April 12, 2018

Northern Mockingbird

Northern Mockingbird

Painted Redstart

Painted Redstart

Here’s your next bird trivia question:  what do Painted Redstarts, Northern Mockingbirds, and Greater Roadrunners have in common?  Well, we know it’s not family, size, color, range, or habitat.  Next time you see one of the three, any of them, instead of moving on, spend a few minutes observing quietly or following along unobtrusively within easy binocular range.

Notice what all three of these species eat and how they forage.  All are insectivorous, to a greater or lesser degree, and they cover a lot of ground in their foraging.  They are extremely active feeders, given to quick, “athletic” movements, and all will take anything smaller than themselves that they can swallow.  This feeding style is aided and abetted in each of these three species by frequent wing flashing.

Northern Mockers are notorious for this as they explore open patches of lawns and fields, pausing, spreading their wings, refolding, then moving a few feet and repeating.  It has long been assumed that suddenly displaying their large white wing patches flushes insect prey from the ground, making it easier to see and catch.  Note that the underside of the mockingbird tail is also white, but typically in this species only the wings, not the tail, are flashed.

Painted Redstarts, of course, forage arboreally rather than on the ground, but as they flip along the tree branches and sometimes even up tree trunks they constantly expose their conspicuous white wing patches while simultaneously spreading their tails, maximizing the bright white undersides.  It is now thought redstart flashing may be a means of visual communication as well as a foraging aid as they flush moths, spiders, and leaf hoppers.

Perhaps because roadrunners are encountered much less frequently than the two aforementioned species, and because larger birds are less confiding than smaller ones, it was only recently that I realized they too employ wing flashing while rambling over their sizeable territories.  One early morning I encountered a pair foraging together through a wide, grassy wash interspersed with patches of gravel and a few widely scattered bushes.  One would trot a few paces, then freeze and watch.  The second, slightly smaller and presumably the female, only loosely paralleled her mate’s progress, and she would trot along but then open and droop her wings before stopping to watch.

I had never observed a roadrunner feeding this way, but it exactly mimicked the Northern Mockingbird behavior which is so familiar to birders.  As I edged close enough for photographs, she employed it for maybe 15 minutes and perhaps 100 yards down through gravel into the wash, around clumps of brush, then back up the slope out of the wash.  Several times she picked at the ground, but any prey item she gleaned on this day was small enough to be swallowed immediately before I could focus camera or binoculars.

I look forward to my next Greater Roadrunner sighting to see if I am handy enough with the camera to capture whatever it is they capture while wing flashing.  I have yet to photograph the stock chase scenario where roadrunner catches lizard or snake, but I have seen our amazingly adaptive Southwest icon jumping three feet off the ground in a desert flower patch to snatch bees in flight out of the air.  It may turn out that, like other wing flashers, spiders and small insects are also a staple of this voracious predator’s diet.
Greater Roadrunner
Greater Roadrunner