Bay-breasted Warbler

A Bay-breasted warbler from my SONGBIRDS OF PELEE WORKSHOP at Point Pelee National Park of Canada.

In contrast to the more stable populations of other warblers, Bay-breasted Warbler numbers go up and down depending on spruce budworm outbreaks. The birds are abundant during infestations but decline or disappear from some areas a few years later. A similar relationship with spruce budworm exists for Tennessee and Cape May Warblers. Blackburnian and Blackpoll Warblers also readily consume budworms but are not as specialized in their diets.

Bay-breasted Warbler

During my recent SONGBIRDS OF PELEE WORKSHOP, a Bay-breasted warbler pauses for a split second at eye level during migration at Point Pelee National Park.

Bay-breasted Warblers eat eastern spruce budworm, a native but often destructive insect. The two species are so closely tied that budworm outbreaks (or declines) affect the warbler's population. Bay-breasted Warbler's overall population has dropped about 74 percent since 1966, likely due in part to pesticide use to control the budworm.