Bird Populations Reduced by Habitat Loss — habitat loss is almost certainly the single biggest reason for the gradual extinction of wild animals on the planet. It is always due to increased human activity and nearly always linked to commercial activity. Mining and logging are the big businesses that are the culprits.
The nice thing about this picture is that it is an authority, the Wisconsin Department of Natural Resources that have declared very transparently that it is humans who are a major threat to wildlife.
The sign relates to an area around Pike Lake State Park north of Milwaukee — see Google map.