Jh. Gammonley et Lh. Fredrickson, BREEDING DUCK POPULATIONS AND PRODUCTIVITY ON MONTANE WETLANDS IN ARIZONA, The Southwestern naturalist, 43(2), 1998, pp. 219-227
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.