According to new research, climate change is affecting even the most remote parts of Amazon that remain unaffected by humans.
According to Science Advances, hotter and drier climates over the past 40 years have led to a decrease in body size for rainforest birds, while increasing their wingspans, according Friday's study.
These changes may be due to physiological and nutritional challenges, particularly during the dry June-November season.
Vitek Jirinec (ecologist at Integral Ecology Research Center, and lead author of the paper) said that the biggest takeaway was that the forest is being reclaimed far away from human disturbance.
He said, "That is something you should ponder on day 26 of COP26."
Jirinec and his colleagues analysed data from more than 15,000 birds captured, measured, weighed and tagged during 40 years of fieldwork.
The researchers found that almost all birds had lost their weight since 1980.
The average loss of most species is 2 percent per decade. This means that a bird species that weighed 30g in 1980 would now weigh an average of 27.6g.
The data were not linked to any particular site, but rather were collected from large areas of the rainforest. This means that the phenomenon is widespread.
More efficient flight
The scientists studied 77 species, whose habitats varied from the dark, cool forest floor to the warmer, sunlit midstory, which is the forest's middle layer.
The most dramatic changes in body weight and wings size were seen in the birds located at the top of the midstory. These birds fly longer and are more exposed to heat.
This was hypothesized by the team to be an adaptation to energy stress - such as decreased availability of fruit or insect resources - as well to thermal stress.
Jirinec stated that there is good theoretical reasoning to support the idea that a smaller body will be more effective in climate warming.
He said, "That's why the 'wing loading hypothesis' was proposed."
A longer wings and a lower mass-to-wing ratio produce more efficient flight. This is similar to the way a glider plane can fly with less energy if it has a small body and long wings.
Higher mass-to-wing ratios require birds to fly faster in order to remain aloft. This increases their energy consumption and produces more heat.
Jirinec stated that this study did not attempt to determine if these differences are due to natural selection leading in genetic changes or if they were caused by different growth patterns based upon available resources.
Both are possible. But, he stated that there is good evidence that evolution can occur over short periods of time. The recent appearance of tuskless African Elephants, poached for their ivory, is a clear example of rapid evolution.
Philip Stouffer, co-author at Louisiana State University, stated that Amazon birds are "very fine-tuned." He also said that when someone in the population is just a few grams smaller it can be significant.
It remains to be seen how they will deal with ever hotter and dryer conditions in the future.
Friday's paper published by the team behind Friday’s paper last month showed a drastic decline in Amazonian sensitive bird species due to a warming climate. This is especially true for those who live on the forest floor, where they forage for insects.
According to the authors, other species may be experiencing similar pressures around the globe that are not yet documented.
Stouffer stated, "This is undoubtedly occurring all over the world and probably not just in birds."
(c) Agence France Presse
