Chimney swifts in rapid decline

BY LINDA BURR

International Migratory Bird Day is May 12

Chimney swifts will soon be returning to Canada from South America. Each spring, thousands of migrating songbirds pass through Ottawa. A few of them, such as the swifts, will make their nests right among us.

Unfortunately, fewer of them are returning each year and scientists are only beginning to understand the cause of their decline. (To read more about Glebe sightings see the August 2012 Glebe Report, p.33.)

Often described as looking like “flying cigars,” the chimney swift’s rapid jittery flight, dark sooty colour and constant chattering make it very distinctive. Pairs of swifts build their nests inside chimneys or under overhangs by sticking small twigs to the walls with their glue-like saliva. During the daytime, they are constantly on the move, searching for flying insects to feed their young. In the evening, they come back to their chimneys for the night. These remarkable birds used to be a common sight in the skies above Ottawa. The Canadian population of chimney swifts has declined by almost 30 per cent over the last three generations of birds (about 14 years) and the area they occupy has also declined by a third. The estimated Canadian population is about 12,000 individuals, and dropping. What is going on with the swifts to cause such a precipitous decline?

Chimney swifts belong to a group known as aerial insectivores, which catch and eat flying insects. Many aerial insectivores (a group that includes swallows and whippoorwills) have suffered severe population declines throughout North America over the past 30 years. But the chimney swift has had the most serious decline, in part because of the steadily decreasing number of suitable chimneys that swifts can use for nesting and roosting. Also, very few natural sites (large hollow trees) still exist.

Other causes for these widespread declines are unknown, but likely involve impacts to insect populations through pesticide use. For example, many municipalities, including Ottawa, actively spray pesticides to reduce mosquitoes and other flying insects that these birds feed on. Fear of the spread of the West Nile virus have led to regular spraying programs throughout many urban areas.

Have you noticed any chimney swifts in your neighbourhood? Would you like to become a “citizen scientist” and help scientists learn about the swifts? You can join the Ontario Swiftwatch Monitoring Program to find and track chimney swift nest and roost locations in your neighbourhood, and act as an urban steward for active nest sites. Bird Studies Canada (BSC) provides training, support, monitoring resources, and data management and analysis. You can find more information on the BSC website: www.bsc-eoc.org under Volunteer Programs.

The chimney swift is just one of a growing number of migratory birds on the official list of species at risk in Canada. All migratory birds face many hazards on their long journeys, but you can help to increase their chances of success.

HOW CAN YOU HELP MIGRATING BIRDS?

Many birds migrate at night, so turn off exterior lights and draw your curtains to help prevent bird collisions with windows, especially during spring and fall migration (May and September are peak months).

Keep your pets (especially cats) in a controlled space to prevent them from killing birds. Cats kill billions of animals per year in North America, including at least 500 million birds in the U.S. alone. Cat predation is one of the reasons why one in three American bird species are in decline.

Create a bird-friendly yard by planting native plants that provide food and cover; leave fallen leaves under shrubs, as they make good foraging sites, and avoid tidying up the garden until later in May when migration is over.

Leave fledglings where you find them; keep people and pets away so their parents can continue to care for them.

Avoid buying fruits and vegetables grown in Latin America. Population declines of some migratory songbirds have been linked to pesticide use on their wintering grounds in Central and South America. Pesticides which have been banned in Canada and the U.S. because of their toxicity to wildlife are still widely used in those countries, and result in significant numbers of bird deaths each year.
Buy shade-grown organic coffee; shade-grown coffee farms mimic native forests and support more bird species than sun coffee farms.

Finally, welcome back the birds this spring by celebrating International Migratory Bird Day on Sunday, May 12. Local groups are hosting a variety of activities in and around the Lac Deschênes Important Bird Area, including bird banding demonstrations, guided walks, and a bird fair at Andrew Hayden Park. For details please consult the website:
http://lacdeschenes.ca/events/.

Linda Burr who lives in Old Ottawa South is a biologist and avid backyard naturalist.