Of the roughly 200 regularly-breeding species in Vermont, nearly 75 percent are migratory.
- 55 percent of these are short- to medium-distance migrants, remaining mostly within the United States
- 45 percent undertake long-distance flights that carry some species (e.g., Upland Sandpiper, Bobolink) to central South America.
Threats during migration
- For some species, mortality during migration may be 15 times higher than during the relatively stable breeding or winter periods.
- Habitat loss at stopover sites perhaps constitutes the single most common threat among species, especially for habitat specialists or species that congregate at a limited number of key sites.
- Collisions: buildings and glass windows, power lines, communications towers, wind turbines, and automobiles are estimated to kill between 285,000,000 and 1,325,000,000 birds annually in the United States
- Migrants may also be harvested where regulations or enforcement are lacking.
- An array of natural hazards, such as severe or disorienting weather and native predators, can take a toll on migrants.
Threats on the wintering grounds
- Loss and degradation of winter habitats.
- Throughout the Americas, forests, shrublands and grasslands have been lost to development, small-scale subsistence farming, intensive commercial agriculture, grazing, mining, or timber extraction.
- Wetlands used by Vermont-breeding birds in winter have been polluted, drained, filled, and developed.
- Other threats include unrestrained cats, pesticides, oil spills and other pollutants, direct persecution, and legal or unregulated harvesting.
- Coastal marine areas are subject to overfishing, oil spills, etc.
- Climate change is expected to result in significant drying of moist tropical forests and more intense storms. Severe storms may lead to direct mortality among migrants and may also destroy habitat for wintering birds.
Conservation measures on the Neotropical wintering grounds generally lag behind breeding season conservation efforts in North America. For example:
- Species may be exposed to pesticides and other contaminants that are banned in North America.
- Hunting is unregulated in some Latin American countries.
- Land protection measures, where they exist, are often inadequate to prevent unchecked habitat loss.
Bird conservation paradigm is shifting to include “full life-cycle stewardship”, in which conservation of migratory birds is conducted across political borders. Conservation of Vermont’s migratory birds will require action well beyond our own borders.
