Declines in migratory bird populations have been linked to habitat fragmentation along avian flyways. Ecosystem conservation along bird migration routes protects food sources and places to rest during migration. Deforestation has reduced the number of safe places to rest on route, while light pollution draws night migrating birds into urban areas where they crash into buildings.
What is an Avian Flyway?
According to the definition used by the Convention on Migratory Species, which came into force in 1982, flyways are:
“the biological systems of migration paths that directly link sites and ecosystems in different countries and continents.”
For birds these flyways include breeding areas, migration stopover areas, areas where immature birds spend the breeding season, molting sites and post-breeding expansion sites. They encompass nearly every type of habitat as routes may change depending on wind.
How Habitat Fragmentation Affects Migratory Birds
Intertidal wetlands are being reclaimed for development in much of Asia, with resultant declines in many common birds that winter or migrate through the area from Europe.
Numbers of one subspecies of red knot (Calidris canutus rufa) in the western hemisphere declined precipitously when horseshoe crabs were over-harvested at important stopovers in Delaware Bay. Development along the shores of Delaware Bay adds to the problem as there are fewer places where red knots, which winter in South America and breed on the Canadian tundra, can rest and forage without being disturbed by humans.
In areas where habitat fragmentation has occurred birds are forced to stopover in what are known as migration bottleneck sites. Overcrowding puts the birds at risk of disease. Reduced food availability at stopovers may result in starvation if the birds are unable to get the calories needed for the rest of the trip.
Using Avian Flyways and Site Networks to Protect Endangered Bird Species
The Convention on Migratory Species attempts to address these problems by working toward international cooperation to protect vital stopover sites. The wide variety of birds that migrate and types of habitat used during their travels has resulted in the avian flyway concept being the basis of their work.
This cooperation is needed to insure that all the countries sharing flyways work together to provide habitat for the birds. A further refinement of the concept is site networks, one of the biggest of which is the Asia-Pacific Migratory Waterbird Conservation Strategy site networks, initiated in 1996. The site network encompases over 100 sites in 14 countries which help conserve shorebirds, cranes, ducks, geese and swans.
Combining knowledge and prioritizing land conservation at key points can protect multiple waterbird species protected more effectively.
It will be through joint actions like this that the effects of habitat fragmentation on migratory birds may be reduced. On an individual level, people can make choices which support these avian flyways and site networks. A simple example would be purchasing only shade grown coffee and thus supporting increased habitat for songbirds in their non-breeding home. Reducing light pollution in both businesses and homes will help reduce unnecessary losses during migration.
Dawn M. Smith - A vet nurse, Dawn has worked in wildlife rehabilitation and conservation around the world in addition to her veterinary hospital ...
Join the Conversation