Open-cup Nesting Passerines


Summary of Geographic Patterns

Species Richness

Because the vast majority of North American birds belong to this group, the species richness map for open cup nesters is very similar to the map for all species. The largest numbers of species occur from the Maritime Provinces and New England across the northern Great Lakes. The fewest species are associated with the southwestern deserts and the western Great Plains.

Population Trends

Negative trends prevail throughout most of North America, especially the eastern and central regions. Local areas with predominantly positive trends are evident from the southwestern states northward along the central Rocky Mountains and northern Great Plains into western Canada.


Discussion

For the open cup nesting group, only 40% of the species have positive trend estimates. While a large number of species comprise this group, all grassland, scrub/successional, and ground/low nesting species are members of this group. These three groups have the lowest percentages of species with positive trends, and may partially explain the prevalence of negative trends for open cup nesters across North America.