Mom’s the Word

I’ve been in horse stables where Barn Swallows (Hirundo rustica) were nesting above the horses’ heads, barely out of arms-reach of people coming and going and everyone got on fine. The several pairs of swallows nesting in the barn here, however, are upset whenever I enter the barn, even though they are far overhead on the roof rafters. They seem to feel they should have the barn to themselves and set up a cacophony of distressed chittering when I arrive.

Meanwhile, just down the field the Tree Swallows (Tachycineta bicolor) are carrying nesting materials to their box.

When I was walking past this small pine tree, putting hay out for the horses’ breakfast, I noticed a dark shape near the trunk of the tree. A closer look revealed this female American Robin (Turdus migratorius) sitting on her nest.

Robins are numerous around here. When I was walking along the river, I noticed another mother robin, incubating her eggs.

Robins usually sit tight. That is, even when disturbed by a person close at hand, they stick to their nest and stay still. One season when Birdgirl was working on a nest monitoring study, she came across one robin who wouldn’t budge until she was actually putting her fingers in the nest to check for eggs. Now that’s a dedicated mom. In contrast to robins, Common Grackles (Quiscalus quiscula) are quite easily disturbed. When I walked past a small spruce tree, a grackle made a hasty exit and I knew to look for a nest. Here it is!

The mother retreated to the top of a nearby tree and complained loudly about my presence from the safety of her high perch. With both robins and grackles, the female incubates the eggs, keeping the eggs warm with her body. In order to warm the eggs efficiently, the female develops a brood patch, an area of skin on the belly that loses its feathers toward the end of the egg-laying period. Most birds shed the feathers automatically, though geese and ducks pluck the feathers and add the to the nest. The brood patch also develops extra blood vessels to bring hot blood close to the surface of the skin. When birds return to the nest after a break to resume incubating, they make settling-in movements while they position the brood patch so it is in contact with the eggs. In species where the male also incubates, males may also develop a brood patch. The feathers gradually grow back in after brooding is done.

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House Raising

Every winter, I think I will get around to building a birdhouse or two. I’m not particularly competent with a saw and hammer, but surely this is a basic enough task that even I might manage it. Every spring arrives with no new birdhouse. This year, I was anxious to get a few boxes up for swallows around the pond, and as the breeding season is upon us, I went out and bought several. I have had good luck in the past with the cedar houses carried by Walmart, pictured above, with Tree Swallows (Tachycineta bicolor), House Wrens (Troglodytes aedon), and on one momentous occasion even an Eastern Bluebird (Sialia sialis) pair successfully nesting and fledging young from this model. Bigger boxes would be better for Tree Swallows. Unfortunately, these are the best I’ve located, but hopefully I’ll be able to find or build bigger ones to replace them with down the road.

The quickest, easiest method I have found to get a birdhouse mounted on a post and installed is to use one of the metal spikes designed to support 4 x 4 posts. Even in rather rocky terrain, I was able to install them myself, and here in sandy soil, it’s a snap.
I put up three houses in likely locations around the pond in the afternoon and when I went out the next morning, they were being checked out by Tree Swallows.

The Atlas of the Breeding Birds of Ontario (2001-2005) offers the most comprehensive information available on who breeds where in the province. The current Atlas is the second edition and updates the status of breeding birds in Ontario from the first Atlas, completed in 1981-85. Since the 1980s, there has been a decline of up to 30 to 50 per cent in birds such as the Common Nighthawk, the Chimney Swift and six species of swallow. According to the Atlas, the Tree Swallow population overall in Ontario declined by 17%, but because of limitations in Atlas methodology in assessing population numbers, the actual decline may be greater. Annual Bird Studies Canada Breeding Bird Surveys show a decline of 2.6% every year over the 1981-2005 period. Barn Swallows (Hirundo rustica) showed a 35% decline using Atlas data, while annual Breeding Bird Surveys show an annual decline of 3.5% every year on average over the 1981-2005 period.

You can read more about the Atlas at the Environment Canada site. You can purchase the Atlas through Ontario Nature.

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A New Nesting Season Begins

Back in March, while there was still snow on the ground, I noticed a nest high up in the hoophouse on a bit of old machinery. It had been deserted last summer before the four eggs had hatched. I removed the nest to photograph it and didn’t replace it. Today, I walked into the hoophouse, looking for a shovel and glanced up. The nest was back! A pair of robins (Turdus migratorius) have replaced the nest in exactly the same spot. I hope they are successful in fledging a family from the new nest.

Meanwhile, out in the old barn, a half a dozen old nests on the roof rafters are evidence of Barn Swallows past. This week, Barn Swallows (Hirundo rustica) returned and when I entered the barn a few days ago, I was greeted by their disapproving chatter. Like robins, Barn Swallows use mud in the construction of their nest, but plaster the cup-like structure to a wall or beam in a sheltered location. The above view, looking up at one of the nests on the roof rafters, reveals the occupants forded tail! Swallow flight is swift and acrobatic, and they were difficult to capture with the camera as they flitted in and out of the barn, but here is one resting on a beam near the barn entrance.

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