Costs of egg caring in the skink, Mabuya longicaudata

Abstract

Why do most animal species not provide parental care to their eggs or progeny? The “cost” hypothesis suggests that parental care can reduce food intake, probable survivorship, and/or subsequent fecundity of the reproductive female, and parental care is not adaptive unless it is balanced by considerable fitness trade-offs. Therefore, parental care would be expected to evolve most often in species in which such costs are minor or insignificant. Although parental care has been reported in more than 140 species of reptiles, few records unambiguously demonstrate the cost of parental care. In the current study, I report the “costs” of maternal activities and survivorship, as well as egg attendance times, and within- and between-seasonal body size variations, of females of Mabuya longicaudata after engaging in parental care. I used those data to test whether parental care necessarily entailed large costs to mother lizards. The proportion of nests guarded decreased with time after eggs were laid, with most females remaining at the nest for at least 1 week, but then some beginning to leave. The loss of mass by females over the first week of egg guarding was on average balanced by a gain in mass during subsequent foraging bouts. The snout–vent length (SVL), body mass (BM), recapture (survival) rates, fecundity, timing of a second clutch, and clutch frequencies of females that exhibited long-term parental care (more than 28 days; mean, 31.6 ± 2.2 days) did not significantly differ from that of females that showed short-term parental care (9∼16 days; mean, 12.5 ± 2.3 days). Thus, my data indicate that intense parental care over a long period does not necessarily entail major energy costs for the mother in terms of SVL, BM, recapture (survival) rates, or fecundity.