No successful breeding attempts were recorded above the threshold air temperature of 35,7☌. When comparing the first three seasons (between 20) to the last three (between 20), the researchers found that the average percentage of occupied nest boxes declined from 52% to 12%, nest success (successfully raising and fledging at least one chick) declined from 58% to 17%, and the average of chicks produced per breeding attempt decreased from 1,1 to 0,4. “During the monitoring period, sub-lethal effects of high temperatures (including compromised foraging, provisioning, and body mass maintenance) reduced the chance of hornbills breeding successfully or even breeding at all,” explained Pattinson. The results showed that breeding output collapsed during the monitoring period (2008-2019) due to the increased maximum air temperature. The team also analyzed climate trends for the region. They looked at the breeding success at broad and fine scales (long term trends and individual breeding attempts, respectively). Data was exclusively collected from pairs breeding in wooden nest boxes. Pattinson and his team studied a population of southern yellow-billed hornbills at Kuruman River Reserve in the southern Kalahari Desert in South Africa between 20. This makes it difficult for them to shift breeding dates outside of the hottest periods. For example, yellow-billed hornbills initiate breeding in response to rainfall, which corresponds with the hottest days of the year. This type of nesting largely protects from predation, which means that breeding success depends primarily on other factors such as climate and food availability. The only opening is a narrow vertical slit, through which the male feeds the female and chicks. They are cavity nesters the female seals herself into the nest cavity and stays there for an average of 50 days to brood and care for chicks. Known for its peculiar breeding and nesting strategy, the southern yellow-billed hornbill is a socially monogamous species. It is thought that their population numbers are declining. The southern yellow-billed hornbill’s distribution includes most of southern Africa, with a large portion falling within the Kalahari Desert. The study was published in Frontiers in Ecology and Evolution. Pattinson and his colleagues have researched whether rapid climate warming influenced the breeding success of the southern yellow-bill hornbill, an arid-zone bird, over a period of 10 years. “For example, heat-related mass die-off events over the period of a few days are increasingly being recorded, which no doubt pose a threat to population persistence and ecosystem function.” “There is rapidly growing evidence for the negative effects of high temperatures on the behavior, physiology, breeding, and survival of various bird, mammal, and reptile species around the world,” said first author Dr Nicholas Pattinson, of the University of Cape Town. They are breeding earlier and for a shorter amount of time. For example, previous research has shown that the breeding success of multiple bird species is affected by a warming climate. The animals that inhabit these regions are already suffering the consequences. The climate crisis is worsening the harsh conditions of extreme climates, such as the high temperatures and the frequency and intensity of drought periods associated with arid regions. This study is one of the first to research the impact of the climate crisis on population-level breeding success over a longer timescale. Researchers investigated the effects of high air temperature and drought on the breeding success of southern yellow-billed hornbills in the Kalahari Desert between 20. The yellow-billed hornbill, cousins of fan-favorite Zazu from The Lion King, faces local extinction due to the climate crisis. By Suzanna Burgelman, Frontiers science writer Image: Nicholas Pattinson
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