Landbird Migration in the American West: Recent Progress and Future Research Directions

Abstract

Abstract. Our knowledge of avian behaviors during the non-breeding period still lags behind that of the breeding season, but the last decade has witnessed a proliferation in research that has yielded significant progress in understanding migration patterns of North American birds. And, although the great majority of migration research has historically been conducted in the eastern half of the continent, there has been much recent progress on aspects of avian migration in the West. In particular, expanded use of techniques such as radar, plasma metabolites, mist-netting, count surveys, stable isotopes, genetic data, and animal tracking, coupled with an increase in multi-investigator collaborations, have all contributed to this growth of knowledge. There is increasing recognition that migration is likely the most limiting time of year for migratory birds, and this places increasing importance on continuing to decipher patterns of stopover ecology, identifying critical stopover habitats, and documenting migration routes in the diverse and changing landscapes of the American West. Here, we review and briefly synthesize the latest avian migration findings and advances and consider research needs to guide future research on migration in the West.

Food Availability, Foraging Behavior, and Diet of Autumn Migrant Landbirds in the Boise Foothills of Southwestern Idaho

“…While in their study of migrating Sedge Warblers (Acrocephalus schoenobaenus) in Britain Bibby et al (1976) established a direct correlation between measured food levels and migrants' condition in different years, few other studies have directly examined the connection between food availability and mass gain of migrating birds. This is particularly true in western North America (but see Kelly et al 2002), where relatively little is known about stopover ecology in general (Carlisle et al 2009) and about food availability in particular.…”

“…Microhabitat and diet data are particularly needed for migrants in western North America given the paucity of data regarding the stopover ecology of these birds generally (Carlisle et al 2009) and the shrinking availability of the riparian habitats thought to be preferred by many species (Finch and Wang 2000, Petit 2000, Mehlman et al 2005, Webb et al 2007 .…”

“…For example, degradation and loss of stopover habitat will likely increase competition, decrease access to resources, and, at a minimum, slow the pace of migration (Moore et al 1995). With the increasing human-induced challenges facing migratory birds (Mehlman et al 2005, Carlisle et al 2009) and the fact that the majority of migratory landbirds' annual mortality occurs during migration (Sillett andHolmes 2002, Paxton et al 2007), there is increasing urgency to understand what makes stopover habitat "suitable" and what factors might affect the success of individuals at stopover sites. In particular, adequate food supplies and sufficient cover from predators are likely the two most important components of suitable stopover habitat.…”

Ecology and conservation of Australia’s shorebirds

“…travel, yet the relative importance of many habitats to such species remains poorly understood (Wilcove & Wikelski, 2008;Carlisle et al, 2009). It is believed that these cumulative threats that migratory animals face throughout their migrations may be why they are now showing increasing signs of widespread population declines (Wilcove & Wikelski, 2008) and might explain the increasing evidence that long-distance migrants are declining more rapidly than resident species or short distance migrants (Sanderson et al, 2006).…”

“…However, identifying factors limiting populations can be difficult for highly mobile species that seek out irregular pulses in resource availability (Bull et al, 2013) or for migratory species that traverse many habitats (Carlisle et al, 2009;Faaborg et al, 2010b). Despite these difficulties, it is crucial that conservation actions are spatially targeted, particularly in the case of migratory species, which are decreasing more rapidly than non-migratory species (Sanderson et al, 2006;Wilcove & Wikelski, 2008).…”