Instead of chasing their prey across long distances in open grass plains, African wild dogs are hunting in wooded areas using multiple short-distance, high-speed bursts. Data from GPS collars reveal that their individual success rates are low, but they share their kills with other pack members: The energy return from group feeding outweighs the cost of multiple short chases. And in this way, their strategy may be more efficient than the sheer athleticism of cheetahs hunting alone in the same area. The findings are published as two papers in Nature Communications this week.
Since the 19th century, African wild dogs (Lycaon pictus) have been traditionally described as highly collaborative endurance pursuit hunters: They chase large prey at relatively low speeds over many kilometers in groups. But as their range became increasingly restricted to woodlands and wooded savannahs with dense vegetation, it's no longer clear that their energetically costly hunting strategy is still a successful one.
To investigate, a team led by Alan Wilson of the Royal Veterinary College attached high-resolution GPS collars with velocity data loggers to all six members of a pack of African wild dogs in the Okavango Delta region of northern Botswana: one dominant pair and their siblings. The collars (pictured to the right) are equipped with solar panels and two rechargeable batteries, allowing the team to track fine-scale movements for up to seven months in 2012.
After analyzing 1,119 chases, the team found no evidence of long-distance pursuits or cooperative chases requiring coordination (beyond greeting and rallying before hunts). Turns out, most of their hunting attempts are short-distance chases of multiple medium-sized prey (mostly impala) by several dogs simultaneously. This is an energetically cheaper strategy, though their individual kill rate is only 15.5 percent.
In a second study, the team developed an energy-balance model to compare the energetic costs of this hunting strategy with the returns. While the success rate of each dog is low, these costs are offset by sharing prey within the pack. On average, each dog chased prey about twice a day, though they do have a strict social hierarchy: Dominant adults and their pups feed first. “This may be why we saw the subordinates hunting more frequently,” Wilson explains to IFLScience. “They are more likely to be hungry.”
Furthermore, the team compare the dogs’ strategy with the stalk and sprint-pursuit of cheetahs (Acinonyx jubatus), an energetically demanding tactic that results in a higher success rate of 26 percent. In terms of the kill gain to kill cost ratio, a solitary hunting cheetah is twice as efficient as a solitary dog, but sharing prey boosts the pack’s efficiency to nearly triple that of one cheetah.
“The energy balance model would suggest it is a good strategy, and arguments can be made that if you can catch prey with short hunts, why invest energy in using long ones,” Wilson adds. As habitats for African wild dogs become less favorable, being flexible with hunting behaviors will become increasingly critical.
Image in the text: African wild dog wearing a collar. Julia Myatt