bird banding

Gobs in the bogs

We have three stations set up for MAPS. Our first visit to the first one was on Wednesday; we made our first visit to the second on Friday, and were out to the third station today. Although they all share some features, be it bird species or landscape, they are all pretty unique from one another. Hemlock Lake is set along the edge of a small lake. The west shore is full of deadfall trees, and, as the site’s name suggests, hemlock is predominant there. Rock Ridge, our third site, is also set on a lake, but while Hemlock Lake is mostly forest, Rock Ridge is mostly pine and rock barrens. Both of these sites are very picturesque, with many postcard photo ops around the site.

If the other two are about the landscape, then Maplewood Bog, our second site, is about the birds. Well, really, all three sites are about the birds, but with Maplewood that’s the feature that makes it stand out from the others. This is in part because there really isn’t the same sort of postcard landscape at the site. Both of the other sites have great vistas looking out over their respective lakes. Maplewood, however, is set into the forest. As per its name, the site’s most prominent feature is a largeish bog set in the middle of the mostly maple and oak forest (we tried out the name Oakwood Bog, but it just didn’t roll off the tongue as well).

Though there is the one large bog in the centre, Maplewood has numerous smaller bogs, vernal pools, swamps, and wet spots. This is somewhat deliberate (the inclusion of these within the station boundaries, not their existence – we can’t take credit for that), as such habitat offers the low, shrubby growth that is crucial for successful mistnetting. In order for a mistnet to catch birds, the birds must be traveling at the level of the net. For them to be moving at net level, there must be suitable low vegetation structure. In a typical mature forest, most of the vegetation is found in the tree canopies. At human level there is mostly just tree trunks, or sometimes sparse young saplings waiting for a big adult to fall and open up a patch of sunlight. These little wet bits are often the best habitat for catching birds in, as it brings the birds down to net level. Unfortunately, they can be a bit wet to walk in. Dan did his best to select the driest bits for the net lanes.

N for Nice? It really is a nice site. What it lacks in vistas it makes up for in easy walking and great bird diversity. This is the only one of our three sites with nesting Cerulean Warblers and Yellow-throated Vireos. Scarlet Tanagers are also common, but we didn’t catch any of these species on our first visit to the site. In the summer they typically favour the tree canopies, rarely coming down low except, perhaps, to drink and bathe. Our best chances for catching them will be later in the summer, once the young birds fledge. Adults will often lead their families to edge habitat and low scrubby areas. I’m not exactly sure what it is that draws them there, but it’s probably to do with food – greater food abundance or foraging opportunities in the increased structural diversity of the scrubby habitat. Late in the summer and into the fall these habitats start hopping with birds as the young-of-the-year disperse out of their natal territories. Gobs in the bogs. Even at this point in the season, of the first days at each of our three sites Maplewood was the busiest, with 26 captures. When we arrived at the site, at 5 am, the woods were just alive with birdsong.

A forest specialty that we did catch was the Wood Thrush above. They are a declining species and so are a target species for our projects. Wood Thrushes are notoriously hard to photograph, or at least to get a good photo of. They have a habit of dropping their head down to their chest, giving them a hump-backed look. This one happens to be a second-year bird – that is, in its second calendar year (meaning last year, 2008, was when it was hatched, its first calendar year). One of the tell-tale features that you can look for in thrushes of all species are these pale streaks up the shafts of some of their wing or head feathers. The feathers of baby thrushes all have these pale streaks, and while the bird will replace most of them in the fall before it migrates, they often hold on to some of them through the spring and summer (but it’s one of those absence of evidence isn’t evidence of absence sort of things – if you notice them it’s definitive of age, but if you don’t then the age is ambiguous and needs to be determined by other criteria). In this photo a few of the feathers on the bird’s forehead still bear those pale streaks.

Red-eyed Vireos are one of the most common species of deciduous forests and are present at all of our sites in good numbers. They are well-named birds, as the eyes of the adults really are a vibrant ruby-red when highlighted by the sun (in the shade they’re still a rich matte red). The eyes of young-of-the-year are a mouse-brown, so it’s easy to tell the young from the adults in the fall, at least if you can get a good look at their eyes. Their irises gradually change colour over the course of the winter. This individual looks like it has a speckled throat, but all those little gray dots are actually feather mites. I have no idea how these mites get on the bird in the first place, but once present they settle in on the feathers and feed on the barbs. In most birds you notice them on the wing feathers, so I was surprised to see them on the throat of this guy. I guess it was one of the few places he couldn’t preen them from.

We’re starting to get into deer fly season, and as the sun crests the treetops they all come out of wherever they spent the night, and start their endless circling of your head. After a long few hours of this at Hemlock Lake a couple days before, I bought some of those deer fly sticky traps for use on future outings. I tried them out at Maplewood on Friday. They proved remarkably effective, distracting the flies from my neck and trapping them on the tape where they could do no harm. This was my collection at the end of the morning.

The deer flies were just as irritating to the birds as to me while I was trying to photograph them. This Common Yellowthroat took matters into his own beak when one landed on his back. He held on to it and left with it when I let him go.

The same thing was repeated by this Veery as I was taking photos of it. This gave me an idea for the fate of the flies stuck to the back of my cap, and as birds were released I offered them a deer fly for their troubles. Most of them snapped it up right away and departed with it.

This Field Sparrow has a mosquito in his mouth. We caught him before the deer flies were out, but there were still plenty of mosquitoes in the early morning cool. He actually snapped it out of the air where it hovered near his face as I took a few photos. Even the sparrows, chickadees and finches, which we think of traditionally as seed-eaters due to their presence at our feeders in the winter, are insectivores in the summer. Insects offer substantially more nutrition and protein than seed does, which is important with all the energy the birds expend in raising a family (or two) over the summer months. Birds that stick around for our winters have evolved to be able to switch their diet to seeds for the cold months, when insects are hard to find, and those that are unable to make the dietary change fly south to where insects are around all year.

If you’re interested in reading more about the site and the birds found there, check out Dan’s post on our Maplewood Bog visit, over at the Frontenac Birds blog.

It’s good to be fat

Dan took advantage of the wonderfully mild weather we’ve been enjoying the past few days to open our feeder net to band some birds. Dan obtained his Master bander permit back in the fall, with the intention of undertaking a number of studies in our area. One of them was to look at the demographics of our winter bird population. He explained it in this October post, excerpted here:

The project will be initiated to benchmark the demographics of birds inhabiting this particular neck of the woods during the cold months (November-March). Data on abundance, diversity, survivorship, condition, and age/sex will be gathered to index and monitor the health of resident bird species in the area. These kinds of projects are important, particularly today with the threats posed by climate change to the ecology of even the most common bird species.

So we set our net up, situated near the feeder so that birds coming or departing hat the chance to be caught in it. Over the course of two hours in the afternoon we caught and banded 33 birds. Most of these were the redpolls and siskins coming to the nyger feeder. We had a lot of chickadees, those boldest of the feederbirds, first to find new seed sources. We also happened to catch our Red-breasted Nuthatch, as well as a White-breasted Nuthatch and a Hairy Woodpecker, all nice birds to see in the hand, although Hairys, with their strong beak designed for drilling, can really do a number on a bander’s hands.

The last couple of days we’ve seen a lot of our banded birds at our feeders, not the least put off by the whole experience. For most species, banding is a mild inconvenience. It takes them out of their routine for a short period, but generally doesn’t result in any ill effects, providing the bander is conscientious and doesn’t keep them longer than necessary. In the winter, this means speedy (though still careful!) work, since the birds need to spend most of their time eating or looking for food, to maintain energy levels. Good thing our net is right next to our house – not only can we keep an eye on it and go retrieve a bird as soon as it’s caught, but we can also transfer them indoors for quick banding.

One of the things banding can tell us is how many birds we have in our area. Banding of course can only sample a portion of them, but the premise of mark-recapture studies is that if you mark a set of individuals, and then measure how many of them appear in subsequent samples, you can extrapolate the size of the population. For instance, if one marked and released 100 fish, and then came back and took a bunch more 100 fish samples, of which there was an average of 10% marked fish per sample, you’d know that your original 100 fish represented about 10% of the total population – which was, therefore, about 1000 individuals.

Similarly, we banded 33 birds a couple days ago. In watching the feeders since then I would estimate that between 1 in 8 or 1 in 10 individuals was banded. Through extrapolation, that would mean that our 33 birds represented between 10% and 12.5% of the total number of birds visiting the feeders, which would mean a total of between 264 and 330 birds coming to our seed. No wonder we’re going through it so quickly!

Another measurement that one can take from birds in the hand that’s impossible to get with simply observing birds in the trees is how much fat they’re carrying. This is extremely important simply for assessing health (for example, a Boreal Owl up near Ottawa a couple weeks ago had looked fine in the tree, and had even been seen with a rodent, but was found dead a few days later and was severely emaciated – a fact that was hidden by its feathers), but it also tells you a lot about their travel plans.

Birds only lay down fat if they’re migrating. You and I and Fido lay down fat as a security against lean times, but wild birds are always on the move, and their metabolism is too high to accumulate much if any fat during regular activities. This is especially true during the breeding season, when they’re busy collecting food for all their young as well as themselves, but it’s also true in the winter, when keeping warm requires a lot of energy. Come spring and fall, though, their daily time budgets change. While flying during migration there’s no opportunity to eat, so they need to make sure they have enough energy stored to get them through the long haul to their next pit stop. This is done in the form of fat.

Birds have translucent skin, and because their feathers grow in tracts, rather than uniformly, it is possible to part the feathers between the tracts and look through the skin. The fat appears yellowish or orangeish beside the red tones of the muscle, so it’s easy to see how much fat a bird has put on. Extremely fat birds are probably preparing to depart in the next couple of days. Birds with just a little bit of fat are either residents that are finding so much to eat they are actually storing a bit, or, more likely, are migrants that have just arrived, having exhausted all their fat reserves in the just-completed leg of their trip, and haven’t had a chance to put more fat on again. They may stay for four or five or more days while they do this, and they may need to do it a dozen or more times over the course of their trip.

The Hairy Woodpecker had no fat. This was no surprise, since we would expect him to be a permanent resident. The same was the case with the nuthatches. The siskins and redpolls all had fairly heavy fat deposits. They may start to peel out over the next week, to be replaced, perhaps, by birds moving in from farther south. But the ones that surprised me the most were the chickadees. The finches are irruptive birds, they don’t breed around here, so we would expect them to be leaving. But chickadees do breed here, so it was a surprise to discover them all with full fat deposits as well.

Dan and I actually noted that there was a recent influx of chickadees at the feeders, and it was hard to tell if they were just birds that had exhausted their winter food caches and were now relying on the feeders, or what the story was. The banding data, however, may provide a clue to the answer. Chickadees, in years of high summer breeding success and low winter food availability, will irrupt south just like redpolls and other winter birds. It may be that the chickadees we have at our feeders, fat as they are, are irruptive birds that had come south back in the fall, spent the winter, and are now preparing to head north again. It could be that they either started coming to our feeder in order to more easily and quickly build up their fat stores prior to departure, or that they are birds from further south who have just arrived and are stopping to fuel up before their next leg.

Since they can’t tell us, we can only hypothesize on the reason. However, we can see, come spring, just how many banded chickadees we still have coming to visit the feeder then.

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!

On your mark… get set…

The last day of March, and this morning found me down at the Tommy Thompson Park Bird Research Station, helping to set up the site for the start of another fabulous spring migration season. The research station’s primary goals are to collect data on local and migratory bird populations to aid with conservation efforts here and afar, to promote awareness of birds and conservation through education programs and demonstrations, and to contribute to research initiatives by helping to collect data or providing a location or means for someone else to do so.

The primary, and initial, project run by the research station, through which these objectives are achieved, is the migration monitoring program. It involves constant-effort bird banding and surveys (that is, we’re out there every single morning for the entire migration period, weather permitting), which provides data on bird population numbers and demographics, including information such as adult:young and male:female ratios in the population, stuff that can’t be easily (or sometimes at all) obtained through non-banding means but that gives you an idea of, for instance, how successful the breeding season was this year. There are some 25 or so similar stations across Canada, each contributing valuable data to fill in their local piece of the puzzle. The birds are banded, measurements collected, and then safely released to return to their regular activities. The Palm Warbler in the top photo popped nearly straight up out of the hand before taking off for the nearby trees.

I’ve been volunteering since 2003. I love being down there, and would happily volunteer all season if I had some other means of making ends meet (who’s seen/read About A Boy? perhaps all I need to do is write a hit holiday song and I’ll be set). I like seeing who’s about every day, watching the migration ebb and flow across the season, the composition of species progressing and changing from week to week. On a daily basis, I like turning the corner to check a net, not knowing what we’ll find this time around. We’ve had some marvelous surprises show up, such as the above Yellow-throated Warbler, the only bird of this species I’ve seen (they’re normally more southerly in range).

I love the opportunity to hold such fragile, but beautiful, life in my hands, to feel the wonder of it. I enjoy seeing the birds up close, at a distance where you can marvel at the intricate feather patterns or subtle plumage details often lost in the field. Who’s seen the orange crown of an Orange-crowned Warbler? I have, but only with the bird in my hand. And who’s paid much attention to a Mourning Dove’s face, the subtle colours of the eye ring, the bright pink at the corner of its mouth, the small patch of iridescence on its neck? But you get a chance to see this when you study the bird up close.

Yes, I’m looking forward to returning. Ironically, tomorrow, the first day of banding, has been rained out (we don’t run in conditions that would threaten the welfare of the birds, though surveys are still a go – we’re less concerned about our own comfort). So we’ll be starting on Wednesday instead.

The setup this morning went smoothly, but was quiet for birds. We had a group of a dozen chickadees moving back and forth through the area, and there were some blackbirds and a few grackles that flew overhead throughout the morning, but not much moving in yet. Perhaps this warm spell will encourage some more movement from the south. Hermit Thrush, American Tree Sparrow, Dark-eyed Junco, perhaps even Eastern Phoebe or Ruby-crowned Kinglet – they should all be around in the first week during a normal season, but the unusually cold weather might delay their arrival this year.

The park and station are open to the public on weekends and holidays, and anybody in the Toronto area who’s interested is invited to swing by Tommy Thompson Park on the Leslie Street Spit, and drop in during a spring or fall morning to check us out, learn about what we’re doing, and get a chance to see a little bird up close and personal.