Adaptive colouration in the largest living cervid, the moose (Alces alces)

@muir @matthewinabinett @aguilita @tonyrebelo @jeremygilmore @beartracker @nyoni-pete @oviscanadensis_connerties @tandala @capracornelius @paradoxornithidae @wjcrins @hereinthewild @bluewhalenowhead @marshall20 @nat_zouieva @marina_gorbunova @simontonge

At first sight, Alces alces seems nondescript in colouration (https://www.inaturalist.org/observations/19029155 and https://www.inaturalist.org/observations/4336204).

Valerius Geist, on pages 229-232 in Grzimek's Animal Life Encyclopedia (https://en.wikipedia.org/wiki/Grzimek%27s_Animal_Life_Encyclopedia), exaggerates somewhat when he states:
"European moose are dark brown with white legs, and American moose are black with a light saddle patch on the back, light-brown legs, and facial markings that vary between the sexes. In the female the face and nose are red-brown, while the bull has a black nose".

The following verify that the face tends to be paler than the neck and torso, in females of A. alces in North America (https://www.inaturalist.org/observations/178372818 and https://www.dreamstime.com/bull-moose-water-image259482733 and https://www.inaturalist.org/observations/8288949) and to some degree also in Europe (https://www.inaturalist.org/observations/175016790 and https://www.inaturalist.org/observations/174910182).

However, the difference in tone between the face and the rest of the figure is noticeable only in A. a. americana (see details in comment below, titled FACIAL FLAG IN ALCES ALCES AMERICANA).

Sexual differences in the colouration of the pelage of A. alces, beyond the face, are remarkably limited (https://www.inaturalist.org/observations/42138516 and https://www.youtube.com/watch?v=bujmogxgtp4 and https://www.youtube.com/watch?v=tsZUaGIt-r8 and https://www.google.com.au/search?q=Moose+mating&sca_esv=567242663&sxsrf=AM9HkKnsy5ar25NAM_QxNryBAc4ELWtrPA%3A1695294882706&source=hp&ei=oiUMZd3UJtixoATxmJzQAg&iflsig=AO6bgOgAAAAAZQwzssn9atv3I45ihgDieVv4Z3QxBVPr&ved=0ahUKEwjdrZPKybuBAxXYGIgKHXEMByoQ4dUDCAs&uact=5&oq=Moose+mating&gs_lp=Egdnd3Mtd2l6IgxNb29zZSBtYXRpbmcyBRAuGIAEMgUQABiABDIFEAAYgAQyBRAAGIAEMgUQABiABDIFEAAYgAQyBRAAGIAEMgUQABiABDIFEAAYgARImklQzg5Y-j5wAXgAkAEAmAGuA6AB_BiqAQkwLjEuOS4xLjG4AQPIAQD4AQGoAgrCAgcQIxjqAhgnwgIEECMYJ8ICCxAAGIAEGLEDGIMBwgIREC4YgAQYsQMYgwEYxwEY0QPCAgsQLhiDARixAxiABMICCxAAGIoFGLEDGIMBwgIHECMYigUYJ8ICCBAuGIoFGJECwgIIEAAYgAQYsQPCAggQABiKBRiRAsICCxAuGIoFGLEDGJECwgILEC4YgAQYxwEYrwE&sclient=gws-wiz#fpstate=ive&vld=cid:25246631,vid:YvNAJLygu9w,st:0). Even in the case of the face, males retain the female colouration as long as the antlers are still in velvet (https://www.daveshowalter.com/photo/bull-moose-portrait/).

Infants, although noticeably paler than adults, have colouration so plain that it, too, is nondescript (https://www.inaturalist.org/observations/4097272).

Seasonal changes in colouration are limited. There is a single annual molt (https://www.inaturalist.org/observations/108839229 and https://www.inaturalist.org/observations/125310240 and https://www.inaturalist.org/observations/22740621 and https://www.inaturalist.org/observations/20313689) in spring/early summer. The pelage, after being worn and weathered for a year, fades somewhat (https://www.inaturalist.org/observations/8449050).

However, the pelage remains dark enough in winter to be conspicuous against snowy backgrounds, even at distance (https://www.inaturalist.org/observations/148799385 and https://www.inaturalist.org/observations/135953868).

Despite the initial nondescript impression, my close scrutiny has revealed several noteworthy patterns of colouration, which deserve names, in A alces.

For example, the following shows a fibular flag, anterior auricular semet, and buccal semet in an adolescent female individual in the spring season, in Alces alces gigas: https://www.inaturalist.org/observations/163382249.

Although these features are subtle, individually variable, and perhaps seasonally variable, most of them occur in most of the nine subspecies.

CORNUAL FLAG

The antlers of A. alces, borne seasonally by males, tend to be conspicuously pale on the upper (dorsal) surface, in the subspecies with the largest antlers (https://unsplash.com/photos/Du8sGaNHVMc).

The cornual flag is derived essentially from the natural paleness of dry bone (https://www.inaturalist.org/observations/127384241).

However, in A. a. gigas and presumably A. a. buturlini,

• the antlers are paler than those of other cervids,
• the palmate surface of the antlers is far larger than in other cervids (https://www.cbc.ca/news/canada/north/possible-world-record-size-moose-shot-in-yukon-1.2075442), and
• the paleness of the antlers contrasts with the darkness of the rest of the figure.

This makes the antlers conspicuous, even at distance (https://www.inaturalist.org/observations/4612251).

The cornual flag in A. gigas

• is apparent mainly in autumn (https://www.josephfiler.com/photo/moose-alaska-2833/ and https://create.vista.com/unlimited/stock-photos/313125682/stock-photo-alaska-yukon-bull-moose-autumn-denali-national-park-alaska/), and
• hypothetically functions intraspecifically, aiding sexual attraction, male advertisement, and masculine rivalry.

Cornual flag in Alces alces gigas:
https://www.inaturalist.org/observations/183421987
https://www.mediastorehouse.com/nature-picture-library/danny-green/moose-bull-alces-alces-walking-forest-clearing-15316906.html
https://www.inaturalist.org/observations/183421709
https://www.inaturalist.org/observations/458438
https://create.vista.com/unlimited/stock-photos/314205726/stock-photo-alaska-yukon-bull-moose-autumn/
scroll in https://www.akwildlife.org/news/wildlife-contest-2022

Cornual flag in Alces alces andersoni:
https://www.inaturalist.org/observations/61216754
https://www.mediastorehouse.com.au/design-pics/animals/bull-moose-peter-lougheed-provincial-park-18135905.html

Possible cornual flag in Alces alces shirasi:
https://www.inaturalist.org/observations/147438040
https://www.gettyimages.com.au/detail/news-photo/bull-moose-stands-on-bunn-trail-near-the-gunflint-trail-news-photo/55992779?adppopup=true and https://www.gettyimages.com.au/detail/news-photo/bull-moose-walks-on-bunn-trail-near-the-gunflint-trail-news-photo/55992785?adppopup=true

Possible cornual flag in Alces alces americana:
https://www.inaturalist.org/observations/76513586
https://visitsunsetcountry.com/hunting/moose

Incipient cornual flag in Alces alces alces:
https://www.mediastorehouse.com.au/nature-picture-library/2009-highlights/moose-alces-alces-taiga-woodland-15260457.html

FIBULAR FLAG

https://www.inaturalist.org/observations/8660028
https://www.gettyimages.com.au/detail/news-photo/november-2020-saxony-moritzburg-last-week-thursday-the-500-news-photo/1229586037?adppopup=true
https://www.behance.net/gallery/99847037/Bull-Moose-Bearspaw-Alberta?tracking_source=search_projects_recommended|Bull+Moose
https://www.closertothewild.com/gallery/p/style-01-slgxj-738cj-bnn5s-3e26g-rewyc-36zgb
https://www.shutterstock.com/image-photo/winter-sunny-day-young-moose-cow-2125295291
https://www.dreamstime.com/stock-photography-bull-moose-image21621952
https://www.dreamstime.com/wet-cow-moose-standing-forest-image183436539
https://www.inaturalist.org/observations/139111514
https://www.inaturalist.org/observations/61913264
https://www.inaturalist.org/observations/134851345
https://www.alamy.com/moose-in-jasper-canada-image348236851.html?imageid=D433EBFE-8D95-490C-BEAE-57C59F4AD201&p=466062&pn=5&searchId=59e69530b8d11356f2f4edcf3f5ed079&searchtype=0
https://www.alamy.com/young-elk-age-about-one-year-male-on-the-edge-of-the-spring-forest-image259781936.html?imageid=A982D41F-5A22-489F-99A6-9C17CFE32440&p=270423&pn=7&searchId=17a6b40e8c8fbef3da4fa2fc3209a279&searchtype=0
https://www.inaturalist.org/observations/35513964
https://www.inaturalist.org/observations/137101323
https://www.alamy.com/stock-photo-bull-moose-in-sweden-147415246.html?imageid=EE970C0F-EFDB-4D8A-94DA-986ACC0035E4&p=141390&pn=1&searchId=773e4e372ef4503cec1f3e748077968c&searchtype=0

Please see https://www.inaturalist.org/journal/milewski/84573-a-new-feature-of-adaptive-colouration-in-ungulates-the-fibular-flag-part-2-alces-alces-cervidae#

The fibular flag is best-developed in the nominate subspecies, A. a. alces, of Europe and western Russia, in which it tends to extend to the inner surface of the buttock (https://www.inaturalist.org/observations/149814632) and/or the hock.

The role of sheen deserves investigation.

The following shows the extreme development of the pale pelage in A. alces, in which it encompasses most of the hindleg (https://www.inaturalist.org/observations/112176729).

PEDAL FLAG

A case can be made that A. alces possesses a pedal flag, in some individuals. This applies particularly to the nominate A. a. alces (https://www.inaturalist.org/observations/142224245 and https://www.inaturalist.org/observations/142020077).

This pedal flag consists of conspicuous pale on the hocks and carpals (particularly on the posterior surface of the carpals), extending to varying extent down the lower limbs towards the hooves, and connected to the fibular flag where the latter is present (https://www.alamy.com/stock-photo-bull-moose-crossing-the-road-denali-national-park-alaska-usa-29001311.html?imageid=984BF44C-2D52-4F90-BF1B-9372BC0185A4&p=29229&pn=1&searchId=acbc6be48e9684687a1dabcb59018a60&searchtype=0).

The fetlocks and pasterns themselves are not whitish (https://www.gettyimages.com.au/detail/news-photo/december-2022-sweden-%C3%B6ster-malma-a-bull-moose-stands-in-the-news-photo/1246124150?adppopup=true and https://www.gettyimages.com.au/detail/news-photo/december-2022-sweden-%C3%B6ster-malma-a-bull-moose-stands-in-the-news-photo/1246124213?adppopup=true and https://www.shutterstock.com/image-photo/front-split-hoofs-moose-standing-on-727556374 and https://www.inaturalist.org/observations/134620144 and https://www.inaturalist.org/observations/35655176 and https://www.inaturalist.org/observations/55865091), except in some individuals of the nominate A. a. alces (https://www.mostphotos.com/en-us/25919107/moose-or-european-elk-alces-alces-hooves).

A factor undermining the validity of a pedal flag in A. alces is that, for much of the year, the pale on the legs is inconspicuous against a background of snow (https://www.inaturalist.org/observations/42170238 and https://www.inaturalist.org/observations/143176855).

https://www.inaturalist.org/observations/51436631
https://www.inaturalist.org/observations/33064841
https://www.dreamstime.com/large-brown-black-bull-moose-standing-park-image193883277
https://www.dreamstime.com/stock-photo-moose-bull-elk-standing-road-image66248282

To the degree that the pedal flag is valid in A. alces, it is linked to, and subsidiary to, the fibular flag (https://www.inaturalist.org/observations/142257592). In A. a. alces, the joint pattern can perhaps be called a pedofibular flag.

ANTERIOR AURICULAR SEMET

Please see https://www.inaturalist.org/journal/milewski/55694-ten-best-illustrations-of-auricular-semets-in-deer#

One of the most consistent patterns of colouration in A. alces is a small-scale dark/pale contrast on the anterior base of the ear pinna (https://www.dreamstime.com/stock-photo-moose-north-america-elk-europe-alces-alces-largest-extant-species-deer-family-moose-distinguished-image50713041).

The location of this pattern is such that it accentuates the movements of the ears, in vigilance and emotional expression. Such accentuation is hypothetically adaptive in social (intraspecific) interactions, and may additionally function in anti-predator, defensive displays.

Several other genera of cervids possess auricular semets. However, that of A. alces is restricted to the anterior surface, and has its own particular configuration.

The following show the anterior auricular semet in various subspecies of A. alces:

A. a. alces:
https://www.inaturalist.org/observations/122347911
https://www.inaturalist.org/observations/119099452

A. a. americana:
https://www.inaturalist.org/observations/183781173
https://www.inaturalist.org/observations/165912205
https://www.inaturalist.org/observations/82792870

A. a. gigas:
https://www.inaturalist.org/observations/172965903
https://www.inaturalist.org/observations/15093287

A. a. andersoni:
https://www.inaturalist.org/observations/170210903
https://www.inaturalist.org/observations/166029819

A. a. shirasi:
https://www.inaturalist.org/observations/174251418

In Alces alces, unlike another large cervid partly sympatric with it, the auricular semet does not disappear in mature males (see https://colombia.inaturalist.org/journal/milewski/69281-intriguing-new-sexual-dimorphism-in-the-wapiti).

The following show that the anterior auricular semet, although absent in newborns, develops before the infantile colouration is lost, and before the muzzle develops:
https://www.inaturalist.org/observations/133091834
https://www.dreamstime.com/stock-photo-small-moose-few-days-standing-woods-next-to-pine-tree-image53403214.

BUCCAL SEMET

The peculiar muzzle of A. alces is so distracting that the colouration around the mouth may go unnoticed. Furthermore, this colouration is subtle and individually variable.

However, there tends to be a pattern in which the broadly dark lower lip is offset by pale ventral to the gape. The clearest illustration is https://www.inaturalist.org/observations/65908659.

The following are additional illustrations:
https://www.inaturalist.org/observations/152098783 and https://www.inaturalist.org/observations/148835598 and https://www.inaturalist.org/observations/13505171 and https://www.dreamstime.com/stock-photo-moose-eating-green-grass-near-water-grand-tetons-national-park-image50021650 and scroll to second photo in https://journals.openedition.org/paleo/5126 and https://www.inaturalist.org/observations/157638267 and https://www.inaturalist.org/observations/120152994 and https://www.inaturalist.org/observations/37290353 and https://www.inaturalist.org/observations/65278592 and https://www.inaturalist.org/observations/56223948 and https://www.inaturalist.org/observations/162881182.

This pattern of colouration hypothetically accentuates the chewing movements (https://www.inaturalist.org/observations/88438853). This hypothetically aids vigilance during rumination, when two or more adult/adolescent individuals rest within sight of each other (https://www.dreamstime.com/stock-photos-moose-image20463023).

Buccal semet in Alces alces buturlini:
https://www.alamy.com/female-moose-alces-alces-in-profile-kronotsky-zapovednik-nature-reserve-kamchatka-peninsula-russian-far-east-december-image263189582.html?imageid=8337E994-E81B-42C7-9D06-32050AEFBBE0&p=216449&pn=1&searchId=693543c6c0b82d61e979d27d23f7d17f&searchtype=0

Buccal semet in Alces alces gigas:
https://www.inaturalist.org/observations/153275621
https://www.inaturalist.org/observations/2646616
https://www.inaturalist.org/observations/13172080

Variation in this feature deserves further investigation. The pattern seems clearest in spring, when the worn, weathered pelage has faded but the dark on the lower lip has not faded (https://www.inaturalist.org/observations/5155147). The following shows the minimal expression of the buccal semet (https://www.inaturalist.org/observations/114831099), but it is unclear whether this is because of the summer season or individual variation.

Of all the features described here, the buccal semet is the most precocial, in the sense that the lower lip is dark even in infants (https://www.inaturalist.org/observations/29864809 and https://www.123rf.com/photo_188787653_portrait-of-a-walking-cow-moose-and-her-calf-alces-alces.html and https://www.inaturalist.org/observations/7440096).

Posted on September 19, 2023 12:46 AM by milewski