Linking climate variability to demography in cooperatively breeding meerkats

Abstract

Animal populations in arid environments, where extreme temperatures and erratic rainfall are normal, are particularly vulnerable to climate change. While numerous studies have examined the effects of temperature and rainfall on the breeding success and survival of arid-zone species, the mechanistic pathways linking climate variation to demography remain poorly described for most species. Using long-term data from meerkats (Suricata suricatta) in the Kalahari Desert, we show that increases in rainfall and primary productivity (as measured by normalized difference vegetation index) were associated with improved foraging success, daily body mass gain, and body condition, which in turn contributed to enhanced breeding success and survival. Conversely, high summer temperatures were associated with reduced foraging performance and body condition. Foraging efficiency declined when daily maximum summer temperatures exceeded 35°C, and at temperatures above 37°C, diurnal mass gains often failed to offset overnight mass losses. While high temperatures had short-term detrimental effects, runs of hot days were relatively infrequent and often coincided with periods of high primary productivity. As a result, individuals were rarely in poor condition during the hottest periods of the year, suggesting that they could recover any mass lost on hot days during subsequent cooler periods. Only when high temperatures persisted alongside low primary productivity did body condition drop sharply. Although temperature variation has not yet affected the demography of our meerkat population as strongly as rainfall variation, further warming in the region and the potential for more frequent and severe hot droughts are likely to have major implications for the species' distribution and persistence. Our study emphasizes the need to consider both rainfall and temperature variations across seasons, as well as their interactions, to better understand and predict the impacts of climate change on arid-zone animals. It also demonstrates the value of long-term, high-resolution behavioral and physiological data, including frequent, year-round weighing of animals, in establishing causal links between climate and demography.