- Researchers examined three populations of African wild dogs in Botswana, Kenya and Zimbabwe to understand if high heat correlates with increased mortality.
- In two out of the three sites, there was a strong relationship between extreme temperatures and increased mortality, with intentional human killings, snare traps, road fatalities, and disease transmission from domesticated dogs responsible for 44% of the deaths.
- The researchers say high heat is pushing both wild dogs and pastoralists out of their typical grounds, creating a higher likelihood of human-wildlife conflict and mortalities for the dogs.
With extreme heat, African wild dogs are dying at a higher rate, according to scientists. New research, published in Ecology and Evolution in June, found that humans are responsible for nearly half of all African wild dog deaths and that human-caused climate change is adding to the burden.
“At high temperatures, the dogs had higher mortality rates. When the previous 90 days had been hotter, they were more likely to die,” said lead researcher Daniella Rabaiotti of the Zoological Society of London’s Institute of Zoology.
Forty-four percent of all African wild dog deaths over the course of the study could be directly linked to humans, consisting of intentional killings, snare traps, road fatalities, and disease transmission from domestic dogs. The remaining deaths were naturally caused, consisting of inner-species fighting, death killing by other predators, and injuries sustained while hunting.
African wild dogs (Lycaon pictus) are the second most endangered carnivorous species in Africa, with fewer than 700 breeding pairs remaining and their range down to just 7% of their historic extent. (Ethiopian wolves, Canis simensis, are the most endangered carnivores.)
To conduct the study on African wild dogs’ mortality, Rabaiotti and her research team attached GPS collars to populations of the dogs in Botswana, Kenya and Zimbabwe. The collars would alert researchers to a potential death by emitting a specific signal when stationary for more than four hours.
Researchers found that in both Botswana and Kenya high temperatures correlated with increased adult dog mortality rates. The Kenya location showed the strongest relationship between increased temperature and human-related deaths due to wildlife conflict, while the Botswana location showed a strong relationship between increased temperature and naturally caused deaths. Rabaiotti said this is due to the Botswana site’s location in a nationally protected area with few human settlements.
Understanding how increased temperature leads to more human-related deaths is complex and not yet completely understood. Rabaiotti’s explanation centers on how both human and animal behavior changes under rising extreme temperatures.
African wild dogs typically hunt around dawn and dusk, when temperatures are cooler. On especially hot days or weeks, their hunting period is shortened, pushing the dogs to hunt in new regions. Hot and dry weather also leads pastoralists and their livestock into new grazing areas for similar reasons. This creates a higher likelihood for overlap between dogs and pastoralists and subsequent wildlife conflict.
As African wild dogs occasionally hunt livestock, this overlap increases the chance of pastoralists directly killing the dogs in revenge.
Since pastoralists and hunters often roam with domesticated dogs, there is also an increased risk for the spread of disease from domesticated dogs to wild ones. At the Kenya site in 2017, an outbreak of canine distemper (a disease spread from domesticated dogs) killed every pack of African wild dogs but one. Rabaiotti said the population there is just now recovering.
The Zimbabwe location was the only site that didn’t show a connection between high heat and adult mortality. Rabaiotti points to the high proportion of death by snare traps in the Zimbabwe location (40%), noting that this overshadows any relation with temperature. Since snare traps are used indiscriminately throughout the year, the deaths would not rise with increased human-wild dog overlap.
The high heat raises rates of naturally occurring deaths as well in the dogs.
“When it’s hot, animals’ immune systems don’t work quite so well. We find the same in people, when it gets hot people tend to die more of diseases,” Rabaiotti said.
Shorter hunting hours at dawn and dusk also means less sunlight during hunting, making African wild dogs a more common victim of roadkill.
While not a direct cause of death, researchers say climate change has exacerbated many other threats to the dogs. Rabaiotti said an increase of just 1° Celsius (1.8° Fahrenheit) has bumped up the death rate.
If African wild dogs continue to decline, the result on the surrounding ecosystem will be varied. African wild dogs are mesopredators, meaning they eat smaller animals, but are also prey for larger predators, such as lions, leopards and hyenas. Because of this, the impact of their loss would be different in each population across the continent.
From a holistic perspective, Rabaiotti said she doesn’t believe their loss would mean a large chain reaction on the ecosystem.
“It’s not like those studies where if you take them out suddenly there’s a big cascading effect. In Africa, because they’ve got so many predators left, [other predators are] often to able to fill the niche,” Rabaiotti said. Still, she found that when wild dogs were absent in Kenya, the vegetation began to change, as the wild dogs’ prey species flourished.
To save wild dog populations, Rabaiotti said it’s essential to vaccinate domestic dogs against rabies and canine distemper. These vaccinations would not only reduce the likelihood of African wild dogs contracting diseases from domestic dogs, it would have the added effect of reducing rabies among local people.
“All conservation is about people … The really key thing is to help the communities living alongside these predators. Because without that it’s not surprising that people end up killing them, because that’s their livelihood, that’s their survival,” Rabaiotti said.
One way of doing this is practicing better herding practices. The fewer livestock killed by African wild dogs, the less incentive there is for locals to kill African wild dogs. Rabaiotti noted a recent study that identified who was best to send with a herd of livestock against the likelihood of predatory attacks.
“If you can, send an adult. If you have to send a child don’t send more than one because they get distracted and let the livestock get eaten,” Rabaiotti said.
For individuals looking to help support African wild dogs, Rabaiotti’s advice is to reduce one’s carbon footprint, as well as donate to conservation organizations and request to see African wild dogs if on a safari.
“The good news is that our findings indicate the impact of climate change on African wild dog mortality could be mitigated both locally and globally: resolving human-wildlife conflict and reducing disease transmission from domestic dogs could help to make African wild dog populations more robust in the face of climate change, while by lowering our individual carbon footprints we can all contribute to the survival of these incredible animals,” Rabaiotti said in a press release for the study.
Citation:
Rabaiotti, D., Groom, R., McNutt, J. W., Watermeyer, J., O’Neill, H. M. K., & Woodroffe, R. (2021). High temperatures and human pressures interact to influence mortality in an African carnivore. Ecology and Evolution, 11(13), 8495-8506. doi:10.1002/ece3.7601
