Alfred M. Dufty

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Relationships between hormones and behaviour can be explored by altering endogenous hormone levels, often through implantation of silastic tubing or osmotic pumps filled with a hormone or its agonists or antagonists. However, organisms in sensitive life-history stages (such as pregnancy) may be adversely affected by the surgical procedures associated with(More)
Stressors encountered during avian development may affect an individual's phenotype, including immunocompetence, growth, and feather quality. We examined effects of simulated chronic low-level stress on American kestrel (Falco sparverius) nestlings. Continuous release of corticosterone, a hormone involved in the stress response, can model chronic stress in(More)
We examined the adrenal response to handling stress of birds in different body conditions. In order to affect the birds' body condition, young (73-d old) female American kestrels (Falco sparverius) were maintained for 6 wk on one of three diets: a control diet (fed ad lib.) and two calorically restricted diets. To invoke a stress response, we removed birds(More)
The importance of singing in the establishment and maintenance of dominance rank was investigated in captive flocks of brown-headed cowbirds (Molothrus ater). Each flock consisted of 3 males and 1 female. In one experiment the two largest males in each of 4 flocks were temporarily devocalized by puncturing the interclavicular air sac just before group(More)
Except for a few studies in the eastern United States, little has been published on hemoparasites in owls. We surveyed the blood parasites of 108 Northern Saw-whet Owls (Aegolius acadicus) and 24 Flammulated Owls (Otus flammeolus) in Idaho during autumn migration in 1999 and 2000. We also surveyed 15 Flammulated Owls (FLOW) during breeding season in Utah(More)
We used a standard handling protocol to examine the stress response of captive young western screech-owls during their active (nighttime) and inactive (daytime) periods and to compare the stress responses of captive and free-living owls. Circulating corticosterone levels were significantly higher during the inactive period than in the active period in this(More)
Triclocarban (TCC) and triclosan (TCS), two of the most commonly used antimicrobial compounds, can be introduced into ecosystems by applying wastewater treatment plant biosolids to agricultural fields. Concentrations of TCC and TCS were measured in different trophic levels within a terrestrial food web encompassing land-applied biosolids, soil, earthworms(More)
Early developmental experiences play an important role in development of the adult phenotype. We investigated the effects of neonatal handling on the hypothalamic-pituitary-adrenal axis in a free-living avian species, the American kestrel (Falco sparverius). In the handled group (H), kestrel chicks were handled for 15 min/day from hatching until 26 days of(More)
Although multiple condition dependence in dispersal is common, the proximate mechanisms that integrate information from multiple sources remain largely unknown. In the common lizard (Lacerta vivipara), earlier studies have shown that maternal plasma corticosterone level interacts with maternal phenotype to affect offspring phenotype and dispersal strategy,(More)
In male House Finches (Carpodacus mexicanus), the extent and color of plumage varies depending on access to carotenoid pigments. "Colorful" males exhibit extensive red pigmentation, while less colorful (i.e., "drab") males exhibit carotenoid pigmentation over a smaller percentage of their plumage, pigmentation of a color besides red (e.g., yellow, gold,(More)