September 26, 2017

The Sneezes Have It: Rallying African Dog Pack Movement

Ever wonder how packs of African wild dogs decide when to pick up and move to another location? We’ve got the scoop!
By JoAnna Pendergrass, DVM
Consensus is necessary for certain benefits of group living, including defense of resources and protection. For African wild dogs and other dominant-led social groups, dominant individuals disproportionately influence group decision-making. In African wild dogs, for example, dominant dogs suppress pregnancies in subordinate females.

Group consensus is also important for deciding when to move. In animals, once a certain threshold of individuals (quorum) makes a particular signal, a collective decision is made to leave. For instance, honeybees use “piping signals” to initiate group movement. To date, though, little is known about how African wild dogs attain group consensus on movement.

In a study published in Proceedings of the Royal Publishing Society B, researchers determined that African wild dogs sneeze to rally pack movement. This was the first study to document sneezing as a major form of communication in African wild dogs.

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Studying the Behavior
The researchers studied 5 packs of African wild dogs in Botswana for 1 year. The following behaviors used to initiate rallies were observed directly or with video recordings:
  • Rising from rest
  • Lowering the head
  • Opening the mouth
  • Folding the ears back

Video recordings of behaviors were analyzed from the beginning to end of each rally. Researchers counted the number of sneezes per rally event, including the per-minute frequency of sneezes before and after rallies. Specific social interactions were also analyzed:
  • Parallel runs: running flank to flank
  • Mob: at least 3 dogs gathered within 3 feet of each other
  • Greeting: touching heads or gathering within 3 feet of each other

Because dominance under the dominant pair is not easily identifiable in African wild dog packs, the researchers determined dominance using priority of access (POA) to a carcass; POA1 indicated first access.

Observations
Of the 68 rallies observed, not all succeeded in spurring group movement. In fact, only about 25% of first rallies were successful. However, nearly 65% of third rallies resulted in movement, indicating that pack movement was more likely after several failed rally attempts.

POA significantly influenced rally success, with POA1 individuals having a greater percentage of successful rallies (76%) than POA2 or POA3 individuals (27% and 33%, respectively). Similarly, once the packs moved, POA1 individuals were most likely to lead them.

Of the factors analyzed for their influence on predicting group movement, sneezing was most important. In particular, a significantly greater number of sneezes were used in successful than unsuccessful rallies. Social interactions, although they are typical rallying behaviors in African wild dogs, were not a major influence.

The researchers identified associations between dominance, number of sneezes, and successful rallies. Higher-ranking individuals needed only 3 sneezes to initiate group movement, while more subordinate individuals required at least 10 sneezes for successful rallies. These findings suggest that, in African wild dog packs, the quorum needed for group movement is variable and does not fully depend on participation of dominant individuals.

Sneezes, the researchers noted, are physically similar to other canid vocalizations that communicate alarm. However, given the non-aggressive dominance of African wild dog packs, sneezes have a nonthreatening contextual meaning in these packs. In this study, sneezes were associated with decision making. Notably, the researchers observed sneezing in relaxed states and a lack of startle behavior when sneezing occurred.

For the Future
Whether sneezing was a true voting mechanism or simply a physiologic response occurring after a group consensus could not be determined; physiologically, the sneezing could have been a preparatory activity before hunting. “Further research is required to confirm causality,” the researchers wrote.

The researchers also suggested analyzing potential correlations between sneeze-like mechanical vocalizations and group decision-making in other species.

 
Dr. Pendergrass received her Doctor of Veterinary Medicine degree from the Virginia-Maryland College of Veterinary Medicine. Following veterinary school, she completed a postdoctoral fellowship at Emory University’s Yerkes National Primate Research Center. Dr. Pendergrass is the founder and owner of JPen Communications, a medical communications company.

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