Research Letter
Long-Term Bird Assemblage Trends in Areas of High and Low Human Population Density
Table 1
Estimated mean year-to-year properties for
bird assemblages in HHPD and LHPD areas over a 25-year period throughout the United States.
All assemblage properties were first compared to the null expectation of no
change, and then each individual assemblage property was compared between HHPD
and LHPD areas. Rate of species increase is defined as a ratio between species
richness in year 1 and species richness in year 2, thus if there is no change
in assemblage structure (the null expectation), this value equals 1.
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