Scott A. MacDougall-Shackleton

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Stimulus-induced expression of the immediate early gene ZENK (egr-1) in the songbird's auditory forebrain presumably depends on the behavioral significance of the stimulus. Few studies, however, have quantified both the ZENK and behavioral responses to a stimulus in the same individuals. We played conspecific male song of either hatch (local) or foreign(More)
Chronic elevations in glucocorticoids can decrease the production and survival of new cells in the adult brain. In rat hippocampus, supraphysiological doses of dehydroepiandrosterone (DHEA; a sex steroid precursor synthesized in the gonads, adrenals, and brain) have antiglucocorticoid properties. With male song sparrows (Melospiza melodia), we examined the(More)
The stress response--increases in circulating glucocorticoids following a stressor--is typically considered adaptive, but few studies address the fitness consequences of individual variation in stress response. Generally, due to negative consequences of prolonged elevation of glucocorticoids, animals should have a transient stress response just sufficient(More)
Previous research presents a mixed picture of seasonal variation in the hippocampus of food-storing black-capped chickadees. One field study has shown an October peak in hippocampus volume, although laboratory studies conducted to determine whether photoperiod regulates this seasonal growth have failed to find changes in the size of the hippocampus. To(More)
Like humans, animals that use acoustic stimuli to perceive their world ought to be able to parse the auditory scene into functionally significant sounds. The ability to do so ought to have significant adaptive value when, for example, an animal can identify the sounds of a predator among other natural noises. In earlier work it was shown that a species of(More)
Birdsong is a sexually selected trait and is often viewed as an indicator of male quality. The developmental stress hypothesis proposes a model by which song could be an indicator; the time during early development, when birds learn complex songs and/or local variants of song, is of rapid development and nutritional stress. Birds that cope best with this(More)
Appropriately timed integration of breeding into avian annual cycles is critical to both reproductive success and survival. The mechanisms by which birds regulate timing of breeding depend on environmental cue response systems that regulate both when birds do and do not breed. Despite there being multiple possible explanations for birds' abilities to time(More)
Stable isotope analysis is an increasingly valuable tool in ecological studies and shows promise as a measure of nutritional stress in wild animals. Thus far, however, the only studies on endotherms that have conclusively shown changes in δ15N and δ13C values in response to nutritional stress were conducted on fasting animals and animals growing under(More)
Songbirds exhibit some of the most extreme sex differences in the brain of all vertebrates. Understanding the function of these sex differences has relied on making interspecies comparisons. In some species, females sing rarely or not at all, and the brain nuclei that control song are many times larger in volume in males than in females. In other species,(More)
Three experiments examined the capacity of European starlings to segregate perceptually 2 superimposed, intermixed auditory stimuli. The stimuli were 10-s song samples from 2 of 4 songbird species: European starling, brown thrasher, mockingbird, and nightingale. The birds first learned a discrimination between the intermixed song pairs. Then, they(More)