Why are listed species considered to be of management concern? To gain some insight into this question, we analyzed the data provided by participants in the Phase II Delphi exercise. Participants were asked to indicate which of five factors were of concern to them. More than one factor could be checked for each species. The 65 species selected in Phase II and examined here received a total of 823 tallies to this question, an average of nearly 13/species (range, 1-30). The primary reasons for concern (i.e., those mentioned by the largest number of Delphi participants) were, in decreasing order:
a. Known or apparent population declines or range retractions 30 species
b. Dependence on restricted or vulnerable habitats 21 species
c. Small populations or restricted range in U.S. 15 species¹
d. Potential impacts of perceived threats 14 species²
In the case of the 30 species that were of concern primarily because of known or apparent population declines or range retractions, significant long- or short-term declines have been documented by the BBS for 22 species. The exceptions are black-shouldered kite (poorly sampled), red-shouldered hawk (significant increase), burrowing owl (no detectable trend), common nighthawk (no detectable trend), Bewick's wren (no detectable trend), gray-cheeked thrush (poorly sampled), golden-winged warbler (no detectable trend), and Lawrence's goldfinch (poorly sampled).
Assuming that concerns for these 65 species are a representative sample of concerns for all 122 listed species, it is apparent that about 46% of the species are of concern because of known or apparent population declines or range retractions, 38% are of concern because of ecological bottlenecks (i.e., this includes the 32% that are dependent on restricted or vulnerable habitats, and the 23% at risk due to small populations or restricted ranges in the United States), and 22% are of concern because of the potential impacts of perceived threats..
¹ Includes 4 species listed under "b" ² Includes 11 species listed under "a," "b," or "c."[Discussion Contents]