Sunday, June 29, 2008

photoblogging: eastern screech-owls

Trouble sleeping tonight, so my thoughts turned to owls, and I decided to reprise a photo essay from the Nebraska hawking journal. [Photos by me and the family.]

In late May and early June of 2005, a pair of eastern screech-owls (Otus asio) with their four recently-fledged young took up residence in our front yard—an excellent opportunity for photography and study.

↓ Owlet in treetop.

↓ Adult female with a mouse. Screech-owl diets vary with season and location. A Michigan population studied by John and Frank Craighead preyed heavily on mice, at least in the winter, but Baylor University researcher Frederick Gehlbach (The Eastern Screech Owl: Life History, Ecology, and Behavior in the Suburbs and Countryside) indicates that owls in his Texas study area relied primarily on birds.

↓ The adult female (center) feeds one of the fledglings (upper left) while another (lower right) waits its turn. The adult male does the majority of the hunting, but his mate always feeds the young. According to Gehlbach, these roles are so stereotyped that if the female is lost before the nestlings are capable of tearing their own food, they may starve in the midst of abundant but whole prey delivered by the male.

To my innocent eyes the only thing that falcons, owls, and parrots have in common is their oddly anthropomorphic habit of holding their food up to their mouths in one foot as they nibble.

—Stephen Bodio, A Rage for Falcons

↓ A study in camouflage: the grey color and tree-bark pattern of adult screech-owls help them remain hidden from predators and prey alike. Eastern screech-owls come in two basic color forms, rufous (red) and grey. Red is dominant to grey in terms of Mendelian genetics, but red screech-owls outnumber grey ones only in humid eastern forests. Grey makes for better camouflage in drier habitats, and for some reason red screech-owls are apparently less hardy in cold weather. Unsurprisingly, then, almost all screech-owls in Nebraska are grey.

↓ Screech-owls do well in suburban environments, partly because suburban owls have fewer predators and competitors to contend with than their rural counterparts. To survive to adulthood, though, these young screech-owls will have to avoid housecats, dogs, and cars—many screech-owls are struck and killed while catching worms on city streets during periods of rainy weather. Secondary poisoning is another threat.

↓ Once acclimated to human activity, screech-owls can become very confiding. The adults would take mice mere feet in front of us, in broad daylight. (The pressure of extra mouths to feed was undoubtedly a factor—outside of the breeding season, screech-owls are more strictly nocturnal.) They were frequently mobbed by robins but paid little attention. Gehlbach reports, incidentally, that the species most likely to mob screech-owls are those which figure most prominently on their menu. [Paper here.]

↓ Adult screech-owl on a favorite perch: shaded and half-hidden, with a good view of the surrounding ground—perfect for napping and hunting.


Chas S. Clifton said...

Great owl photos -- yours are so cooperative!

Val said...

I live in North TX and have recently discovered an Eastern Screech Owl in my back yard - there almost every night and also roosting during the day in our pine on the outer branches. He is the red variety. I enjoyed reading this post, and admire your photography! I don't have such a great camera, but am motivated to make the investment since Mr. Owl has taken up residence. I have posted one piture on my blog, and last night captured him singing on video. I hope to post that soon as well.

Mark Churchill said...

Thanks for writing, Val. I'm always curious when someone new finds my blog, especially an older post such as this one, so if you want to tell me how you found Flyover Country, I'd be glad to hear it.

I appreciate your feedback on the photography, and I'll pass your compliment on to Susan & Ellie as well. Truth be told, our camera isn't really all that advanced. It's just that, as Chas noted, our screech-owls were very cooperative. As I noted in the text, urban and suburban screech-owls can become quite habituated to humans, and I think the need to find enough food for four fledglings made this pair unususally accomodating—diurnal and tolerant of our presence. Consequently, we were able to take photos from just a few feet away, with scant need of zoom lenses. Your late-September screech-owl is likely to be more wary.

Val said...

Mark, I found your blog by googling "eastern screech owl" funny enough. We have named ours Mr. Spock (assuming he is a he)- he has been "trilling" back and forth with another owl in the neighborhood lately at dusk. It's such a wonderful thing to experience!

I will enjoy reading your blog, glad I found it!

Janet said...

I found your blog Googling Owls in Nebraska. I have a little owl in my yard in a BIG old tree that's been dead for a number of years. I heard funny noises coming from it and peeked at the hole in the side and saw a little owl. I believe it's an Easterm Screech owl. I also found their call on another web page and identified them from that. I'd been hearing a lot of calls in the evening not knowing what they were. Thanks for the photos! I haven't seen "my" owls that close.