BREEDING DUCK POPULATIONS AND PRODUCTIVITY ON MONTANE WETLANDS IN ARIZONA

We estimated and compared breeding population sizes and productivity f or duck species using high-elevation (2,069 to 2,871 m) wetlands on po rtions of the San Francisco Plateau (SFP) and the White Mountains (WM) of Arizona, 1991-1999. Densities of breeding pairs increased annually from 0.60 to 1.08 pairs/km(2) (0.83 to 1.50 pairs/10 ha of wetland) o n the SFP site, and from 0.94 to 1.96 pairs/km(2) (3.12 to 6.51 pairs/ 10 ha of wetland) on the White. Productivity varied among species, bet ween sites, and among pears, but breeding populations and brood:pair r atios of all common species except northern pintails (Anas acuta) were greater on the WM site than on the SFP site each year. Mean number of ducklings in age class IIb broods did not differ between sites or amo ng years for each species. Consequently, estimates of total production of fledged young and recruitment rates were greater on the WM site fo r all species except northern pintails. Despite the small breeding pop ulations these areas support, production on these and other isolated w etland landscapes throughout the intermountain west may collectively c ontribute substantially to regional and continental populations of som e duck species, particularly on areas where productivity is relatively high.