Eastern Screech-Owl in Daylight

Yesterday afternoon, I noticed this Eastern Screech-Owl along the Delaware and Raritan Canal. Since the owl was small and its cryptic plumage blended well with the trunk, the bird was actually hard to recognize, despite the large opening. When I photographed it, I initially was not sure if my hunch was right, but the photo showed that it was.

While screech-owls are primarily nocturnal predators, they sometimes emerge from their roosting places during the day, especially the late afternoon. In the winter, sitting in an opening gives them the opportunity to bask in the afternoon sun and warm themselves after a cold day of sleeping. So if you happen to be out on a winter afternoon, it is worth checking openings in tree trunks for the characteristic shape of an owl.

If you do happen to find a roosting owl, be careful about how you share the sighting and do not post an exact roost or nest location publicly. Owls can be sensitive to disturbance, so frequent visits may push an owl to change roosts, possibly to a less favorable location.

Yosemite Great Grays from the Ice Age

Recent genetic analysis shows that the Great Gray Owls of Yosemite National Park are a subspecies stranded by the last Ice Age rather than a remnant chased out of northern California by logging and development.

The Yosemite owl is not only genetically different from great gray owls in Oregon, Idaho and Canada, it also nests slightly differently and prefers a more narrow diet of rodents, scientists say.

More than half of California's great gray owls are in the Yosemite region, and there are very few between the park and southern Oregon. Scientists say they still do not understand why there are only a few great grays in Northern California forests.

It is not unusual to find species in the Sierra that were stranded during the last Ice Age, said wildlife ecologist John Keane, who led the research for the U.S. Forest Service Pacific Southwest Research Station....

Great gray owls live at an altitude of 4,000 to 8,500 feet in the Sierra, but they migrate to lower elevations in snowy winters or when there is a lack of food.

While other Great Gray populations eat a diverse array of rodents, ones in the Sierra specialize in pocket gophers and voles.

One interesting note is that the researchers are working on a method for finding Great Gray Owl populations. Rather than doing foot searches, they are setting up microphones to record all of the sounds of a meadow for a week at a time. The sounds are analyzed by computer to detect owls.