WatchList Species Account for Bay-breasted Warbler |
the list as a Declining Yellow List Species
|Photo: Ralph Wright
The Bay-breasted Warbler breeds in the
boreal coniferous forests in central and eastern Canada and
winters in Central America and northern South America. Its
populations rise and fall dramatically with outbreaks of the spruce budworm,
which form part of the natural cycle in maturing balsam firs.
During one outbreak of spruce budworm in New England, population
increases up to 300% occurred due to greater clutch sizes
and immigration of conspecifics into the area. Typically,
population crashes follow outbreak years.
Recent overall population declines in the
warbler may be in part due to insecticide spraying to control
the budworm; in addition, high levels of the insecticide have
been found in the birds. Changes in forestry practices in
eastern Canada such as shorter cutting cycles, large-scale
clearcutting and replanting with tree species more resistant
to spruce budworm mean less favorable habitat for the bird.
In winter its preferred habitat is forest edge and second-growth.
The species may be at risk because of habitat destruction
on its wintering grounds, where much land has been cleared
for cattle grazing.
Adoption of silvipasture practices on
the wintering grounds and a more judicious use of pesticides
on the breeding grounds—meaning lower dosages and less
frequent application—would benefit the species and help
reverse its decline.