Geology topics

Daniel Esler

Publications and source records attributed to Daniel Esler.

80 records · Page 5Linked to original sources

USGS1999

Surgical and immediate postrelease mortality of harlequin ducks ( Histrionicus histrionicus ) implanted with abdominal radio transmitters with percutaneous antennae

Radiotelemetry is an essential tool in the study of free-ranging bird populations, and a variety of transmitter-attachment methods have been developed. A promising new method is abdominal implantation of a transmitter with a percutaneous antenna. Researchers using this technique should be concerned about and aware of mortality during surgery and during the immediate postrelease period (the 14-day period following surgery). Of 307 radio-implant surgeries performed between 1995 and 1997 in harlequin ducks ( Histrionicus histrionicus ), 7 (2.3%) deaths were documented during surgery or anesthetic recovery. Of 295 birds released with implanted radios, 10 (3.4%) died during the immediate postrelease period. Modifications to anesthetic procedures used in the 204 surgeries performed in 1996 and 1997 reduced mortality to 1.5% during surgery and 1.5% during the immediate postrelease period. Anesthetic modifications included intubation of all birds, placement of birds on an elevated platform that allowed the head to rest at a level lower than the body during surgery, placement of a heated water blanket under the birds during surgery, monitoring of body temperature, and use of electrocardiogram and Doppler ultrasound to monitor heart rates and arrhythmias. Low levels of mortality associated with abdominal implantation of radio transmitters may be unavoidable, but mortality can be minimized with adjustments to anesthetic technique.

Journal of Zoo and Wildlife Medicine↗

USGS1999

Loss from harlequin ducks of abdominally implanted radio transmitters equipped with percutaneous antennas

We documented extrusion and loss of abdominally implanted radio transmitters with percutaneous antennas from adult female Harlequin Ducks (Histrionicus histrionicus). Birds were captured during wing molt (late August to mid-September) in 1995-1997. Of 44 Harlequin Ducks implanted with radios and recaptured, 7 (16%) had lost their transmitters and 5 (11%) had radios in the process of extruding. Most (11 of 12) extrusions and losses occurred in birds implanted with radios in 1996 and recaptured in 1997. We suggest that transmitter extrusions and losses were due largely to changes in transmitter design made between 1095 and 1996. Transmitters implanted in 1996 were cylindrical rather than spherical, had a flat end with an abrupt edge, and the lower portion of the antenna was reinforced. Radio losses occurred after the 7-mo monitoring period and caused no apparent harm to the birds. Investigators using implanted radios with percutaneous antennas for long-term projects should be aware of the potential for radio extrusion and should minimize the problem by using transmitters that have no sharp edges and that are wide, rather than narrow.

Journal of Field Ornithology↗

USGS1999

Evaluation of bursal depth as an indicator of age class of harlequin ducks

We contrasted the estimated age class of recaptured Harlequin Ducks (Histrionicus histrionicus) (n = 255) based on bursal depth with expected age class based on bursal depth at first capture and time since first capture. Although neither estimated nor expected ages can be assumed to be correct, rates of discrepancies between the two for within-year recaptures indicate sampling error, while between-year recaptures test assumptions about rates of bursal involution. Within-year, between-year, and overall discrepancy rates were 10%, 24%, and 18%, respectively. Most (86%) between-year discrepancies occurred for birds expected to be after-third-year (ATY) but estimated to be third-year (TY). Of these ATY-TY discrepancies, 22 of 25 (88%) birds had bursal depths of 2 or 3 mm. Further, five of six between-year recaptures that were known to be ATY but estimated to be TY had 2 mm bursas. Reclassifying birds with 2 or 3 mm bursas as ATY resulted in reduction in between-year (24% to 10%) and overall (18% to 11%) discrepancy rates. We conclude that age determination of Harlequin Ducks based on bursal depth, particularly using our modified criteria, is a relatively consistent and reliable technique.

Journal of Field Ornithology↗

USGS1998

Birds of the Indigirka River Delta, Russia: Historical and biogeographic comparisons

We documented the breeding status and relative abundance of all avian species on the coastal portion of the Indigirka River Delta during spring and summer 1993-95. Data on avifaunal composition were then compared to data from adjacent areas from Eastern Siberia to the Chukotka Peninsula to evaluate how species composition changes longitudinally within the arctic and typical tundra zones of northern Russia. We recorded 63 species on the Indigirka River Delta, 37 (58.7 %) of which were confirmed breeders during at least one of the three years. Five new species were recorded breeding ( Arenaria interpres , Calidris acuminata , Limnodromus scolopaceus , Stercorarius parasiticus , and Asio flammeus ), and 13 previously unrecorded species were observed during this study. We also identified several species of rare or threatened status in Russia and North America, including Branta bernicla , Somateria fischeri , Polysticta stelleri , and Rhodostethia rosea . We used parsimony and distance matrix methods to compare the breeding species richness on the Indigirka River Delta to that of six other Russian Arctic areas. Biogeographic comparisons revealed the presence of two clades in the Russian Arctic: the Lena River Delta east to Chaun Delta and the Chukotka Peninsula.

Indigirka River Delta↗

USGS1994

Assessment of shoreline vegetation in relation to use by molting black brant Branta bernicla nigricans on the Alaska Coastal Plain

To evaluate the importance of large thaw lakes on the Alaska Coastal Plain for molting Pacific black brant Branta bernicla nigricans , distribution and life form of shoreline vegetation were assessed using several scales: satellite imagery, point-intercept transects, cover quadrats, and a parameter for water regime. Brant population and distribution estimates from aerial surveys were used to classify large lakes into high, moderate, and low use. Correlations between brant and abundance of their preferred feeding site - moss flats - were best demonstrated by satellite imagery. Intercepts and cover ratings were not correlated, presumably because these techniques were less efficient at assessing area. General observations suggested that the presence of islands, large ice floes, and possibly other physical attributes of the habitat, influenced brant distribution. This area is unique because of low-lying, drained-lake basins that have ideal combinations of moss flats and large water areas where brant seek protection disturbance is vital to the success of this declining species because alternate habitats may not be available elsewhere on the Coastal Plain. in water or on ice floes. Protection of the area from disturbance is vital to the success of this declining species because alternate habitats may not be available elsewhere on the Coastal Plain.

Alaska↗

USGS1994

Comparison of age determination techniques for female northern pintails and American wigeon in spring

Accurate age-class determination of waterfowl is necessary for studies addressing age-specific effects (e.g., Serie et al., 1992) and age structure of populations (e.g., Raveling and Heitmeyer 1989). Duck ages can be determined in fall by morphological and color characteristics of tertial and tail feathers (Carney 1992); however, these feathers are replaced during fall and winter, thus their characteristics cannot be used in spring (Dane 1968). Other methods used to determine waterfowl age include the presence or absence of the bursa of Fabricius (hereafter bursa; Gower 1939, Hochbaum 1942, Hanson 1949) and characteristics of primary and secondary wing feathers and their coverts (e.g., Wishart 1981, Duncan 1985).

Wildlife Society Bulletin↗

USGS1994

Dynamics of ovarian follicles in breeding ducks

I quantified ovarian rapid follicle growth (RFG) and regression of postovulatory follicles of Northern Pintails ( Anas acuta ), American Wigeon ( A. americana ), and Lesser Scaup ( Aythya affinis ) by a method that accounted for within-day variation in follicle size. Objective methods for identifying onset of RFG also are presented; this is crucial for accurate classification of breeding status. Duration of RFG was estimated as 4.2, 5.1, and 5.0 days for pintails, wigeon, and scaup, respectively; these are shorter than previously reported. Diameters of follicles at the beginning of RFG were estimated to be 8.2, 6.9, and 7.9 mm for pintails, wigeon, and scaup, respectively. For all species, RFG was linear, using follicle diameters, and exponential, using dry masses. Models of RFG and postovulatory follicle regression have practical value for calculating nest initiation dates, number of developing follicles, clutch size, renesting intervals, and daily energy and nutrient commitment to reproduction of collected breeding females.

Alaska↗

USGS1993

Factors influencing depredation of artificial duck nests

Because artificial nests can facilitate controlled experiments of nest success, we used them to assess whether human visitation, nest density, vegetation structure, and proximity to habitat edge could affect depredation of duck nests on Yukon Flats National Wildlife Refuge, Alaska. More (P < 0.01) nests in a plot visited daily (100%) were depredated than those in plots visited at intervals of 7 (40%), 14 (35%), or 28 days (45%). More (P < 0.01) nests were depredated in a plot with 10 nests/ha (95%) than nests in a plot of a lower density (2/ha; 40%). Vegetation height, vegetation density, distance to a wetland, distance to forest edge, or distance to the nearest ecotone did not differ (P > 0.05) between depredated and undisturbed nests. We suggest that daily visitation of duck nests increases depredation, but longer intervals, typical of most nest studies, do not. High nesting densities, which could occur when flooding limits nesting habitat, may result in higher depredation rates.

Alaska↗