Predation risk affects egg mass but not egg steroid hormone concentrations in yellow-legged gulls

Predation risk affects egg mass but not egg steroid hormone concentrations in yellow-legged gulls

Predators have both direct, consumptive effects on their prey and non-lethal effects on physiology and behavior, including reproductive decisions, with cascading effects on prey ecology and evolution. Here, we experimentally tested such non-lethal effects of exposure to increased predation risk on c...

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Bibliographic Details
Published in:Current zoology Vol. 65; no. 4; pp. 401 - 408
Main Authors: Possenti, Cristina Daniela, Bentz, Alexandra Bea, Romano, Andrea, Parolini, Marco, Caprioli, Manuela, Rubolini, Diego, Navara, Kristen, Saino, Nicola
Format: Journal Article
Language:English
Published: England Oxford University Press 01-08-2019
Subjects:
Analysis
Animal behavior
Animal reproduction
Behavior
Clutch size
Corticosterone
Egg laying
Eggs
Gulls
Hatching
Hawks
Hormones
Nests
Novels
Physiological aspects
Predation
Predation (Biology)
Predators
Prey
Reproductive behavior
Social behavior
Steroid hormones
Testosterone
Yolk
Italy
egg size
clutch size
testosterone
corticosterone
predation effects
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Summary:Predators have both direct, consumptive effects on their prey and non-lethal effects on physiology and behavior, including reproductive decisions, with cascading effects on prey ecology and evolution. Here, we experimentally tested such non-lethal effects of exposure to increased predation risk on clutch size, egg mass, and the concentration of yolk steroid hormones in the yellow-legged gull . We simulated increased predation risk by displaying stuffed predators (adult fox , and adult buzzard ) to breeding adults before egg laying. The concentration of corticosterone, which has been shown to increase under exposure to maternal predation risk in other species, and of testosterone did not differ between eggs from mothers exposed to the predators and eggs from control mothers (i.e., eggs exposed to a novel object of similar size and position to the stuffed predators). The concentration of the two hormones negatively covaried. Clutch size did not vary according to experimental treatment, whereas egg mass was markedly larger in clutches from nests exposed to predators than in clutches from control nests. By increasing egg mass, mothers may reduce the risk of cooling of the eggs when incubation is impeded by predators, boost energy reserves, reduce post-natal detectability caused by food solicitation, and/or enhance development at hatching, thus increasing the chances of offspring survival. In general, our results are inconsistent with most of the few previous studies on similar non-lethal predator effects and suggest that such effects may vary among species according to ecological conditions, social behavior, and developmental mode.
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ISSN:1674-5507
2396-9814
DOI:10.1093/cz/zoy064