Similarities/differences between the porcupines of different Hemispheres: Erethizon vs Hystrix, part 3

continued from https://www.inaturalist.org/journal/milewski/65187-similarities-differences-between-the-porcupines-of-different-hemispheres-erethizon-vs-hystrix-part-2#

HABITAT

The latitudinal ranges of the two genera overlap at 28-41 degrees N.

This means that the southern part of the distribution of Erethizon, in northern Mexico and many states of the USA, is at similar latitudes to

  • the northern part of the distribution of Hystrix indica in e.g. Turkey, Iran, Afghanistan, Azerbaijan, Turkmenistan, and Kyrgyzstan, and
  • the southern part of the distribution of Hystrix africaeaustralis in most of South Africa.

Furthermore, both genera occur in a wide range of ecosystems from semi-desert (e.g. Erethizon in Nevada, https://www.birdandhike.com/Wildlife/Mamm/06Rod/09_Ereth/Erethi_dor/_Ere_dor.htm and https://www.fs.fed.us/psw/publications/zielinski/psw_2017_zielinski002_appel.pdf) to forest (e.g. Hystrix in Borneo, https://www.alamy.com/malayan-porcupine-hystrix-brachyura-acanthion-brachyura-walking-indonesia-image8113983.html and https://www.inaturalist.org/guide_taxa/178762).

However, the habitat of Erethizon is partly subarctic, whereas that of Hystrix is mainly tropical and subtropical.

In their zone of latitudinal overlap, Erethizon depends on woody vegetation (https://www.inaturalist.org/observations/13334310 and https://www.alamy.com/stock-photo-a-north-american-porcupine-walks-up-a-sand-dune-in-the-desert-177548000.html), whereas Hystrix does not (e.g. https://www.inaturalist.org/observations/104564486 and https://www.inaturalist.org/observations/103038302).

REPRODUCTION

Both Erethizon and Hystrix are long-lived in captivity (maximum lifespan 30 vs 28 years). However, the natural lifespan of Erethizon is effectively limited by the wear of its cheek-teeth to less than 10 years.

Both genera reproduce slowly, with usually one offspring per birth and per year. In both Erethizon and Hystrix, the newborns are precocial, with open eyes and some spines already formed.

However, Hystrix is more fecund than Erethizon. The former bears up to four offspring per birth and can breed twice per year (https://www.nature.com/articles/s41598-021-99819-3). Gestation is far shorter in Hystrix (90-112 days) than in Erethizon (205-217 days).

The extreme gestation of Erethizon
(https://www.degruyter.com/document/doi/10.1515/mamm.2001.65.1.73/html and https://www.jstor.org/stable/1375243) seems related to the extreme seasonality in the quality of its diet.

It is consistent with the extended gestation in Erethizon that the weight of the newborn relative to the mother (about 7%) exceeds that in Hystrix - even if the single neonate of the former is compared with a collective litter of two in the latter.

Unlike Erethizon and most other mammals, Hystrix tends to be monogamous (https://www.tandfonline.com/doi/pdf/10.1080/11250009709356189 and https://www.researchgate.net/publication/355180627_Reproductive_behaviour_in_free-ranging_crested_porcupine_Hystrix_cristata_L_1758 and https://www.degruyter.com/document/doi/10.1515/mamm.1991.55.2.187/html and https://www.sciencedirect.com/science/article/abs/pii/0018506X85900376), with paternal as well as maternal care.

FORAGING AND DIGESTION

Both Erethizon and Hystrix are basically terrestrial, which is unsurprising for such large-bodied rodents. However, they deviate from this in opposite ways. Erethizon is partly arboreal (https://www.dreamstime.com/porcupine-tree-close-up-portrait-deag-branch-image186080332) and seldom digs for food, whereas Hystrix cannot climb and is partly fossorial (https://en.wikipedia.org/wiki/Fossorial).

Both genera eat a wide variety of mainly plant matter, from cambium to fruits and roots. However, Erethizon depends mainly on woody plants and (particularly in winter, https://academic.oup.com/jmammal/article/92/3/601/867307?login=false and https://pubmed.ncbi.nlm.nih.gov/20306197/) foliage for its staples, whereas Hystrix depends mainly on herbaceous plants (particularly tubers such as bulbs and corms) and does not eat fibrous foliage.

Both genera have an enlarged caecum in which fermentation occurs (http://www.jafs.com.pl/Digestive-physiology-resting-metabolism-and-methane-production-of-captive-Indian,102741,0,2.html), and neither is caecotrophic or coprophagous. Their feces are similar (Erethizon https://www.inaturalist.org/observations/113658290 and Hystrix https://www.inaturalist.org/observations/93737688).

Digestion is extremely efficient in Erethizon despite:

Both genera supplement their mineral nutrients by gnawing bones (https://www.istockphoto.com/photo/north-american-porcupine-erethizon-dorsatum-in-the-snow-near-haines-alaska-gm1266698735-371403945 and https://www.istockphoto.com/photo/porcupine-on-snow-with-moose-antler-and-birch-tree-in-winter-gm682855252-125266463 and https://www.yumpu.com/en/document/read/28237877/nutrition-of-the-north-american-porcupine-erethizon- and https://www.nature.com/articles/s41598-020-69252-z). Erethizon is well-known to seek out inorganic sources of sodium, which seems necessary owing to a seasonal excess of potassium to which Hystrix is not subject.

Both Erethizon and Hystrix hold food with their fore feet while eating.

However, a difference is that Erethizon, like most rodents, sits while doing so (https://www.istockphoto.com/photo/porcupine-gm490640318-75310819 and https://www.istockphoto.com/photo/north-american-porcupine-also-known-as-canadian-porcupine-or-common-porcupine-is-a-gm1391478903-448081294), whereas Hystrix keeps the forelegs on the ground (https://www.youtube.com/watch?v=8Q3TiLfH504 and https://www.alamy.com/porcupine-the-prickliest-of-rodents-though-its-latin-name-means-quill-pig-image179580322.html).

The lack of a sitting or squatting posture in Hystrix is possibly owing to the obstruction by long spines on the rump.

SOCIAL BEHAVIOUR

Erethizon shows minimal social behaviour. By contrast, Hystrix is not only monogamous but also somewhat gregarious in its underground refuges (https://animaldiversity.org/accounts/Hystrix_cristata/ and https://rep.bioscientifica.com/configurable/content/journals$002frep$002f92$002f1$002fjrf_92_1_004.xml?t:ac=journals%24002frep%24002f92%24002f1%24002fjrf_92_1_004.xml).

Both genera tend to be noisy in normal activity. Erethizon is by far the more vocal (e.g. https://www.inaturalist.org/observations/16521684 and https://www.inaturalist.org/observations/48843732 and https://www.inaturalist.org/observations/42157159). However, Hystrix snuffles loudly, and sometimes grunts, during foraging.

In most species of mammals, male offspring are more likely than female offspring to move far from the parental location. Erethizon is unusual in that it is the females that leave (https://sites.warnercnr.colostate.edu/wp-content/uploads/sites/30/2017/11/1998-Sweitzer-Berger-evidence_for_femalebiased_dispersal_in_north_american_porcupines_erethizon_dorsatum.pdf and https://www.jstor.org/stable/41717257).

to be continued...

Posted by milewski milewski, May 05, 2022 04:40

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