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Mammalian females generally carry the bulk of reproductive costs. They gestate for relatively long periods of time and provide the majority of parental care for dependent offspring. For this reason, many studies have examined how females deal with the energetic costs of reproduction. Here, we examine the influence of reproductive state on activity budgets, diet quality, and sociality in free-living female chimpanzees (Pan troglodytes) at Gombe National Park, Tanzania. After controlling for dominance rank, we found that pregnant and lactating females consumed higher quality foods than nonpregnant, nonlactating females. However, pregnant females also traveled less. This result did not reflect differences in sociality, as the pregnant female group sizes included in our analyses were comparable to those in other reproductive categories. [ABSTRACT FROM PUBLISHER]

In mammalian species with prolonged maternal investment in which high-ranking males gain disproportionate numbers of mating opportunities, males that quickly ascend the hierarchy may benefit from eliminating the dependent offspring of their competitors. In savanna baboons, high-ranking females are the most profitable targets of infanticide or feticide, because their offspring have higher survival rates and their daughters reach sexual maturity at a younger age. However, such patterns may be obscured by environmental stressors that are known to exacerbate fetal losses, especially in lower-ranking females. Using 30 years of data on wild olive baboons (Papio anubis) in Gombe National Park, Tanzania, we found evidence that rapidly-rising immigrant males induced miscarriages in high-ranking females outside of drought conditions. However, miscarriage rates were largely reversed during prolonged periods of low rainfall, suggesting that low-ranking females are particularly vulnerable to low food availability and social instability. Infanticide did not emerge as a recurrent male strategy in this population, likely because of the protective behavior of resident males towards vulnerable juveniles.

The wild chimpanzees in Gombe National Park, Tanzania, fish for termites with flexible tools that they make out of vegetation, inserting them into the termite mound and then extracting and eating the termites that cling to the tool. Tools may be used in different ways by different chimpanzee communities according to the local chimpanzee culture. Here we describe the results of a four-year longitudinal field study in which we investigated how this cultural behaviour is learned by the community's offspring. We find that there are distinct sex-based differences, akin to those found in human children, in the way in which young chimpanzees develop their termite-fishing skills.