Authors:
Reguera, S.1; Santos, X.2; Feriche, M.1; Mociño-Deloya, E.1; Setser, K.1; Pleguezuelos, J.M.1
Canadian Journal of Zoology, Volume 89, Number 12, November
2011 , pp. 1178-1187(
Abstract:
Optimal diet theory predicts that predators
optimize energy intake by balancing costs and benefits of foraging. One extreme
strategy of snake foraging ecology is shown by specialist species that forage
on low-energy prey, such as Thamnophis scaligerent (Jan, 1863) which feeds almost exclusively on earthworms. Compared with other
prey types such as small mammals, lizards, or arthropods, earthworms are low-energy
prey because of their small size and high water content. Given the importance
of energy acquisition for fueling snake reproduction, we expect that a
low-energy dietary specialist such as T. scaliger needs to forage frequently to
store enough fat to reproduce. The high frequency of snakes containing prey,
the presence of multiple earthworms in snakes, and the fact that females
continue to feed when gravid suggest that T. scaliger is a voracious consumer
of earthworms. Despite these foraging behaviours, females did not reproduce in
sequential years, suggesting constraints in energy input to reproduce more
frequently. A meta-analysis of the diet, body size, and reproductive frequency
of some species of the genus Thamnophis Fitzinger,
1843 confirms that consumption of invertebrate prey is associated with small
snake size, but not with biennial reproductive frequency within the genus.
Affiliations:
1: Departamento de Biología Animal, Facultad de Ciencias, Universidad de
Granada, E-18071 Granada, Spain. 2: Departamento de Biología Animal,
Universidad de Barcelona, Avinguda Diagonal 645, E-08028 Barcelona, Spain;
CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos,
Universidade do Porto, Campus Agrário de Vairão, 4485-661 Vairão, Portugal.
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