Taylor and Littlefield examined the effects that a reduction in disturbance had on the population numbers of two passerine species in southeastern Oregon. Cattle have grazed quite extensively on the Malheur National Wildlife Refuge since the late 1930's. Cattle use peaked in the early 70's but was dramatically reduced by the early 80's. Taylor and Littlefield looked at the change in yellow warbler and willow flycatcher populations from 1972 to 1982. Seven yellow warblers were sighted within the study area in 1972 while 56 were seen in 1982. During this time period AUM's had decreased by a factor of four. Willow fly catchers were absent during the first several years of the study, but began to show up by 1978 and 30 birds were recorded in 1982. The main factor involved in the reoccurance of both bird specie was an increase in shrub cover, mainly willow. Yellow warblers nest within two meters of the ground. Cattle grazing and made most of the willow species top heavy with vegetation and had taken away most of the prime nesting habitat for warblers. Taylor and Littlefield urged for more standard riparian habitat restoration, especially for shrubs that line streams, in order to enhance habitat quality for passerine birds.
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