Yellow-bellied Sapsucker

On banding birds

Yesterday I started a new job, running the spring migration monitoring program for Innis Point Bird Observatory on the Ottawa River. It’s a short-term contract, running until June (the length of the spring migration, unsurprisingly), but during that period I’ll be out there six days a week. Even after just two days, I’m quickly realizing that my available time is going to be considerably more limited than it was before, and I’m going to have trouble keeping up with everything, at least as I do it now. So, at least for the time being, I’ll be scaling back my blog posts a bit; instead of doing the occasional “Tay Meadows Tidbit”, they’ll all be tidbits, and I’ll do away with the title (which would just get repetitive). Now let’s just hope I can keep my rambly fingers in check!

The focus of the migration monitoring program is to monitor birds, of course. It’s a bird banding program, where birds are captured using standardized methodology that allows for comparison of results over many years. Data is collected for each bird caught, including age and sex, weight and fat levels. The former two measurements tell us something about the demographics of the population, which can be useful in detecting and assessing population trends. For instance, if a particular species starts showing a lower-than-normal proportion of young birds in the captured sample, it’s a suggestion that they’re having trouble reproducing successfully, perhaps due to poor breeding seasons because of weather conditions, or because of environmental problems that are causing increased chick mortality. The latter two measurements (weight and fat) are used in assessing the health of the birds arriving at the station. Low weights and fat levels are generally an indication of a bird that’s just arrived from a long flight, but if it doesn’t bulk up quickly in preparation of its next leg (which is detectable through recaptures of the birds again before they leave the site to carry on) then it could be the bird is in poor health, or it’s having trouble finding food. Over and above all that, though, is simply a documentation of the numbers of each species banded. If you start to notice long term trends – for instance, you band fewer of a species now than you did ten years ago – it’s probably cause for concern. The migration monitoring is especially useful for bird species that nest in the boreal, north of what’s sampled by the Breeding Bird Survey, since it’s often the only reliable means of monitoring their populations.

Of course, each bird also gets fitted with a band that will identify where and when it was banded if it should ever be encountered again. Historically banding was used as a way to track migration routes and patterns, but fewer than one of every 1000 birds banded is ever seen again away from the site where it was banded. That’s pretty slim returns; you have to band a heck of a lot of birds to get even a small sample size. Still, hundreds of banders banding over several decades have built up a pretty good database of re-encounters, and these days we’ve got a decent idea of where birds go. The focus of banding has shifted to population monitoring, as explained above. The bands are still useful for this, though. A substantially higher percentage of birds are recaptured again between their first banding and when they leave the site to finish their migration. By recording their weight and fat levels again next time they’re encountered (for which you need a band in order to be able to identify individuals again) it’s possible to track how the birds are faring and how well the site fulfills its role as a stopover location.

A sweet treat

Yesterday I had the opportunity to spend the morning at the TTPBRS research station. It was a lovely day, and as I’d spent the weekend indoors tackling other (interesting, but not outdoor) projects on my computer, it was nice to get outside for a while. It was a busier morning than I gather they’d had over the weekend, and the final tally of birds banded was a little over 50. The species included many Song Sparrows (while I was in the bander’s seat, anyway, it seemed like every other bird I banded was a Song Sparrow), juncos, and Golden-crowned Kinglets, with a few other odds and ends such as Eastern Phoebe, Ruby-crowned Kinglet, and American Tree Sparrow thrown in for variety.

Also among them were two Yellow-bellied Sapsuckers, including the striking male pictured above (in sapsuckers, males have a red throat, while in females it’s white). It is possible to age most birds based on a number of criteria in their wing and tail feathers, but for most songbird species you can only really determine whether during the previous breeding season (so, last summer) they were an adult or a young bird. Woodpeckers are an exception to that, you can usually determine back one year further. In the case of the above male, he was an after-third-year – meaning that 2008 is at least his fourth (“after-third”) calendar year, if not more (birds are generally aged according to calendar year to make it easier to keep track of). You can’t determine his age with more precision than that, but it still means we know he was hatched either in or prior to 2005. So he’s a good old boy.

Later in the morning I spotted another bright male who flew across my path and perched on the trunk of a birch tree. I couldn’t see his legs, so I don’t know if it was the same one as we’d banded earlier. As I watched him, he systematically checked out a set of sap wells that presumably he had drilled earlier. Although I couldn’t see it from my distance, I presume he lapped up what sap had oozed from the holes since last time he visited. He was only there less than a minute, but he checked out all four holes.

Look at him stretch that neck to reach the last one without moving!

Once he left, I went up and checked out the tree he’d been at.

He’d drilled five holes, which were all running slightly, although the sap trails on the bark weren’t substantial. I’m not sure why sapsuckers drill their holes in such a neat line like that, but I would assume that it has something to do with ease of checking them (like in the above photos; he didn’t have to move to reach them all). Probably the sapsuckers won’t tell us if we ask them, so we’re left to make our best guess.

He landed on another tree not much further from the first which, when I went to check it, had a single hole drilled into the trunk. Right next to it, however, was one that was half-started. What I find particularly interesting is how a woodpecker is very methodical in its drilling – it’s not like driving a nail where you keep pounding the same spot. Instead, and as you can see here, they actually chisel out a section of the bark which they can then chip off, exposing the softer wood underneath (which is easier to hammer through). I guess after he’d done one on this tree he was either disturbed, or decided that the sap from this one tasted funny.

Underneath the fresh work you can see a couple of old, scarred-over wells from years past.

Here’s another tree that was visited in years past. There’s probably a number of different years represented there, judging by the relative scarring of some holes to others. Sapsucker holes are often square or rectangular, rather than round, which you can see well on this tree. Nearly all of the trees with sapsucker wells (old and new) down there are birch. The trees around the station are probably 90% birch and cottonwood, but the cottonwood doesn’t seem to appeal to them at all. My guess would be that there’s enough of a difference in the thickness of the bark between birch and cottonwood, and there’s enough birch in the area, that they can afford to be picky about the trees they choose.

An old section of sapsucker wells, now so scarred over it’s forming a cracked swelling in the trunk. The wells don’t do serious damage to the tree, aside from this sort of thing. It’s not all that different from tapping maple trees for their syrup. The main concern would probably be the potential for the tree to be infected by a fungus through the open wound, and even that is rare.

Aside from the obvious benefit to the sapsucker, the sap wells are often visited by other creatures as well, including many nectar-feeding insects and hummingbirds. For these guys the sap provides a sugar-rich source of food in the early spring, before many flowers have started blooming, and can often be invaluable for their survival through that period. I have yet to see a hummingbird visiting a sap well in the spring – by the time they reach us here, in early May, there’s already a fair bit blooming.

Woodpecker wuz here

While out hunting for fungus last week, I happened to notice quite a number of trees with woodpecker holes. The absence of foliage on the plants provides a much different view of the forest (or other habitat). Things that are usually obscured are now exposed. Sometimes it’s not that the thing was obscured, but rather that you just looked past it because there was so much going on that you were distracted by other things. But now with the leaves gone, and the ground cover under a thick layer of snow, other things start to pop out at you. Like birds’ nests (but that’s another post). It’s actually possible to determine who made the holes in the tree you’re looking at, if you know the characteristics to look for.

There are five species of woodpecker that regularly frequent the woods around my parents’ place. There are actually seven that can be found in southern Ontario, nine in Ontario as a whole, but only five that are particularly widespread. The first one is the Northern Flicker. These birds actually migrate south in the winter, and very few remain in the province during the cold months. This is because, although a woodpecker, their primary foraging method is by probing the ground for grubs. They will and do forage on trees, but you’re more likely to find them feeding on your lawn. Of course, when your lawn is under several inches of snow, it’s difficult for flickers to make a living. So they head south to warmer climes (this is unfortunate, because they are beautifully plumaged woodpeckers and would add a nice splash of colour to the winter landscape – do a google search for Northern Flicker to check them out).

The smallest of the remaining four is the Downy Woodpecker. They are the quintessential woodpecker of birdfeeders, the bold little guy who is often found hanging out at suet feeders (check out the suet feeder image in my previous post). My parents had some emergency roof repairs done last week, and at one point the workers were tidying up shingles from the ground by the house while the local Downy watched from the suet feeder six feet away. Being the smallest, they also make the smallest holes in trees. The holes in the above image are only about half an inch wide on the largest ones, and can be a quarter of an inch on the smaller ones. Because of their size, Downy Woodpeckers will often perch on goldenrod stalks with galls (those little balls you sometimes see halfway up the stem) and peck out the grub from inside. If you check out galls in the winter, as often as not there’ll be a hole in one side from a Downy (chickadees will also peck out gall larvae – you can tell who was there by the tidiness of the hole – chickadees are very messy as their bills aren’t as specifically designed for the job).

The Hairy Woodpecker looks superficially similar to the Downy, but is actually a larger bird, with a longer, stronger beak. Their handiwork can usually be found on dead tree snags or logs. Their typical hole is slightly larger than that of Downys, up to a couple inches, and often has a slightly rectangular shape to it. You’ll usually find a series of such holes in the log or dead branch, grouped together. The holes in the birch at the top of the post were probably also made by a Hairy. Most woodpeckers have barbed tips to their tongues that they use like spears to snag bugs or larvae hidden deep within the wood. These barbs are coated with a sticky saliva that makes them extra secure. A woodpecker’s tongue wraps back behind its skull, and can be as much as three times as long as the length of its beak! Check out the photos at the above link, pretty amazing.

The largest woodpecker in Canada is the Pileated Woodpecker (pronounced either pill-ee-ate-id or pie-lee-ate-id, depending on your preference – I say the former). These stunning birds are about the size of a crow, with a long neck with white stripes, and a gorgeous red crest. They’re such beautiful birds, I have to post a photo of this female I photographed foraging on my parents’ lawn a few years ago. You can tell she’s a female because, while both sexes have the red crest, the black “moustache” is actually red in males.

Lovely, isn’t she? While she’s foraging on the ground in this photo, Pileateds more often search for grubs on dead trees or logs, or even in live trees with heartrot (decaying inside, where you can’t see it – but the birds can tell!). With those massive, powerful beaks they can really do some damage. Pileated holes are often as big as, or larger than, your fist, going deep into the heart of the tree. As you can see in the photo above, the Pileated who hammered these holes dug into a live tree (the sap is dripping down the bark) into its decaying centre. It must have found a good haul, too, because it made many holes, and digging through the still-live outer bark is no easy feat!

Pileateds also have the power to pry up the bark off dead trees in order to get at bugs right underneath. In the photo above, the bird has removed most of the bark from the trunk by inserting its beak under a loose edge and using it like a lever to flake it off. On this particular tree the bird had started at about our eye level and worked its way all the way up to near the top, about ten or twelve feet of bark-flaking. Also another sign that there must have been good eats underneath!

Indeed, if we look closer, we can see the trails of bark beetles and their larvae. These trails went all the way around the trunk, and as far up as I could see. Speaking of things you see in the winter… but that’s also for another post. If you scroll back up to the Downy’s hole photo, you’ll notice that at the bottom there’s a small bit of bark flaked off there, too. It was taken on the same tree, and they were obviously interested in the same good food source.

The fourth, and final, woodpecker my parents get is the Yellow-bellied Sapsucker. And no, that’s not a made-up name! It is indeed yellow-bellied, and it really does suck sap. Or feeds on sap, anyway, if not by a sucking method. Sapsuckers lack the barbs that the other woodpeckers have, instead having a feathery texture that absorbs liquid to allow the bird to drink by lapping at the sap, much like a cat laps up a bowl of milk. Sapsuckers drill “sap wells” into live trees and feed on the sap that oozes out of the wounds. They have a characteristic habit of drilling in straight rows, like above, that are easy to identify. The sap produced by sapsucker wells is not only used by the sapsuckers themselves, but also provides food to other animals, such as some insects like ants and bees, and hummingbirds, who, particularly in the spring before many flowers are blooming, need an additional source of sweet food. Sapsuckers are also migratory, and leave for the winter. We haven’t seen the sapsucker pair that used to nest on my parents’ property for a couple years, and it may be they’ve died and nobody’s moved into their empty territory. The sapsucker holes in the photo are a few years old.

This last hole wasn’t made by any woodpecker! This is an example of a live tree with heartrot. In this case, a branch was torn off, likely in a storm, and exposed the decaying interior of the tree. Although the outside and branches look superficially healthy, it’s obvious the tree is in decline. Some of the sawdust from the cavity was on the ground at the base of the tree, and I suspect this hole is likely used as a frequent snoozing spot by a raccoon. Seems pretty cozy to me!