A Pileated Woodpecker captured and banded at our Blue Lakes MAPS station this season – only the second we’ve caught in three seasons of MAPS work. It’s such a privilege to see these guys in the hand. This one was an after-third-year – that is, at least four (or more) years old. Close-up of the bird here.
I’m halfway through a second post on the Frontenac Biothon, but kept letting myself get distracted by things and now it’s bedtime (well past, in fact!) so I’ll have to finish it up tomorrow. Instead, I’ll post this photo of a Scarlet Tanager. We caught this guy at our Maplewood Bog MAPS station last week. This gorgeous bird is, of course, a male. The females are always a greenish-yellow with brownish wings. In the fall males will also be greenish-yellow, but they’ll retain the black wing feathers of their summer plumage so it’s easy to tell them apart. This handsome fellow is an after-second-year individual (that is, he was hatched at least two years ago [2009 or earlier]; birds’ ages are labeled by calendar year, so birds hatched this summer are called “hatch-year”, those from last summer are “second-year”). You can tell second-year males from after-second-years by the blackness of the wings and the redness of the body – second-year birds will have browner wings and oranger body plumage. The after-second-years practically glow.
During the process of bird banding, several bits of data are collected on each bird captured and banded. Species is recorded, of course, and measurements are taken on how much fat it’s carrying and the length of the wing. Sex is noted, if possible. And the age. Ageing birds has always been my favourite part of the banding process; I find it fascinating that it’s possible at all to determine how old a bird is. Not only is it possible, it’s actually not all that hard.
The theory of ageing birds is based on molt patterns. Many birders are familiar with the concept of graduated plumage from gulls and eagles, but passerines (songbirds) can and do show a type of graduated plumage, too. For most species of birds, the end-of-summer molt undertaken by a young-of-the-year bird will be different than that for an adult, an individual that was a parent that summer. Young birds grew a full set of feathers while in the nest, of course. Feathers are very energetically costly to grow, so if the bird can avoid having to grow a whole nother set of feathers so soon after the first set, it will. As a result, hatch-year birds will only replace a subset of their feathers during their end-of-summer molt. How many and which ones varies from species to species, but very few species will replace all of their feathers as a hatch-year bird.
The adults, on the other hand, are wearing the same feathers they’ve had since the last year’s end-of-summer molt (some might have replaced their body feathers back in the spring, but very few will also replace wing feathers in the spring). After a year of use, of being subjected to wind and sun and thick vegetation, they’re a little worse for wear. At that end-of-summer molt, the adults will replace all of their feathers. And while they replace them sequentially, the timing is close enough together that they appear to be relatively the same age.
Compare that to the feathers of the hatch-year bird. Feathers grown as a nestling tend to be poor-quality: they’re grown all at once, and very rapidly – you can guess just how energetically costly this would be. To try to minimize the costs, the feathers grown are usually slightly narrower and shorter than those grown by an adult bird, more tapered at the tips, are less richly coloured, have fewer barbs, and are weaker such that they fade and wear faster than adult feathers. The feathers replaced in the end-of-summer molt, because the bird has more time to grow them, typically look like those of adults. Even though it may only have been two to three months between when the nest feathers are grown and when the end-of-summer molt is completed, there is often a noticeable difference between feathers of the two ages. This becomes even more pronounced by spring.
The bird in the top photo replaced the topmost tertial (the tertials being the three layered feathers that line up all in a row when the wings are folded) during its end-of-summer molt last year, but not either of the two lower tertials. The difference is subtle, but visible if you know what you’re looking for. The feathers are a richer, darker brown, with richer, wider edging. There’s a little bit of wear at their edges, but that’s to be expected with feathers that are exposed all of the time, and the wear along the outer edge isn’t as great on the upper tertial as it is on the lower two. This visible difference in age, called a molt limit, tells us this bird was hatched last summer.
The bird below is the same age; it was also hatched last summer. But the reason we know this is different. For some reason, this bird has had to replace all of the tertials and some of the inner greater coverts (those shorter feathers at the top of the tertials) on its left side. This might have been a run-in with a predator, maybe a fight with another bird, perhaps feather mites or some disease like that; I don’t know. Whatever the reason, it’s had to replace these feathers independently of its usual molt – we know this because all molts, whether hatch-year or adult, occur symmetrically on both wings. These feathers are relatively fresh. Dark, broad, richly-edged, these are adult-type feathers and it’s pretty easy to see the contrast between them and the hatch-year feathers on the right wing. Having them side-by-side like this makes the differences especially apparent. You can even see how the hatch-year feathers are shorter than those of the adult.
It’s obviously a lot harder to see molt limits on live birds in the field than it is while they’re in your hand, but in a few species it might be possible to spot them on birds at your feeders, for instance. The second bird here would undoubtedly stand out. It’s kind of neat to be able to look at a bird and know its age.
Like any thoughtful Significant Other would, Dan brings me gifts regularly. But unlike the usual bouquet of flowers or similar traditional items that most women probably get, my gifts are from nature, and perhaps the more thoughtful for it. I’ve had a little collection of such items on the shelf in my study, and when Dan brought me another the other day I decided I’d put them all together for a blog post.
The Blue Jay feathers have been on my shelf for a little while. I didn’t actually ask where specifically he picked these up from, but a jay was partially de-feathered along the trail back in our fields a few months ago, so perhaps it was from there. Blue Jay feathers are so pretty, such a surreal cerulean blue, a shade not well-captured in photos on a monitor. He just gave me the two feathers, shown here; can you tell from which part of the bird they came? The one on the left is a tail feather, while the one on the right, the one with the white tip, is a wing feather. The easiest way to determine this is by the placement of the feather shaft. On the tail feather it’s almost directly down the center of the feather, while on the wing feather, it’s offset slightly to one side. This offsetting actually tells you from which wing it came from, too; the shaft is closer to the outside of the wing than the inside. So this is a feather from the left wing. Blue Jays only have white on the tips of their secondaries, not the primaries, so we can narrow it down even further to a secondary on the left wing of a Blue Jay. Most passerines have 9 primaries and 9 secondaries, three of the latter group being shortened and modified to form the tertials, leaving only six full-length secondaries. We can tell within six feathers where this one came from on the bird.
The beetle bits are pretty neat. Dan found the single elytra, on the left, first and brought it back for me. I knew what it was from the size and pattern: it’s from a Giant Water Beetle, one of which I’d found at about this time last year. A few days later he found another, this one nearly intact except for missing its abdomen. Even the legs were still there, curled underneath. The interesting thing about the second, nearly whole one is the obvious puncture in the middle of the back. Was that made by a sharp bird beak? Or by the canine of a hungry raccoon? I asked Dan’s opinion, and he thinks it’s definitely a bird predation; I’m inclined to agree. We mused over what would be small enough to make a hole that size, that would be feeding along the water’s edge; his suggestion was grackle. All of the blackbirds have narrow, pointy beaks that would fit that size, and would forage at the edge of the pond, so this seems like as good a guess as any to me.
And the third item he brought to me Raven actually found. It was an egg that she’d picked up from under the cedar bushes near our house. Dan retrieved it before she’d damaged it too much; we’re not sure if she’d found it on the ground or where it came from, but couldn’t see a nest in the cedars. Dan’s guess is that it was from a Mourning Dove, which seems about right in terms of size and colour. He suggested I open it up to see if anything was inside.
So I did. And there was. At first it looked like it was just a lumpy blob of yolk, but then I noticed a darker bit at one side, partly concealed.
Finding a twig to use, I gently cleared away the yolk sac to expose the dark area. It turned out to be an embryo, still small, only about a centimeter (< 1/2″) long. The dark spots are its eyes, and its body curls beneath its head. Look at the network of arteries that has developed, running through the yolk to absorb the nourishment the chick needs to grow; the bird’s equivalent of our mammalian umbilical.
I stretched it out away from the yolk for a better look. Check out the tiny, translucent beak, the developing wings. You can see the rudimentary thumb on the wing, near the bend. Notice the pale spot in the eye. Birds have a ring of bone inside their eyeball, inherited from their reptilian ancestors, called the sclerotic ring. It serves to strengthen the eye and is often found in animals that lack spherical eyeballs. The pale spot is the hole in the center of the sclerotic ring.
Mourning Doves have an incubation period of about 14 days. Diagrams on this page (which is for chickens and therefore an incubation period of about 21 days) suggests the embryo is about halfway through its development; perhaps 7 days old for this Mourning Dove chick.
Check out this list of developmental events in the growth of a chicken embryo (taken from that same page). Look at how fast those first stages happen! And now think of it sped up by a third again for a Mourning Dove chick. Pretty amazing.
16 hours – first sign of resemblance to a chick embryo
18 hours – appearance of alimentary tract
20 hours – appearance of vertebral column
21 hours – beginning of nervous system
22 hours – beginning of head
24 hours – beginning of eye
25 hours – beginning of heart
35 hours – beginning of ear
42 hours – heart beats
60 hours – beginning of nose
62 hours – beginning of legs
64 hours – beginning of wings
!!!!! I prepared this last Friday (the 22nd), and thought I had posted it then. I just now noticed that WordPress didn’t publish it (or I forgot to hit the button?). Ordinarily I double-check to make sure it appears okay, too.
In the meantime, I’ve recently started a short-term job working as the bander-in-charge at Innis Point Bird Observatory – a post I also held last spring. I’m up at 3:45am (and getting earlier each week) so despite that I’m home by early afternoon I’m actually shorter on time. I’ll try to post regularly, as I can. Now, if only spring would hurry up and start happening instead of this dreary trickle we’ve been subjected to this year.
My image-editing program broke this week. If there’s one thing that inconveniences a photographer more than a broken camera, it’s broken editing software. I’m not quite sure what went wrong, but it required a full re-install, which meant digging out the installation files, uninstalling the previous copy, re-installing the program again, and then organizing all my internal settings again (I like my software to be just so). I’ve been putting it off because it’s a pain, but I finally got around to it this evening because I have some photos, taken today, that I’m looking forward to sharing.
I’ve been planning for a little while to make a trip back to the area where we used to live, near the lake house, to look for Infants, those early-spring day-flying moths. Although I could, in theory, find the species just about anywhere where the host species grows, they were just so abundant along the road near the lake house. But not only that; there was also that rare one that I found there, and I was keen to see if I could locate it again. I had intended to make a trip down last spring, but between one thing and another I never made it. I resolved I would definitely go this year.
And then this spring turned out to be cold. Cold and rainy, and slow, slow, slow in coming. We’re lagging about two weeks behind where we’ve been at this date the last couple of years. Our wildflowers are only just beginning to bloom. Insects have yet to emerge in any numbers. Migrant birds are running behind schedule. And we’ve only had a couple of those absolutely gorgeous days that one looks forward to at the start of spring. I’d been waiting to make my trip down to Frontenac, first for nature to get a move on, and then for a good day weather-wise to go. I was looking for something in the high teens Celcius (sixties Fahrenheit), sunny, and preferably not too windy. I waited… and waited, and waited.
Finally, today, I bit the bullet. It was a mild day, if not really warm, it was sunny, and the wind was light enough that in the shelter of the forest it wouldn’t be a problem. Given that on Sunday I’m beginning work running the bird banding (migration monitoring) program up in Ottawa, I was out of chances to get this trip in. So today it was.
Since I had a particular goal in mind I wanted to be prepared in case I should actually find my target species. I brought my camera, of course, but two lenses: the wide-angle for landscape shots and my macro for insects and flowers (I also had the telephoto, but after a bit of debate decided to leave it in the car). I brought my binoculars, for (hopefully) checking out any fluttery insects from a distance to decide if they needed to be snuck up upon. Also for looking at birds. I brought my bug net, just on the off chance that the moth wasn’t being cooperative and settling on the road for a photo; I could scoop it out of the air if it came down to it. I brought moth jars, and stuffed three of them in my back pocket to have close on hand. And I brought a cooler containing ice packs (which I left in the car), so that when I snagged the uncooperative moth and put it in a jar I could then put it in with the ice packs to cool down (hopefully) for a photo.
I walked about 5 km (3 mi) along the roads from where I parked my car, checking out the spots where the moths had been most frequently encountered a couple of springs ago. I saw quite a few other things, but lepidoptera were not in great abundance, and I didn’t find any of the moths at all. I’d gone with the expectation that I probably wouldn’t find the rare species, but I didn’t even see a single individual of the common one. Was I too late in the season? Was it too cool out? Too windy? Too much road traffic? (Being Good Friday, I had probably fifteen cars pass me in the two hours I was out there, which is pretty busy for that area, at least compared to what it was when we lived there.) Maybe it was simply that I jinxed myself by being over-prepared.
I was a little disappointed to not find any at all, but it was still a really nice outing. I spent two hours outdoors enjoying the sunshine and checking out flora and fauna. One of the first things I noticed was that the hepaticas were all out in full bloom. We don’t have hepatica up at our current house, but none of our other wildflowers are blooming yet, so this was a pretty nice surprise. Various shades of purples and pinks and whites, little patches of colour dotting the forest floor.
Also blooming was coltsfoot. Some patches of it can be quite large. It seems to like damp or poorly-drained areas (but not wet), and also favours disturbed habitats; I find it most often in the ditches along road edges where the ground gets a bit soggy. It’s an interesting plant in that the flowers come up before the leaves do.
I saw two individual blooms of bloodroot. The landlord has some planted in our garden, right near the foundation of the house, and they’ve been up and blooming for about a week now, but I haven’t seen any yet growing wild in our woods. These are one of my favourite wildflowers, so I was pleased to discover a couple.
As I was heading back to the car, having turned up nothing, I paused to listen to a funny bird call. I didn’t immediately place it, but it was easy to spot the caller, perched up in a tree: a Wood Duck! I can never quite get used to seeing a duck perched in a tree, despite knowing that Wood Ducks come by their name honestly. Both the male and female were perched there, though I didn’t immediately see the female and she wasn’t visible in the photo I took. Presumably they were scouting for a nest cavity. Wood Ducks will nest up to 2 km (1.2 mi) from water if cavities are hard to find; these guys weren’t nearly that far, only a few hundred meters.
While I was standing still, watching the ducks, I noticed (and was noticed by) a moth. It flew back and forth and up and down the section of road a few times, but when it came close to me it seemed to be attracted to something. I thought at first it was maybe the white bug net, or my white hat, or perhaps the orange vest. It landed on me a few times (once even on my sunglasses!) but when I went to peer at it, or even when I flipped the on switch of my camera, it took off again. It seemed disinclined to settle on the road for some reason, but I stayed patient with it, hoping it might put down somewhere. Well, it did – on my camera lens! It started dabbing with its proboscis, obviously picking up the salts from my palm (I wasn’t sweating, so there couldn’t have been much). I was able to coax it off the lens and onto my palm, where it started walking about and then up my arm. It finally stopped at the edge of my shirt (which was pushed up to my elbow; not the most convenient for photos, macro lens notwithstanding).
Check out the little hairs on its proboscis; I presume these are used to trap nectar when it’s drinking.
After taking a few shots, I touched it gently to try to get it to move back to another position, but instead it let go of my arm, folded its wings and dropped to the ground. This is a defense mechanism used by many species when disturbed: a fast and inconspicuous way to escape from a potential predator.
Once it was on the ground I could finally get a good look at it to identify it: it’s a Morrison’s Sallow, a relatively common species at this time of year. But since the Infants were a no-show, I’d take what I could get. :)
This was the only other moth I found. There were a couple of these, and I haven’t bothered identifying it to species, as moths in this group can be tricky. However, it looks like a Pseudexentera sp., or something closely related. Little micromoths often encountered out during the day.
I saw only two butterflies; one was what looked to be a Compton’s Tortoiseshell, fluttering in the tree canopy, and the other was this little guy, a species of blue. I always have to double-check my blues when I get home to be sure, but it turned out I correctly guessed on the ID of this one: a Spring Azure (Celastrina ladon), one of the first blues to be seen. Or, it could be the very closely related Lucia Azure (C. lucia), which the Kaufman butterfly guide notes, “The ‘spring azure’ in the northeast may actually be C. lucia“, though beyond this no notes are offered for specificity or overlap in range.
So all in all, a good outing, even without the Infants. Perhaps next year!