G. Bortolotti

Publications164
h-index59
Citations8,555
Highly Influential Citations600
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Simplifying the phytohaemagglutinin skin‐testing technique in studies of avian immunocompetence
TLDR
Results from PHA skin tests conducted on 608 birds in seven studies representing passerines, waterfowl, upland game birds and raptors are examined and the only disadvantage identified is that hypersensitive individuals (outliers) could be missed.
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Corticosterone in feathers is a long-term, integrated measure of avian stress physiology
TLDR
The analysis of feather CORT is a novel methodology that allows for meaningful interpretations of how individuals respond to environmental perturbations and adjust to life-history stages, and shows the HPA activity of an individual with a flexible time frame from days to months depending on the length of time taken to grow the feather.
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Stress response during development predicts fitness in a wild, long lived vertebrate
TLDR
It is shown that the magnitude of the adrenocortical response to a standardized perturbation during development is negatively related to survival and recruitment in a wild population of long lived birds, providing empirical evidence for a link between stress response, not exposure to stressors, and fitness in a vertebrate under natural conditions.
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Tracking stress: localisation, deposition and stability of corticosterone in feathers
TLDR
By understanding how the hormone is deposited in feathers, in combination with specific sampling protocols, one can identify localised patterns of CORT deposition that reveal different temporal patterns of a bird's response to stressors.
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Food resource utilisation by the Magellanic penguin evaluated through stable-isotope analysis: segregation by sex and age and influence on offspring quality
TLDR
Sex and age differences in diet, as revealed by stable isotopes, may be the consequence of individual morphology (sexual size dimorphism) and re- productive constraints imposed by chick development since growing young require more nutritive prey than adults and yearlings.
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Influence of Sibling Competition on Nestling Sex Ratios of Sexually Dimorphic Birds
TLDR
It is shown that the probability of brood reduction is not equal among broods of different sex composition, andGolden eagles do not adjust their prenatal sex ratio, but there is a postnatal sex bias in favor of females caused by brood reduction in years of poor food availability.
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High trophic overlap within the seabird community of Argentinean Patagonia: a multiscale approach
TLDR
Based on stable isotope values of individuals, groups of phylogenetically related species generally showed a high degree of overlap within each group, and coexistence could be interpreted as a consequence of superabundance of food or species diversification in morphology and foraging strategies.
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Testosterone increases bioavailability of carotenoids: Insights into the honesty of sexual signaling
TLDR
Experimental evidence is provided for a link between testosterone levels and immunoenhancing carotenoids that reconciles conflicting evidence for the immunosuppressive nature of androgens, provides physiological grounds for a connection between two of the main signaling systems in animals, and explains how these signaling systems can be evolutionary stable and honest.
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Regulation of integumentary colour and plasma carotenoids in American Kestrels consistent with sexual selection theory
TLDR
The results suggest kestrels may have the ability to regulate (rather than merely control) their colour physiologically, the variation in colour and carotenoids is consistent with that expected of a sexually selected trait, and the loss of colour after breeding may suggest a trade-off between the show and health functions of carOTenoids.
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REPRODUCTIVE SUCCESS OF AMERICAN KESTRELS: THE ROLE OF PREY ABUNDANCE AND WEATHER
TLDR
American Kestrels are limited by the availability, as opposed to abundance, of food on territories, and it is likely that during this study, prey abundance was above some minimum threshold necessary to support successful reproduction, and so variation in weather affected reproduction more than variation in prey abundance.
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