Northern Saw-whet Owl

Today at Kingsford – Northern Saw-whet Owl

While visiting my new favourite property, I heard the sound of a predator being mobbed. It’s a very distinctive sound, the sound of a dozen chickadees going absolutely crazy. Chickadees are big talkers in general, usually keeping up a running chatter amongst themselves when they’re foraging. But when one stumbles onto a predator, they ramp it up a notch. In this case, the dozen chickadees were joined in by a few nuthatches, who lended a higher-pitched version of their regular nasal eenh to the cacophony.

Almost invariably when you hear that, the little songbirds have discovered themselves an owl. Owls have to roost during the day, since most are primarily nocturnal hunters, and generally try to find a spot that’s sheltered and hidden from view. During the winter, when the deciduous trees have lost most of their leaves, they usually choose conifers. By following the racket I was able to locate this individual, a Northern Saw-whet Owl, sitting in a white pine, doing her best to try to remain unperturbed by the alarm-callers. Indeed, she showed the most concern with the dog, who, oblivious of the spectacle going on above, dashed under the tree. Even that only warranted barely more than a glance. Eventually the chickadees moved out to carry on with their lives, feeling assured that they’d let that owl know its place, and Raven and I moved out to head home, leaving the owl in peace.

So the moral of the story here is, if you hear a flock of chickadees really kicking up a fuss, go check it out, they’ve probably found something good.

Today at Kingsford

A couple weeks ago, Dan applied for his Master Bander permit, and last week it was approved. Dan has been banding for some 15+ years, and is one of the most skilled, conscientious and research-oriented banders I know (our relationship naturally has nothing to do with this bias, of course…). Master permits are not handed out lightly, as you need not only a wealth of knowledge and experience, but also a worthy project for the Bird Banding Office to justify giving you a permit to band birds independently. Both of us previously held subpermits under a Master permit held by someone else at the Toronto and Region Conservation Authority, for the bird research station project in Toronto. Because the TRCA’s projects are confined to Toronto, we needed our own permit to be able to do research here.

Dan’s initial plans include three primary projects, the first, and soonest, of which is migratory owl monitoring. The only species of owl that migrates in large numbers is the diminutive Northern Saw-whet Owl. The grown adult is one of the smallest owl species on the continent, and certainly the smallest here in the east, only about the size of your outstretched palm. They breed in boreal and montane mixed forests, but move south in the fall. This movement, plus the fact that they respond to tape broadcasts of their call, makes them easy to monitor through banding studies, and there are many stations and individuals across North America who go out every night in the fall to see who’s passing through. Banding is a quick and painless procedure (the aluminum band goes around the leg, like a permanent bracelet, rather than attaching to the bird), and is generally over in just a minute or two for the birds with a minimum of stress. Yet it provides us important information on population sizes, demography (age and sex ratios), the relative success of the breeding season, and other data that can be very helpful in monitoring the owl populations and, through them, the ecosystems they are a part of.

We set up our mistnets on our property a couple days ago and have caught three saw-whets in two nights (running just a few hours each night). This is an excellent capture rate for these little birds, and we have high hopes about what we might find this fall. Undoubtedly you’ll see another post on owls in the next couple of weeks, which will go into more detail on these delightful and remarkable creatures. (For one, they’ve got oodles of personality – check out the expressions of these two different individuals, both telling me what they think of the whole experience).

(Incidentally, I had planned to post this last night after I got home from working the Canadian election – a long day, at some 13 hours start to finish, but one that at least goes quickly. Not long after my return home at 10pm, the puppy chewed through the telephone cord that connects the computer to the internet. I felt that was a sign I should just go to bed, tired as I was, and we worried about replacing it this morning.)

Start of the season

Contrary to the forecast made for yesterday, the weather wasn’t actually all that bad. While there was rain in the city, by the time I drove the ten minutes down to the spit, there was no rain down on the lakeshore, and there was even some patches of blue sky struggling to show through the blanket of grey cloud. It’s a funny thing about the research station, that the weather conditions that affect the city can often be quite different than what’s happening out on the spit. Usually, it’s that it’s raining, sometimes heavily, in the city with little to no precipitation on the lake. Strange.

Today dawned clear, beautiful and sunny, but c-c-cold. Well, for this time of year. It was -5 celcius when we arrived at the crack of dawn, about 6:30am. It took until 9:30 for it to warm up to 0 degrees. Ordinarily we would open the mist nets half an hour before sunrise, and run for 6 hours, but both yesterday and today, due to weather, we opened halfway through the morning and put in just a half day’s worth of effort.

The first bird banded of the spring season was this impatient American Tree Sparrow (can you see the look he’s giving me? “Are you done there yet, missy?”). After my comments about expecting migrants to be late this year, they all seemed to come in on the warm front Monday night. We had Golden-crowned Kinglets and Eastern Phoebes, in good numbers. Song Sparrows, juncos, a few Brown Creepers. A Winter Wren was around, as was a Yellow-bellied Sapsucker and a Belted Kingfisher, all firsts for the spring.

We totaled a huge 41 species on the morning, which I think is more than any other opening day in past years. One of the birds present was this little Northern Saw-whet Owl. They’re not often seen in the spring, so it was a real delight to find. Saw-whets are funny migrants, they come through in largeish numbers in the fall, spread out for the winter, and then seem to just disappear come spring. We run a saw-whet owl monitoring program in the fall which is pretty successful (we banded over 300 owls last fall), but don’t run in the spring because there’s no owls around to band!

The trails are still partially covered in snow. This photo was from yesterday, and the rain and wind yesterday helped to melt some of it, but there’s still some left yet to go. It can be a little bleak down there on cloudy days in late fall or early spring, with the grey skies and empty trees. The trees take a while to leaf out, longer than on the shore, because of cooler temperatures due to lake effects. We can just be seeing the start of greening when trees are already well-progressed in town. The dogwoods really help add a pop of colour to the landscape there. I’m going to try to do a once-a-week photo series documenting the greening of the station this spring.

As I was leaving yesterday, this woodcock wandered across the road in front of my car. Naturally, I had my camera already packed away, and of course it had the short lens on it. So while it was a rare opportunity to see a woodcock out in the open, this was the best shot I could manage. I love these birds, they’re so bizarre-looking! They’ve been doing their beautiful twittery sky-flights in the mornings when we arrive, I wish it was brighter when they do it so that I could capture some of it to film, but they only fly at dusk and dawn.

I’ve been busy lately, wrapped up in an interesting and hopefully promising project that will hopefully be the subject of some future post if it all works out, so haven’t had much time for research – I’ve got a small backlog of such photos that I need to get to. It’s amazing to me how much there’s been to talk about during the winter, the months that I figured would be the hardest to fill… My camera will be overflowing when life really starts stirring in a few weeks!

Winter bird irruptions

I have more to add to the winter colours theme of the last couple of posts, but feel like a change of pace today. I haven’t done any posts yet about birds, which is a little surprising given that birds are really my primary interest in nature (first birds, everything else second). So here’s a post on birds.

This winter, southern Ontario, and indeed most of northeastern North America, is enjoying a phenomenon called “irruption”. An irruption is similar to migration in birds, but takes place irregularly, usually every two to four years (depending on the species), rather than every year. Most irruptions are the result of food shortages in the areas where the birds usually spend their winters. Because the birds can’t find sufficient food there, they start to move south in large numbers. In many of these species, small numbers may be seen every winter, but an irruption is marked by a great abundance of the species south of its usual range. This winter seed crops, especially of deciduous trees, did very poorly in much of the north, resulting in low food availability for most seed-eating species.

The above photo is of a Common Redpoll, named for the red cap on its head, a regular irruptive species that usually comes south into southern Ontario and the northeastern states every couple of years. On their wintering grounds, redpolls feed primarily on the catkins of birch and alder trees. In a year of poor catkin production, redpolls will begin to move out of their regular range in search of an area with good food availability. In the south, this is often in the form of bird feeders. Redpolls love nyger seed (thistle seed), and will swarm nyger feeders in large numbers. They’re rarely seen in small numbers or individually, and flocks can reach 40 or 50, to upwards of 100 birds. This year is a bigger year for redpolls.

Another frequently seen irruptive species is the Pine Siskin. This year they seem to have carried on through southern Ontario to places further south, but in some years they can be just as, or often more, numerous at the feeders than the redpolls. Siskins depend on evergreen cone seeds, but are also enthusiastic visitors to nyger seed feeders. Although they’re not very flashy, they can be distinguished from some other brown, streaky finches by their sharp, narrow beak (not well seen in this photo), and the yellow tints to their wing feathers.

Pine Grosbeaks and Bohemian Waxwings have also been reported in large numbers this winter. I haven’t had a chance to go out to look for either, yet, unfortunately. The last time I saw a Pine Grosbeak was some four or five years ago, and the only ones I’ve seen in Ontario were at the University of Guelph, back when I was a student there. They’ve been reported there again this year. That gives you an idea of the frequency of their irruptions this far south. I’ve never had the luck to see a Bohemian Waxwing, although I’ve gone looking for them.

These aren’t the only species that come south in years of low food availability. Red-breasted Nuthatches are seen periodically in larger numbers, and this year they moved out early in the fall, to destinations further south. My parents have one coming to their feeder this winter, however, and they’re usually gone by mid-fall. Black-capped Chickadees are usually year-round residents on their territories, but in years of good breeding success (that is, lots of babies!) coupled with poor winter food supply, large numbers of primarily young birds will move south looking for food. Chickadees moving through in the fall was slightly elevated this year, but 2005 was the biggest movement over the last few years. Blue Jays will also irrupt in larger numbers some years than others. We had a moderate movement this year, but the best year since I’ve been keeping track was probably 2003.

Seed-eaters aren’t the only group of birds that undergo periodic irruptions. The seed shortages that cause birds to move also affect rodent populations in those areas, which depend heavily on seeds as their food source. In years of poor seed crops, rodent populations suffer sharp declines (often called “population crashes”). This year rodent populations had an especially severe crash, as last year’s seed crop had been good, encouraging a good breeding season this summer. That breeding success was followed by this fall’s seed shortage, causing a precipitous decline in numbers.

Birds that prey on rodents, such as owls, tend to follow their population cycles fairly closely. Because rodents were so abundant, owl populations, particularly the Northern Saw-whet Owl (pictured above), had a very successful breeding season. When rodent populations crashed this fall saw-whets began moving south in huge numbers. Saw-whets usually follow a four year cycle, where every fourth year their rodent prey, Red-backed Vole, peaks in number and so does their population. Saw-whets are naturally migratory and will move south every year, but the numbers encountered in the south vary according to the size of the movement. The combination of high saw-whet numbers due to this year’s breeding success and the low prey availability because of poor seed crops resulted in a larger-than-normal movement of saw-whets this fall.

Great Gray Owls follow a similar pattern, although they usually only move as far as they need to to find food, which means they don’t often make it as far south as most human communities. A bird of northern Ontario, they often just move to another part of the north when prey shortages occur, since such shortages are often regional in nature, although small numbers are usually seen as far south as cottage country every winter. A few years ago, in the winter of 2004-5, a huge movement of these beautiful northern owls occurred in southern Ontario, and I had the opportunity to get out and see several. They’re the only ones I’ve seen.

Another species of owl that comes south every year, but can move in larger numbers some years, is Snowy Owl. There’s usually one bird that winters at Tommy Thompson Park (home of the research station, and as close to a backyard as I have here in the city) every year, although I haven’t seen reports of it this year. However, in years of larger movements, such as 2005-6, many Snowy Owls can be seen in a relatively small area (of suitable habitat, of course). The photo below was taken on Amherst Island, near Kingston, where we had up to 13 individuals during one day.