Sunday, March 1, 2009

Portrait: Eastern Screech-Owl

I have decided to start a portrait series exhibiting interesting aspects of the behaviour and ecology of a particular species. I thought I should start with my favourite group - owls. In fact, why not start with the species I have spent the past 4+ years researching - the Eastern Screech-Owl (Megasops asio). These photos are all taken in Manitoba, Canada, at the northern limit of this species' range. Here is a portrait of a male grey Eastern Screech-Owl... you can see the tufts are held in a relaxed position here. Due to the cold dry climate in Manitoba, red morph birds are extremely rare here (<1%).

The underpart pattern of the Eastern Screech-Owl offers superb camouflage with the bark patterns of many eastern North American deciduous trees. This male is roosting in an American elm. Notice how his pattern matches the grooves in the bark.

This female is equally well camouflaged...

The photo below shows an adult taking off and using powerful strokes to gain height quickly. Note the strong rufous colouration of the thighs, which is shown on many grey morph adults in Manitoba.

This next shot shows the extended underwing of an adult that has just fed two fledglings. Note the greenish wash on the base of the primaries and the pinkish wash to some of the underwing coverts. Such colour on the underwing is common in both adults and juveniles, although I haven't reached any firm conclusions about its significance yet. You'll notice this feature in other photos on this page.

Eastern Screech-Owls catch a lot of their prey on the ground. In the breeding season much of their prey is invertebrate. Here two different adults illustrate some of their worming strategies: the pull and the pounce.

Moths are one of the few items usually caught in flight. The fledgling shown here eating a moth (fed by parents) is only 3 days out of the nest.

An adult brings a caterpillar to the nest (in a Wood Duck box) while the chicks compete for the best position in order to be fed first (there are two more chicks inside the box).

Though invertebrates may constitute as much as 70% of captures when feeding young (the photos above are just a few examples), many birds and mammals are also consumed. Here, clockwise from the top left corner: an adult with a House Sparrow, an adult carrying a North American Deermouse with one foot, a cached Meadow Vole, a cached Catharus thrush (probably Swainson's), an adult feeding a Meadow Vole to a fledgling, and an adult feeding a Cedar Waxwing to a fledgling. Cached items permit capitalising on a glut for times of inclement weather. Sometimes they are placed in a roost tree, sometimes in the nest proper, and sometimes in an alternate cavity.

Mother and child: after a month in a dark cavity, a chick joins their mother in expanding their worldview.

Squabbling siblings: three chicks peek out of a nest with a large opening (left), but sometimes there is only room for one at a time (right).

Nothing like a little mischief to learn about the world...

Five fledglings of a brood of six (the other is just a few wings away, as are mum and dad) roosting in an oak.

And here are all 6 from a different brood. In Manitoba, brood size ranges from 2 - 6 and is correlated with seasonal precipitation levels.

Getting a little older: By late July - August, the fledglings are looking less fluffy and have begun to hunt for themselves, starting with small items such as beetles captured on the ground (right) or on branches. The wing feathers are among the first to develop and so, at this stage, fledglings look more adult-like from the back than from the front (compare two photos on left). In the upper left photo you will notice the pattern of white splotches on the outer primary coverts which are retained throughout the first year. The outer webs of these feathers will become entirely white by their second/third year.

By September, they are looking very adult like, except if there are any down feathers remaining they sometimes look a little like a misfit in their own coat. If they survive their first winter, they will hopefully complete the cycle and breed the following spring.

More of my photos of owls are viewable at:


  1. Very informative.The pictures also tell the story well.

  2. What an awesome collection of bird (and other wildlife) photos!! As a volunteer for the World Bird Sanctuary, an organization dedicated to preserving, rehabbing, and educating the public about birds of prey, I am especially impressed with the wonderful photos in your Screech Owl series. Keep shooting - they are wonderful!


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