Vireos

In spite of their small size, vireos are economically important. Sightings of these birds are avidly sought by birdwatchers. Birding is a nonconsumptive field sport, and is increasing rapidly in popularity. Birding and related activities such as bird feeding have large economic impacts, and give great aesthetic pleasure to many people.

Unfortunately, the populations of many species of birds that are the targets of these activities, including vireos, are declining greatly because of human activities. This is especially true of many species native to North America.

Vireos and other birds that share their habitat are at risk from changes occurring in both their breeding and wintering ranges. There have been tremendous decreases in the areas of mature forests that most vireos require for breeding in North America. The vireos are affected directly by these losses of area of their essential habitat, as well as by indirect effects associated with the fragmentation of much of the remaining habitat into small woodlots.

Small, isolated, habitat "islands" are highly influenced by their proximity to edges with younger habitat. This circumstance exposes vireos and other birds of the forest-interior to a greater intensity of predation, and to the disastrous effects of nest-parasitism by the brown-headed cowbird (Molothrus ater). Many ornithologists believe that these factors are causing large declines in the populations of numerous species of migratory forest birds, including many of the vireos.