Time filter

Source Type

Fairbanks, AK, United States

Dodge M.,San Francisco State University | Guers S.L.,Alaska Bird Observatory | Sekercioglu C.H.,University of Utah | Sehgal R.N.M.,San Francisco State University
Journal of Parasitology | Year: 2013

The geographic structuring of parasite communities across the range of a single host species can illuminate patterns of host-population connectivity. To determine the location of parasite transmission in a Neotropical migrant bird species, we sampled adult and hatch-year (HY) birds across the breeding and wintering range of the Swainson's thrush (SWTH), an abundant passerine with a migratory divide. We examined the phylogenetic relationships among cytochrome b lineages of the avian blood parasite genera Haemoproteus, Plasmodium, and Leucocytozoon and determined the transmission location of unique lineages. We found that Haemoproteus and Plasmodium lineages are transmitted on California breeding grounds, whereas Leucocytozoon transmission occurs on Alaskan breeding grounds. The presence of hemosporidians on wintering grounds and shared lineages between the SWTH and resident species suggests that transmission of some of these lineages occurs on both breeding and wintering grounds. We emphasize that the sampling of HY birds and local resident heterospecifics will supplement vector studies to determine the key players in hemosporidian host switching and range-expansion events. © 2013 American Society of Parasitologists.

Spotswood E.N.,University of California at Berkeley | Goodman K.R.,University of California at Berkeley | Carlisle J.,Boise State University | Cormier R.L.,PRBO Conservation Science | And 4 more authors.
Methods in Ecology and Evolution | Year: 2012

The capture of birds using mist nets is a widely utilized technique for monitoring avian populations. While the method is assumed to be safe, very few studies have addressed how frequently injuries and mortalities occur and the associated risks have not been formally evaluated. We quantified the rates of mortality and injury at 22 banding organizations in the United States and Canada and used capture data from five organizations to determine what kinds of incidents occur most frequently. Analyses focused on passerines and near-passerines, but other groups were included. We evaluated whether body mass, age, sex, mist net mesh size, month and time of day or frequency of capture are related to the risk or type of incident. We also compared the recapture histories over time between birds that were injured and those that were never injured for 16 species. The average rate of injury was 0·59%, while mortality was 0·23%. Birds captured frequently were less at risk to incident. Body mass was positively correlated with incident and larger birds were at greater risk to predation, leg injuries, broken legs, internal bleeding and cuts, while smaller birds were more prone to stress, tangling-related injuries and wing strain. Rates of incident varied among species, with some at greater risk than others. We found no evidence for increased mortality over time of injured birds compared with uninjured birds. We provide the first comprehensive evaluation of the risks associated with mist netting. Our results indicate that (1) injury and mortality rates below one percent can be achieved during mist netting and (2) injured birds are likely to survive in comparable numbers to uninjured birds after release. While overall risks are low, this study identified vulnerable species and traits that may increase a bird's susceptibility to incident that should be considered in banding protocols aimed at minimizing injury and mortality. Projects using mist nets should monitor their performance and compare their results to those of other organizations. © 2011 The Authors. Methods in Ecology and Evolution © 2011 British Ecological Society.

Matsuoka S.M.,U.S. Fish and Wildlife Service | Matsuoka S.M.,University of Alberta | Shaw D.,Alaska Bird Observatory | Sinclair P.H.,Environment Canada | And 6 more authors.
Condor | Year: 2010

We examined the nesting ecology of the Rusty Blackbird (Euphagus carolinus) from 162 nests monitored for nest survival in Alaska and 252 incidental records from Alaska and Canada to identify important habitats for nesting and to test whether low rates of nest success are contributing to populations declines in Alaska. In coastal Alaska and throughout Canada, nests were primarily in conifers (85% of 212 nests). All conifer nests in Alaska and 80% of those in Canada were placed in spruce (Picea spp.), primarily black spruce (P. mariana). In Alaska use of small spruces (<8 cm dbh) was selective and resulted in high reproductive success - nest survival increased with black spruce density, and success of nests in spruce (79%) was higher than that of nests in deciduous vegetation (52%). Survival of nests in taller spruce declined, possibly from predation by red squirrels (Tamiasciurus hudsonicus). Rusty Blackbirds nested near water in interior (x- = 8 m) and south-central Alaska (x- = 30 m), and small spruces near water appear to be important over much of the species' range. In interior Alaska, however, most nests were in willows (78%), which dominated the vegetation near water. Nest success in Alaska averaged 56%, similar to rates over the same period in New England but higher than those of other North American blackbirds (30-39%). Studies are needed to verify whether nest survival is also high in Canada and to investigate where and why deficits in survival of adults or juveniles may be limiting population growth. © The Cooper Ornithological Society 2010.

Matsuoka S.M.,U.S. Fish and Wildlife Service | Matsuoka S.M.,University of Alberta | Shaw D.,Alaska Bird Observatory | Johnson J.A.,U.S. Fish and Wildlife Service
Condor | Year: 2010

W e used double sampling to estimate densities of Rusty Blackbird (Euphagus carolinus) nests among boreal wetlands in Anchorage and Tanana Flats, Alaska, 2007-2008. We also assessed habitat selection by examining the number and location of nests relative to the availability of various wetland types. We rapidly surveyed 78 sample units for adult Rusty Blackbirds and intensively searched for nests in a subset of 55 units to determine actual numbers of nests. Rapid surveys detected 97% of the 75 nests when we restricted counts to pairs and lone females. They overestimated nest numbers by 17% when we included in the counts lone males, which sometimes made long flights within and between sample units. Nest densities in sampled wetlands averaged 2.2 and 3.4 nests km-2 in Anchorage and Tanana Flats, respectively, surprisingly similar despite wetlands being rare in Anchorage. An abundance of wetlands made identifying important breeding habitats difficult on the Tanana Flats, where blackbirds used most wetland types in relation to their availability and avoided wetlands with low shrubs. Habitat selection was clearer in Anchorage, where ponds, lakes, and wetlands with emergent vegetation were positive predictors of nest abundance. In this area blackbirds also selected forested wetlands and avoided upland habitats for nest sites. An affinity for open water has been noted throughout the Rusty Blackbird's breeding range. Research is needed to understand whether this affinity is due to specialized food requirements and to assess whether this species is vulnerable to widespread drying of wetlands across boreal Alaska. © The Cooper Ornithological Society 2010.

Benson A.-M.,U.S. Fish and Wildlife Service | Johnson W.N.,Tetlin National Wildlife Refuge | Barry R.P.,University of Alaska Fairbanks | Guers S.L.,Alaska Bird Observatory
Wildlife Society Bulletin | Year: 2012

We evaluated the data from 2 autumn mist-netting stations for monitoring passerine population trends and measuring the timing of migration. Migration-monitoring stations were operated during autumn from 1993 to 2009 at 2 interior Alaska locations: in Fairbanks (64°50′N, 147°50W) by the Alaska Bird Observatory (ABO) and near the Tetlin National Wildlife Refuge (NWR), Alaska, USA (63°22′N, 143°13′W) by the U.S. Fish and Wildlife Service. The location of these 2 stations, near the north and western limits of the continental landmass, provides information from the initial stages of long-distance migration. The timing of migrant passage through ABO and Tetlin NWR were similar when all 17 years were combined. Juveniles preceded adults in 10 of 14 species at ABO and in 13 of 14 species at Tetlin NWR. Relative capture rates (log of weather-corrected capture rates) from the ABO and Tetlin NWR stations from 1996 to 2009 were correlated for 2 of 7 species: ruby-crowned kinglet (Regulus calendula) and yellow warbler (Dendroica petechia). A high proportion of captured birds were juveniles; therefore, these stations are most useful for monitoring an index of productivity. Power calculations indicate that for 6 of 7 species, a 50% decline in relative capture rates could be detected in a 20-year period. These stations provide a unique contribution for monitoring passerine populations by providing a large sample of the timing of migration and productivity indices at 2 interior-Alaska locations.

Discover hidden collaborations