Monthly Archives: November 2010

They came back! The Evening Grosbeaks that I first mentioned having visited us in this post returned yesterday; or, it’s perhaps more likely that another group found us, since this flock was bigger than the ones we saw before. I spotted them first at the feeder, before they were flushed into one of the maple trees. They made a couple of trips back to the feeder and away again, before disappearing.

Interestingly, it was always this house-on-a-platform feeder that they came to, even though we have a plain, flat, open platform on the other side of the house which we would have expected them to like better. It’s possible they didn’t find it, but maybe they did, and simply found it too busy. It’s trafficked by most of the smaller birds, chickadees, nuthatches, goldfinches, etc, and is constantly active.

I snatched up my camera as soon as I saw them, and ran off several dozen photos. Dan came down and joined me, and got some video with his camera that I thought would be neat to share, but it was taken through the glass and apparently didn’t turn out too well. It’s a funny thing about certain birds like this: you can run off five or six dozen shots, but ultimately every single one of them is simply a bird sitting at a feeder eating. What am I hoping to capture with that thirtieth or fortieth photo? I’m not sure. The excitement of the encounter, perhaps. As I’d mentioned last time, it’s been a decade and a half since I last had Evening Grosbeaks coming to my feeder. I recall them being one of my favourite feeder birds, growing up, one I always looked forward to seeing.

A female. They’re very pretty in their own right, with the subtle yellow at the nape, and the soft brown-gray plumage. A delicate tracing of black about the base of the bill. I’d never noticed the white throat before.

I already mentioned a fair bit about the ecology of grosbeaks in the first post, but I’ll repeat it at the bottom here to save you some time if you didn’t catch it the first time or want to read it again.

The species has an interesting range, found in a narrow band through the lower boreal forest, and south through the western mountains, all the way down into Mexico. I’m excited to see an Evening Grosbeak here in Ontario, but I recall that the summer I took a field ornithology contract out in Lake Tahoe, California, the birds were regular visitors to the pines in the yard of the place we were staying. I was searching for nests that summer, and though I saw numerous grosbeaks, and I ended up the summer with the most nests found of our team members, I don’t think I ever found a nest of a grosbeak. I’m sure they were around, but they typically nest quite high in coniferous trees, anywhere from 20-100 feet (6-30 meters), so to find one you’d really have to trail the female if you caught her carrying nest material, or either of the parents when they were carrying food back to the nest. Or you’d have to be very lucky. And I was pretty lucky with some of my finds, but not when it came to grosbeaks, apparently.

What do you think the purpose of that heavy unibrow is? It must be a signal to females about the overall “fitness” of the male (that is, how studly he is and how great a father he’d be). Research has shown that many (most?) species of birds have some UV reflectance to their feathers, which the birds can detect but our eyes are unable to. In chickadees, for instance, the really studly males have brighter backs and cheeks, and darker blacks, than the poorer males. These brighter males get the girls, and they also rank higher up the social ladder. Perhaps the same thing is happening here: males with high fitness will have brighter white patches on the wings, brighter yellow unibrows, and darker heads, showing more contrast. We humans won’t be able to tell the difference without doing detailed study with special tools, but the birds all know.

Speaking of social dominance, we found it interesting to note that the grosbeaks, for the most part, appeared dominant over the larger Blue Jays. I saw one of the females chase away a nearby jay a couple of times, and they mostly kept their distance. Of course, with a beak like that, I wouldn’t want to risk getting too close, either. Any bird bander will tell you that being bitten by one of the thick-billed species, like grosbeaks and cardinals, hurts like the dickens. The Birds of North America account for Evening Grosbeak notes that the Hawfinch, a European species of the same genus and with a similar bill, can crack seeds that require up to 57 kg (125 lb) of force to open. Strangely, though Evening Grosbeaks rarely eat anything that large or tough, taking mostly caterpillars such as Spruce Budworm or small fruits and seeds such as maple keys.

Bohemian Waxwings, Evening Grosbeaks… and it’s only November. Looks like it’s shaping up to be a good winter.

From the last post:

The last time I had an Evening Grosbeak visiting the feeders of the house I was living in was about 15 years ago or so, while I was young enough to be still considered “growing up”, and well before I’d taken up birding as a hobby. I recall the birds being nearly annual when I was a child in the 80s (or that part of the 80s that I was old enough to remember), but numbers petered out into the 90s, and then they stopped coming altogether.

The decline is due to the forestry industry’s control of Spruce Budworm outbreaks, the timing of which corresponds nearly exactly. Evening Grosbeaks are budworm specialists in the summer, even becoming pseudo-nomadic to take advantage of the bounty afforded by outbreaks, and the suppression of these outbreaks has meant a corresponding decline in all of the bird species that depend on them (the grosbeaks aren’t the only ones – several species of warbler are also strongly tied to budworm outbreaks). When I was growing up, budworm outbreaks affected between 8 million and 18 million hectares (20-45 million acres) annually. Since 2000 the average area affected in a given year is only a fraction of that: 81k to 337k hectares (200k-830k acres).

On the other hand, Evening Grosbeaks aren’t originally native to eastern North America. They’re from the west, and moved east as human activity started to create more extensive tracts of the sort of habitat (and vegetative communities) that they prefer. The first breeding record of the species in Ontario wasn’t until 1920, up at the Manitoba border. Twelve years later they’d reached Algonquin Provincial Park. Survey data suggest that Ontario population peaked in the 80s. That said, they’re also on the decline in other parts of Canada, even where they’re historically native – most likely also due to Spruce Budworm control.