The birds were right along the road at Hardware Gap, the place in Jamaica most visited by birders. Knowing where warblers winter is key to conservation efforts. We've shown how birds are affected by forest fragmentation, cowbirds, pesticides, microwave towers, even pet cats. And we go to all the trouble to preserve breeding habitat for certain populations, but it's not going to make one bit of difference to their ultimate survival if we don't know where these birds are wintering. There's more than just the size of available habitat at stake.
Habitat quality is also a concern of scientists.
You may see a habitat with a lot of birds. But you have to remember that density of birds is not a good indicator of habitat quality. Maybe they're packed in there because they've been forced out of better habitat. The issue is not simple survival. The quality of winter habitat also influences a bird's success months later on the breeding grounds.