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When Cyclone Idai struck Gorongosa National Park in Mozambique in May 2019, the 2008 park – one of the most technologically advanced wildlife parks in its management – was facing one of its deadliest natural disasters, resulting in the loss of a large number of wildlife. Animals in this park.
Thanks to the presence of surveillance cameras and animal tracking devices linked to the global positioning system that were present in the park, an international team led by researchers from Princeton University in the United States was able to track and study the responses of animals living in the park, moment by moment. The team presented the results of its study in a paper recently published in the journal Nature.
Mammal behavior in real time
The paper focused on tracking mammalian behaviors in particular. As the researchers say in the Phys.org press release, “This is the first study ever to track the real-time responses of a large mammal community to a natural disaster.”
Researchers watched the rising waters and the animals’ reactions in the hours, days and weeks after the hurricane, and how some of them survived the flood waters, and others did not, says Haley Brown, a postdoctoral research associate in the Department of Ecology and Environmental Biology at Princeton University and first author on the paper.
The researchers used the data they had from before, during and after the storm to create not just a description of that event alone, but a broader set of forecasts, so park managers could “better anticipate the impacts of increasing severe weather events.”
Size…the best indicator of survival
The research team found that the best predictor of survival was size, as the small oribi – a type of antelope the size of a greyhound – saw its numbers decline by 50%, and about half of the reedbugs, a type of larger African antelope, also died. The average-sized bushbuck saw a loss of only 4% of its total population.
GPS data revealed that the bushbuck were searching for hills to climb, including termite mounds up to 5 meters high and 20 meters long, which had become islands in the flood.
The researchers saw that one of the surviving members of that antelope was jumping from hill to hill, quickly passing through the floodwaters between them, before finding safety in the forest at higher altitudes. There were no deaths in the four largest herbivores, the nyala, kudu, sable, and elephant.
The researchers found that body size also provided protection in a secondary way, as smaller animals were not only unable to traverse the water, but were also unable to overcome dietary restrictions afterwards. Because the flood was so high for such a long time, it killed a lot of the low grasses and plants, and the small animals could not tolerate these nutritionally limited periods as well as the larger animals who had more fat to rely on.
The park’s few carnivores weathered the storm well, Brown said, with wild dogs and leopards taking advantage of the concentration of their prey at higher elevations, and the lions’ primary food source being pigs remained at higher elevations for several months, but they were largely unaffected by the hurricane.
So the researchers made two key recommendations for wildlife managers: evacuate the smallest and most ecologically vulnerable creatures to safer areas before storms occur, and provide supplemental forage after the storm.
