Publication Type:
Journal ArticleSource:
American Birds, American Birding Association, Volume 40, Issue 5, p.1169-1173 (1986)Call Number:
A86TAY01IDUSURL:
https://sora.unm.edu/node/114426Keywords:
cattle grazing, Dendroica petechia, Empidonax traillii, willow flycatcher, yellow warblerAbstract:
Focusing on the Malheur National Wildlife Refuge and the lower Blitzen River valley in Harney County, southeastern Oregon, the authors found that populations of the willow flycatcher and the yellow warbler, and the willow habitat in which they nest, recovered with reduced cattle use and associated disturbances. Breeding Bird Survey (BBS) data show yellow warblers steadily increasing on the refuge (7 birds in 1972 increasing to 56 birds by 1982). Grazing intensity (AUMs) decreased by a factor of four over the same period. Willow flycatchers were absent the first several years of the BBS, but began increasing in 1978, after AUMs had decreased by one-half. By 1982, 30 flycatchers were recorded on the BBS Data from transects set in 1981 and 1982 show the same trends. In those two years, the transects had a negative correlation between shrub volume and the frequency of cattle use on an annual basis. Yellow warblers were more numerous on transects with abundant willow and little or no cattle than on transects with heavy cattle use and low shrub volume. Willow flycatchers were found in high numbers only on transects with high shrub volume and which were either undisturbed or rarely used by cattle; they were in low numbers or absent on transects with low shrub volume and heavy cattle use. The yellow warbler and willow flycatcher population increases on Malheur NWR coincide with a dramatic decrease in cattle on the refuge and elimination of willow cutting and spraying. The transect data indicate that higher numbers of both species are correlated with amounts of healthy willows, which are used for nesting sites. The data gathered during this study show that actions improving riparian brush habitat in the temperate latitudes can increase populations of the yellow warbler and willow flycatcher.
Notes:
Reference Code: A86TAY01IDUS
Full Citation: Taylor, D. M., and C. D. Littlefield. 1986. Willow flycatcher and yellow warbler response to cattle grazing. American Birds 40(5): 1169-1173.
Location: ANIMAL EF: BIRDS; ELECTRONIC FILE - Zoology