Why Killdeer Have Orange Butts

When sitting in the green room between acts, Killdeer display a somber tawny brown back. The long wing tips cover the red-brown color of the rump when the bird is at rest.  Although legendary for their acting prowess, they are relatively plain looking (and acting) by choice. As residents of open ground this color combination serves well as camouflage on exposed gravelly surfaces. When their nest is threatened, the birds instantly fan out their tails and launch into their famous “broken wing” act in order to lure away potential robbers.  Sir Lawrence Olivier could do no better in this regard.

One feature that attains prominence during the defensive act are the black and white neck bands (see above). The birds crane their necks to expose the broad white patch located between the upper and lower dark neck bands. Take a good look at one of these famous Killdeer performances, however, and you’ll see how they make the most out of their bright orange-red butts (see beginning photo). This is the feature put on prominent display whenever one of these birds is compelled to defend a nest location.  Even though the overall theme of the act is to call attention to the alleged broken flapper, the rump colors are meant to call attention to this fact. They act as playbills announcing “horribly broken wing now showing – come and get an easy meal.”

A bird in full performance will flop from side to side with its wing upturned at an awkward angle. It will drop to the ground as if lame and flash that orange butt by  fanning the tail from side to side.  When approached, they manage to recover from this mortal injury just long enough to run a few dozen yards further away from the nest – at which point they become re-afflicted.  They will keep this up until luring the danger well out of the vicinity of the eggs. For a fox or coyote, the act is very convincing.

I came upon the Killdeer pictured here in a marina parking lot. But, instead of leading me away from the nest, the bird’s performance actually led me to it (am I smarter than a fox? Well, maybe). One can judge the proximity of the eggs by watching the intensity of the act. Like a game of “hot & cold” the well-intentioned display often serves as a means of nest betrayal. When I took the video, shown here, I was nearly on top of the nest and the bird was going ballistic. I never suspected the location until the bird “doth protested too much.”

The actual nest – a shallow scrape really – was located under a boat trailer and contained four neatly speckled eggs (see here). Although there are occasionally five eggs in such a nest, four is the typical number. The narrow ends always face inward in a tight shamrock pattern.

This bird returned to incubate the clutch only after I walked well away from the site. Both the male and female birds participate in both incubation and nest defense, so I am not sure whether the individual pictured here was a he or a she.  With a dedication that would drive most birds insane, Killdeer will keep up this routine for 24-28 days until the fluffy chicks finally hatch out (and work on their own method acting skills). Unlike human actors, each and every acting performance is as good as that performed on opening day. Bravo, your Shakespearean orange rumpus does you proud my ‘deer.

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