Publications

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Monte Carlo simulations were conducted to evaluate robustness of four tests to detect density dependence, from series of population abundances, to the addition of sampling variance. Population abundances were generated from random walk, stochastic exponential growth, and density-dependent population models. Population abundance estimates were generated with sampling variances distributed...

Stomach oil, a complex mixture of neutral dietary lipids, is a unique attribute of seabirds in the order Procellariiformes. With the exception of diving-petrels, all procellariiforms produce stomach oil and feed it to their young. We conducted an interspecies cross-fostering experiment on Bird Island, South Georgia, that was designed to reveal how the presence or absence of stomach oil...

We studied habitat use by nesting and brood-rearing northern pintails (Anas acuta) on the coastal Yukon-Kuskokwim (Y-K) Delta, 1991-93. We used a digital habitat map constructed from color infrared aerial photos to assign habitat types to nest and brood locations and estimate habitat availability. Sixty-nine percent of females nested on slough banks in highly saline, tidally influenced...

Mature pelagic forage fish species (capelin, sand lance, squid) had greater lipid concentrations than juvenile age-classes of large demersal and pelagic fish species (walleye pollock, Pacific cod, Atka mackerel, greenling, prowfish, rockfish, sablefish). Myctophids preyed on by puffins have at least twice as much lipid per gram compared to mature capelin, sand lance and squid, and an...

Measurements of soil-surface CO2 fluxes are important for characterizing the carbon budget of boreal forests because these fluxes can be the second largest component of the budget. Several methods for measuring soil-surface CO2 fluxes are available: (1) closed-dynamic-chamber systems, (2) closed-static-chamber systems, (3) open-chamber systems, and (4) eddy covariance systems. This paper...

Egg size is an important determinant of reproductive investment by birds. For many species, total investment in a clutch is limited by the size of stored reserves (Ankney and MacInnes 1978, Esler and Grand 1994a). Egg size determines the unit by which these stored reserves are partitioned. Individual females in most species of waterfowl show a high repeatability for egg size, implying...

We studied nesting chronology and success of Northern Pintails (Anas acuta) on the coastal Yukon-Kuskokwim Delta, Alaska during the summers of 1991-1993. We found a total of 795 nests during three annual searches of a 27.4 km2 area. Minimum nest density averaged 9.67 nests per km2. Nesting success varied among years and ranged from 43.12% in 1991 to 10.74% in 1993 (average 23.95%). Most...

We used radio telemetry to study renesting by wild, free-ranging Northern Pintails (Anas acuta) on the coastal Yukon-Kuskokwim Delta in 1994 and 1995. Fifty-six percent of females (n = 39) renested at least once. Propensity to renest declined among females that initiated later first nests. Renesting interval was not related to female weight, year, or initiation date of first nests. Mean...

We studied survival rates of Northern Pintail (Anas acuta; hereafter pintail) broods and ducklings along the lower Kashunuk River on the Yukon-Kuskokwim Delta, Alaska. Survival rates were determined for 770 ducklings in 111 broods. Brood sizes at hatch were smaller in 1993 versus 1991 and 1992. Duckling survival rates were lower than those reported in previous studies and differed among...

In June 1992 we collected 53 blood plasma samples from nestling red‐winged blackbirds (Agelaius phoeniceus), house sparrows (Passer domesticus), and brown‐headed cowbirds (Molothrus ater) at five study sites in northwestern Minnesota to evaluate the feasibility of using plasma and brain cholinesterase (ChE) activity and reactivation as a means of assessing exposure of nontarget organisms...

We examined whether trichomoniasis had been a factor in a dramatic mourning dove (Zenaida macroura) population decline in Fillmore, Utah (USA). We reasoned that if we could not find a high proportion of doves showing clinical signs of disease then the population was not being affected. Prevalences of Trichomonas gallinae in doves were 21% for 1992 and 14% for 1993. We also examined 230...