(ORDO NEWS) — Due to climate change, wild dogs are trapped in a phenological trap. Over the past 30 years, they have moved their breeding dates forward by 22 days in order to produce offspring in the coolest weather, when hunting is most comfortable.
However, as a result, the ninety-day period the puppies spend in the burrow now falls during the warmer season, negatively impacting reproductive success.
However, as noted in an article for the journal Proceedings of the National Academy of Sciences, interannual weather fluctuations mask the negative effect of global warming on the wild dog population.
Representatives of many biological species shift the timing of reproduction and migration in response to climate change.
For example, due to the fact that spring is getting warmer, the Kyoto cherry blossoms are now blooming eleven days earlier than usual. And many migratory birds from Eurasia and North America return earlier to their nesting grounds from their winter quarters.
However, in some cases, attempts to adapt to a changing climate drive entire species into an ecological trap. This is exactly what happened to tree swallows (Tachycineta bicolor). Due to the earlier onset of spring, they now breed one to two weeks earlier than they did in the middle of the 20th century.
However, despite the general warming of the climate, the number of cold spring days has not decreased over the past decades.
As a result, swallows are increasingly faced with days when flying insects are inactive due to bad weather, making it impossible to find enough food for the chicks. Not surprisingly, their breeding success is declining.
A similar example was described by a team of zoologists led by Briana Abrahms from the University of Washington in Seattle. The focus of researchers was hyena dogs (Lycaon pictus).
Although these large predators live in Africa, they do not like to hunt in the heat. In regions with a seasonal climate, wild dogs even breed during the coolest months of the year.
As a result, for ninety days after the birth of the cubs, while they are sitting in a hole, adult members of the flock can hunt at relatively low temperatures that are comfortable for them and provide the nursing mother, and then her offspring, with a sufficient amount of food.
Abrams and her colleagues suggested that due to climate change, wild dogs are having to shift breeding dates. To test this hypothesis, the authors analyzed data on 60 wild dog packs collected from 1989 to 2020 in northern Botswana.
Each of these groups was followed for an average of 2.38 years. It turned out that in thirty years the hyena-like dogs really began to breed twenty-two days later. If in 1990 cubs were born around May 20, then in 2019-2020 this happened around June 12.
In other words, now puppies of wild dogs are born not at the end of the southern hemisphere autumn, but at the beginning of the southern hemisphere winter.
The authors attribute this shift to an increase in temperatures in the study area. Since the end of the 1980s, the average daily maximum air temperature here has increased by 1.6 degrees Celsius.
Apparently, by shifting the timing of the birth of cubs forward, hyena-like dogs are trying to time breeding dates for periods of cool temperatures that are familiar to them.
Additional analysis confirmed this idea. The average air temperatures on the birthdays of puppies of wild dogs really remained stable for thirty years due to a shift in breeding dates.
However, when the researchers compared how the average air temperature changed during ninety days, when the cubs of hyena-like dogs sit in holes, it turned out that in thirty years it increased from 28.5 degrees Celsius to 30 degrees Celsius.
The attempt of predators to synchronize the start of breeding with the coolest days of the year has paradoxically led to the fact that the period of rearing offspring has shifted to a warmer season than before.
This negatively affects reproductive success: the higher the air temperature for ninety days after the birth of puppies, the lower their chances of survival.
This may be due to the fact that in hot weather, females need to spend more energy on cooling, which is why she cannot produce enough milk to feed her cubs. On the other hand,
Abrams et al note that until now it was believed that the phenology of large predators at high trophic levels should be relatively stable under conditions of climate change. However, the example of wild dogs demonstrates that this is not always true.
The rate at which the timing of these canids shifted (by twenty-two days in thirty years) is twice the average rate of phenological shifts associated with climate change in other animals.
The situation in which wild dogs find themselves due to climate change can be described as a phenological trap. The environmental cues they relied on to boost their breeding success now cause them to breed at the wrong time of the year.
This can significantly worsen the situation of a species that is already endangered. However, the authors emphasize that so far interannual temperature fluctuations mask the negative effects of climate change on the reproductive success of wild dogs.
In addition, the size of the flocks of these predators increased slightly during the study period, which may offset the negative effect of warming.
The hyena-like dogs are not only successful predators, but also supporters of democracy. A few years ago, zoologists figured out that they decide when to go hunting by voting with a sneeze.
At the same time, the number of sneezes, after which the pack moves off, depends on the rank of dogs in the group hierarchy.
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