We tested the hypothesis that aerial invertebrate biomass would vary with proximity to water and thereby impact food availability and habitat quality for insectivorous birds. We used malaise trapping of aerial invertebrates and video-camera observation of nests to test whether food availability (biomass of aerial invertebrates) and nestling provisioning rates varied with distance from standing water for Southwestern Willow Flycatchers (Empidonax traillii extimus) We then used a longer-term data set to test whether two indices of habitat quality (clutch size and nest productivity) were higher in nests placed near standing water. We found that 1) aerial invertebrate biomass declined by half at 30m from standing water, 2) parents provisioned nestlings at a lower rate (one fewer delivery per hour for every 100m) as distance to water increased, and 3) nests more likely to lay fewer eggs and times more likely to fledge fewer young as distance to water increased. These results indicate that for some Willow Flycatcher populations, patterns of inundation throughout the breeding season may drive invertebrate prey availability and potentially habitat quality.
|Advisor:||Theimer, Tad C.|
|Commitee:||Benford, Russell, McLeod, Mary Anne|
|School:||Northern Arizona University|
|School Location:||United States -- Arizona|
|Source:||MAI 51/06M(E), Masters Abstracts International|
|Keywords:||Food limitation, Invertebrate biomass, Nestling provisioning|
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