*Notes of Elizabeth Bernay, subject to augmentation
Given the diversity of habitats – sky islands, riparian areas, grasslands, deserts etc, it is not surprising that exceptional biodiversity is to be found in Santa Cruz and Cochise counties of Arizona. We are working to quantify what most biologists seem sure of and what many of them have found in their own specific areas of enterprise.
Bob Minckley published that the San Bernadino ranch has more than 600 species of bees, a greater number than any area of comparable size in the world.
This is a center of diversity for ants and grasshoppers though I cannot locate the references at present.
There known to be more species of hummingbirds and sparrows in SE Arizona than any other part of the USA.
The sky islands have 5 cat species, more than anywhere of similar area except African plains; also more mammal species than Yellowstone Park (which boast having the most mammal species in the USA)
For butterflies the top three states are Texas with 430, Arizona with 326 and New Mexico with 318 species. Of the Arizona species 267 occur in the SE corner: Santa Cruz and Cochise counties.
There are good data from natureserve on "species at risk". Santa Cruz and Cochise counties have an unusually high numbers of species at risk-- defined by natureserve website as species and distinct populations that are extinct (GX, TX), presumed extinct (GH,TH) and highly threatened (G1,T1), threatened (G2,T2), and vulnerable (G3,T3). Below are plotted these data by county in AZ and NM. Obviously larger areas have more species, so the plot is “species at risk” against area and as predicted the area relationship is shown with the black line.
The two extreme outliers, with many more species than predicted by the species/area relationship, are Santa Cruz county (3207:91) and Cochise county (16106:120)