A field guide to nestlings

Checking a nestbox

Yesterday afternoon Dan and I went out with our cordless drill to check the nestboxes in the fields behind the house here. There were ten nextboxes in these meadows, and another seven or eight at the 100-acre woods. We didn’t have time to get over to the latter group. One of the ten here had come unattached at one end and was hanging sideways. I wasn’t too surprised at this as they do seem to be fairly old boxes, but I hadn’t been expecting it. Fortunately, this seems to have happened before anyone got around to using it, but I intend to replace a few of the worst boxes and make sure the others are firmly secured so it won’t happen again.

The remaining nine boxes were all occupied, however. And all of the occupants were birds. This was gratifying for me, since I’d gone to the trouble of cleaning them all out back in March. It was fun to open each up and see who had made it home.

House Wren nestling

The first box we opened was the one that the bluebirds had nested in last summer. We had seen the bluebirds checking it out early this spring, but they had disappeared from that field soon after, and seemed to be hanging about the fields farther back. When we took the door of the box, it was apparent why they’d decided to leave: the box had been taken over by House Wrens. At the bottom of the box was the grassy base of a bluebird nest, and on top of that were the thick twigs that the wrens prefer for their foundation.

The nestlings we found yesterday were all at different developmental stages. This one is about halfway through growing. Its eyes are opened and the feathers are just starting to burst from their waxy sheaths. When I first lifted it out of the box the blue-gray sheen from the sheaths made me initially think “bluebird!” before I realized it didn’t see quite right, and noticed the brown fuzz of the emerging feathers. He’s still naked enough that you can see the big hole that is his ear, behind and about the same size as his eye. Once all the feathers are grown out these holes will be protected by a handful of special feathers with a low density of barbs that allow more sound to pass through.

Four of the nine boxes contained House Wren families. I knew about two of them, the two boxes nearest the house, as I’d heard the two males countersinging from time to time, but I didn’t realize that we actually had four pairs in the area. Most surprising was that the distance between the two farthest apart was only about 330m (1090 ft); four pairs crammed into less than four acres, food must be abundant here. All four boxes had baby wrens, some younger than others.

Tree Swallow nestling

There were two boxes with Tree Swallows nesting in them. The nestlings in the first box were younger than those in the second, and the adults were using a box that had been used by House Wrens last year. Even at this young age you can really see the difference in shape between the different species. The Tree Swallows are noticeably longer, with stubbier beaks, than the House Wrens.

Tree Swallow nestling

The young swallows in the second box were much nearer to fledging, perhaps only a few days away. This one sat alertly but quietly while I took its photo, but this was probably the last day on which it would; any older and it would likely try to make a break for it.

These guys were in last year’s chickadee box. We found a box that had housed chickadees this year, too, though I didn’t get any photos as the young seemed to have already fledged (perhaps they’re the ones I’ve been hearing begging for food in the trees around the house just recently). This year’s chickadees were in a box used by wrens last year. It’s interesting to note how the species all seem to move around, like they’re playing musical nestboxes. I would have thought that the “microhabitat” around each of the boxes would have more of an influence on who chose what box.

Bluebird chicks in nest

We had a sense of which areas the bluebirds might be in, but the first one took us a bit by surprise, as I’d actually thought this box was being used by Tree Swallows, and the one around the corner, which it turns out is being used by swallows, was the one I thought the bluebirds were in. As the chicks get larger it starts to be quite a tight fit in the little nest, and when you look in often all you see is a big mound of feathery bodies. It makes it hard to count how many individuals there are, especially once they’re past the stage of lifting their head to beg for food at any sign of movement. It looks to me like there might be five bluebirds in this box, but we didn’t lift them all out to check.

Eastern Bluebird nestling

The bluebirds are easy to identify because of the blue feathers, and the speckling on the back and shoulders that are characteristic of the thrush family (robins and the spot-breasted thrushes also show these speckles). The male chicks have got these lovely blue tail and wing feathers. Feathers of female chicks will be more grayish, perhaps with just a tinge of blue. I only removed the one chick, above, which happened to be a male, and I’m not sure what the ratio of males to females in the nest was, though I can see at least two males in the nest photo above.

Bluebird eggs in nest

The very last nestbox, at the very back of the property, was the second bluebird. While every other nest we’d check had nestlings (except the chickadee, which was empty), this last nest still contained eggs, the smooth blue-green that’s typical of thrushes (including robins). Tree Swallows have white eggs, and House Wrens speckly brown ones. The grassy lining here is typical of our bluebirds, too.

It’s great to see all the nestboxes being used, and all of the broods doing so well. On our next sunny day I’ll make a trip around to the 100-acre woods and see what’s happening over there, too.


Home among the colewort

Wren box and colewort

One of the things I love about waking up at my parents’ house is the sound of the birds singing in the morning. Specifically, the House Wren, who has settled in just under the guest bedroom’s window. For the last half a dozen years he’s sung from the garden, adding some very bubbly life to the backyard. Although my mom had always put out seed for the birds, we only put up some birdhouses when I got into birding myself, in university. It didn’t take long for the wren to discover them; I think he moved in the next summer, and he, or his offspring, has been there since.

There are now six nestboxes set up at various spots on the property (one of which has two compartments). In any given year most get used. In previous years there have been Tree Swallows in one, and Eastern Bluebirds in another, but for whatever reason they’re absent this year. However, to make up for that, we have three House Wren pairs that have set up territories at three of the boxes. I occasionally hear them counter-singing at one another, reinforcing their territory boundaries.

The garden wren has three boxes to choose from, but picked the one right next to a large flowering colewort. To put it in perspective, in the photo above the shepherd’s hook the box is hanging from is about as tall as I am. The colewort is a pretty amazing plant, growing to huge proportions, and it completely dominates that section of the garden. When my mom first planted it I don’t think she knew at the time just how big it would get. She had intended to pull it up after the first year because it took up so much space, but ended up leaving it. The wren thinks this is great, as it provides lots of good cover, right near the nest. I’ve seen the little birds foraging in and under the bush frequently.


When I went out to wander about the garden this week, I noticed the wrens took great exception to my presence. They hopped about first the crabapple tree, then the nearby apple tree, chirring at me and expressing their displeasure. When I located one with my binoculars, I could see it was carrying a mouthful of food. I didn’t leave right away, and it ended up swallowing the food so it could more easily focus its attention on distracting me. Birds only carry food, and get this worked up, when there are young nearby, so I knew they must have a brood in the garden nestbox.


I hid myself behind the corner of the garden shed, and waited for the adults to calm down enough to return to the box. Eventually the one (I think the male) did, coming to perch on the top of the shepherd’s hook and scout the area. He had a fat mouthful of bugs. It amazes me how much they can cram into their little beaks, you’d think as soon as they opened their mouth to grab another food item the first would fall out, a little like watching a dog try to pick up two tennis balls. Birds have amazingly dexterous bills, considering that they’re not flexible or opposing like our fingers. Can you imagine trying to weave a nest using just a pair of chopsticks?


I leaned around and propped my camera up on the corner of the shed, hoping to remain out of sight, but the wren spotted me and decided it wasn’t safe yet to duck in to feed the youngsters. He took off for the crabapple tree again, mouth still full of insects. Birds generally won’t approach their nest unless they feel confident that the coast is clear. It’s less their own safety they’re concerned about, and more trying to prevent tipping off a potential predator to the whereabouts of their young. A lot of time, effort and energy goes into raising a brood of young, and by the time they get to the age where they’re needing to be fed a lot, often it’s too late in the season to re-lay. So it behooves the parents to be overly cautious – given the harsh realities of migration, there’s a good chance one or both of the parents may not return to try again next summer.


Eventually they did both settle down, and came in to the box where the hungry mouths were waiting. I think this is the female, as she was quieter, and appeared a mousier brown than the bolder male, who somewhat resembled a Winter Wren in the darkness of his patterning and barring of the chest. Of course, there’s also two colour morphs of the eastern subspecies of House Wren, a brown and a grey, and it could be the pair is composed of one of each, unrelated to sex.


Delivering the goods.


Off for another load. Young birds, like young humans, basically spend all their time eating and sleeping and growing. A newly hatched nestling will need to be fed every 15-20 minutes, which keeps the parents hopping to try to find enough food to fill as many as five or six hungry bellies.


About 40 meters/yards away, another male sang atop his chosen nestbox. I notice this one’s paler, but is definitely a male, so maybe the colour difference in the first pair is simply a morph after all. There wasn’t any evidence of a female associating with this guy, but she could be inside the house incubating. While she’s on the eggs, the male doesn’t have a lot to keep him busy and will spend most of his time singing and defending the territory.


He moved to some nearby saplings where the lowering sun’s rays illuminated his pale breast. It’s really a shame that a single photo can’t capture the burble of a House Wren’s song. Their mandibles tremble rapidly like the bird is shivering with joy as the cheerful notes tumble out of its mouth. I might see if I can borrow Blackburnian’s camcorder to get some video clips of the House Wren and other things.

Life and death in a birdhouse

House Wren at birdhouse

With the nice weather yesterday, and perhaps also as a symbol of the new season, I took my screwdriver and went out to clean out the birdhouses to make room for this year’s residents. When I was growing up we didn’t have birdhouses set up. I’m not sure why, because we always had feeders. Perhaps it just hadn’t occurred to us. Sometime in university I think I won a birdhouse in a bird-related contest that I’ve since forgotten the details of. We put it up that summer, and it wasn’t long before a House Wren set up shop. The burbling song brought such life to the garden – not that the garden hadn’t been lively before, but the wren just added that sparkle.


There’s now five and a half birdhouses out in the garden: four traditional single-unit houses, and a double-unit house. The double-unit is the above covered wagon, which my mom won at a convention or AGM some years ago. By the end of the summer, every single one of these houses has been checked out or used, and they all need cleaning the next winter. The primary residents are the House Wrens, although we have had Tree Swallows and Eastern Bluebirds using a couple of them during the early part of the season (once they’ve fledged the wrens move in and raise a second brood there). There’s perhaps as many as three pairs of wrens on the property, although it can be a little hard to keep track of them.

House Wren nest

Both compartments of the covered wagon had been stuffed with twigs. Wrens make very characteristic nests in boxes, you can always tell it’s a wren when you take it out. Somehow they manage to tote these twigs, many longer than their own body, back to the nestbox, pull them through the small opening, and stuff them into every corner. They fill every nook and cranny in the box, and the result is a firm rectangular nest that holds its shape even when you take it out of the box.

House Wren nest

This wren has lined its nest with horse hair, which is abundant at the property, what with there being five of them plus a donkey within easy flying distance. You can tell which horses donated their hair to the nest by the colour of the strands. There’s also downy breast feathers from several birds, which suggests that this was a late-summer nest, after some other species had already finished raising their brood and had started moulting in fresh feathers. The bright orange one is obviously from a Baltimore Oriole; the others I’m less sure about, but could possibly be from a robin.

House Wren dummy nest

In the compartment on the other side of the wagon was this nest, which fell apart as I removed it. It had no lining and appeared to never have been finished. House Wren males will build multiple nest structures that they then show off to their prospective females. The female decides which one she likes best, and then works to finish lining it to start the family in. You can tell a lot about the surrounding trees by what the wren has stuffed in its box; in this case, the box isn’t far from a grove of cedars that would have provided a fair bit of easy, short building material.


This is the Tree Swallows’ box. They usually arrive early in the spring (perhaps in the next couple weeks) and start checking out the boxes in the yard. They invariably choose this one in the end. They raise one brood and then move off. They leave at about the same time that the wren is looking to start up a second brood (or a third), and he’ll often move in to build his own in there.

Wren nest in birdhouse

Here’s the house with the door open. I can’t recall now whether we cleaned this house out between tenants or not, but the wren’s twigs go right down to the bottom of the box, so it’s possible we did, or he stuffed more in there around the swallow’s nest. Either way it’s very much a wren nest now. They like for their nests to be a certain height below the entry hole, and will fill the bottom up with twigs to bring the lined nest up to that height as necessary.

House Wren nest

The hole in the covered wagon is much closer to the bottom than in this nestbox, and so the twigs were used more to fill the back of the space than to fill the bottom, you could actually see the snow through the bottom of the cup. In this case they needed to bring the height up a fair bit, and the bottom two or three inches are solid twigs. I’m not sure what laundry Mom was hanging out on the line at the time, but it may have been a sleeping bag or comforter – the lining at the top of the nest is partially composed with synthetic fluffy filling.

House Wren nest

When I opened the nest up to check out what the wren had used in building it, I was surprised to discover something in it. At first I thought it was a clump of fur, maybe leftover from an owl’s rabbit kill or something like that, that the wren had picked up. But it turned out to be a little baby wren, old enough to have fledged, but still in the nest. Why?

House Wren chick

The answer was in its position. One leg was stretched out way in front of its body, and in removing the little bird from the nest I found a strand of the synthetic filling wrapped around its foot. I actually had to snap the strand to get the bird out of the nest. Evidently the nestling had become caught, and couldn’t leave the nest when its siblings did. It would have starved to death as a result. It’s rather sad.

House Wren wing

The nestling was soft in my hand. They are the most beautiful mousey brown, even the colour suggests soft. Their wing feathers are a little rustier, particularly when young, and barred in neat lines characteristic of wrens. I left it in the nest contents where I found it. I feel sad for it, but I also have to consider that this is nature. Perhaps only one of those young birds that left the nest last summer will survive to return to the area this spring. A bird’s first year is brutal, and the death rate among first-year birds is very high. Once a bird has made it through its first year its chances of surviving to three or four years, or perhaps even longer, is greatly increased. So instead of dwelling on this one death, I look forward to the return of these cheerful little birds, the ones who’ve made it through another winter, in the coming month.