The time immediately following birth is a period of high predation risk for ungulate neonates. Ungulate mothers exhibit perinatal behaviors that appear to mitigate offspring risk during this time. However, few studies of infant mortality include the postpartum period. Therefore, the function and effectiveness of these maternal behaviors are untested. We observed perinatal behavior in 11 Thomson’s gazelle (Eudorcas thomsoni) mother–infant pairs in a free-ranging population under predation pressure. Five of the six fawns that were detected by predators during the perinatal period were killed. Fawn survival therefore depended on avoiding detection by predators. Considered individually, neither prepartum isolation from conspecifics nor birth site selection affected the risk of being detected by a predator. However, analyses revealed two distinct perinatal tactics: mothers either isolated and gave birth in tall grass or remained in their social groups and gave birth in short grass. Both of these tactics resulted in lower risk of predator detection compared to behavior that was inconsistent with either tactic. The tactics represent a maternal trade-off between minimizing the duration of the highly vulnerable postpartum period and minimizing conspicuousness to predators.

No abstract

The three-spined stickleback Gasterosteus aculeatus was introduced into Lake Constance in the 1940s and occupied a limited range until late 2012. Since then the species has expanded from a solely littoral habitat in Upper Lake Constance, but now makes seasonal migrations into the pelagic zone. This behavioral change has been accompanied by a drastic increase in stickleback abundance. In order to integrate information about feeding of sticklebacks in Upper Lake Constance over two consecutive years, stomach content analysis was combined with seasonal stable isotope analysis on two types of tissue (muscle and liver). Isotope values were also obtained for zooplankton, whitefish larvae and eggs. We calculated the contribution of potential food sources for sticklebacks’ diet using a Bayesian mixing model (SIMMR). Furthermore, we determined stickleback trophic position, and δ15N and δ13C values were compared with those of other fish species of Lake Constance. The results of the Bayesian model as well as the stomach content analysis showed clear evidence of stickleback predation on fish eggs and larvae. Stickleback δ15N values were elevated during winter and comparable to those of piscivorous pike, while δ15N values of zooplankton were reduced, and those of whitefish larvae were similar to those of sticklebacks after accounting trophic fractionation of N isotopes. Trophic position calculations further identified sticklebacks as piscivorous, while the δ13C values of the liver and stomach content analysis suggests that a benthic-pelagic species pair may exist in Lake Constance. These findings support the hypotheses that sticklebacks in Lake Constance can display piscivorous feeding behaviour on sympatric fish species, most likely whitefish larvae and eggs.

This paper describes the postpartum behavior of a wild Grevy's zebra (Equus grevyi) mare and foal. The foal first attempted to stand within 5 min of birth and succeeded at approximately 10 min after birth. Within 40 min of birth, the infant could walk steadily. The foal did not suckle during the observation time. An ethogram of observed behaviors is provided.