Readers’ wildlife photos

We have two contributors today, both with lovely bird photos for show and tell. First is Stephen Barnard, who sent two photos and his comments—made while tugging on his tie. Click to enlarge:

The eagles regard me as irrelevant. I get no respect. No respect at all, I’m telling ya. The ripples in the water are reflected from the neck and breast of this American Avocet.

Recurvirostra americana  (click to enlarge):

And a passel of photos from reader Bruce Lyon, along with his notes:

I recently returned from a nine day trip to Costa Rica and took tons of wildlife photos, some of which might be of interest to your readers.

I came across a couple of nice owls during my recent visit to Costa Rica. Ferruginous Pygmy Owls [Glaucidium basilianum] are fairly common in the northwestern Costa Rica, but they are easier to hear than see. They are small—smaller than an American Robin in weight. April is the beginning of the breeding season and I was lucky to stumble on a pygmy owl nest, but it took a bit of sleuthing to find the actual nest.  I flushed the owl from the same general location on two different hikes, a suspicious pattern that suggests “nest”. Pygmy owls nest in tree cavities—typically old woodpecker nests—but I could not see any contenders. I eventually found what looked like a perfect nest cavity and confirmed it was the owl nest by returning at night and finding the bird in the hole.

Pygmy owls are often mobbed by songbirds and it seems they don’t like to perch exposed in open areas too long because they risk being mobbed. Another reason I was initially suspicious that this owl had a nest was that when it flushed up into the trees, it did not fly to cover but remained exposed and vulnerable. It was soon mobbed by two different flycatchers—a Greater Kiskadee and a Tropical Kingbird—both of which dive-bombed the little guy. The first two photos below show the tropical kingbird perched behind the owl, waiting for its chance to strike. Note the fake eyes on the back of the owl’s head in the second photo—studies with northern pygmy owls in Montana, using balsa wood models painted with and without false eyes on the back of the head, showed that fake eyes reduce close approaches from behind the bird by mobbing birds [Deppe  et al. 2003. Effect of northern pygmy-owl (Glaucidium gnoma) eyespots on avian mobbing. Auk 120: 765-771]. Thus study suggests that fake eyes might reduce the risk of injury from attacks to the back of the birds head, where the owl might not see the attacker coming. Small cats like Bobcats and Servals also have what seem to me to be fake eyes—the white patches on their ears. Wikipidia suggests various functions, including intraspecific communication, but not anti-mobbing. Perhaps a reader can weigh in on whether there have been studies of fake eyes in cats serving an anti-mobbing function.

Below:  Owl with a tropical Flycatcher perched nearby, waiting for an opportunity to strike:

Below:  Plumage markings on the back of the owl’s head thought to resemble eyes and deter birds mobbing the bird from behind. [JAC: that’s a new on one me!]

Nervous-looking pygmy owl [JAC: It was mobbed by a magpie jay right after this photo was taken.]

A white-throated magpie jay [Calocitta formosa], not the one that attacked the owl.

I also stumbled on another small owl, a Pacific Screech Owl [Megascops cooperi]. Several Rufous-napped Wrens were making a huge ruckus by some dense foliage—this behavior often indicates mobbing an owl or snake. A Pacific Screech Owl soon flushed from the foliage and sat in the open for a couple of minutes.

Pacific screech owl after being flushed by some mobbing wrens:

The mobbing culprit—a Rufous-naped Wren [Campylorhynchus rufinucha]