Brisbane, Aug 13 (The Conversation) Human-induced climate change poses significant challenges to numerous species, particularly birds. While most research has traditionally focused on gradual climate alterations like rising average temperatures or changing rainfall patterns, the increasing frequency and intensity of extreme weather events require more direct attention.
Our recent study highlights that extreme heat is having a profound impact on tropical birds. Our findings indicate that heightened exposure to extreme hot temperatures has reduced bird populations in tropical areas by 25–38 percent since 1950. This decline isn’t momentary; it’s a long-term trend continuing to gain momentum as global temperatures rise.
This research sheds light on why bird populations are decreasing even in untouched natural habitats, such as remote preserved tropical forests. It emphasizes the urgent need to cut greenhouse gas emissions and conserve the world’s remaining biodiversity.
Diving into extensive global datasets, we analyzed data from long-term surveillance of more than 3,000 bird populations globally from 1950 to 2020, incorporating over 90,000 scientific observations. While it has some gaps, this dataset provides a comprehensive view of how bird populations have evolved. Though Western Europe and North America are more represented, all continents feature in the study.
We combined this bird data with detailed daily weather histories sourced from a global climate database dating back to 1940, allowing us to examine how bird populations reacted to specific changes in daily temperatures and rainfall, including extreme heat events. Additionally, we considered average annual temperatures, total yearly rainfall, and episodes of intense rainfall.
Accounting for human pressures like land use changes and human density by integrating a dataset reflecting industrial activities over time, we developed computer models to assess how climate factors and human influences affect bird population growth.
Our research corroborates findings from other climate scientists regarding the dramatic increase in extreme heat events over the last 70 years, especially close to the equator. Tropical birds now face dangerously hot days about ten times more frequently than in the past.
Key Finding: Extreme heat poses the greatest climate threat to birds.
While shifts in average temperatures and rainfall impact bird species, our research indicates that the surge in dangerously hot days has the most significant effect, particularly in tropical regions. This poses substantial concerns, given that tropical birds often have small territories and are highly specialized regarding their habitat and climate preferences. Often, these birds have a narrow heat tolerance range.
When temperatures surpass their tolerance, birds experience hyperthermia — where their body temperature rises uncontrollably. In such cases, they may display symptoms like drooped-wing posture, panting, spreading feathers, and lethargy. In extreme instances, they may lose balance, fall from perches, or even collapse.
If they survive these conditions, they risk suffering lasting damage, such as organ failure or decreased reproductive capacity due to heat stress. Elevated heat levels reduce breeding success by compromising adult body condition and cutting down on foraging times, as birds need to seek shelter or rest during peak heat hours.
Moreover, heat stress affects eggs and nestlings, with extreme cases leading to nestling fatalities from hyperthermia or parent birds abandoning nests for self-preservation. Birds also require more water as heat rises, triggering dehydration unless they can find water more frequently or consume moister foods, as evaporative cooling increases water loss through methods like panting and gular fluttering.
Our study reveals that in tropical areas, the climate change impact on birds is now even greater than direct human activities like logging, mining, or farming. This doesn’t diminish the serious threat habitat destruction presents to tropical biodiversity, but underscores the existing challenges climate change introduces to birds in tropical regions.
Urgent Call for Action
Our findings reiterate the necessity of focusing beyond average climate metrics to include extreme weather events. Heatwaves aren’t rare anymore but are becoming regular occurrences in many parts of the world.
If climate change proceeds unabated, tropical birds, and likely numerous other organisms, will face intensifying survival threats. The rate of change might prove too rapid and severe for many species to adapt.
Given that tropical regions house a significant portion of global biodiversity, including almost half of all bird species, the repercussions could be extensive.
Conservation tactics need to incorporate these insights. Protecting habitats from industrial development remains crucial but isn’t sufficient alone. Proactive measures to assist species in adapting to climate change should feature prominently in conservation strategies, particularly in tropical zones.
Ultimately, halting and potentially reversing climate change is vital for safeguarding global biodiversity. This involves reducing greenhouse gas emissions, investing in initiatives to reduce existing carbon dioxide levels, and supporting policies that lessen our global impact. The fate of tropical birds, along with countless other species, hinges on these actions. (The Conversation) SKS GRS GRS
(Only the headline of this report may have been reworked by Editorji; the rest of the content is auto-generated from a syndicated feed.)
