Birds in the western United States time their breeding and molting (annual replacement of feathers) behaviors with seasonally abundant food resources. Understanding how birds move across the western landscape to acquire the food they need to successfully breed and molt represent critical pieces of information for wildlife managers.
To measure bird movements in the western United States, researchers from Klamath Bird Observatory and U.S. Forest Service Pacific Southwest Research Station have been capturing and marking birds throughout northern California and southern Oregon. These data have now been used to analyze movements of breeding and molting birds to better understand the habitat requirements of multiple species throughout their annual life-cycle.
“After the breeding season, many species were found to move away from their breeding grounds before they began molting” says Jared Wolfe, co-author and KBO research associate. “My graduate student leading this research, Andrew Wiegardt, and I, in addition to the KBO scientific team, believe that dry, late-summer environments prevent many birds from remaining on their breeding grounds late in the season. To find the insect and fruit-rich habitats necessary to molt, many birds left their breeding territories and made small-scale movements to environments with more food, such as wet meadows and riparian forest”.
Results from this recent research highlight that most migratory species are reliant on multiple locations and habitats in northern California and southern Oregon to breed and molt prior to fall migration. For long-distance migrants, such as Wilson’s Warblers, these different locations used for breeding and molting often occurred on an altitudinal gradient where birds tended to breed in lower elevations during the spring, and then moved upslope to molt at higher elevations late in the summer.
KBO Research Associate Dr. Jared Wolfe received his BS and MS from Humboldt State University. He completed his PhD at Louisiana State University studying landscape demography of Amazonian birds. Dr. Wolfe is a science advisor for Costa Rica Bird Observatories, co-founder of the Louisiana Bird Observatory, North American Banding Council certified trainer and current board member serving as a trainer-at-large, and a permitted master bander in the USA and Brazil. He regularly coordinates bird monitoring and statistical workshops in the USA, Costa Rica, Peru and Brazil. Dr. Wolfe is an Assistant Professor at Michigan Tech University.
Jared’s affiliation with KBO has been long and fruitful, resulting in multiple scientific publications focused on migratory and resident bird demography as well as the influence of climate on migratory bird condition, molt patterns and novel ageing systems for tropical birds.