Cliff Swallows

Royal Botanical Gardens. Hendrie Valley, Burlington. ON. June 22 2022. On a day forecasted to be a scorcher, I did a quick and early hike of the length of the valley looking for better evidence of certain breeding  birds. This was as part of my data-gathering efforts for the Ontario Breeding Bird Atlas.

I’m particularly interested in spotting higher levels of breeding evidence for Green Herons and Yellow-billed Cuckoos. I’m pretty sure the herons nest somewhere along the creek and I’ve watched a pair of cuckoos that seemed well settled in. For the record I didn’t see either species today, but I did happen upon a surprise colony of Cliff Swallows.

The valley is crossed by a lofty road bridge, the supporting piers of which are enjoyed as wide canvasses by spray-paint artists.  Those decorators’ reach is about 3 meters at best, but some 30 or 40 metres above them, where the piers meet the road deck, Cliff Swallows have built their gourd-shaped nests. Their nests are constructed of mud, and adhere, largely by the grace of God, to the underside of concrete bridge decks and ledges. Here they’re using a road bridge, which evidently works well for them, but railway bridges with all of their attendant vibration are high-risk nest sites.  Collapse and disintegration of the nests are an unhappy fact of life and death for the species.

Cliff Swallows are considered common, yet I don’t see them very often, probably because of their rather preferred habitat. Originally, they were birds of the western mountains, they have spread east and are adapting to man-made structures that substitute for steep canyon walls with overhangs.

Today’s colony is the third that I know of within my 10Km.X10Km. atlas square. And I probably wouldn’t have noticed it had it not been for a lively group of swallows, mostly adults as far as I could tell, alighting along the water’s edge and apparently picking at the soft mud. Adults  are distinctive for having a bright white or cream triangle on the forehead, like a headlight. It seemed to be a social gathering with much wing fluttering and apparently brief, good-natured tussles. I tried for photographs but my results were disappointing, too gloomy or, more likely, too much handshake, but here’s one, for the record…..