Factors affecting maternal care in an income breeder, the European roe deer

Abstract

1. Maternal care is a major component of demographic tactics in mammals. In ungulates most work has been done on capital breeders (e.g. bighorn sheep), which rely heavily on body reserves to raise their young. Roe deer, in contrast, are close to the income breeder end of the capital–income breeder continuum, and show high levels of maternal care.2. The aim of this study was to explore the factors determining the level of maternal care in roe deer, in particular the effects of maternal body weight, mother's parity, litter size and year of birth on the amount of prenatal care (i.e. the average mass of an offspring multiplied by the number of offspring) and postnatal care (i.e. the average growth rate of the offspring multiplied by their number). The study was carried out on a captive population of roe deer fedad libitum, and in a wild population.3. In both populations prenatal care increased with increasing maternal body weight. In the population fedad libitumthis effect was found in light females only (< 22 kg); in the wild population the positive relationship between maternal body weight and prenatal care was entirely accounted for by variation in litter size (i.e. heaviest females produced larger litters) and density (i.e. females were lightest in years with high population density). Parity did not affect prenatal care.4. In 14 females fedad libitumthere was no relationship between postnatal care and maternal body weight. Multiparous females had higher levels of postnatal care. In contrast, 20 wild females showed a positive relationship between postnatal care and maternal body weight, and only litter size affected the level of postnatal care.5. Even after accounting for the confounding effects of maternal body weight, parity, litter size and population density, we found no trade‐off between pre‐ and postnatal care in any of the two populations. The conditions under which the pattern of maternal care could impose trade‐offs that affect the individual offspring are discussed.