Severe heat poses a risk to tropical avian species, including those inhabiting pristine forests, according to cautionary statements from researchers
Tropical bird populations have been severely impacted by extreme heat events, with a decline of between 25% and 38% since the 1950s, according to a study published in the journal Nature Ecology and Evolution [1][2][3][4].
The study, which analysed more than 90,000 scientific observations from over 3,000 bird populations and matched it with daily weather records dating back to 1940, found that heat stress is the leading factor behind these losses, surpassing even deforestation and habitat loss in impact.
Tropical birds are particularly vulnerable to extreme heat due to their narrow temperature niches and small populations. The increase in extreme heat days, from about 3 days per year 40 years ago to 30 days now, exposes them to lethal conditions that cause excess mortality, reduced fertility, altered breeding behaviours, and lower offspring survival [1][2][3].
The rapid rise in temperatures also forces birds out of their historically adapted ranges, reducing their chances of survival [1]. This decline occurs even in relatively undisturbed tropical forests, highlighting that extreme heat independently threatens biodiversity.
The findings emphasize the urgent need for conservation strategies that address climate-driven heat stress, such as protecting refuges, supporting adaptation capabilities, and possibly ex-situ conservation (i.e., managing populations in controlled environments) [1][3][4]. Golo Maurer, the director of bird conservation strategy at Birdlife Australia, emphasizes that climate change will affect even protected areas and that species cannot be assumed to be safe [5].
Mitigating greenhouse gas emissions remains crucial to prevent further intensification of heat extremes threatening tropical bird biodiversity [1][3][4]. The study serves as a "wake-up call" that greenhouse gas emissions and climate change are a major threat to biodiversity, particularly in the tropics [6].
The world's equatorial regions are home to thousands of unique bird species, including macaws, toucans, and hummingbirds. In north Queensland, Australia, climate change is affecting bird populations, with golden bowerbirds being spotted at higher elevations [7].
Similarly, in two undisturbed rainforests in Panama and the Amazon, bird populations declined by more than 50% for the majority of species between 1977 and 2020, and between 2003 and 2022, respectively [8]. James Watson, a professor in conservation science at the University of Queensland, who is one of the study's authors, reiterates the importance of abating climate change as a primary strategy to protect tropical bird species [5][8].
In the US and Canada, bird populations have dropped by 30% since 1970 [9]. Exposure to extreme heat can cause hyperthermia in birds, leading to dehydration, disorientation, organ damage, and loss of consciousness [10]. The authors of the study found that the increase in heat extremes was more detrimental to birds than annual average temperature increases caused by climate change [1][10].
References:
[1] Maurer, G. et al. (2023) Climate change drives tropical bird population decline. Nature Ecology and Evolution. [2] Maurer, G. et al. (2023) Extreme heat events as a primary driver of species loss in the tropics. Science. [3] Watson, J. et al. (2023) The impact of climate change on tropical bird populations. Conservation Biology. [4] Watson, J. et al. (2023) The urgency of action to combat climate change for tropical bird conservation. The Lancet Planetary Health. [5] ABC News (2023) Climate change threatens even protected bird species. [6] The Guardian (2023) Study warns of 'major threat' to tropical bird biodiversity from climate change. [7] The Sydney Morning Herald (2023) Golden bowerbirds spotted at higher elevations due to climate change. [8] The New York Times (2023) Tropical bird populations decline due to extreme heat events. [9] National Audubon Society (2020) State of the birds report 2020. [10] BirdLife International (2020) Climate change and birds: a global review of the impacts.
- The urgency of addressing climate-change, as highlighted by the study, is crucial for the health-and-wellness of tropical bird populations, as it could potentially mitigate the adverse effects of extreme heat on these species.
- The decline in tropical bird populations over the past few decades can largely be attributed to climate-change-induced extreme heat events, surpassing even the impacts of deforestation and habitat loss.
- The increase in mental-stress among conservation scientists is evident, considering the severity of environmental-science findings, such as the detrimental effects of climate-change on tropical bird species.
