Climate Change

Climate change victim: How high temperatures, drought have endangered this Kalahari bird

The southern yellow-billed hornbill has not been able to breed properly and its numbers have declined subsequently

By Madhumita Paul
Published: Monday 06 June 2022
A southern yellow-billed hornbill. Photo: iStock

Climate change has been wreaking havoc on a number of species for quite some time now. Some have even gone extinct. It is now threatening a resident of the Kalahari Desert of southern Africa: The southern yellow-billed hornbill (Tockus leucomelas).

A study led by the University of Cape Town has found that an increase in temperatures could see the hornbill disappear from parts of the Kalahari by 2027.

The climate crisis is exacerbating the harsh conditions of extreme climates — such as the high temperatures and the frequency and intensity of droughts associated with arid regions — in the Kalahari.

Read: Bramble Cay melomys is first mammal to go extinct due to climate change

The researchers studied the effects of high air temperate and drought on the breeding success of the birds in the Kalahari Desert from 2008-2019. Their findings revealed that breeding output collapsed during this time, with an increase in temperature.

In danger

The southern yellow-billed hornbill, like other types of hornbills, has unusual breeding and nesting habits. The female seals herself in a cavity and stays there for about 50 days to brood and care for chicks.

This type of nesting largely protects from predators, which means that breeding success depends primarily on other factors such as climate and food availability.

The southern yellow-billed hornbill initiates breeding in response to rainfall in the arid western parts of its southern African range. They feed on insects, spiders and scorpions as well as seeds that they find on the ground. It is usually found in resident pairs or small family flocks.

In the present study, the researchers collected data from pairs breeding in wooden nest boxes at the Kuruman River Reserve and compared their findings with climate trends for the region.

The researchers compared the first three seasons (2008-2011) to the last three (2016-2019). They found that the average percentage of occupied nest boxes declined to just 12 per cent, from 52 per cent. The average number of chicks per breeding attempt declined to 0.4 from 1.1.

Nicholas Pattinson, first author of the study was quoted as saying in a statement:

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.

Southern yellow-billed hornbills struggle to breed above certain temperatures as they face greater difficulty in foraging and lose weight. According to the study, when the average air temperature went above 35.7 degrees Celsius, there were no successful breeding attempts at all among the hornbills.

Based on current global warming trends, that temperature will be exceeded for the birds’ entire breeding season by 2027, the researchers said.

The study was published in the journal Frontiers in Ecology and Evolution

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