Phainopepla Utilization of Honey Mesquite Forests in the Colorado River Valley

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Abstract
Phainopeplas [Phainopepla nitens] annually overwinter, breed and then leave the Colorado River Valley [USA] in May. Their distribution among 20 and 40 ha plots of slightly different vegetative structure was fundamentally dissimilar for the time periods of Oct.-Feb., March-April, and May. During each period distributions were similar. Although the evenness of distribution of phainopeplas among the transects did not change from Oct.-Feb., the portion of the overall vegetation actually occupied in Oct. was different than at other times. In Oct., phainopeplas occupied areas with fewer total trees than in winter or early spring. In winter they occupied areas with the greatest volume of mistletoe (a major food) and in spring (March and April) they were associated with denser vegetation (important for nesting). In late spring (May) they occupied relatively sparse areas that supported wolfberry bushes, and their diet consisted primarily of insects and wolfberries.