Discovering an auricular semet in a kangaroo

Macropods (https://en.wikipedia.org/wiki/Macropodidae) vary greatly in the colouration of their ear pinnae, from plain (https://www.dreamstime.com/close-up-face-australian-kangaroo-australian-kangaroo-close-up-image110723140 and https://www.alamy.com/australia-western-australia-rottnest-island-close-up-of-quokka-setonix-brachyurus-image407731469.html and https://www.megapixl.com/quokka-with-baby-stock-photo-87442) to patterned (https://www.dreamstime.com/western-grey-kangaroo-macropus-fuliginosus-grazing-hiding-grass-deep-creek-south-australia-western-grey-kangaroo-macropus-image216721185 and https://fineartamerica.com/featured/western-grey-kangaroo-1600-stephen-reid.html and https://en.wikipedia.org/wiki/Western_grey_kangaroo#/media/File:Grey_Roo_with_Joey_SMC_2006.jpg).

Kangaroos, defined as the five species of macropods with the largest bodies, are generally plain in colouration. However, their ear pinnae have ambivalent patterns.

In this Post, I try for the first time to classify these patterns in terms of the dichotomy between camouflage-colouration on one hand, and small-scale conspicuous colouration for social signalling on the other.

In all kangaroos, the earlashes (see https://www.twenty20.com/photos/ig-272766529165172542_10102) are whitish, and noticeable at close quarters. However, at some distance the species vary between earlashes which could plausibly function as camouflage (https://www.dreamstime.com/eastern-grey-kangaroo-brisbane-queensland-australia-kangaroo-let-me-get-quite-close-didn-t-seem-too-bothered-me-just-kept-image124674030) and those which, by virtue of dark emphasis, could plausibly function as an auricular semet (https://www.dreamstime.com/stock-photo-western-grey-kangaroo-close-up-mountainside-along-backstairs-passage-deep-creek-conservation-park-fleurieu-image84117707).

Along similar lines, the back-of-ear of kangaroos, which is brought partly into view by turning the ears, is plain in certain species but differentiated into dark and pale in others (http://www.arthurgrosset.com/mammals/photos/macful41897.jpg and https://www.alamy.com/stock-photo-a-close-up-shot-of-the-head-and-shoulders-of-a-kangaroo-58978456.html).

Of the five species, only the western grey kangaroo (Macropus fuliginosus, https://en.wikipedia.org/wiki/Western_grey_kangaroo) combines relatively conspicuous earlashes with a relatively conspicuous back-of-ear. The pattern in this species is certainly conspicuous enough to qualify as an auricular semet: https://www.dreamstime.com/stock-image-kangaroo-image19861361 and https://www.dreamstime.com/western-grey-kangaroo-resting-some-grass-stubble-western-grey-kangaroo-image145350377 and https://www.dreamstime.com/kangaroo-island-kangaroo-eating-hay-kangaroo-island-kangaroo-looking-over-its-shoulder-image175272279 and https://www.dreamstime.com/portrait-young-cute-australian-kangaroo-standing-field-waiting-portrait-young-cute-australian-kangaroo-standing-image139403458 and https://www.dreamstime.com/two-cute-australian-kangaroo-standing-field-waiting-two-cute-australian-kangaroo-standing-field-image139403587 and https://www.dreamstime.com/portrait-young-cute-australian-kangaroo-standing-field-waiting-joey-image139403370.

Presumably, the function of an auricular semet in the western grey kangaroo is to facilitate the monitoring of companions in this somewhat gregarious species. However, this raises a question for a future Post: why is it that the closely-related eastern grey kangaroo (Macropus giganteus) has a pattern probably too faint to qualify as an auricular semet?

Macropus giganteus

https://www.dreamstime.com/male-kangaroo-portrait-close-up-australian-wildlife-male-kangaroo-portrait-bush-australian-marsupial-wildlife-image215924572
https://www.istockphoto.com/photo/kangaroo-close-up-gm94025073-11210235
https://www.canstockphoto.com/kangaroo-up-close-0739304.html
https://es.123rf.com/photo_1150862_kangaroo-close-up.html
https://www.dreamstime.com/joey-young-kangaroo-portrait-close-up-australian-wildlife-joey-young-kangaroo-portrait-australian-marsupial-wildlife-image215925302
https://www.twenty20.com/photos/5777479a-229e-4496-9e09-73419962bee3
https://www.dreamstime.com/close-up-australian-kangaroo-against-background-sand-beach-sunrise-close-up-australian-kangaroo-image117548937
https://www.dreamstime.com/stock-photo-kangaroo-resting-up-grasslands-australian-outback-young-kangaroo-resting-close-up-australian-wildlife-australia-image81647860
https://www.dreamstime.com/close-up-australian-kangaroo-face-image110723062
https://www.dreamstime.com/royalty-free-stock-photos-beautiful-kangooro-australia-close-up-head-kangaroo-image35226858

Macropus fuliginosus

https://www.dreamstime.com/stock-photo-close-up-young-kangaroo-wildlife-image60746879
https://www.dreamstime.com/stock-photo-kangaroo-lovely-australian-up-close-image54746870
https://www.dreamstime.com/royalty-free-stock-photos-kangaroo-portrait-image2322248
https://www.dreamstime.com/royalty-free-stock-photography-australian-kangaroo-image1783707
https://www.dreamstime.com/portrait-young-cute-australian-kangaroo-big-bright-brown-eyes-looking-close-up-camera-portrait-young-cute-australian-image139051408
https://www.sciencephoto.com/media/384499/view/western-grey-kangaroo
http://www.birdway.com.au/macropodidae/western_grey_kangaroo/source/westerngrey_kangaroo_38550.php
https://www.dreamstime.com/close-uo-kangaroo-island-kangaroo-portrait-kangaroo-island-kangaroo-image175916539
https://www.dreamstime.com/portrait-young-cute-australian-kangaroo-big-bright-brown-eyes-looking-close-up-camera-portrait-young-cute-australian-image139051481
https://www.dreamstime.com/portrait-young-cute-australian-kangaroo-big-bright-brown-eyes-looking-close-up-camera-australia-image139050157
https://www.dreamstime.com/close-up-portrait-western-grey-kangaroo-wild-picture-its-right-side-yanchep-national-park-australia-wa-image193425978
https://www.dreamstime.com/close-up-powerful-kangaroo-top-half-image140481299
https://www.dreamstime.com/close-up-kangaroo-island-kangaroo-kangaroo-island-kangaroo-image100099307
https://www.dreamstime.com/western-grey-kangaroo-standing-its-hind-legs-male-image182903078
https://www.dreamstime.com/western-grey-kangaroo-macropus-fuliginosus-melanops-mainland-western-grey-kangaroo-macropus-fuliginosus-melanops-also-known-as-image103309237
https://www.dreamstime.com/kangaroo-island-joey-begging-food-image100099317
https://www.dreamstime.com/kangaroo-marsupial-family-macropodidae-macropods-meaning-large-foot-western-gray-eating-hand-image107071113

Osphranter robustus

https://www.inaturalist.org/observations/65800211
https://www.inaturalist.org/observations/84058357
https://www.inaturalist.org/observations/90517070
https://www.inaturalist.org/observations/66857109
https://www.inaturalist.org/photos/8362359
https://www.inaturalist.org/photos/94936327
https://www.inaturalist.org/observations/91494096
https://www.alamy.com/stock-photo-beautiful-wallaroo-euro-macropus-robustus-among-green-grass-staring-89301398.html
https://www.dreamstime.com/stock-photo-kangaroo-australia-outback-image65764183
https://www.alamy.com/stock-photo-beautiful-wallaroo-euro-macropus-robustus-among-green-shrubs-turning-89301412.html
https://www.flickr.com/photos/graham_by_the_sea/3677337194/
https://www.agefotostock.com/age/en/details-photo/common-wallaroo-or-euro-macropus-robustus-male-western-australia/AAM-AAES01506
https://www.naturepl.com/stock-photo-euro-common-wallaroo-macropus-robustus-grazing-cape-range-national-image01227379.html
https://worldfoto.photoshelter.com/image/I0000j5zxBy9ADEM

Osphranter antilopinus

https://www.inaturalist.org/observations/69094515
https://www.inaturalist.org/observations/67219606
https://www.inaturalist.org/observations/46799796
https://www.inaturalist.org/observations/7702299
https://timgrahamstock.photoshelter.com/image/I0000PSmBntcRkLc
https://www.sciencesource.com/archive/Image/Antilopine-Kangaroo-SS2298700.html
https://www.zoochat.com/community/media/antilopine-wallaroo-macropus-antilopinus.408547/
https://www.naturepl.com/stock-photo-antelopine-wallaroo-macropus-antilopinus-australia-captive-image01477042.html
https://www.gettyimages.co.nz/detail/news-photo/antilopine-kangaroo-antilopine-wallaroo-or-the-antilopine-news-photo/492756579
https://commons.wikimedia.org/wiki/File:Macropus_antilopinus_1.jpg
https://www.flickr.com/photos/centralaustralia/2296280726
http://www.oceanwideimages.com/Large-Image.asp?pID=9839&cID=444&rp=species%252Easp%253Fs%253DMacropus%2Bantilopinus%2526p%253D1
http://www.oceanwideimages.com/Large-Image.asp?pID=15070&cID=444&rp=species%252Easp%253Fs%253DMacropus%2Bantilopinus%2526p%253D1

Osphranter rufus

https://www.dreamstime.com/kangaroo-close-up-face-image113887795
https://theoallofs.photoshelter.com/image/I0000TgnYnvW0ZvY
https://www.alamy.com/stock-photo-red-kangaroo-portrait-18441991.html
https://www.dreamstime.com/royalty-free-stock-photo-cute-portrait-kangaroo-close-up-red-macropus-rufus-image36513575
https://www.dreamstime.com/portrait-australian-kangaroo-big-bright-brown-eyes-looking-close-up-camera-looks-like-boss-australia-image139618268
https://www.dreamstime.com/close-up-red-kangaroo-red-kangaroo-image126276196
https://www.dreamstime.com/stock-photo-close-up-brown-kangaroo-male-australian-sitting-ground-image49390554
https://www.dreamstime.com/kangaroo-green-grass-image157073456
https://www.dreamstime.com/stock-photos-kangaroo-portrait-image1839673
https://www.dreamstime.com/stock-photo-young-kangaroo-joey-portrait-young-kangaroo-joey-up-close-personal-sharp-detail-image92974756

פורסם על-ידי milewski milewski, ספטמבר 13, 2021 08:40 אחה"צ

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