Interspecific variation in flags as features of adaptive colouration in hares, part 2: other species of semi-arid North America

@azgulo @panza_rayada @marcelo_aranda @aguilita @juancruzado @maxallen

I continue by turning from Lepus californicus to other, partly sympatric species in North America.


Lepus callotis ( and differs from most subspecies of L. californicus in that:

A dark spot near the tip on the anterior surface of the ear pinna may possibly be prominent enough to qualify for a second auricular flag ( and and and scroll in

Lepus callotis is the only member of its genus in which a patch on the lower flank and upper hindleg is conspicuously pale even when the figure is stationary ( and and and and and and This species occurs in bonded pairs, and the pale feature may possibly provide a mechanism of monitoring each other's whereabouts.

The pale feature on the lower flank and upper hindleg qualifies as a haunch flag when expanded, as follows.

In alarm and while fleeing, the pale patch is stretched in a dorsal direction by twitching of the skin to encompass the haunch and the posterior upper flank ( and and and This brings it into particularly conspicuous contrast with the dark upper surface of the tail ( and and second photo in and

An expanded position seems sometimes to remain in rigor mortis (

Lepus callotis seems to qualify for stotting, based on Best and Henry (1993): "When flushed, L. callotis alternately flashes its white sides while running away from the intruder...Another escape behavior is that of leaping straight upward while extending the hind legs and flashing the white sides. This behavior is seen when the white-sided jackrabbit is startled or alarmed by a predator."

What may not previously have been noticed is that the pale patch can also be contracted when the figure crouches in hiding ( and compare the second and third photos in, presumably by movement of the skin in a ventral direction.


Lepus alleni ( and does not possess caudal or auricular flags. Instead, this species is specialised in a haunch flag comparable with that in L. callotis but differing somewhat in its mechanism.

The following show general aspects of L. alleni:

Note that:

However, the particularly extensive haunch flag can be 'flashed' by twitching of the skin, which exposes the whitish aspect of the fur. The dark on the tail is not extensive enough to add much to this display.

Best and Henry (1993, state the following, which I have interspersed with illustrations:

"The antelope jackrabbit runs in a nearly horizontal plane for several strides then may make a stride higher than the others. Although not common, this behavior usually takes place in tall grass or when brush obstructs its sight of possible danger (Howell, 1944). As it starts to run, it makes four or five long hops on the hind legs alone, kangaroo fashion, then reverts to the usual mode of locomotion. Occasionally, with ears erect, the kangaroo hops are again displayed, apparently to see or hear possible pursuers (Swarth, 1929)...The leisurely moving, unfrightened individual that is not flashing its white sides ( and and and does not make observation leaps. When the antelope jackrabbit runs away from an observer, a conspicuous white area is displayed on the rump ( and and and and and and and and and This area appears to shift each time the animal turns, the white being kept toward the observer, partly by the manner of holding the skin and partly by the zigzag course taken by the running animal. The white is flashed by a set of skin muscles that pulls the skin of the hind quarters over the back and up one side and at the same time everting the hairs, thereby exposing a surprisingly large white area on the left or right rear. Individuals hopping about to feed, or running but not alarmed, as in play or chasing each other, do not show this white (Vorhies and Taylor, 1933)."

The following show the difference, on the haunch, between:

The flared effect seems sometimes to remain in rigor mortis (


Lepus townsendii exceeds all three previous species in its emphasis of caudal and auricular flags. This is because:

What this means is that L. townsendii possesses:

  • a caudal flag, present only in the summer coat, consisting of a tail that is conspicuously pale depite blending with the grey body, and
  • three different auricular flags, viz. darkish anterior surface of the ear pinnae (in winter coat), dark-tipped posterior surface of the ear pinnae (in the winter coat), and pale posterior surface of the ear pinnae (in the summer coat).

The following further illustrate the above features.

The following shows that the colouration of the anterior surface of the ear pinnae is inconspicuous in the summer coat: The following shows that the feet can be pale enough, in the summer coat, to be a candidate for a pedal flag:

Summarising the first four species:

Lepus californicus, L. callotis, L. alleni, and L. townsendii are all ecologically similar, replacing each other (with wide overlap) in various regions of North America under relatively dry climates. However, they are surprisingly different in the incidence and location of flags as part of their adaptive colouration. The poor development of flags in L. californicus is partly explained by its habitat, which contains shrubs that provide cover and allow this species to rely on hiding.

to be continued...

Publicado el abril 14, 2022 07:58 TARDE por milewski milewski


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