Rising temperatures linked to cellular ageing in wild birds: study

Hotter temperatures are causing hidden, cumulative cellular damage in wild birds that could contribute to population declines, according to research led by Australia's Monash University.

The study examined how non-lethal heat exposure affected telomeres -- protective caps at the ends of chromosomes -- in purple-crowned fairy-wrens, a species native to tropical Australia, according to a statement released Thursday by the university.

Telomeres shorten naturally as an animal ages or experiences physiological stress. Shorter telomeres are closely linked to reduced lifespan and lower reproductive success.

Researchers found that hotter conditions accelerated telomere loss during two critical periods of purple-crowned fairy-wrens: when juveniles moved toward nutritional independence and when adults entered their reproductive phase.

Neither favorable social conditions nor other environmental factors reduced the impact of heat exposure. However, adult birds living in areas with high-density vegetation experienced less severe telomere erosion, according to the findings.

"Even when temperatures aren't hot enough to kill an animal outright, heat stress inflicts hidden damage at a cellular level. Over time, this cumulative degradation reduces individual fitness and could quietly drive population declines," said the study's co-author Justin Eastwood from the Monash University School of Biological Sciences.

The researchers called for protecting natural microclimates, including dense vegetation canopies along riverbanks or in deep forests that block direct sunlight, to help species cope with rising temperatures.