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Author and Title	Abstract
Benson, A-M., B.A. Andres, W.N. Johnson, S. Savage, and S.M. Sharbaugh. 2006. Differential timing of Wilson's Warbler migration in Alaska. Wilson Journal of Ornithology. 118:547-551.	We examined age- and sex-related differences in timing of Wilson’s Warbler (Wilsonia pusilla pileolata) migration at four locations in Alaska: Fairbanks, Tok, Mother Goose Lake, and Yakutat. We captured Wilson’s Warblers with mist nets during several years of spring and autumn migration. In spring, males arrive on their breeding grounds significantly earlier than females at Tok and Fairbanks. During autumn, timing of migration did not differ between sexes in adults, but immatures migrated earlier than adults at all four sites. Migration of adults and immatures was earlier at the southwestern and southern sites than at interior Alaska sites, likely because they are sampling different populations. The lack of age-related differences found in studies sampling fall migrant passage at lower latitudes could be attributed to adults migrating faster than immatures or to mixing of breeding populations. Article
Benson, A-M. and K. Winker. 2005. Fat deposition strategies among high-latitude passerine migrants. Auk 122(2): 544-557.	We studied fat stores in passerine migrants at a high-latitude site in Fairbanks, Alaska (64^o 50^o N, 147^o 50^o W). We examined fat deposition strategies during the final (spring migration) and initial (autumn migration) stages of long-distance migration from 1992-1998 to: 1) improve understanding of geographic fat deposition patterns by adding a high-latitude perspective; 2) to determine whether there are age-related differences in fat deposition strategies in autumn; and 3) to test the "spring fatter" hypothesis of seasonal fat deposition, which suggests that migrants should carry more fat in spring as they near their breeding areas than in autumn as they depart. Our analyses examined factors affecting daily fat scores during migration and compared between-season differences in fat stores among a total of 18,685 individuals of 16 migrant species. In autumn, adults had higher visible subcutaneous fat scores than immatures in 11 of 16 species. However, in all but two species these differences were attributable to the effects of overnight low temperature, day length, and time of day, rather than age, probably due to later departures by adults. Fat scores were higher in autumn than spring in 6 of 16 species, and body condition indices were higher in autumn in 5 of 16 species. Only one species showed higher fat scores in spring, but this difference was not reflected in a seasonal comparison of body condition indices. No species arrived with high fat loads in spring, and generally low fat levels in autumn suggest that high-latitude passerine migrants in North America are paying most of the energetic costs of long-distance migration from resources obtained en route to their wintering grounds. Among passerine migrants near these high-latitude breeding grounds, seasonal fat deposition strategies appear to be in response to energetic needs at the level of daily maintenance rather than to hypothesized insurance needs in spring or to the forthcoming needs of a long-distance migration in autumn. Article.
Erwin, C.A., K. B. Rozell and L.H. DeCicco. 2004. Update on the status and distribution of Wilson's Phalarope and Yellow-bellied Sapsucker in Alaska. Western Birds 35:42-44.	Link to Article
Benson, A-M. and K. Winker. 2001. Timing of Breeding Range Occupancy Among High-Latitude Passerine Migrants. Auk 118 (2):513-519.	The brief subarctic summer limits the time available for birds to complete their reproductive activities, yet the temporal requirements of high-latitude passerine migrants are not well understood. Our analyses examined the timing of spring and autumn migration among 18 passerine species to obtain indirect estimates of the time they occupy their breeding ranges in northwestern North America. From 1992 to 1998, the Alaska Bird Observatory (64º50'N, 147º50'W) banded 31,698 individuals during the most intensive standardized mist-netting study ever conducted in subarctic North America. Among the migrants examined, the estimated number of days that species were present in interior Alaska ranged from 48 days for adult Alder Flycatchers (Empidonax alnorum) to 129 days for American Robin (Turdus alnorum). Adults departed significantly later in autumn than immatures in 10 of 18 species we examined and significantly earlier than immatures in only one species, Alder Flycatcher. Breeding range occupancy of Nearctic-Neotropic migrants occurs in this region within the range of average frost-free temperatures in Fairbanks, Alaska, and is significantly shorter in duration than among Nearctic-Nearctic (“short distance”) migrants at this latitude.
Benson, A-M., T.H. Pogson and T.J. Doyle. 2000. Updated geographic distribution of eight passerine species in central Alaska. Western Birds 31:100-105.	We documented the occurrence of eight rare passerines in central Alaska. Our observations of the Yellow-bellied Flycatcher, Red-breasted Nuthatch, Arctic Warbler, Golden-crowned Kinglet, Tennessee Warbler, Palm Warbler, Mourning Warbler, and Clay-colored Sparrow provided new distributional information on the occurrence of these species in central Alaska. Mist netting was essential to documenting the geographic distribution of these species because mist-net captures represented the only occurrence of several species. Additionally, many of these records could not have been identified to subspecies without collecting individuals as voucher specimens that could be verified by other scientists.
Paton, Peter W.C. and T. H. Pogson. 1996. Relative abundance, migration strategy, and habitat use of birds breeding in Denali National Park, Alaska. Canadian Field-Naturalist 110:599-606.	The breeding bird community in Denali National Park, Alaska, was studied over a three-year period (1993-1995). Birds were surveyed from nine off-road routes in spruce forests from 1993-1995 and from four on-road routes in 1994 and 1995. Thirty-nine species were detected during off-road routes, whereas 80 species were detected from on-road routes. The most abundant species were sparrows (White-crowned Sparrow [Zonotrichia leucophrys], American Tree Sparrow [Spizella arborea], and Savannah Sparrow [Passerculus sandwichensis]) and warblers (Wilson’s Warbler [Wilsonia pusilla] and Orange-crowned Warbler [Vermivora celata]. The avian community in Denali National Park was similar to other areas in the region, although there were some distinctive differences. The majority of detected individuals (69%) presumably migrate to the tropics; residents accounted for only 9% of the individuals detected. Shrublands had the greatest relative abundance of any habitats surveyed, whereas species richness was greatest in tall shrub and spruce forest habitats. These findings generally concur with previous research in the region. Both habitats should be important components in any program that attempts to monitor avian populations in interior Alaska.

Author and Title

Abstract

Benson, A-M., B.A. Andres, W.N. Johnson, S. Savage, and S.M. Sharbaugh. 2006. Differential timing of Wilson's Warbler migration in Alaska. Wilson Journal of Ornithology. 118:547-551.

We examined age- and sex-related differences in timing of Wilson’s Warbler (Wilsonia pusilla pileolata) migration at four locations in Alaska: Fairbanks, Tok, Mother Goose Lake, and Yakutat. We captured Wilson’s Warblers with mist nets during several years of spring and autumn migration. In spring, males arrive on their breeding grounds significantly earlier than females at Tok and Fairbanks. During autumn, timing of migration did not differ between sexes in adults, but immatures migrated earlier than adults at all four sites. Migration of adults and immatures was earlier at the southwestern and southern sites than at interior Alaska sites, likely because they are sampling different populations. The lack of age-related differences found in studies sampling fall migrant passage at lower latitudes could be attributed to adults migrating faster than immatures or to mixing of breeding populations. Article

Benson, A-M. and K. Winker. 2005. Fat deposition strategies among high-latitude passerine migrants. Auk 122(2): 544-557.

We studied fat stores in passerine migrants at a high-latitude site in Fairbanks, Alaska (64^o 50^o N, 147^o 50^o W). We examined fat deposition strategies during the final (spring migration) and initial (autumn migration) stages of long-distance migration from 1992-1998 to: 1) improve understanding of geographic fat deposition patterns by adding a high-latitude perspective; 2) to determine whether there are age-related differences in fat deposition strategies in autumn; and 3) to test the "spring fatter" hypothesis of seasonal fat deposition, which suggests that migrants should carry more fat in spring as they near their breeding areas than in autumn as they depart. Our analyses examined factors affecting daily fat scores during migration and compared between-season differences in fat stores among a total of 18,685 individuals of 16 migrant species. In autumn, adults had higher visible subcutaneous fat scores than immatures in 11 of 16 species. However, in all but two species these differences were attributable to the effects of overnight low temperature, day length, and time of day, rather than age, probably due to later departures by adults. Fat scores were higher in autumn than spring in 6 of 16 species, and body condition indices were higher in autumn in 5 of 16 species. Only one species showed higher fat scores in spring, but this difference was not reflected in a seasonal comparison of body condition indices. No species arrived with high fat loads in spring, and generally low fat levels in autumn suggest that high-latitude passerine migrants in North America are paying most of the energetic costs of long-distance migration from resources obtained en route to their wintering grounds. Among passerine migrants near these high-latitude breeding grounds, seasonal fat deposition strategies appear to be in response to energetic needs at the level of daily maintenance rather than to hypothesized insurance needs in spring or to the forthcoming needs of a long-distance migration in autumn. Article.

Erwin, C.A., K. B. Rozell and L.H. DeCicco. 2004. Update on the status and distribution of Wilson's Phalarope and Yellow-bellied Sapsucker in Alaska. Western Birds 35:42-44.

Link to Article

Benson, A-M. and K. Winker. 2001. Timing of Breeding Range Occupancy Among High-Latitude Passerine Migrants. Auk 118 (2):513-519.

The brief subarctic summer limits the time available for birds to complete their reproductive activities, yet the temporal requirements of high-latitude passerine migrants are not well understood. Our analyses examined the timing of spring and autumn migration among 18 passerine species to obtain indirect estimates of the time they occupy their breeding ranges in northwestern North America. From 1992 to 1998, the Alaska Bird Observatory (64º50'N, 147º50'W) banded 31,698 individuals during the most intensive standardized mist-netting study ever conducted in subarctic North America. Among the migrants examined, the estimated number of days that species were present in interior Alaska ranged from 48 days for adult Alder Flycatchers (Empidonax alnorum) to 129 days for American Robin (Turdus alnorum). Adults departed significantly later in autumn than immatures in 10 of 18 species we examined and significantly earlier than immatures in only one species, Alder Flycatcher. Breeding range occupancy of Nearctic-Neotropic migrants occurs in this region within the range of average frost-free temperatures in Fairbanks, Alaska, and is significantly shorter in duration than among Nearctic-Nearctic (“short distance”) migrants at this latitude.

Benson, A-M., T.H. Pogson and T.J. Doyle. 2000. Updated geographic distribution of eight passerine species in central Alaska. Western Birds 31:100-105.

We documented the occurrence of eight rare passerines in central Alaska. Our observations of the Yellow-bellied Flycatcher, Red-breasted Nuthatch, Arctic Warbler, Golden-crowned Kinglet, Tennessee Warbler, Palm Warbler, Mourning Warbler, and Clay-colored Sparrow provided new distributional information on the occurrence of these species in central Alaska. Mist netting was essential to documenting the geographic distribution of these species because mist-net captures represented the only occurrence of several species. Additionally, many of these records could not have been identified to subspecies without collecting individuals as voucher specimens that could be verified by other scientists.

Paton, Peter W.C. and T. H. Pogson. 1996. Relative abundance, migration strategy, and habitat use of birds breeding in Denali National Park, Alaska. Canadian Field-Naturalist 110:599-606.

The breeding bird community in Denali National Park, Alaska, was studied over a three-year period (1993-1995). Birds were surveyed from nine off-road routes in spruce forests from 1993-1995 and from four on-road routes in 1994 and 1995. Thirty-nine species were detected during off-road routes, whereas 80 species were detected from on-road routes. The most abundant species were sparrows (White-crowned Sparrow [Zonotrichia leucophrys], American Tree Sparrow [Spizella arborea], and Savannah Sparrow [Passerculus sandwichensis]) and warblers (Wilson’s Warbler [Wilsonia pusilla] and Orange-crowned Warbler [Vermivora celata]. The avian community in Denali National Park was similar to other areas in the region, although there were some distinctive differences. The majority of detected individuals (69%) presumably migrate to the tropics; residents accounted for only 9% of the individuals detected. Shrublands had the greatest relative abundance of any habitats surveyed, whereas species richness was greatest in tall shrub and spruce forest habitats. These findings generally concur with previous research in the region. Both habitats should be important components in any program that attempts to monitor avian populations in interior Alaska.

Updated Wed, Jan 17, 2007