On the Snowy Owl Invasion

Snowy Owls have migrated south in impressive numbers this winter. Unlike some irruptions, which affect one part of the continent but not others, this year's Snowy Owl irruption has been observed across North America. Even Hawaii recorded a Snowy Owl, a first state record (which was promptly shot by airport officials). The New York Times reports on the scale of the Snowy Owl irruption:

The irruption started in late fall and is expected to end by March or April. In few places are people as excited as in Kansas and Missouri, where snowy owls are exceedingly rare. Ninety have shown up in Kansas this winter and 40 in Missouri. Until this year, the highest number counted in Missouri had been eight.

“It’s a massive movement,” said Mark Robbins, the ornithology collection manager at the University of Kansas.

When five of the birds took up residency at Smithville Lake, near Kansas City, Mo., it created an “owl jam,” Mr. Robbins said. Thousands of people have driven there to see them, he said, and hundreds of owl seekers have shown up at Clinton Lake near Lawrence, Kan....

Geoff LeBaron, director of the Audubon Society’s Christmas bird count, said that it was hard to estimate how many snowy owls flew south in this irruption because the latest data has not been tallied, but that the overall number was probably a few thousand. Despite the surge, the society says, snowy owls are thought to have been in decline since 1945.

There is far more data on the scope of this migration than in years past, thanks to a citizen science project based at Cornell called eBird, which is run by the Cornell Lab of Ornithology and the Audubon Society. Bird-watchers around the country call in sightings, which are plotted on a map that shows precisely where the birds are wintering.

“A lot of people who have never seen one before have rushed out and seen multiples,” said Marshall Iliff, an ornithologist at Cornell and the project’s leader. “And photographers are having a field day.”

Additional hot spots include the mouth of the Columbia River in Washington State, with 10 to 13 birds; 20 at Lake Andes National Wildlife Refuge in South Dakota, and 30 in Boundary Bay, near Vancouver in British Columbia.

The owls are even showing up in urban and suburban areas, along highways, on signs and fence posts, and in other places where people can more easily spot them. It has been a good snowy owl year at Logan Airport in Boston, too. Because the airfield looks like tundra, snowy owls tend to flock there, and they must be trapped and removed.

“We’ve removed 21 so far this year, and the average is six,” said Norman Smith, who works for the Massachusetts Audubon Society and traps the birds. The most ever trapped was 43 in 1986, Mr. Smith said, “but the year’s not over.”

To be more precise, birders do not "call in sightings" to eBird but enter sightings through web-based checklist forms on the eBird website. For more on the causes behind this year's Snowy Owl irruption, see this post by David Sibley. He gives a more clear account of what probably happened than The New York Times does.

I have only seen the one Snowy Owl (pictured) that was present at Merrill Creek Reservoir so far this winter. So this winter has not been quite as memorable for me as the winter of 2009, when I saw four Snowy Owls over the course of the winter, or the winter of 2010, when I saw two Snowy Owls at Parker River NWR in Massachusetts during the Superbowl of Birding.

Snowy Owl at Merrill Creek Reservoir

A few weeks ago, a Snowy Owl was reported at Merrill Creek Reservoir in Warren County, New Jersey. If current trends continue, it may turn out to be part of the vanguard in a Snowy Owl irruption year. That aside, it has stuck around for a few weeks and has been seen by numerous observers. Yesterday, I finally got a chance to visit the reservoir and see it. Normally, when I visit Merrill Creek, I prefer to stay in the wooded wildlife sanctuary on the north end of the reservoir, but yesterday I decided to walk all the way around to see the owl and look for any waterfowl that might be hanging around the edges of the reservoir.

As you can see from the photo, I was successful in finding the Snowy Owl. Thanks to some directions posted on Friday on Jerseybirds, the owl was fairly easy to find. The owl is visible from the top of the main dam, on the south side of the reservoir. The dam is very high, so a scope will give better views, but I was able to see the owl and watch it turn its head back and forth just with binoculars.

The rest of my walk was fairly quiet, with only a few bird flocks here and there. I saw a lot fewer waterbirds than I expected: only about two dozen Buffleheads and a half dozen Horned Grebes. It felt a little strange to be walking around a body of water with no Canada Geese or Mallards visible. Land birds were also a little sparse. The highlights were a couple of calling Hairy Woodpeckers and a pair of Eastern Bluebirds. Somehow, though, I managed to add 13 species to my bird list for Warren County.

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.

British Columbia Spotted Owl Population Critically Low

Pat's Nature News contained a piece of very bad news about Northern Spotted Owls. The species is down to six wild individuals in British Columbia.

Spotted owls live up to 17 years in the wild, but they breed slowly, mating for life and producing just one or two chicks every two years. Silent hunters with excellent vision and hearing, the owls swoop through the open canopy of old-growth forests at dusk to catch wood rats, voles, mice, and squirrels. At one time, at least 500 pairs lived in B.C.’s forests, but over the past 100 years, their habitat has been so heavily logged that the owls have been unable to survive.

Spotted owls are particularly vulnerable to logging because of the way they nest and hunt. The owls don’t build nests but lay eggs in trees hollowed out by age or decay. And when a forest is cleared and prey populations decline, the birds often starve.

The B.C. government is belatedly trying to save the owls, with plans to capture two of the remaining males to breed with two single females in captivity. The government now has 10 owls in its breeding program and hopes to have 30 or 40 pairs so that 70 or so of the birds can be released back into the wilderness in the next decade. Government biologists have also been killing barred owls, which compete with the spotted owls for habitat.

As in the United States, the problem is attributed to habitat loss. Over 70% of the species's habitat throughout its range has been logged. British Columbia's population is much worse off than the one in the U.S. Pacific Northwest, where there is still a viable (if endangered) breeding population in the wild. It also appears from the linked article that the owls in B.C. lack the habitat protections afforded under the U.S. Endangered Species Act. If so, it may be difficult to restart a breeding population in appropriate habitat.

Finally, a Northern Saw-whet

This weekend I traveled to Massachusetts to participate in the Superbowl of Birding, an annual big day competition sponsored by Massachusetts Audubon. Christopher of Picusblog invited my to join the Bloggerhead Kingbirds this year along with Nate of The Drinking Bird; Corey of 10,000 Birds; Mike of The Feather and the Flower; and Andrew the Birding Dude. I will have a report on the competition in a subsequent post.

On Friday morning, I met Corey and Andrew in Queens to ride up with them to Massachusetts in our rental van. Along the way, we made a stop at the Pruyn Sanctuary in Westchester County to follow up on a report of a Yellow-headed Blackbird being seen at the sanctuary's feeders. We stood and waited in the cold for about an hour and a half. During that time we saw many sparrows, including a Fox Sparrow; a Sharp-shinned Hawk, and a couple hundred blackbirds, including a Rusty Blackbird. Sadly, we saw no Yellow-headed Blackbird. Eventually time constraints forced us to leave, and we continued on our way to Massachusetts.

Once we had arrived at our hotel, met the other bloggers, and checked in, we set out to do a little bit of birding. Christopher knew the roost location for a Northern Saw-whet Owl, a bird that was a lifer for me and (I think) one or two others. (This species was also a source of frustration for me when I lived in Cape May, since I missed seeing one on multiple occasions.) Christopher guided us to the roost, and we saw this:

We stayed just long enough for everyone to get a good look and take a few photos. I shot this photo through Corey's spotting scope. When I reviewed the photo later, I noticed just how good its camouflage is. If you look closely at this photo, you can see that the feather pattern on the top of its head fades into the tree. You may see the crown of its head, and you can see the eyebrow, but the feathers between those two curves look almost like bark. Owls as a group are especially adept at cryptic camouflage, which helps these birds stay hidden in their daytime roosts. It takes very careful searching and a lot of luck to locate one of these tiny birds.

Northern Saw-whet Owls are fairly common migrants, from what I understand. However, their cryptic feather pattern and tiny size make them extremely difficult to find for the average birder. Saw-whets breed in the coniferous forests of northern North America and migrate south for the winter months.