Bird experts aflutter over drop in rufous hummingbird numbers
Aug 16 2012
Rufous hummingbirds are dropping in numbers on the south Island, possibly because their migratory range has shifted due to climate change.Photograph by: Submitted photo , Jonathan Moran
The number of rufous hummingbirds visiting southern Vancouver Island over the summer is dropping and the cause may be climate change, says a local bird expert.
"It would appear that some of the declines we're seeing in the Victoria area may be related to a shift in the range, which may in turn be related to change in climate," said Ann Nightingale, co-president of the non-profit Rocky Point Bird Observatory.
Bird surveys show that populations of rufous hummingbirds, which migrate from Alaska to Mexico, have been dropping throughout southern B.C., Nightingale said Wednesday while on a break from the North American Ornithological Conference in Vancouver.
"We don't know for certain that this is happening, but it does appear that what is happening is the range is changing," she said.
Other bird species also appear to be shifting their range, which can put species at risk if they can't find food in the new areas.
For instance, Nightingale said, the hatching of mosquito larvae may be out of sync with the arrival of birds that traditionally feed on them.
People with backyard feeders will notice fewer rufous hummingbirds, said Nightingale, who noted that the number of the tiny birds visiting her feeders in Central Saanich is just 10 per cent of what it was in 1999.
Rufous hummingbirds are not to be confused with Anna's hummingbirds, which don't migrate and live in the area year-round. The number of Anna's hummingbirds has increased dramatically, said Nightingale.
The males differ in appearance, with the Anna's being larger than the rufous. The rufous males have a bright orangered throat while the Anna's males have a throat colour that's fuschia-pink.
Anna's hummingbirds are more commonly seen in urban areas while the rufous show up in the West Shore and in rural areas. The birds are territorial and will often chase away other birds from feeders within their territory.
Rufous hummingbirds tend to return to the same flower plots and feeders each year. Nightingale said one rufous hummingbird was captured at the same feeder where it had been caught and banded eight years earlier.
Birds that migrate face more dangers than those that stay put, another possible factor in the rise of Anna's hummingbirds and the decline of rufous hummingbirds.
Hummingbirds can live up to 12 years.
The Rocky Point Bird Observatory began in 1994 as a pilot project of the Canadian Wildlife Service. It became a society in 2000 and is connected to 25 migration monitoring stations across the country.