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Kathleen E Hunt

Publications and source records attributed to Kathleen E Hunt.

9 recordsLinked to original sources
PubMed2006

Analysis of fecal glucocorticoids in the North Atlantic right whale (Eubalaena glacialis).

Very little is known about the endocrinology of the baleen whales. The highly endangered North Atlantic right whale (NARW; Eubalaena glacialis) is a good model species, because most NARW individuals are photo-identified with known histories. We used an 125I corticosterone assay, shown to reliably measure cortisol metabolites, to determine glucocorticoid metabolite concentrations in 177 NARW fecal samples collected between 1999-2004 in the Bay of Fundy, Canada. Fecal glucocorticoid metabolite concentrations varied significantly with sex and reproductive category, being highest in pregnant females (mean +/-SE: 238.14+/-74.37 ng/g) and mature males (71.6+/-11.36), intermediate in lactating females (39.33+/-5.82), and lower in non-reproducing females (23.11+/-4.25) and immature males (34.33+/-5.01) and females (14.0+/-0.41). One case also suggests that glucocorticoids rise markedly in response to severe entanglement in fishing lines. Whales with fecal glucocorticoid content over 100 ng/g (termed "high-cort" samples) were rare, and included most pregnant females, some mature males, a fatally entangled whale, and several very young animals. Glucocorticoid concentrations were highly correlated with androgen concentrations in males and pregnant females. We analyzed the elution profiles of glucocorticoid and androgen metabolites in 13 samples with high-performance liquid chromatography (HPLC) to determine the extent to which androgen metabolites cross-react with our glucocorticoid assay. Males, pregnant females, non-pregnant females, and "high-cort" whales each had distinctly different immunoreactive HPLC profiles of glucocorticoid and androgen metabolites. A major glucocorticoid metabolite was prominent in all "high-cort" whales including the fatally entangled whale. The major fecal androgen was not testosterone but was instead a more nonpolar steroid (possibly dihydrotestosterone), which may be diagnostic of males. Androgen metabolites showed only minor cross-reactivity to our glucocorticoid assay, having a slight influence on glucocorticoid results in particular individuals. We conclude that fecal glucocorticoid analysis appears to be a useful measure of adrenal activity and reproductive condition for NARW.

Androgens↗
PubMed2005

Assessing reproductive status of right whales (Eubalaena glacialis) using fecal hormone metabolites.

Long-term studies of the endangered North Atlantic right whale, Eubalaena glacialis, have revealed declining reproductive parameters over the past two decades, threatening recovery of this small population if current trends continue. Little is known about right whale reproductive physiology, and investigating this reproductive decline has been limited by a lack of non-lethal methods for assessing reproductive status (e.g., sexual maturation, ovarian activity, pregnancy, lactation, and reproductive senescence) in free-swimming whales. This paper describes validation of existing radioimmunoassay techniques to study reproduction in right whales by measuring estrogens, progestins, androgens, and their related metabolites in fecal samples. Over the past decade fecal steroid hormone assays have been used to assess reproductive status and function in a wide range of terrestrial wildlife species, but this is the first application of this methodology in wild cetaceans. Analysis of fecal hormone metabolite levels in combination with life history data from photographically identified whales shows that this non-invasive method can be used to determine gender, detect pregnancy and lactation, and to assess age at sexual maturity in right whales and potentially other endangered whale populations.

Androgens↗
PubMed2005

Noninvasive measures of reproductive function and disturbance in the barred owl, great horned owl, and northern spotted owl.

There is an urgent need for noninvasive methods to study reproduction and environmental stress in at-risk species such as the northern spotted owl (Strix occidentalis caurina). Two related owl species (barred owl and great horned owl) were used as surrogates to validate hormone assays for fecal metabolites of progesterone, 17beta-estradiol, testosterone, and corticosterone. Infusions of radiolabeled hormones showed that the owls excreted most hormone within 6 h. Feces and urine contained roughly equal amounts of hormone, and most fecal hormone metabolites were quite polar. The testosterone and corticosterone assays in this study bound to the major excreted metabolites of these hormones, but two progesterone assays did not appreciably bind to the major progesterone metabolites. All assays showed excellent parallelism with hydrolyzed and unhydrolyzed samples and with previously dried or undried fecal samples. Thus, samples do not require hydrolysis or prior drying. Samples from a female barred owl had significantly higher fecal estrogen, lower fecal testosterone, and higher fecal estrogen/testosterone ratio than samples from two male barred owls. The fecal estrogen/testosterone ratio was the most accurate predictor of owl gender, particularly if two or more samples are available from the same individual. Fecal corticosterone metabolites also demonstrated considerable utility for wild northern spotted owls. Fecal glucocorticoid levels varied by gender and breeding stage, being highest in male northern spotted owls early in the breeding season and highest in females when nestlings were fledging. Collectively, these studies show that noninvasive fecal hormone measurements show great promise for noninvasive assessment of reproduction and stress in wild owls.

Animals↗
PubMed2004

Validation of a fecal glucocorticoid assay for Steller sea lions (Eumetopias jubatus).

The Steller sea lion (Eumetopias jubatus) is listed as endangered in parts of its range and is suspected of suffering from ecological stressors that may be reflected by fecal glucocorticoid hormones. We validated a fecal glucocorticoid assay for this species with an adrenocorticotropic hormone (ACTH) challenge. Feces were collected from captive Steller sea lions (two males and two females) for 2 days before injection with ACTH, and for 4 or more days postinjection. Feces were freeze-dried, extracted with a methanol vortex method, and assayed for glucocorticoids. The assay demonstrated good parallelism and accuracy. All animals showed the expected peak of fecal glucocorticoid excretion after ACTH injection. However, the two males had higher baselines, higher peaks, and more delayed peaks than the females. Peak glucocorticoid excretion occurred at 5 and 28 h postinjection for the two females, and at 71 and 98 h for the two males. Correction for recoveries by the addition of tritiated hormones produced ACTH profiles that were virtually identical in pattern to uncorrected data, but with higher within-sample coefficients of variation. Based on these results, we conclude that this fecal glucocorticoid assay accurately reflects endogenous adrenal activity of Steller sea lions, and that recovery corrections are not necessary for this species when using the methanol vortex extraction method. More research is needed to address possible sex differences and other possible influences on fecal glucocorticoid concentrations.

Adrenal Cortex Function Tests↗
PubMed2004

Effect of estradiol implants on reproductive behavior of female Lapland longspurs (Calcarius lapponicus).

The role of estrogens in reproductive behavior of free-living birds has been little investigated, despite the importance of estrogens in coordinating reproductive behavior and the need for information on potential effects of estrogenic contaminants on wildlife. We gave subcutaneous implants of estradiol (E2) to 15 female Lapland longspurs (Calcarius lapponicus), an arctic bird with a six-week breeding season. Controls were 9 females with empty implants and 14 unimplanted females. After implantation, E2 females had greater E2 levels and greater body mass than controls. We did not detect any increases in, or prolongation of, sexual or nest-building behavior. The incubation period was longer for E2 nests than for control nests. Nest videotapes showed that E2 females and their mates exhibited normal nestling care, and nestling growth, fledging success, and overwinter survival were also unaffected. However, whenever the males arrived at the nests, E2 females showed a significantly greater likelihood of begging from the male rather than leaving the nest. Courtship or incubation feeding have been considered atypical for this species, and it is not clear what role E2 normally plays in promoting begging behavior. Overall, elevated E2 levels did not result in any obvious costs for the female, save perhaps for slightly reduced incubation efficiency. The weak response to hormonal implants is similar to patterns seen in male Lapland longspurs, and may be related to the short breeding season. However, since little is presently known about the role of estrogens in behavior of wild female birds, it remains to be seen whether these patterns are typical of female passerines in general, or of short-season breeders. Further research on effects of estrogens (both exogenous and endogenous) on free-living female birds is needed.

Animals↗
PubMed2002

Arctic spring: hormone-behavior interactions in a severe environment.

Arctic breeding birds arrive on their nesting grounds in spring when weather conditions may still be extreme (low temperature, snow). The brief Arctic summer requires that they begin breeding as early as possible to take advantage of the ephemeral abundance of food to feed young. Failure to adjust to the local phenology results in drastically reduced reproductive success. Hormone-behavior adaptations may have evolved that maximize survival and reproductive success in the Arctic. It has been shown that the interrelationship of testosterone and territorial aggression, as birds arrive on the Arctic breeding grounds, varies according to species and locality. In some, territoriality is extremely brief following which birds become apparently refractory to the effects of testosterone. Others are territorial throughout the breeding season, but the dependence of these behaviors upon activation by testosterone is lost. Extensive data also indicate that Arctic birds modulate the adrenocortical response to acute stress. Secretion of corticosterone in response to a standardized capture stress protocol, used to mimic acute stress as a function of local environmental conditions, varies with the stage in the breeding cycle. Arctic breeding birds modulate the sensitivity of the adrenocortical response to acute stress at both the population and individual levels. These modulations are thought to be adaptations to allow the onset of territorial behavior and breeding in the face of potentially stressful conditions. Behavioral and physiological responses to corticosterone treatment are also diminished. A combination of these two hormone-behavior interrelationships can form important components of the proximate mechanisms by which birds, and other vertebrates, breed successfully in a severe and often capricious environment.

Adrenocorticotropic Hormone↗
PubMedDate not supplied

Ecological factors affecting the adrenocortical response to stress in chestnut-collared and McCown's longspurs (Calcarius ornatus, Calcarius mccownii).

Secretion of the steroid hormone corticosterone (CORT) in response to perturbations results in behavior patterns that can maximize survival. Three commonly cited hypotheses suggest that during breeding, there are advantages associated with suppressed (CORT) secretion in (1) the sex that is most important for parental care, (2) individuals in good body condition, and (3) species with a short breeding season and limited renesting opportunities. We addressed these hypotheses in two midlatitude breeders, chestnut-collared and McCown's longspurs, by assessing CORT secretion over a 1-h period of handling. These species have congeners that are exclusively arctic breeders, and this provides a unique opportunity to assess adrenocortical responsiveness both within a phylogenetic framework and across environmental variables. In both species, males and females showed similar CORT secretion patterns in response to handling, and body condition was unrelated to CORT secretion. Additionally, although these midlatitude breeders have more opportunities to attempt a renest than their arctic congeners, their hormonal response to stress was similar to that reported for their arctic congeners. We suggest that an attenuated stress response may relate to the severity of the breeding environment and a low likelihood of successful renesting, since these variables are common to both arctic and grassland habitats.

Analysis of Variance↗
PubMedDate not supplied

Factors associated with fecal glucocorticoids in Alaskan brown bears (Ursus arctos horribilis).

The aims of this study were to validate a radioimmunoassay (RIA) for quantifying glucocorticoid metabolite concentrations in the feces of Alaskan brown bears (Ursus arctos horribilis) and to investigate whether any of the following factors are associated with those concentrations: the presence of humans or other bears, fishing difficulty, sex-age class, diet, and season. We tested an established corticosterone RIA for assay sensitivity, similarity, precision, and sample matrix effects of brown bear feces, and it proved satisfactory. We collected fecal samples from brown bears along salmon-spawning streams and assessed fecal glucocorticoid (FG) concentrations. We observed that the factors explaining the most variation in measured concentrations were date and diet type and that there was a significant interaction between the two. We did not observe a significant effect of human and bear activities or sex-age class on FG concentrations. This study demonstrates that although FG concentrations may be assessed in brown bears, complex dietary patterns and seasonal variations must be taken into consideration in the study design in order to make inferences regarding stress.

Age Factors↗