• Donald Attwood

Chimney swifts lose another round


PHOTO COURTESY SHUTTERSTOCK

The Chimney swift’s name is derived from its habit of nesting in brick chimneys after most of their natural habitat – hollow trees in old growth forests – were razed for development.

Acting on a phone tip, I went to Hudson’s Saint-Thomas Church shortly before sunrise on June 19. I saw three Chimney swifts circling overhead, but none emerged from inside the church chimney. After the planned installation of a cap and liner, none of the birds that roosted there would be able to return.

Ten days earlier, another phone tip enabled me to see these marvellous creatures which are scarce and threatened everywhere in their range. Five local residents were gathered in a parking lot across from the church, waiting to see the swifts gather at sunset and fly down into the chimney. Some slowed as they descended, but many dove headlong – how they found spots to land without bumping each other was a mystery. Two slender lightning rods were sticking about two feet above the chimney top and somehow the swifts avoided these hazards with ease. Here was yet another demonstration of the routine, high-precision, aeronautical virtuosity of birds.

In some locations in the southern US, it’s possible to see thousands of Chimney swifts funneling down nightly into a big chimney. People travel long distances to view these flights and there are numerous videos on YouTube. One of the best, ‘The Portland Swifts’ shows a closely related species (Vaux’s swift) swirling en masse into a school chimney in Portland, Oregon. Here in Hudson, with just a few dozen swifts, it was a moving sight. We were blessed to have these rare birds in our midst.

Swifts are among the most aerial of birds – their feet are unsuited to perching on branches and they spend the entire day in the air, gobbling insects. They even bathe on the wing, swooping down to skim the surface of a lake or river. The Chimney swift has been described as a ‘cigar with wings’ – a small, dark bird with a stubby tail. When they glide, their swept-back wings look like a dark crescent.

Chimney swifts winter in South America, in the upper Amazon basin (Peru, Ecuador, Brazil). They migrate every spring to eastern North America, arriving in southern Canada in May. Chimney swifts used to nest here in hollow trees, but European settlers and their descendants cut down all the old-growth forests and their old, hollow trees. In response, the swifts discovered chimneys. Numerous swifts roosting inside a chimney keep each other warm during cold spells. They have become almost entirely dependent on man-made structures for nesting and roosting sites. Communal roosts occur in large chimneys, those attached to schools, factories, and churches; smaller chimneys are used by nesting pairs.

Chimney swift numbers have been carefully monitored by researchers at QuébecOiseaux and at the federal ministry of Environment and Climate Change. They are listed as a ‘Threatened’ species in Quebec and are protected in Canada and the USA by the Migratory Birds Treaty Act. For years, the birds at Saint-Thomas Church have been observed by volunteers, and a band of neighbourhood enthusiasts took to watching them at sunset. The new chimney cap and liner came as a shock to these people. (Swifts cannot roost or nest on a metal liner.)

In an interview, Father Roland Demers, the priest at Saint-Thomas, confirmed that the church was having a liner installed. This would reduce a fire hazard, as he explained.

There are several reasons why Chimney swifts are in steep decline. As at Saint-Thomas, brick chimneys are being capped to protect them from weather, squirrels, and racoons, and metal liners are inserted to reduce the risk of chimney fires. New buildings tend not to have masonry chimneys, and old buildings are gradually being demolished.

Aside from roosting and nesting sites, these birds need food. Insects are being destroyed by pesticides, creating a general problem of environmental health. Helpful and attractive insects, such as bees and butterflies, are being wiped out along with many that prey on more harmful insects. Birds consume hordes of insects and if the latter have toxins in their tissues, these poisons accumulate in the birds – as happened earlier to Bald eagles and Peregrine falcons when DDT nearly killed them off.

Insects are an irreplaceable food source for a great many bird species – exterminate the insects and you exterminate the birds. The seriousness of this problem is signalled by the finding that a whole suite of aerial insectivores (swallows, martins, nighthawks, and flycatchers, as well as swifts) are disappearing. Grassland birds, such as meadowlarks, bobolinks, and kestrels (our smallest falcon), eat many low-flying insects, and they too are in steep decline.

Chimney swifts may also be threatened by climate change, which is causing more extreme weather events, like hurricanes, during migration season. And their winter habitat, the rainforest, is threatened by the expansion of cattle ranching in the Amazon basin.

The previous week, I saw several dozen swifts descending into the chimney of Saint-Thomas Church. In these troubled times, in this troubled land, they offered a sign of hope.

But on June 19, except for the three I saw at dawn, it was too late to say goodbye.

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