A new study published in the journal Ecosphere has found that spotted hyenas (Crocuta crocuta) are able to adjust to a reduced presence of migratory prey in their territories induced by climate change. An observation-based dataset spanning three decades has revealed that, although the substantial increase in annual rainfall during this period halved the presence of migratory herbivores inside the hyenas’ territories in the Serengeti National Park in Tanzania, it did not affect female hyenas’ access to prey and the successful nursing of their offspring.
Changes in the timing and amount of precipitation can alter vegetation growth and hence the distribution of migratory herbivores, such as the zebras or blue wildebeest from Tanzania’s Serengeti ecosystem. Ultimately, such climate changes may influence the location of feeding areas for predators like the spotted hyenas, who feed upon these herbivores.
However, by daily monitoring three clans of spotted hyenas from 1990 to 2019, researchers from the Leibniz Institute for Zoo and Wildlife Research in Germany (Leibniz-IZW) and the Center for Functional and Evolutionary Ecology in France (CEFE) have made a surprising discovery: spotted hyenas seemed perfectly able to adjust their foraging behavior to shifts in migratory prey presence in their territories that were linked to climate-related changes.
The scientists found that, although increases in rainfall volume over the years were correlated with a decrease in the presence of migratory herbivores, maternal den attendance of hyenas (the presence of lactating hyenas with entirely milk-dependent offspring at communal dens) did not decrease, matching periods of high prey abundance.
“The presence of mothers at the communal den is a key behavior directly related to cub survival. Spotted hyenas in the Serengeti National Park reproduce throughout the year. Their cubs entirely depend on milk for their first six months of life,” explained study co-authors Dr. Marion East and Professor Heribert Hofer, senior scientists at the Leibniz-IZW.
“When large aggregations of migratory herbivores occur in the clan territory, all lactating mothers feed inside the territory and nurse their cubs daily. When migratory herds are absent, there is no other prey around and females fuel milk production by regularly commuting to distant areas to feed on migratory herbivores. After one to several days, they return to the communal dens to nurse their cubs.”
According to the researchers, these findings suggest that hyenas may not so much rely on expectations of where aggregations of migratory herds should be at a given time, but rather employ other means of locating good foraging locations when commuting, such as observing the movements and behaviors of well-fed members of their clan, or using established commuting routes that cross many territories.
Thus, hyenas appear particularly well-suited to cope with changes in the presence of their prey in their territories induced by climate change. “This indicates a high plasticity in the response of this keystone predator to environmental variability,” concluded study co-author Dr. Sarah Cubaynes, a scientist at CEFE.