The mystery of megafaunal microcamouflage

Everyone knows that giraffes and big cats are spotted, and zebras are striped.

And most would agree that these patterns function as camouflage in at least a loose sense.

However, how many have noticed that the disruptive markings in giraffes include spotting/striping too small-scale to make sense as camouflage?

The dark blotches/spots on the pelage of giraffes range in diameter from tens of centimetres to mere millimetres, despite the likelihood that both sizes will be viewed from similar distances by potential predators (https://www.istockphoto.com/photo/masai-giraffe-gm900610478-248476170 and https://www.istockphoto.com/photo/baby-masai-giraffe-stands-near-thorn-trees-gm1163986460-319800417).

Under which circumstances could it possibly be true that the tiny spots - which are visible only at close range - on the forehead, temples and/or crown help giraffes to hide?

Forehead of adult female Giraffa tippelskirchi:
https://www.istockphoto.com/photo/giraffe-in-kennya-on-safari-africa-gm1354464097-429280909
https://www.istockphoto.com/photo/giraffe-in-kennya-on-safari-africa-gm1354465295-429280938
https://www.agefotostock.com/age/en/details-photo/africa-african-animal-background-beautiful-big-brindled-brown-camouflage-close-up-culture-cute-ear-face-fun-funny-giraffa-giraffe-head/ZON-8453742
https://www.istockphoto.com/photo/curious-giraffe-portrait-on-the-savannah-gm1128231346-297651521
https://pixels.com/featured/close-up-of-a-maasai-giraffes-eyes-panoramic-images.html
https://www.shutterstock.com/nb/image-photo/wild-giraffe-close-head-shot-chewing-2037362243

Temples and crown of mature male Giraffa tippelskirchi:
https://www.istockphoto.com/photo/masai-giraffe-gm1310309401-399758914

Temples of adolescent male Giraffa tippelskirchi:
https://www.istockphoto.com/photo/masai-giraffe-gm467510293-34473716

Temples and crown of infant Giraffa tippelskirchi:
https://www.agefotostock.com/age/en/details-photo/close-up-of-a-masai-giraffe-giraffa-camelopardalis-tippelskirchi-also-known-as-the-maasai-giraffe-or-kilimanjaro-giraffe/X5T-2549599

Temples and crown of mature male Giraffa camelopardalis:
https://www.istockphoto.com/photo/giraffe-eating-grass-giraffe-head-green-trees-in-the-background-gm1339433342-419773508

Forehead of mature female Giraffa camelopardalis:
https://www.istockphoto.com/photo/contented-giraffe-gm115789869-4253424

Forehead and temples of Giraffa reticulata:
https://www.istockphoto.com/photo/a-reticulated-giraffe-gm805665456-130614787

In zebras, the striping on the forehead and temples is smaller-scale than that on the neck. However, the disparity is not as great and the fine-grained pattern is not as anatomically localised as in giraffes:
https://www.worldanimalfoundation.org/animal_encyclopedia/params/category/173341/item/994138/#gallery
https://www.alamy.com/stock-photo-close-up-side-view-of-zebra-face-147513723.html
https://www.alamy.com/african-animal-lion-zebra-wildebeest-elephant-calves-giraffe-birds-stars-sunset-sunrise-image241375085.html
https://www.alamy.com/african-animal-lion-zebra-wildebeest-elephant-calves-giraffe-birds-stars-sunset-sunrise-image241395544.html

In big cats there is no particular disparity, because the spots are all of the same order of magnitude:

Panthera onca:
https://image.shutterstock.com/shutterstock/photos/53686768/display_1500/stock-photo-close-up-portrait-of-jaguar-panthera-onca-53686768.jpg
https://www.jacadatravel.com/wp-content/uploads/2016/08/pantanal-jaguar-1024x576.jpg

Panthera pardus:
https://pxhere.com/en/photo/617310
https://s2.best-wallpaper.net/wallpaper/1280x1024/1209/Leopard-face-HD-close-up_1280x1024.jpgi

Panthera uncia:
https://i.ebayimg.com/images/i/400990455879-0-1/s-l1000.jpg
https://images.freeimages.com/images/large-previews/da0/close-up-of-snow-leopard-1243841.jpg

Panthera tigris:
https://www.australiazoo.com.au/wildlife/our-animals/sumatran-tiger/
https://image.freepik.com/free-photo/close-up-tiger-s-face_58995-594.jpg
https://thumbs.dreamstime.com/z/close-up-tiger-s-face-25875004.jpg

One possible explanation is that the micro-spotting on the heads of giraffes functions not for camouflage but for individual recognition. This is not necessarily undermined by the fact that most individuals lack spotting on the forehead (https://www.istockphoto.com/photo/giraffe-at-tarangire-national-park-tanzania-africa-gm619525138-108056915 and https://www.istockphoto.com/photo/giraffe-mikumi-national-park-tanzania-gm1177849689-328971616), temples and crown.

This explanation would be in line with the general tendency for antelopes to be most individually variable in their colouration on the face, particularly the forehead (e.g. https://kith.co/blog/fear-in-crisis/). However, it is undermined by the observations that gregariousness in giraffes tends to be promiscuous, bonds among individuals seem to be weak, and the form of the horns and horn-tufts would seem sufficient for individual recognition.

Posted by milewski milewski, November 25, 2021 22:41

Comments

Add a Comment

Sign In or Sign Up to add comments