Yesterday while down at the research station I spent some time watching a pair of Barn Swallows collect mud from a little puddle we have out front and carry it off to build their nest with. They spent most of the morning working on it, or at least the portions where I was outside to observe them (yesterday was an exceptionally busy morning, and as it was the coordinator’s day off I was the sole bander, which kept me inside for a good portion of it). Once things had slowed down enough in the lab, such that I had a bit of time to grab a snack and catch my breath, I took my camera out to shoot a few photos of the pair.
I believe the above two photos are of the male. The female Barn Swallow usually has a paler belly than the male. In Europe, where it’s simply called the “Swallow”, hers is nearly white. The species, Hirundo rustica, is found through most of the northern hemisphere, with six distinct subspecies across its range. The North American subspecies is H. r. erythrogaster, separated from others by the absence of a dark blue breastband separating the orange throat from the creamy belly.
I also noticed that the male appears to have a pale collar across the back of his neck, visible in these photos. I’m not sure what this is the result of, or even whether it’s just a plumage anomaly, or caused by an injury or somesuch. You see this sort of marking often with mammals, where the hair that grows in over a scar is white (this is the premise used behind branding livestock).
Here he picks up a leaf, probably more out of curiosity than desire to use it in the nest, since he dropped it quickly.
Both individuals of a pair will collect mud to build the nest with, and they were coming regularly to the little puddle, not much more than a few feet across. They would perch on the stones beside the puddle and were fairly tame, in that they wouldn’t fly if you walked by some metres away, providing you didn’t appear to be focused on them. The female is caught mid-step in this photo. I loved watching the two of them walk across the ground, since their especially short, stumpy legs meant they more waddled than walked. All swallows have very short legs, I presume so that they tuck out of the way and increase aerodynamics when flying, since much of their life is spent on the wing.
After getting what he felt was a satisfactory beakful of mud he took off to add it to the nest. Barn Swallows spend so much time on the wing because that’s their primary foraging method. They’ll chase flying insects in the air, demonstrating swiftness and maneuverability characteristic of swallows. They’ll skim the water’s surface with their mouth open to scoop up water to drink, and will even bathe this way. The wings of swallows and other aerial foragers are built for spending long periods in flight while minimizing the energy required to do so, and are characteristically long and narrow.
Along with the other swallow species, and other aerial foragers such as nighthawks and swifts, North American Barn Swallow populations have been declining over recent decades. The cause of this is unclear, but given the similar foraging habits of the group, it’s likely at least in part caused by declines in the flying insects they rely on for food. For those of you old enough to have been driving for a while, think of the number of bugs you see stuck to your grill or splattered on your windshield in the summer these days, compared to a decade ago – when you stop to consider it, probably you’re not seeing as many as you used to. In just the last 20 years, the Ontario population of Barn Swallows is estimated to have declined by 60% (and an even greater 75% Canada-wide), meaning only 40% of the swallow population from 20 years ago still remains today. Twenty years isn’t a long period of time, and it’s disturbing to think what may happen to this and other species in another twenty – within all of our lifetimes.
There are hardly any buildings in the area, so I knew the pair had to be building on one of them. The obvious choice was a nearby building, the other side of the parking lot from the research station’s building, which sported a nice broad covered deck. I walked around and across the deck looking for their nest, but didn’t spot anything. As I was pausing to consider other locations, the pair returned with more mud, alighting on a nearby picnic table to decide whether I posed enough of a threat to not want to give away the nest location.
Eventually the male decided I was harmless and flew up to the nest location, a spot I had completely overlooked. The nest was still in the early stages of construction, which is why I hadn’t spotted it immediately.
Barn Swallow nests are made primarily of mud layered up into a thick caked wall, and lined with softer material such as grasses, feathers, or hair. Before humans came about to offer excellent nesting locations, the swallows would build their nests on cliff faces or in caves, against the sheer vertical rock walls. They ordinarily either build it on a ledge, or butted up in a corner, but in either case it’s placed high up under an overhang. Human structures, with their eaves, rafters, porches, gables, etc, have been perfect for building nests on. Unfortunately, because of the droppings that tend to accumulate under a nest during the weeks it’s being lived in, they can also be an unwelcome tenant for some homeowners.
Perhaps because I’d moved in a few steps closer to get a better angle with the camera, or perhaps simply because I was still there, he was less inclined to go directly to the nest the second time he came back with mud. He flew up to the other light and stared pointedly at me until I turned to leave them to it. I’ll poke my head in next time I’m down to check in on their progress.