Interspecific variation in flags as features of adaptive colouration in hares, part 1: Lepus californicus

@biohexx1 @aguilita @marcelo_aranda @clint_perkins @mooseandsquirrel @asemerdj @maxallen @zarek @lefebvremax @saber_animal @tordenvinge @stephen54

Flags are conspicuous features of adaptive colouration in animals. Because of their medium scale relative to the whole figure, they require motion for their activation (see

For example, a caudal flag is present in several families and many genera of ruminants: the tail is erected to display striking contrast between dark and pale (

The genus Lepus ( contains about 30 species, most of which - although smaller-bodied than ruminants and with proportionately longer ears - are ecologically similar.

In this series of Posts, I examine the various flags in the various species of Lepus.


I begin with Lepus californicus ( because this is the most frequently photographed species in the Americas.

The following view of L. californicus shows cryptic colouration with no conspicuous features: However, in certain subspecies, the pale ventral tract extends high enough on the flank to be conspicuous:

The anterior surface of the erect ear pinnae lack conspicuous colouration ( and and

All flags are rather poorly developed considering that both the tail and the ear pinnae are relatively long in this species (

The colouration on and near the tail may not qualify as a caudal flag. This is because the tail:

The moderately conspicuous posterior surface of the ear pinnae of L. californicus qualifies as an auricular flag, particularly when the figure is fleeing and viewed from behind.

The pale, sheeny posterior bases of the ear pinnae ( and and are more conspicuous than the dark tips. However, in most subspecies the nape is not dark enough to offset this pallor.

Please see

The following show that the posterior surface of the forelegs is whitish whereas that of the hindlegs is relatively dark: and However, this is possibly owing simply to soiling.

The following further illustrate the features described above.

I have not investigated differences among the 17 subspecies. However, ssp. altamirae in Tamaulipas, Mexico (, is different enough to be a different species: and Also see and

When L. californicus is viewed from a perspective based on ruminants, it gives the impression that it uses the ear pinnae in place of the tail to flag its flight.

In summary, the only flag for which L. californicus qualifies is a pale auricular flag. As caveats, the conspicuous pale is

  • restricted to the posterior surface of the ear pinnae and appears only when the ear pinnae are erect,
  • basal/proximal rather than distal (the darkness of the posterior tips of the ear pinnae thus providing limited contrast),
  • dependent on sheen, and
  • not offset by dark on the nape although it is offset to some degree by the dark on the hindquarters when viewed directly from behind.

to be continued...

Posted on April 13, 2022 01:51 PM by milewski milewski


Add a Comment

Sign In or Sign Up to add comments