The Coves Subwatershed is home to a multitude of songbirds, including forest-dependent species like the Great Crested Flycatcher, Eastern Wood-pewee, Red-eyed Vireo, Wood Thrush, and Rose-breasted Grosbeak; wetland-dependent species like the Red-winged Blackbird, Common Yellowthroat, and Willow Flycatcher; and threatened species like the Eastern Meadowlark. Despite this apparent diversity, songbirds in Canada are in decline.
How do we know that songbird populations are in decline?
A National Audubon Society report called “Common Birds in Decline,” shows that some widespread species generally thought to be secure have decreased in number by as much as 80 percent since 1967. Ornithologists (i.e. bird scientists) use a variety of methods to reach these kinds of conclusions. Researchers from York University, for instance, tracked the migration of purple martins from the Amazon basin to two breeding sites in eastern North America using tiny geolocator “backpacks.” Many scientists (with less money, or more undergraduate students) use the low-tech method of observing the number of species they encounter in the field, and then extrapolating this number using statistics to determine the approximate number of birds in the study area. The scientists who created the Coves Natural Heritage Inventory used this method by first dividing the Coves into suitable blocks of habitat, searching for birds where they are known to perch and forage, and finally conducting nighttime bird surveys for nocturnal birds like the Whippoorwill and Common Nighthawk.
Why are songbird populations in decline?
Scientists have provided several theories that might explain why songbird populations are declining. One reason might be that, due to climate change, spring is arriving earlier each year, so birds are arriving late to their feeding grounds. The consequence of arriving late is that there is much less food available for birds to eat. Less food for the parents means that fewer fledgling birds survive to adulthood, resulting in smaller songbird populations. Climate change is also known to increase the frequency and intensity of hurricanes, which can disrupt avian migration patterns and lead to massive bird deaths. Further, climate change, deforestation, agricultural and industrial development and urban sprawl are leading to the destruction of songbird habitat and isolating populations, causing inbreeding and a consequent decline in population health.
Other factors contributing to the decline in songbird populations include the death toll caused by skyscrapers and housecats. Smithsonian scientists released a report in January indicating that free-ranging domestic cats kill far more birds than previously believed: between 1.4 and 3.7 birds annually in the lower 48 states of the U.S. Similarly, millions of songbirds annually collide with city skyscrapers or communication towers, or fly into the glass windows of suburban houses.
What are some solutions to this problem?
Although the problem of songbird death is dire, it is not unsolvable. Let’s not forget that the Canada Goose was once hunted to near-extinction in North America. The problems of development, urban sprawl, climate change, and deforestation can be drastically improved by prioritizing and reforming economic and environmental policies. Unfortunately this is easier said than done. According to the American Bird Conservancy, however, cat predation, not these larger issues, may well be the greatest source of human-related bird mortality in the country. For this reason, the American Bird Conservancy has launched its Cats Indoors campaign, aimed at convincing cat owners and local lawmakers that the environment is better off when cats are kept inside -- as are the cats themselves. The Cats in Treehouses, Cats in Castles, Cats in Cardboard, Cats in Catnip, and Cats in Caps campaigns declined to comment on this contentious issue.