Yellow-Billed Hornbill Faces Local Extinction, Climate Change at Fault

Another bird species, the yellow-billed hornbill, is facing local extinction due to climate change.

A new study reports the collapse of the southern yellow-billed hornbill (Tockus leucomelas) population in its native Kalahari Desert in southern Africa. Data were collected between 2018 and 2019, and the study was published in the journal Frontiers in Ecology and Evolution.

The Kalahari Desert is a 900,000 km² semi-arid, sandy savanna in southern Africa, which covers much of Botswana, parts of Namibia, and South Africa.

The researchers pointed out that the local extinction of the bird species is almost certainly linked to rising temperatures in much of their habitat.

Yellow-billed Hornbill

The southern yellow-billed hornbill is notable for its unusual breeding behavior. It is a socially monogamous species, opting for long-term relationships with a single individual.

Once the male Southern Yellow billed Hornbill has mated, he stays with his mate to defend her nest. However, as temperatures continue to rise, this breeding strategy is coming under increasing pressure.

Researchers compared the first three seasons between 2008 and 2011 with the last three between 2016 and 2019, and the studies found that the average percentage of nest boxes occupied declined from 52% to 12%.

The study also found that the number of successful nesting attempts decreased from 58% to 17%. The average number of chicks produced during hatching attempts decreased from 1.1 to 0.4.

Climate Change, Rising Temperatures

The researchers pointed out that the decline in broods is strongly linked to rising temperatures in the region associated with climate change.

They observed that when temperatures were high, above 35.7°C, breeding attempts were unsuccessful. Breeding attempts in the field were directly correlated with the number of days when the air temperature was too high.

The researchers indicated that if this continues, significant portions of southern Africa may not see a Southern Yellow-billed Hornbill by the end of the decade.

Dr. Nicholas Pattinson, the lead author of the study from the University of Cape Town, pointed out that much of the public perception of the impact of the climate crisis is related to scenarios calculated for 2050 and beyond; however, the impacts are current and can manifest not just within a lifetime, but within a single decade.

Pattinson explained that there are no noticeable large mortality events in the study. However, the study indicates that the southern yellow-billed hornbill could be extirpated in the warmest parts of its range as early as 2027.

Fights of the birds

This is not the first time that high temperatures in the Kalahari Desert have affected the breeding of various bird species.

In 2020, a study was published describing the effects of high temperatures on the mortality of bird offspring.

The study found that nestlings and young birds of the pied babbler (Turdoides bicolor) are vulnerable to periods of excessive heat. When daily maximum temperatures exceeded the 38°C duty, no fledglings survived.

The researchers pointed out that if the pied babbler, a bird species adapted to the difficult climate of the Kalahari, cannot cope with rising temperatures, other species may also be at risk.