Island systems and species are susceptible to extinction because of their small population size and an ecological naiveté from an evolutionary past lacking strong competition and predation. For example, only one-fifth of the world’s bird species occur on islands, yet more than 90% of the avian extinctions witnessed during historic...
I examined the avian biogeography of the islands of Lago Gatun, Panama, in an effort to better understand the effects of forest fragmentation in this biodiverse region, and specifically to understand the importance of fragment isolation and the mechanism behind its effects on tropical bird distribution. I combined exhaustive surveys...
Seabirds are an integral component of marine ecosystems, however, because humans typically observe only snapshots of their lives at sea, our understanding of seabird foraging ecology is often limited. A more complete understanding of the ecological roles of seabirds and identification of critical foraging habitats requires the ability to follow...
Historically, least terns (Sterna antillarum) were one of the most common tern species in North America. However, population declines have resulted from direct and indirect anthropogenic pressures on their breeding and foraging habitat. Three subspecies of least terns have been described within the United States: California least tern (S. a....
I studied developmental rates in a suite of temperate and tropical passerine bird species from the New World to test the hypothesis that tropical passerines exhibit slower patterns of growth and development than temperate birds. I also investigated how the expression of several developmental rates varied with life history traits...
Vegetation provides food for many insects, and many insects serve as food for bats. We investigated the linkages among these three trophic levels in riparian areas throughout the Oregon Coast Range by examining the influence of vegetation cover, composition, and structure on the activity of nocturnal insects and bats, the...
This research was designed to evaluate the Fatty Acid Signature (FAS) technique as a non-lethal alternative to more traditional, and sometimes destructive, methods of studying the diet composition of piscivorous birds. Specifically we tested the technique with Caspian terns (Hydroprogne caspia) which currently nest in large numbers in the Columbia...
Greater sage-grouse (Centrocercus urophasianus) populations have declined across their geographic range during the last century. They were once widespread throughout the Intermountain West, but lower annual productivity, likely caused by degradation and loss of suitable habitat, has greatly reduced their distribution and population densities. Habitat used for reproduction has been...
Wavelet analysis is an analytical and modeling tool for optimizing sampling efficiency and accuracy, particularly in the context of designing long-term, large-scale monitoring plans. As a pattern analysis method that accommodates and preserves non-stationarity, wavelet analysis provides novel visualization and analytical capabilities for increased insight into interactions between multi-scalar heterogeneous...
The United States Fish and Wildlife Service currently uses fire as a management tool to improve Greater Sage Grouse (Centrocercus urophasianus Bonaparte) nesting and brood-rearing habitat at Hart Mountain National Antelope Refuge (HMNAR) in S.E. Oregon. Previous studies at HMNAR revealed use of burned areas by sage grouse throughout the...