African wild dogs (Lycaon pictus) are one of the most endangered mammals in the world, with only about 6,600 adults remaining in 39 subpopulations across sub-Saharan Africa
These social and cooperative hunters are adapted to living in hot and arid environments, but they may face a bleak future if global temperatures continue to rise due to climate change.
A new study by researchers from the University of Zurich and the Botswana Predator Conservation Trust has examined how African wild dogs cope with heat stress and how they may respond to a 3°C increase in global mean temperature, which is projected to occur by 2100 under a high-emissions scenario
The study, published in the journal Nature Communications, suggests that African wild dogs may not survive such a warming, as it would reduce their hunting time, food intake, and reproductive success
How African wild dogs cope with heat stress
African wild dogs are active during the day, hunting mostly in the early morning and late afternoon when temperatures are cooler.
They rely on their large ears and panting to dissipate heat and regulate their body temperature.
However, when ambient temperatures exceed their body temperature, panting becomes ineffective and they have to seek shade or rest to avoid overheating.
The researchers used GPS collars equipped with temperature sensors to monitor the movements and body temperatures of 19 African wild dogs from six packs in northern Botswana over two years.
They found that the dogs adjusted their activity patterns according to the seasonal and daily variations in temperature.
During the hot dry season, they spent more time resting and less time hunting than during the cooler wet season.
They also shifted their hunting times to earlier in the morning and later in the afternoon, avoiding the hottest hours of the day
The researchers also measured the energy expenditure and food intake of the dogs using a technique called "doubly labeled water", which involves injecting a small amount of water containing isotopes of hydrogen and oxygen into the dogs and then collecting urine samples to track how much of the isotopes are lost over time.
They found that the dogs' energy expenditure was higher during the hot dry season than during the wet season, likely because of the increased panting and resting.
However, their food intake was lower during the dry season, as they had less time and opportunity to hunt.
This resulted in a negative energy balance, meaning that the dogs were losing more energy than they were gaining from food
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How African wild dogs may respond to a 3°C increase in global mean temperature
The researchers used a mechanistic model to simulate how African wild dogs may respond to a 3°C increase in global mean temperature, assuming that their physiology and behavior remain unchanged.
They found that such a warming would reduce the dogs' hunting time by 1.8 hours per day on average, resulting in a 25% reduction in food intake and a 38% reduction in reproductive success.
The model also predicted that some packs may experience periods of up to five months with no hunting time at all, leading to starvation and local extinction
The researchers cautioned that their model did not account for other factors that may affect the survival of African wild dogs, such as habitat loss, human persecution, disease, competition with other predators, and adaptation to changing conditions.
They also noted that their study was based on data from one region of Africa and that different populations of African wild dogs may have different responses to climate change depending on their local environment and genetic diversity.
However, they stressed that their findings highlight the vulnerability of African wild dogs to heat stress and the urgency of reducing greenhouse gas emissions to limit global warming.
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