Canadian bird species are in severe decline
A host of reasons have led to a severe decline in many of Canada's bird species. Birds are at risk due to habitat loss, climate change, collisions, and cats.
Canada is home to over 450 native bird species, many of which are in serious population decline. In the past we have successfully collaborated to bring birds such as the eagle, falcon, and osprey back from the brink of extinction. There is no reason we cannot do so again.
Canadian bird monitoring programs that began in the 1970s show that 44 percent of monitored birds have declined significantly. Currently 66 different species are listed as either endangered, threatened, or of special concern. The reasons for this decline are varied, but habitat loss seems to be the primary force directing this trend. Climate change, infrastructure development, cats, and pollution are also significant contributing factors.
Birds live in a variety of habitats in Canada, including grasslands, wetlands, forests, offshore, and in the mountains, oceans, and arctic tundra. Birds can be placed into groups representing their habitat or lifestyle. For instance, aerial insectivores catch and eat insects in flight; grassland birds make their home in native grasslands; and shorebirds are often found in shallow waters, on mudflats, or along shorelines.
Aerial insectivores, including chimney swifts, are experiencing the greatest decline of all the groups. In eastern Canada in particular they have decreased by 70 percent. The reason why this group is so hard hit is not clear, but a combination of habitat loss, climate change, and pollution may be to blame.
Grassland birds are facing severe habitat loss and fragmentation. Agricultural intensification practices, such as the conversion of pastureland to cropland, increased chemical input in the form of pesticides and fertilizers, and low fallow ratio (period of time cultivated land is allowed to “rest” relative to cultivation period), result in loss of grassland habitat that many bird species, such as the burrowing owl, live in.
Waterfowl are also experiencing significant habitat loss. The wetlands of the Prairie Pothole Region are considered the “waterfowl nursery of North America,” and half of the continent’s ducks come from this region. This habitat, which is located mainly in Canada, consists of thousands of temporary, small, shallow wetlands that serve as home and nesting grounds to millions of ducks, geese, and other waterfowl each year.
Anywhere from 50 to 90 percent of this habitat has been degraded, due to drainage for agricultural use or drought caused by climate change. Many sources believe the Prairie Pothole Region is the most important and most threatened waterfowl habitat in North America.
Changes in our climate are also changing the landscape, particularly for migrating birds, causing habitat loss in the form of altered wetlands, estuaries, deltas, and mudflats. Shorebirds, who migrate long distances and so are vulnerable to habitat loss during their entire journey, have declined by almost half.
Flying into man-made buildings and structures kills hundreds of millions of birds in North America each year. A recent study puts annual bird mortality from collisions with communication towers at 7 million, most of which results as the birds migrate from Canada and the US to South and Central America.
A US study from 2005 indicates collisions with homes and buildings cause nearly 58 percent of the annual bird mortality estimate, or nearly 550 million bird deaths each year. As for claims that collisions with wind-power generation sites cause a significant number of bird deaths, the study estimates that wind-turbine-related bird mortality accounts for less than 0.01 percent of the annual bird mortality estimate (US), or approximately 30,000 bird deaths annually.
Certainly, the death of 30,000 birds a year is significant, but this number is dwarfed when compared to the number of birds killed annually by cats in Canada: 100 million. Cat-related bird deaths amount to nearly 11 percent of the annual mortality estimate.
Lessons from the past
In the early 1960s, Rachel Carson’s book Silent Spring caused widespread public concern about declining raptor bird populations, such as the eagle, osprey, and falcon. Thanks to the grassroots environmental movement and conservation efforts that grew out of this concern, raptor populations have steadily increased and rebounded.
The success of this past intervention to prevent extinction of raptor birds shows that grassroots conservation efforts can create positive change. It is important to keep such lessons in mind as we move forward and tackle new environmental and ecological challenges, such as our current bird population decline.
There are many lifestyle choices we can make to help the birds.
10 of Canada’s at-risk birds
|burrowing owl||has been in steady decline since the 1930s; in 1995 was put on the endangered species list|
|chimney swift||population has declined to less than 25 percent of its size in 1970|
|eskimo curlew||a member of the sandpiper family, this critically endangered shorebird may be extinct, but reports of potential sightings give hope there may still be a small population|
|ivory gull||an arctic species that is losing its feeding grounds to climate change; it is believed there are only 500 to 700 adults living in Canada|
|loggerhead shrike||in 2003, fewer than 30 breeding pairs of this songbird existed in small pockets of Southern Ontario; although small gains had been made through a capture-and-release program, the loggerhead shrike is still considered critically endangered|
|piping plover||this species builds nests on beaches, which are often disturbed or destroyed by tourists and recreational vehicle users|
|sage grouse||current estimates put the sage grouse’s population size at less than 100 individuals|
|sage thrasher||considered one of the rarest birds in Canada|
|whooping crane||down to only 15 individuals in 1938, conservation efforts have increased their numbers to nearly 600 individuals; although considered a success story, the whooping crane is still significantly endangered|
|wood thrush||once a common forest species, its population has decreased by almost 70 percent in the last 40 years|