Geology topics

J.B. Grand

Publications and source records attributed to J.B. Grand.

23 records · Page 2Linked to original sources

USGS2003

An adenovirus linked to mortality and disease in long-tailed ducks (Clangula hyemalis) in Alaska

An adenovirus was isolated from intestinal samples of two long-tailed ducks (Clangula hyemalis) collected during a die-off in the Beaufort Sea off the north coast of Alaska in 2000. The virus was not neutralized by reference antiserum against known group I, II, or III avian adenoviruses and may represent a new serotype. The prevalence of the virus was determined in live-trapped long-tailed ducks at the mortality site and at a reference site 100 km away where no mortality was observed. Prevalence of adenovirus antibodies in serum samples at the mortality site was 86% compared to 10% at the reference site. Furthermore, 50% of cloacal swabs collected at the mortality site and only 7% of swabs from the reference site were positive for adenoviruses. In 2001, no mortality was observed at either of the study areas, and virus prevalence in both serum and cloacal samples was low, providing further evidence that the adenovirus was linked to the mortality event in 2000. The virus was used to infect long-tailed ducks under experimental conditions and resulted in lesions previously described for avian adenovirus infections and similar to those observed in long-tailed duck carcasses from the Beaufort Sea. The status of long-tailed ducks has recently become a concern in Alaska due to precipitous declines in breeding populations there since the mid-1970s. Our findings suggest that the newly isolated adenovirus is a disease agent and source of mortality in long-tailed ducks, and thus could be a contributing factor in population declines.

Alaska↗

USGS2003

Body molt of male long-tailed ducks in the nearshore waters of the north slope, Alaska

We examined the timing and intensity of body molt in relation to stage of remige growth for postbreeding adult male Long-tailed Ducks ( Clangula hyemalis ) off the coast of northern Alaska. During this period, remige and rectrix feathers are molted simultaneously with body feathers during the prebasic molt, which results in a period of increased energetic and nutritional demands. We collected birds from late July through mid-August and recorded intensity of molt in eight regions: head and neck, back and rump, greater coverts, lesser coverts, flank and sides, breast, belly, and tail. Using nonlinear regression, we estimated the peak intensity and variation for each region in relation to ninth primary length. We found little evidence of molt in the head and neck region. The greater and lesser coverts, and back and rump reached peak molt intensities earliest and were followed by tail, breast, and belly. Molt intensity in the flank and side region was highly variable and indicated a more prolonged molting pattern in relation to other regions. While body molt occurs simultaneously with wing molt, we found that molt among regions occurred in a staggered pattern. Long-tailed Ducks may employ this staggered molting pattern to minimize the energetic and nutritional requirements of molt.

Alaska↗

USGS1999

Incubation behavior of Spectacled Eiders on the Yukon-Kuskokwim Delta, Alaska

We studied incubation behavior of Spectacled Eiders ( Somateria fischeri ) on the Yukon-Kuskokwim Delta in 1996. We trapped 19 females on their nests and weighed them in early incubation and again at hatch. Average daily weight loss for incubating females was 16.6 ± 1.0 g day -1 , which resulted in a cumulative loss of 26% of body weight throughout incubation. Nest attendance was monitored for a portion of the incubation period using temperature sensing artificial eggs. Incubation constancy averaged 90 ± 1%. Average recess length was 37.1 ± 0.9 min, and nests cooled an average of 4.2 ± 0.1°C during recesses. Recess frequency averaged 2.5 ± 0.1 recesses day -1 , and most recesses (70%) occurred between 10:00 and 22:00. Incubation constancy varied among females, but was not related to changes in body weight or incubation period. There was no influence of ambient temperature on incubation recess length, however most recesses were taken during the warmest part of the day. We found considerable variation among females in patterns of daily incubation constancy, nest cooling, recess frequency, and recess length. It is not clear from our results what factors constrain incubation behavior of Spectacled Eiders, but we suggest that individual females respond to a complex suite of variables.

Condor↗

USGS1997

Productivity of nesting spectacled eiders on the lower Kashunuk River, Alaska

We studied the chronology and success of nesting Spectacled Eiders ( Somateria fischeri ) along the lower Kashunuk River on the Yukon-Kuskokwim Delta from 1991-1995. Nest initiation dates ranged from 16 May-22 June. Median nest initiation dates were correlated with the break-up of ice on the Kashunuk River. Clutch sizes declined seasonally, and mean clutch size varied among years ranging from 4.8-5.6 eggs. The frequency of nests containing inviable eggs (24% of successful nests, x = 0.6 unhatched eggs per successful nest) did not differ among years or nest initiation dates, and may be related to exposure to contaminants. The rate of partial depredation also did not vary among years or initiation dates (23% of nests, x = 0.5 eggs taken/successful nest). We detected no effect of marking or visitation on daily survival rate of nests. Nests initiated early in the year were more successful than late nests; thus, early nesting females laid larger clutches and were more likely to nest successfully than late nesters. Nest success varied among years and declined from 73% in 1991 to 18% in 1994. Nest success increased to 76% in 1995 when we reduced the Mew Gull ( Larus canus ) population on the study area. While inviability and partial depredation averaged over 1 egg per successful nest, the production lost in nests that were abandoned or completely destroyed by predators was much greater. Our data indicate that Spectacled Eiders nesting on our study area experience relatively high production; however, without information regarding annual survival and recruitment. it is not possible to draw conclusions about population growth rates.

Condor↗

USGS1996

Breeding populations of northern pintails have similar mitochondrial DNA

Northern pintails (Anas acuta) are highly nomadic, which may result in high levels of gene flow among nesting areas. To assess the extent of genetic differentiation among nesting areas, we analyzed mitochondrial DNA (mtDNA) variation in northern pintail females from three regions: Alaska, California, and midcontinent prairies and parklands. Abundant mtDNA variation was evident (20 genotypes among 289 birds), but there was no significant genetic differentiation of nesting areas within or among regions. Results indicate that pintails have had historically large breeding population sizes and a high rate of gene flow among North American nesting areas. Specific nesting areas are not independent units, but part of a larger continental population. High rates of gene flow suggest that over time, localized reductions in recruitment or survival may be compensated for by immigration.

Canadian Journal of Zoology↗