaters, pipits, 'wrens' and 'chats) generally lay similar numbers of eggs, of similar size, per clutch.

However, one reason why there are fewer ground-nesting species in the Australian than in the southern African study area is that the several genera of larks (Alaudidae), common in the southwestern Cape of South Africa, have no counterparts in winter-rainfall Western Australia. The species, present in or near Agulhas National Par, lay 2-3 eggs, diameter 15-17 mm, per clutch (see part 2).

Anthus novaeseelandiae (usually 3-4 eggs, diameter 16-17 mm) is closely related to, and reproductively indistinguishable from, Anthus cinnamomeus in South Africa. However, there is an additional, common motacillid (Macronyx, egg diameter 18 mm) in the southern African study area.

Chats that forage and nest mainly on the ground (e.g. Saxicola) in the southern African study area lay about 4 eggs, of diameter about 15 mm. In the Australian study area the only possible counterpart to the larks and chats is the meliphagid 'chat' Epthianura, which lays about 3 eggs, of diameter about 14 mm.

Quails and button-quails lay eggs on the ground in both study areas (Coturnix 7-10 eggs, diameter 22-23 mm; Turnix 4 eggs, diameter 19-23 mm). Coturnix is fecund on both continents but it is rarer in the Australian than in the southern African study area.

Two additional phasianids (Pternistis, Scleroptila) lay large clutches (more than 5 eggs of diameter less than 38 mm). Their only counterpart in the Australian study area is Leipoa ocellata, which differs from all African birds in burying its eggs - which are unusually large (diameter 61 mm).

'Wrens' and nightjars lay slightly fewer eggs per clutch in the Australian than in the southern African study area. For example:

  • Drymodes 1 vs Chaetops, 2, Cercotrichas 2-3,
  • Dasyornis 2 vs Sphenoeacus 2-3,
  • Sericornis and Calamanthus sometimes as few as 2 vs Cisticola never 2 but sometimes as many as 5,
  • the caprimulgid in the Australian study area (1 egg, diameter 25 mm) vs that in the southern African study area (2 eggs, diameter 20 mm).

Focussing further on the shared clades of ground-nesting birds:

In both study areas there are the following plovers:

  • larger-bodied (Vanellus, 3-4 eggs, diameter 29-32, although now rare in the Australian study area), and
  • several smaller-bodied (Charadrius and allied genera, usually 2 eggs, diameter 20-24 mm).

Bee-eaters (Merops): about 4-5 eggs, diameter 18 mm in the Australian vs 22 mm in the southern African study area.

A guild of ground-nesting birds for which comparisons are complicated phylogenetically is the 'wrens': Drymodes, Dasyornis, Malurus, and Sericornis in the Australian vs Erythropygia, Sphenoeacus, Cisticola, and Chaetops in the southern African study area. Drymodes spp. are larger-bodied (body length without tail 12 cm) than Cercotrichas (body length without tail 8.5-10.1 cm; 9.7 cm in Cercotrichas coryphoeus), yet lay fewer eggs (1 and up to 2, vs 2-3 and up to 4).

Let us turn now to birds other than those nesting at or below ground-level.

Among 'warblers', Acanthiza and Stipiturus lay perhaps one egg fewer (3-4; 3 in the species most common in and near Fitzgerald River National Park) than does Prinia (2-5, usually 4) in or near Agulhas National Park. However, the difference is not borne out by Apalis (3 and up to 4).

Do nectar-, fruit- and insect-eating passerines in the Australian study area lay fewer eggs than those in the southern African study area? The answer is no.

Meliphagids lay no fewer eggs per clutch (1-3, usually 2) than promeropids and nectariniids. Zosterops, a shared genus, lays no fewer eggs in the Australian (2-4, usually 3) than in the southern African (2-3) study area.

Partly fruit-eating meliphagids lay scarcely fewer eggs (3 or less than 3, except for Manorina which often lays 4) than do the more specialised fruit-eaters (pycnonotids 2-3, coliids 3-4) in southern Africa. Pomatostomus (https://www.inaturalist.org/taxa/14491-Pomatostomus-superciliosus) lays 2-3 and up to 5, whereas Cossypha (https://www.inaturalist.org/taxa/12786-Cossypha-caffra) lays 2 and up to 3.

In both study areas, certain passerine birds nest colonially. These are omnivorous, aggressive species dependent on the most productive situations: small areas combining relatively rich alluvial soils, perennial moisture, tree growth, and bare ground with fast-growing annual plants.

The only species in this category in the Australian study area is the meliphagid (Manorina flavigula, https://www.inaturalist.org/taxa/12223-Manorina-flavigula). By contrast, several species occur in the southern African study area:

Species additionally relevant here are the ploceid Euplectes (https://www.inaturalist.org/taxa/13964-Euplectes-capensis), and the starling Lamprotornis (https://www.inaturalist.org/taxa/517007-Lamprotornis-bicolor).

Manorina (2-5) lays no fewer eggs than Ploceus (2-5) or Euplectes (2-4, usually 3).

However, the meliphagid is likely to be less productive of eggs than the ploceids. Males outnumber females in the meliphagid, whereas females outnumber breeding males in Ploceus. Furthermore, adolescents of the meliphagid assist a relatively small number of parents to rear offspring, whereas in the ploceids a) the only cooperative breeding is nest-sharing, and b) males alone build the nests, leaving females free to devote all their energy to laying and provisioning.

Lamprotornis bicolor does not breed gregariously. However, it often nests in burrows, accessible to snakes; and it often lays two clutches (each of usually 4 eggs but with a range of 2-6) in a given season (https://en.wikipedia.org/wiki/Pied_starling#Breeding).

The fecundity of phasianids is noteworthy. Members of this family are common in the southern African study area but rare in the Australian study area. They lay eggs small, numerous, exposed, and localised enough to be viable for the dietary specialisation of Dasypeltis scabra (https://www.inaturalist.org/taxa/26717-Dasypeltis-scabra).

Several relevant kinds of birds present in or near Agulhas National Park have no counterparts in or near Fitzgerald River National Park. Since most birds breed at a restricted time of year in winter-rainfall climates, an egg-eating snake depends on large concentrations of eggs to allow it to lay down enough fat to tide it over seasonally.

Thus, the ability of the southern African study area to support a specialised egg-eating snake may be owing to a combination of:

  • the presence of ploceids that breed gregariously,
  • the presence of starlings that nest below ground level, and
  • the commonness of phasianids.

Summarising more generally:
For most families/genera/guilds of birds, any intercontinental differences in the number of eggs per clutch, or the size of eggs, are negligible. However, in a few important cases the Australian study area has no counterparts for particularly fecund birds, such as relatively large-bodied phasianids. This may help to explain the differences between continents in the incidence of bird-eating predators and in particular Dasypeltis.

Please see part 2 for faunal lists of the ground-nesting birds in the study areas...

Posted on March 05, 2022 22:33 by milewski milewski | 6 comments | Leave a comment

March 06, 2022

Are birds less fecund in Australia than in southern Africa?, part 2

The following is information on the clutches and eggs of ground-nesting birds in and near Fitzgerald River National Park in Western Australia, compared with Agulhas National Park in South Africa.

Data for clutches and eggs are excluded for species:

  • with eggs exceeding 40 mm diameter (on the assumption that these exceed the capacity of Dasypeltis scabra, see part 1), and
  • nesting on water, cliffs or steep banks, or higher than 20 centimeters above ground-level.

In the following avifaunal lists for the study areas in Australia and southern Africa, I have grouped the species intercontinentally by genus or family where possible, and otherwise according to foraging guild. The figures shown are number of eggs per clutch, and diameter of eggs.

FLIGHTLESS BIRDS, BUSTARDS, and CRANES (all of which nest on the ground but have eggs with diameters exceeding 40 mm)

Australia:
(Dromaius novaehollandiae)
(Ardeotis australis, rare in study area)

southern Africa:
(Struthio camelus)
(Eupodotis afra)
(Neotis denhami)
(Anthropoides paradiseus)

OYSTERCATCHERS

(Haematopus spp. lay about 2 eggs of diameter about 42 mm on the shores of both study areas)

DUCKS

Australia:
Anas gracilis https://www.inaturalist.org/taxa/6969-Anas-gracilis
4-14, 39 mm
Anas castanea https://www.inaturalist.org/taxa/6958-Anas-castanea
7-15, 37 mm
(Anas superciliosa https://www.inaturalist.org/taxa/6987-Anas-superciliosa
7-13, 41 mm)
Spatula rhynchotis https://www.inaturalist.org/taxa/558437-Spatula-rhynchotis
9-11, 38 mm

southern Africa:
Anas capensis https://www.inaturalist.org/taxa/6986-Anas-capensis
6-10, 35 mm
Anas erythrorhyncha https://www.inaturalist.org/taxa/6984-Anas-erythrorhyncha
5-12, 37 mm
Spatula smithii https://www.inaturalist.org/taxa/558436-Spatula-smithii
6-11, 39 mm

PLOVERS and THICKNEES

Australia:
Charadrius bicinctus https://www.inaturalist.org/taxa/4826-Charadrius-bicinctus
4, 22 mm
Charadrius ruficapillus https://www.inaturalist.org/taxa/4803-Charadrius-ruficapillus
2, 21 mm
2-3, 24 mm
Elseyornis melanops https://www.inaturalist.org/taxa/4914-Elseyornis-melanops
3-4, 19 mm
Thinornis cucullatus https://www.inaturalist.org/taxa/144487-Thinornis-cucullatus
1-3, 27 mm or 2-3, 24 mm
Vanellus tricolor https://www.inaturalist.org/taxa/4874-Vanellus-tricolor
4, 32 mm
Burhinus grallarius rare https://www.inaturalist.org/taxa/4925-Burhinus-grallarius
2, 39 mm

southern Africa:
Charadrius hiaticula https://www.inaturalist.org/taxa/4801-Charadrius-hiaticula
Charadrius marginatus https://www.inaturalist.org/taxa/4806-Charadrius-marginatus
1-4 usually 2, 23 mm
Charadrius pallidus https://www.inaturalist.org/taxa/4819-Charadrius-pallidus
2, 23 mm
Charadrius pecuarius https://www.inaturalist.org/taxa/4828-Charadrius-pecuarius
Charadrius tricollaris https://www.inaturalist.org/taxa/4805-Charadrius-tricollaris
2, 22 mm
Vanellus coronatus https://www.inaturalist.org/taxa/4877-Vanellus-coronatus
2-4 usually 3, 29 mm
Burhinus vermiculatus https://www.inaturalist.org/taxa/4926-Burhinus-vermiculatus
2, 36 mm
Burhinus capensis https://www.inaturalist.org/taxa/4922-Burhinus-capensis
1-2 usually 2, 38 mm

NIGHTJARS

Australia:
Eurostopodus argus https://www.inaturalist.org/taxa/19554-Eurostopodus-argus
1, 25 mm

southern Africa:
Caprimulgus pectoralis https://www.inaturalist.org/taxa/19392-Caprimulgus-pectoralis
2, 20 mm

CIRCUS

Australia:
Circus approximans https://www.inaturalist.org/taxa/5168-Circus-approximans
3-6 usually 3-4, 40 mm

southern Africa:
(Circus maurus https://www.inaturalist.org/taxa/5174-Circus-maurus)
(Circus ranivorus https://www.inaturalist.org/taxa/5165-Circus-ranivorus)

MEROPS

Australia:
Merops ornatus https://www.inaturalist.org/taxa/2238-Merops-ornatus
3-7 usually 4-5, 18 mm

southern Africa
Merops apiaster https://www.inaturalist.org/taxa/2191-Merops-apiaster
4-6, 22 mm

GALLIFORMS

Australia:
Coturnix pectoralis https://www.inaturalist.org/taxa/825-Coturnix-pectoralis
7-14 usually 7-8, 23 mm
Synoicus ypsilophorus https://www.inaturalist.org/taxa/505881-Synoicus-ypsilophorus
7-11 and up to 20, 23 mm
Turnix varius https://www.inaturalist.org/taxa/20907-Turnix-varius
4, 23 mm
Turnix velox https://www.inaturalist.org/taxa/20866-Turnix-velox
3-5 usually 4, 18 mm
(Leipoa ocellata https://www.inaturalist.org/taxa/2040-Leipoa-ocellata)

southern Africa:
Coturnix coturnix https://www.inaturalist.org/taxa/804-Coturnix-coturnix
6 up to 12, 22 mm
Pternistis capensis https://www.inaturalist.org/taxa/343746-Pternistis-capensis
6-8 and up to 14, 38 mm
Scleroptila afer https://www.inaturalist.org/taxa/550880-Scleroptila-afra
6, 30 mm
Turnix hottentotus https://www.inaturalist.org/taxa/980032-Turnix-hottentottus
2-5, 19 mm

LARKS and PIPITS

Australia:
Anthus novaeseelandiae https://www.inaturalist.org/taxa/204462-Anthus-novaeseelandiae
3-5 usually 4, 17 mm

southern Africa:
Galerida magnirostris https://www.inaturalist.org/taxa/7358-Galerida-magnirostris
2-3, 17 mm
Calandrella cinerea https://www.inaturalist.org/taxa/204473-Calandrella-cinerea
1-4 usually 2, 15 mm
Certhilauda brevirostris https://en.wikipedia.org/wiki/Agulhas_long-billed_lark
2-3, 15.5 mm
Mirafra apiata https://www.inaturalist.org/taxa/204543-Mirafra-apiata
2-3, 15 mm
Anthus cinnamomeus https://www.inaturalist.org/taxa/145208-Anthus-cinnamomeus
2-4 usually 3, 16 mm
Anthus leucophrys https://www.inaturalist.org/taxa/13708-Anthus-leucophrys
2-4 usually 3, 15 mm
Macronyx capensis https://www.inaturalist.org/taxa/14098-Macronyx-capensis
3-4, 18 mm

SUNDRY WATERBIRDS

Australia:
Tribonyx ventralis https://www.inaturalist.org/taxa/144480-Tribonyx-ventralis
5, 30 mm

southern Africa:
Gallinula chloropus https://www.inaturalist.org/taxa/201282-Gallinula-chloropus
5-8 usually 8, 30 mm
Gallinago nigripennis https://www.inaturalist.org/taxa/3924-Gallinago-nigripennis
2, 30 mm
Sarothrura rufa https://www.inaturalist.org/taxa/352-Sarothrura-rufa or elegans https://www.inaturalist.org/taxa/349-Sarothrura-elegans
3-4 or 5, 21 mm
Rostratula benghalensis https://www.inaturalist.org/taxa/3999-Rostratula-benghalensis
3-5, 25 mm

'CHATS'

Australia:
Epthianura albifrons https://www.inaturalist.org/taxa/12651-Epthianura-albifrons
2-4 usually 3, 14 mm

southern Africa:
Cercomela familiaris presence needs confirmation https://www.inaturalist.org/taxa/980204-Oenanthe-familiaris
2-4 usually 3, 15 mm
Saxicola torquatus https://www.inaturalist.org/taxa/55371-Saxicola-torquatus and https://www.jstor.org/stable/3675997
3-4, 14 mm
Oenanthe pileata nests in rodent burrows https://www.inaturalist.org/taxa/12839-Oenanthe-pileata
3-5, 18 mm

PARROTS

Australia:
Pezoporus flaviventris https://en.wikipedia.org/wiki/Western_ground_parrot
3-4, 21 mm

PARDALOTES

Australia:
Pardalotus punctatus xanthopyge https://www.inaturalist.org/taxa/13531-Pardalotus-punctatus
3-6 usually 4, 14 mm

STARLINGS

southern Africa:
(Lamprotornis bicolor, when nesting in tunnels below ground-level, uses steep banks; see part 1)

'WRENS'

Australia:
Drymodes brunneopygia https://www.inaturalist.org/taxa/14157-Drymodes-brunneopygia
1, 19 mm
Dasyornis longirostris https://www.inaturalist.org/taxa/13479-Dasyornis-longirostris
2, 19 mm
Malurus splendens https://www.inaturalist.org/taxa/12083-Malurus-splendens
2-4 usually 3, 14 mm
Malurus pulcherrimus https://www.inaturalist.org/taxa/12072-Malurus-pulcherrimus
3, 12 mm
Sericornis frontalis https://www.inaturalist.org/taxa/13510-Sericornis-frontalis
2-3, 17 mm
Calamanthus montanellus https://www.inaturalist.org/taxa/548191-Calamanthus-montanellus
3 and up to 4, 16 mm
Hylacola cauta https://www.inaturalist.org/taxa/72928-Hylacola-cauta
2-3, 14 mm

southern Africa:
Chaetops frenatus rare in study area https://www.inaturalist.org/taxa/116869-Chaetops-frenatus and https://sabap2.birdmap.africa/docs/sabap1/611.pdf
2, 20 mm
Cisticola fulvicapilla https://www.inaturalist.org/taxa/72731-Cisticola-fulvicapilla
3-5, 12 mm
Cisticola tinniens https://www.inaturalist.org/taxa/7660-Cisticola-tinniens
3-5, 12 mm
Cisticola textrix presence needs confirmation https://www.inaturalist.org/taxa/7700-Cisticola-textrix
4, 12 mm
Cisticola subruficapilla https://www.inaturalist.org/taxa/72733-Cisticola-subruficapilla
3-4, 12 mm
Cercotrichas coryphoeus https://www.inaturalist.org/taxa/522938-Cercotrichas-coryphoeus
2-3 and up to 4, 15 mm
Sphenoeacus afer https://www.inaturalist.org/taxa/15717-Sphenoeacus-afer
2-3, 16 mm

Posted on March 06, 2022 00:55 by milewski milewski | 4 comments | Leave a comment

March 07, 2022

Evolutionary convergence in amphibians between Australia and southern Africa depends on predatory regimes rather than just climates and soils

@alexanderr @spixii @stephenmahony @reiner @mothchild @briancadam @patrick_campbell @tom-kirschey @joelknightnz @adammyates @asimakis_patitsas @olvr_a @calebcam @tyroneping @herping_with_berks @rion_c @danieleseglie @smuele @johngsalamander @franciscodocampo @martin_schluepmann @tszentiv @samuel_guiraudou @stamatiskalogiannis @grathwohl @amarzee @ilias_strachinis @ludwig_muller @sandboa

I have shown, in other Posts, that there is negligible evolutionary convergence (https://en.wikipedia.org/wiki/Convergent_evolution) between Australia and southern Africa, in

Having covered the above groups, I now turn to amphibians.

To make intercontinental comparison as rigorous as possible, I have chosen study areas carefully matched in climates, landforms and soils: Fitzgerald River National Park (https://en.wikipedia.org/wiki/Fitzgerald_River_National_Park) and its environs in Western Australia and Agulhas National Park (https://en.wikipedia.org/wiki/Agulhas_National_Park) and its environs in South Africa.

The results:

All the amphibians in the study areas are anurans.

In sharp contrast to vertebrate-eating birds, the faunas of amphibians in the study areas are so phylogenetically different that not even a single family is shared intercontinentally.

This means that any close similarity in the forms and functions of the anurans between the continents is likely to result from evolutionary convergence rather than ancestral recruitment of similar forms. Unrelated intercontinental counterparts have presumably been modified by natural selection to conform in their adaptations to similar environments.

However, the similarities to be found in these local faunas are minor. Once again it is the differences that seem important.

As in the mammals, snakes, and vertebrate-eating birds, the anurans are more differentiated in the southern African study area than in the Australian study area. This includes differentiation in body sizes.

Absent from the Australian study area are any counterparts to the following:

Absent from the southern African area are any counterparts to the following:

The anurans in the Australian study area are weakly defended against predation, even relative to their congeners in eastern Australia. For example, only one species in or near Fitzgerald River National Park is known to inflate its body when accosted, whereas this tactic is obvious in several genera in the southern African study area.

Perhaps the closest counterparts in the two study areas, showing considerable evolutionary convergence, are the limnodynastid Neobatrachus albipes (https://www.inaturalist.org/observations/26018363) in Australia and the pyxicephalid Tomopterna delalandii (https://www.inaturalist.org/observations/38250345 and https://thebdi.org/2022/02/21/cape-sand-frog-tomopterna-delalandii/ and http://frogmap.adu.org.za/Species_text.php?sp=1000) in South Africa. Both are small but stout frogs that breed in seasonal pools and shelter underground during the dry summer.

However, a certain pattern is far more noticeable in amphibians than in mammals, snakes or vertebrate-eating birds.

This is that potential counterparts do in some cases occur somewhere on these landmasses, but without precise correspondence in the physical environment (latitude, climate, and soil).

The clearest examples of this 'geographical displacement' in evolutionary convergence can be found in the remarkably speciose and heterogeneous pelodryadid genera Litoria (https://en.wikipedia.org/wiki/Litoria) and Ranoidea (https://en.wikipedia.org/wiki/Ranoidea_(genus)).

These examples are as follows:

The remarkable 'plasticity' in form and function of pelodryadids - which to this day continue to defy traditional taxonomy - indicates that any failure of adaptive matching in the study areas is hardly owing to phylogenetic constraints.

So, this is the important finding:

Lookalikes for several of the species in and near Agulhas National Park can be found, but not in or near Fitzgerald River National Park - or for that matter anywhere in the southwestern third of Australia. Instead they occur on the other side of Australia, under different climates.

This indicates that the failure of adaptive matching in the study areas is owing to subtle differences in the biotic environment (particularly the intensity of the predatory regime), rather than to any small differences remaining in the physical environment.

This seems to make sense in terms is the biogeography of islands.

The full suite of selective pressures associated with continents does not reach the southwestern tip of Australia. This is the most isolated part of an island continent because it is separated from eastern and northern Australia by semi-arid tracts, barring most predators. By contrast the full intensity of the African predatory regime extends uninterrupted all the way to the southwestern tip of South Africa.

The result is what seems to be a pattern of geographic displacement in evolutionary convergence.

For amphibians, the Australian study area - despite its close similarity in climate and soils to the southwestern tip of southern Africa - is effectively on an island as much as on a continent. This isolation is reflected in the nature of its anuran fauna, which has been shaped as much by its relative freedom from predation as by its latitude, climate, and soils.

A similar explanation applies, less cleary, to certain snakes I have discussed in previous Posts (see https://www.inaturalist.org/journal/milewski/62557-no-evolutionary-convergence-between-australia-and-southern-africa-in-snakes-and-legless-lizards-part-2#).

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FITZGERALD RIVER NATIONAL PARK and environs, WESTERN AUSTRALIA

Limnodynastidae:

Heleioporus albopunctatus https://www.inaturalist.org/taxa/22045-Heleioporus-albopunctatus and https://museum.wa.gov.au/explore/frogwatch/frogs/western-spotted-frog

Heleioporus eyrei female SV up to 6.3 cm https://www.inaturalist.org/taxa/22046-Heleioporus-eyrei

Heleioporus psammophilus https://www.inaturalist.org/taxa/22044-Heleioporus-psammophilus

Limnodynastes dorsalis female SV up to 8.7 cm https://www.inaturalist.org/taxa/22035-Limnodynastes-dorsalis

Neobatrachus albipes SV up to 4.5 cm https://www.inaturalist.org/taxa/22074-Neobatrachus-albipes

Neobatrachus pelobatoides female SV up to 4.5 cm https://www.inaturalist.org/taxa/22077-Neobatrachus-pelobatoides

Myobatrachidae:

Crinia georgiana female SV 3-3.6 cm https://www.inaturalist.org/taxa/25232-Crinia-georgiana

Crinia pseudinsignifera https://www.inaturalist.org/taxa/25236-Crinia-pseudinsignifera

Crinia subinsignifera https://www.inaturalist.org/taxa/25235-Crinia-subinsignifera

Metacrinia nichollsi https://www.inaturalist.org/taxa/25304-Metacrinia-nichollsi and see https://www.researchgate.net/publication/315304182_Evolutionary_and_natural_history_of_the_turtle_frog_Myobatrachus_gouldii_a_bizarre_myobatrachid_frog_in_the_southwestern_Australian_biodiversity_hotspot

Myobatrachus gouldii up to 5 cm https://www.researchgate.net/publication/315304182_Evolutionary_and_natural_history_of_the_turtle_frog_Myobatrachus_gouldii_a_bizarre_myobatrachid_frog_in_the_southwestern_Australian_biodiversity_hotspot and https://www.inaturalist.org/taxa/25298-Myobatrachus-gouldii

Pseudophryne guentheri 3 cm https://www.inaturalist.org/taxa/25254-Pseudophryne-guentheri

Pelodryadidae:

Litoria adelaidensis up to 4.7 cm https://www.inaturalist.org/taxa/23618-Litoria-adelaidensis

Ranoidea cyclorhynchus 5.5-7.5 cm https://www.inaturalist.org/taxa/517081-Ranoidea-cyclorhynchus

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AGULHAS NATIONAL PARK and environs, SOUTH AFRICA

Brevicepitidae:

Breviceps acutirostris marginal to study area on northwestern side https://www.inaturalist.org/taxa/25000-Breviceps-acutirostris

Breviceps montanus SV 3.8? cm https://www.inaturalist.org/taxa/24994-Breviceps-montanus

Breviceps rosei vansoni SV 2.6 cm https://www.inaturalist.org/taxa/24992-Breviceps-rosei

Bufonidae:

Sclerophrys capensis SV up to 12 cm https://www.inaturalist.org/taxa/517132-Sclerophrys-capensis

Sclerophrys pantherina female SV 12.2 cm https://www.inaturalist.org/taxa/517449-Sclerophrys-pantherina and https://zslpublications.onlinelibrary.wiley.com/doi/10.1111/j.1469-7998.1992.tb04431.x and https://neag.org.za/wp-content/uploads/10.2305_IUCN.UK_.2016-3.RLTS_.T54723A77159333.en_.pdf

Vandijkophrynus angusticeps SV 6.8 cm https://www.inaturalist.org/taxa/67258-Vandijkophrynus-angusticeps and https://www.tyroneping.co.za/amphibians-of-southern-africa/vandijkophrynus-angusticeps-cape-sand-toad/

Hyperoliidae:

Hyerolius horstockii SV 3.5 cm up to 4 cm https://www.inaturalist.org/taxa/23370-Hyperolius-horstockii

(Hyperolius marmoratus https://www.inaturalist.org/taxa/23331-Hyperolius-marmoratus)

Semnodactylus wealii https://www.inaturalist.org/taxa/23528-Semnodactylus-wealii

Pipidae:

Xenopus gilli https://www.inaturalist.org/taxa/25453-Xenopus-gilli

Xenopus laevis https://www.inaturalist.org/taxa/25457-Xenopus-laevis

Pyxicephalidae:

Amietia fuscigula SV 9.5 cm https://www.inaturalist.org/taxa/64912-Amietia-fuscigula

Arthroleptella villiersi SV 2.2 cm https://www.inaturalist.org/taxa/25325-Arthroleptella-villiersi

Cacosternum australis SV 1.9? cm https://www.inaturalist.org/taxa/476925-Cacosternum-australis

Microbatrachella capensis SV 1.5-1.8 cm and up to 2.0 cm https://www.inaturalist.org/taxa/25432-Microbatrachella-capensis and https://amphibiaweb.org/species/3734

Strongylopus bonaespei https://www.inaturalist.org/taxa/26212-Strongylopus-bonaespei

Strongylopus fasciatus SV 4.7 cm marginal to study area on eastern side https://www.inaturalist.org/taxa/26218-Strongylopus-fasciatus

Strongylopus grayii SV 4.2 cm https://www.inaturalist.org/taxa/26214-Strongylopus-grayii

Tomopterna delalandii SV 4.8 cm https://www.inaturalist.org/taxa/25806-Tomopterna-delalandii

Posted on March 07, 2022 12:11 by milewski milewski | 17 comments | Leave a comment

March 08, 2022

No evolutionary convergence in vertebrate-eating vertebrates between Australia and southern Africa

(writing in progress)

To make intercontinental comparison as rigorous as possible, I chose study areas carefully matched in climates, landforms and soils: Fitzgerald River National Park and its environs in Western Australia and Agulhas National Park and its environs in South Africa (see https://www.inaturalist.org/journal/milewski/62510-no-evolutionary-convergence-between-australia-and-southern-africa-in-snakes-and-legless-lizards-part-1#).

The following is my arrangement of intercontinental counterparts.

No counterpart in study area on other continent:

This category represents complete failure either to converge or to recruit suitable candidate.

present in southern African study area

Panthera pardus
Hyaena brunnea
Lycaon pictus
Vulpes chama
Felis libyca
Herpestes pulverulentus
Sagittarius serpentarius
Ardea melanocephala
Bubo capensis rare
Gyps coprotheres
Prosymna sundevalli
Dispholidus typus
Dasypeltis scabra

present in Australian study area

Lialis burtonis rare (diet similar to e.g. Lycophidion capense capense, but morphologically and behaviourally too different to be seen as counterparts)
Lophoictinia isura (closest counterpart is Polyboroides typus, which is too rare and too specialised)

Closely matched:

Tyto (same sp., alba, in both cases)
Circus spp.
Elanus
Aquila
Falco peregrinus (same sp.)

Approximately matched, but not enough to show convergence:

Dasyurus geoffroii vs Genetta tigrina
Accipiter spp.-complex
Haliastur sphenurus vs Buteo spp.
Pseudonaja affinis vs Naja nivea
Acanthophis antarctica and Echiopsis curta vs Bitis arietans and Bitis afra (viperids are far more specialised)
Elapognathus coronatus and Suta nigriceps vs Crotaphopeltis hotamboeia, Amplorhinus multimaculatus and Lycodonomorphus rufulus (latter rare) (Southern African forms more specialised)
Rhinoplocephalus bicolor vs Lamprophis fuscus
Notechis scutatus (certainly present) vs Hemachatus haemachatus (marginal)
Morelia imbricata vs Lycodonomorphus inornatus and Boaedon capensis

vs Homoroselaps lacteus

Still account for Suta gouldii and Lycodonomorphus inornatus

Would be matched if only the counterpart actually reached the study area:

Milvus migrans
?Hieraaetus pennatus
Aust hobby
Psammophis crucifer

Phylogenetically related but more ecologically different than in the case of Elanus, Aquila or Circus:
Falco spp.

No match because too generalised:
Falco berigora
Psammophylax rhombeatus

(writing in progress)

Posted on March 08, 2022 01:09 by milewski milewski | 0 comments | Leave a comment

No evolutionary convergence in the vertebrate-eating birds of Australia and southern Africa

@maxallen @karimhaddad @jamesjarrett00 @douglasriverside @camilojotage @mc1991 @fauna_maya @aguilita @ivanresendizcruz @ptexis @aplomadobirdy @luissilva4 @ececc @sambiology @psweet @mako252 @jimsinclair @hawksthree @birdwhisperer @jnelson @cliygh-and-mia @sitszasadam @kakariki14 @gumnut @johnnybirder @karoopixie @alexanderr @ratite @gposs @nyoni-pete @louisb @vicfazio3 @chuditch @hdavid @graham_winterflood @wildlife1607

I have shown, in previous Posts, that there is negligible evolutionary convergence (https://en.wikipedia.org/wiki/Convergent_evolution) between Australia and southern Africa, in:

The intercontinental differences are particularly great for vertebrate-eating mammals: one small dasyurid vs a whole guild of herpestid, viverrid, felid, canid, and hyenid species.

Interpreting these anomalies is complicated by the isolation of the island continent. It is hard to distinguish the poverty of the resources in nutrient-poor Australia from the coincidence of geographical isolation.

For example, all the indigenous, fully terrestrial, vertebrate-eating mammals throughout Australia - with the exception of one species of bat (https://en.wikipedia.org/wiki/Ghost_bat) - are marsupials; and an important family (Lamprophiidae, https://en.wikipedia.org/wiki/Lamprophiidae) of snakes is absent from Australia.

So it remains possible that the ultimate cause of the faunal anomalies is phylogenetic constraints, rather than differences in the non-biotic environments (climates and soils).

Volant birds can cross seas barring mammals, and they can survive shortages by moving around within a given landmass. And indeed it is the vertebrate-eating birds that have produced the avian species most naturally widespread on Earth: Falco peregrinus (https://en.wikipedia.org/wiki/Peregrine_falcon).

Therefore, the isolation of Australia - and the associated phylogenetic constraints - should be far less confounding for birds than for snakes or mammals.

Here, I compare the vertebrate-eating avifaunas of Australia and southern Africa, within the same framework as for the previous Posts.

To make intercontinental comparison as rigorous as possible, I have chosen study areas carefully matched in climates, landforms and soils: Fitzgerald River National Park (https://en.wikipedia.org/wiki/Fitzgerald_River_National_Park) and its environs in Western Australia and Agulhas National Park (https://en.wikipedia.org/wiki/Agulhas_National_Park) and its environs in South Africa.

I have restricted the avifaunal lists to species taking vertebrates as more than half of their diets, by volume. I.e. by 'vertebrate-eating' I mean 'eating mainly vertebrates'.

The results:

The vertebrate-eating birds show far greater correspondence between continents than do the vertebrate-eating mammals. In both study areas there are large eagles, small eagles, falcons/kestrels, kites, harriers, goshawks, and the same two families of owls - including a shared species, the barn owl. Furthermore, in most cases the intercontinental counterparts are congeneric.

Based on the overall relatedness of the two avifaunal lists, we would expect that any remaining incongruities would have been relatively easily corrected by natural selection. That is to say, this test of evolutionary convergence sets rather low standards compared to those performed on snakes and mammals.

Nonetheless, the remaining differences are so obvious that, once again, negligible evolutionary convergence is actually evident.

A parallel with my previous study of the snakes is that there is more differentiation in the avifauna of vertebrate-eating birds in the southern African than in the Australian study area.

The following, found in the southern African study area, have no counterparts in the Australian study area:

  • Sagittarius serpentarius, an eagle-like form specialised for terrestrial foraging,
  • Buteo buteo, which is migratory,
  • Ardea melanocephala, a specialised heron eating vertebrates including on dry land,
  • Bubo capensis, a large terrestrial owl, and
  • Gyps coprotheres, a large, specialised scavenger.

On the converse side:

The only species found in the Australian study area, with arguably no true counterparts in the southern African study area, are:

  • Lophoictinia isura, a kite associated with the canopy of patches of eucalypts, but otherwise similar to Milvus migrans and Polyboroides typus in the southern African study area, and
  • Falco berigora, a remarkably generalised falcon that can be interpreted as a diminutive counterpart to Buteo rufofuscus - and in any case belongs to a genus well-represented in both study areas.

A noticeable pattern is that Falco and strigid owls are diminutive in Australia relative to southern Africa, in the context of this focus on vertebrate-eating species.

The Australian study area has counterparts for both Falco biarmicus and Buteo rufofuscus, but at a fraction of the body mass: Falco longipennis and Falco cenchroides.

Ninox boobook is only half the body mass of Bubo africanus.

(The small-bodied species in the southern African study area, namely Falco rupicolus (https://www.inaturalist.org/taxa/472764-Falco-rupicolus) and Ciccaba woodfordi (https://www.inaturalist.org/taxa/19965-Strix-woodfordii#Habits_and_ecology), eat mainly invertebrates.)

An alternative way of interpreting the small-bodied species of Falco in the study areas is as follows:

On each landmass there are closely related kestrels and hobbies. These qualify as vertebrate-eating birds in the Australian study area, where larger-bodied members of the same guild are not competitive owing to limited quantity and reliability of prey. However, in the southern African study area - where Falco biarmicus and Buteo rufofuscus are indeed competitive - the small forms are either

However, the pattern is inconsistent because, in the case of Circus and to a slight degree Elanus, it is the southern African species that are the smaller-bodied ones.

Geographical isolation hardly explains the lack of certain vertebrate-eating vertebrates in Australia. This is best illustrated by

Milvus migrans is extremely widespread, extending to much of Australia (subspecies affinis, https://onlinelibrary.wiley.com/doi/full/10.1111/jav.02822).

This species penetrates to the southwestern tip of Africa but not to similar latitudes in southwestern Australia.- suggesting a difference in the productivity of prey. Is Fitzgerald River National Park and its environs too poor in various vertebrates to support more than a limited and rather generalised fauna of predators and scavengers?

In the case of Elanus, the southern African species (E. caeruleus) has actually reached Australia.

Elanus caeruleus occurs in southernmost New Guinea, separated from the island continent by only the narrow Torres Strait. Given that this water was broad dry land for most of the Pleistocene, E. caeruleus almost certainly occurred previously in at least northern Australia.

Hence the fact that a different species of Elanus occurs today in the Australian study area

  • can hardly be attributed to isolation, and
  • has little adaptive meaning given that, apart from the barn owl, the most precise matching of counterparts in this study is that in Elanus: lookalike species that seem virtually interchangeable.

In summary:

There is considerable correspondence between continents in the vertebrate-eating birds. However, this similarity has been achieved mainly by faunistic recruitment, rather than by evolutionary convergence in the sense of adaptive modification of the recruits.

The vertebrate-eating avifaunas in and near Fitzgerald River National Park in Western Australia, and Agulhas National Park in South Africa, are remarkably similar phylogenetically, at the level of family, genus and even species. However, the remaining differences in form and function - and phylogeny in the cases of heron, vulture and secretary bird - are as important as the similarities.

It remains unclear whether the evident shortfall in convergence here is owing to

  • residual differences in the environments - limiting the productivity and reliability of prey in Australia, or
  • a failure of the adaptive process, i.e. of evolutionary modification by natural selection.

—―—————-———-――――――――――
AUSTRALIA: species occurring in and near Fitzgerald River National Park

Accipitridae:

Accipiter cirrhocephalus female 218 grams https://www.inaturalist.org/taxa/5138-Accipiter-cirrocephalus

Accipiter fasciatus female 355 grams https://www.inaturalist.org/taxa/5114-Accipiter-fasciatus

Circus approximans female 870 grams https://www.inaturalist.org/taxa/5168-Circus-approximans

Circus assimilis female larger-bodied than southern African counterpart https://www.inaturalist.org/taxa/5175-Circus-assimilis

Elanus axillaris female 300 grams https://www.inaturalist.org/taxa/5276-Elanus-axillaris

Lophoictinia isura female 590-680 grams mean 635 grams https://www.inaturalist.org/taxa/5286-Lophoictinia-isura and https://www.birdlife.org.au/afo/index.php/afo/article/viewFile/927/906

Haliastur sphenurus female 750-1000 grams, or mean 830 grams https://www.inaturalist.org/taxa/5407-Haliastur-sphenurus

Falconidae:

Aquila audax female 3-5.8 kilograms https://www.inaturalist.org/taxa/5080-Aquila-audax

Falco berigora berigora female 520-840 grams, mean 681 grams https://www.inaturalist.org/taxa/4680-Falco-berigora and https://www.une.edu.au/__data/assets/pdf_file/0010/24211/mcdonald-et-al-2012.pdf and https://bioone.org/journals/Journal-of-Raptor-Research/volume-40/issue-3/0892-1016(2006)40[228:TBDODB]2.0.CO;2/THE-BREEDING-DIET-OF-DIFFERENT-BROWN-FALCON-span-classgenus-speciesFALCO/10.3356/0892-1016(2006)40[228:TBDODB]2.0.CO;2.full

Falco cenchroides cenchroides possibly qualifies as vertebrate-eating female 115-273 grams https://www.inaturalist.org/taxa/4681-Falco-cenchroides and https://absa.asn.au/wp-content/uploads/2017/05/V41_P27-31_FalconDiets_Tsang_v3.pdf

Falco longipennis longipennis female 290 grams https://www.inaturalist.org/taxa/4663-Falco-longipennis and https://search.informit.org/doi/10.3316/INFORMIT.604341808414911 and https://www.birdlife.org.au/afo/index.php/afo/article/viewFile/2176/2196

Falco peregrinus rare in study area female 0.7-1.5 kilograms https://www.inaturalist.org/taxa/4647-Falco-peregrinus and https://www.researchgate.net/publication/332040949_Diet_of_the_Peregrine_Falcon_Falco_peregrinus_in_inland_south-western_Australia

Hieraaetus morphnoides female about 825 grams https://www.inaturalist.org/taxa/5150-Hieraaetus-morphnoides

Strigidae:

Ninox boobook ocellata female 300 grams https://www.inaturalist.org/taxa/979816-Ninox-boobook

Tytonidae:

Tyto alba deliculata female ?600 grams https://www.inaturalist.org/taxa/20445-Tyto-alba

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SOUTHERN AFRICA: species occurring in and near Agulhas National Park

Accipitridae:

Accipiter tachiro female 279-510 grams https://www.inaturalist.org/taxa/204453-Accipiter-tachiro

Buteo buteo vulpinus migratory female 710-1180 grams https://www.inaturalist.org/taxa/204472-Buteo-buteo and https://sabap2.birdmap.africa/docs/sabap1/149.pdf

Buteo rufofuscus female 1150-1700 grams, mean 1530 grams https://www.inaturalist.org/taxa/5198-Buteo-rufofuscus

Circus maurus female 550 grams https://www.inaturalist.org/taxa/5174-Circus-maurus

Circus ranivorus female probably less than 500 grams, smaller-bodied than Australian counterpart https://www.inaturalist.org/taxa/5165-Circus-ranivorus

Elanus caeruleus caeruleus female 230 grams https://www.inaturalist.org/taxa/5275-Elanus-caeruleus and https://journals.co.za/doi/pdf/10.10520/AJA0012723X_2116 and file:///C:/Users/Antoni%20Milewski/Downloads/151413-Article%20Text-397314-1-10-20170210.pdf and file:///C:/Users/Antoni%20Milewski/Downloads/Mendelsohn_John_M_1982.pdf

Gyps coprotheres https://www.inaturalist.org/taxa/5365-Gyps-coprotheres

Milvus migrans parasitus rare in study area female 560 grams (or 592 grams in Australia) https://www.inaturalist.org/taxa/5268-Milvus-migrans

Polyboroides typus rare in study area https://www.inaturalist.org/taxa/5246-Polyboroides-typus and https://www.tandfonline.com/doi/abs/10.1080/00306525.1981.9633580

Ardeidae:

Ardea melanocephala https://www.inaturalist.org/taxa/4972-Ardea-melanocephala and https://www.degruyter.com/document/doi/10.2478/s11756-006-0037-5/html

Falconidae:

Aquila verreauxi rare in study area female 3-7 kilograms https://www.inaturalist.org/taxa/5077-Aquila-verreauxii

Falco biarmicus biarmicus female 850 grams https://www.inaturalist.org/taxa/4684-Falco-biarmicus

Falco peregrinus rare in study area female 0.7-1.5 kilograms https://www.inaturalist.org/taxa/4647-Falco-peregrinus

Hieraaetus pennatus rare in study area female 840-1025 grams https://www.inaturalist.org/taxa/5154-Hieraaetus-pennatus and https://sabap2.birdmap.africa/docs/sabap1/136.pdf

Polemaetus bellicosus rare in study area female about 4 kilograms https://www.inaturalist.org/taxa/5344-Polemaetus-bellicosus

Sagittariidae:

Sagittarius serpentarius 3.7-4.3 kilograms mean 4.0 kilograms https://www.inaturalist.org/taxa/117214-Sagittarius-serpentarius

Strigidae:

Bubo africanus 454-904 grams https://www.inaturalist.org/taxa/204470-Bubo-africanus

Bubo capensis rare in study area female 1240-1800 grams https://www.inaturalist.org/taxa/20095-Bubo-capensis and https://sabap2.birdmap.africa/docs/sabap1/400.pdf

Tytonidae:

Tyto alba affinis (large-bodied subspecies) female ?700 grams https://www.inaturalist.org/taxa/20445-Tyto-alba

Posted on March 08, 2022 03:49 by milewski milewski | 18 comments | Leave a comment

March 14, 2022

Birds in grasslands: a comparison of East Africa with North America

Grasslands are extensive in west-central North America, and far less extensive in East Africa. The climates in these areas are quite different, but the vegetation is similar.

How similar are the avifaunas of grasslands in North America vs East Africa?

Certain similarities, both phylogenetically and ecological, are obvious.

Several birds are closely related - down to the same genus in some cases. And approximate ecological analogues occur, as reflected by size, shape, microhabitat, foraging niche, and movement patterns.

Taxa shared are Accipitridae (e.g. Buteo, https://en.wikipedia.org/wiki/Buteo), Falconidae, Tytonidae, Strigidae, Gruidae, Columbidae, Caprimulgidae, Hirundinidae, Corvidae (e.g. Corvus), and Motacillidae (e.g. Anthus, https://en.wikipedia.org/wiki/Pipit).

Some sharing of families applies also to the birds entering the grassland only in association with trees and shrubs, e.g. Cuculidae, Picidae, Paridae, Turdidae, and Laniidae.

Phylogenetically unrelated birds that have evolved to have comparable ecological characters include:

  • Cathartidae with African vultures,
  • Tetraonidae with African Phasianidae/Pteroclidae/Otidae,
  • Icteridae (e.g. Sturnella) with African Motacillidae (e.g. Macronyx), and
  • Icteridae and Cardinalidae with African Ploceidae.

Among the birds associated with trees in grasslands are:

  • Tyrannidae vs African Muscicapidae,
  • Corvidae vs African Coraciidae, and
  • Trochilidae vs African Nectariniidae.

A further similarity is the way the bird community becomes poorer where trees and shrubs disappear from the grassland. Many birds are closely associated with stands of trees and shrubs irrespective of the presence of grass. The birds extending into treeless grassland are relatively few on both continents.

However, the differences seem more important than the similarities.

The avian community of treeless grassland is poorer in North America than in East Africa. This applies particularly to scavengers, large raptors, large terrestrial birds with mixed diets (e.g. Otidae of Africa), doves (Columbidae), walking insect-eaters (Alaudidae, Motacillidae, Turdidae), perching insect-eaters (e.g. Laniidae), and 'wrens' (e.g. see https://www.inaturalist.org/taxa/7596-Cistothorus-platensis and https://en.wikipedia.org/wiki/Cisticolidae).

The birds of North America are also more restricted seasonally in their occupation of grassland, and are progressively impoverished northwards - presumably a result of the increasingly cold and snowbound conditions at higher latitudes.

Guilds of birds associated with trees and shrubs on both continents extend into pure grassland in East Africa whereas they fail to do so in North America, especially in the northern parts of the North American grassland.

'Wrens', in particular, do not occur in treeless grassland in North America (see https://www.inaturalist.org/taxa/7596-Cistothorus-platensis), but are common in East Africa in the form of several species of Cisticola.

Starlings (Sturnidae) are common in woodlands and grasslands alike in East Africa, whereas in North America the birds most closely resembling starlings, drawn from e.g. Bombycillidae (https://en.wikipedia.org/wiki/Waxwing), and Icteridae (Euphagus https://en.wikipedia.org/wiki/Euphagus and grackles https://en.wikipedia.org/wiki/Grackle), barely enter treeless grasslands.

The same is true for widowbirds (types of Ploceidae) and their North American counterparts, viz certain Icteridae (blackbirds Agelaius https://en.wikipedia.org/wiki/Agelaius, and bobolinks https://en.wikipedia.org/wiki/Bobolink) and certain finch-like birds (https://www.inaturalist.org/observations?place_id=97394&taxon_id=9079&view=species).

The only birds of grasslands, commoner or represented by more species in North America than in East Africa, seem to be:

Posted on March 14, 2022 04:28 by milewski milewski | 0 comments | Leave a comment