The Big Picture: Large-scale Summary of
Population Change and Species Richness
for Species Groups
This part of the Home Page provides an overall summary and
discussion of large-scale patterns of bird species richness and
population change (since 1966) for North American grassland birds.
Analysis of Percentage of Species with Positive Trends
Grassland bird species have the smallest percentage of increasing
species of any group of North American birds. Here is a histogram
comparing percentage of increasing species for 12 groupings of North
American bird species and for the collection of all species. See below
for a listing of the groups and their component species.
Click here to view histogram showing percentages by species groups
Maps and Summaries for Grassland Birds
Description of Methods
Click here for a description of the methods and rationale for analysis
of species groups
Click here for a note about calculation of species richness
Species Group List
Click here to view species lists for each group