Every year we check the various nest boxes at FWG to see how they are faring and for signs of use. This report outlines our findings – and it might be of interest for others who do work with tree swallows, build nest boxes or are curious about who does actually move in! 2013 will see us unroll a project to ascertain which design we find works best, so stay tuned!
General comments: The decline in tree swallows using the nest boxes at FWG continues. While the species is definitely decreasing across its range, along with other swallow species, some tree swallow nest boxes within the Ottawa district had more success than we did. Some things that could contribute to the problem include increasingly unsuitable habitat around the pond (too many trees, not enough open areas), too much disturbance from visitors to the garden (some deliberate, for example, opening the nest boxes (but I have now remedied that), most of it inadvertent), and factors unknown.
Discussion: In 2012, only eight tree swallows nested at the FWG. This is fewer than in either 2011 or 2010. Ten boxes were unused by any birds or animals, and the rest were used by chickadees, house wrens, red squirrels and mice.
Last year, no eggs or dead tree swallows were found in any of the nests. This year, two dead, well-feathered young were found, in separate boxes, while one box contained a broken egg. The tree swallow nests were not particularly well-made, being very poorly feathered and rather sparse in makeup. Only two were typically well-feathered nests. The same thing occurred last year as well. Now, as then, I am not sure why.
One house wren nest and one black-capped chickadee nest were found.
Red squirrels nested in seven boxes, none of them in locations that are particularly appealing or attractive to swallows. I have left these boxes where they are because squirrels do use them and by so doing, they appear to leave the better located boxes alone. Peromyscus mice (probably the white-footed species) made nests in some of the boxes. Nests had also been started on top of some of the swallow nests, probably recently. One nest box had four mice in it, one had two.
I think house sparrow nestings at FWG are a thing of the past, as yet again, there was no sign of the species either nesting or visiting. Although abundant in winter until 2008, only a few pairs ever nested at the FWG, even when they were regularly seen at the garden.
Paper wasp (Polistes dominula) nests were found in four nest boxes.
One nest box was destroyed in the spring, before swallows returned, and several have fallen apart over the last winter. We need more nest boxes and we need to re-locate a few posts and nest boxes.
One nest box at the beginning of the hedgerow by a walnut tree (numbered 1A because we cannot recall when it was put there, or by whom) has always been used by red squirrels.
One nest box was not checked as it was at the far side of a wild raspberry stand and I didn’t want to create a trail by cutting through the dense plants. I will try to check it out later in the winter. In general, it has not been used by swallows more than once, and that was some years ago. Since then, it has been either empty or used variously by mice and red squirrels.
Our last batch of nest boxes were made without screws to lock the doors in place. This has meant that the boxes are more easily opened and tampered with. This year I closed the doors with screws of all but a few.
Nest box cleaning – results: My definition of successful is any nest that was completely built and obviously used and which contained no dead birds or unhatched eggs. The presence of a dead juvenile or of an unhatched egg or two, doesn’t mean a nest was unsuccessful, but neither was it a complete success. I note these as partial successes.
•Eight (8) tree swallow nests.
•One (1) box had a black-capped chickadee nest.
•One (1) box had a house wren nest.
•Six (6) boxes had mouse nests.
•Seven (7) boxes had red squirrel nests.
•Ten (10) boxes were unused.
•One (1) nest box was removed.
Back in 2005, Colin Freebury and I were trying to come up with a good nest box design. We developed a checklist of ideal features with a view towards building a better box, but we never really implemented this because we had a good supply of boxes in 2005. By 2008, when we needed more new boxes, Glebe Collegiate got in touch with us and built a batch of new boxes but they were to the old design we’d given them some years before.
Over the winter we’ll be developing two box designs for testing – very exciting!