Birds are twice as vulnerable to climate change as mammals, an international team of scientists has concluded after checking 481 species in 987 populations around the world.
The vulnerability of the tiger and bald eagle get extensive press, but the fact is that most mammalian and avian populations have been declining for decades. There are myriad causes, but a chief one turns out to be the sheer speed at which climate change is progressing.
The scientists wanted to check how the double whammy of climate change and human encroachment affects birds and mammals. What they found is that climate change matters more, and especially to birds.
That absolutely does not mean human encroachment, and habitat devastation, aren’t huge problems, the team clarifies. They are. They confined their examination to land-use and climate. But clearly the changes happening so rapidly to the planet are more than many species can cope with, even if their favorite tree is still there.
One problem birds have is that their mating season is triggered by temperature changes, explains lead author Fiona Spooner. “We think this could be leading to a desynchronization of their reproduction cycle, leading to the negative impacts we’re seeing. Mammal breeding seasons are a lot more flexible, and this is reflected in the data,” she says.
Their research shows that in areas where the rate of climate warming is worse, bird and mammal population declines measured over at least five years are more rapid, says co-author Robin Freeman. "The arctic for example has experiences quite high rates of warming and we have seen simultaneous population declines. We also see rapid rates of warming in central and northern Africa where many mammal populations are in decline," he told Haaretz.
In some places, such as Europe, the declines in populations are less rapid, he says. "This may be because many of the impacts occurred historically. However, threats such as climate change are pervasive and continuing."
The truth is that many birds, leaving sheltered poultry out of it, are in trouble. A 2017 report in Scientific American warns that changing temperature patterns are causing birds to mistime their migration: “Bird species trace their migratory paths based on where they can find the most resources, but changes to the climate might soon make their knowledge outdated,” the report said.
Birds become accustomed to certain routes that pass over lush lands swarming with food, usually insects. But green land today could be desert tomorrow, the study points out. Species that travel the farthest are particularly vulnerable.
Everywhere they look, scientists are observing changes in the patterns of life – from germs to insects to birds to ocean animals.
The new ZSL study specifically names a few species of birds and mammals in marked decline, such as the black-tailed godwit (Limosa limosa) in Germany and Senegal; and Senegal; the pink-footed goose in Canada (Anser brachyrhynchus) and black-backed jackal (Canis mesomelas) in Tanzania.
Germany, for instance, has been experiencing more extreme weather. Also, while the Middle East gradually dries out, Germany has been soaked, with an 11 percent increase in rainfall since 1881.
However, certain areas have become drier, especially in summer. Alpine snow is melting earlier. Canada has a tough young prime minister, Justin Trudeau, who instated aggressive policies that horrified big business: two years later, the jury is still out. Meanwhile, it’s getting pretty hot there: average temperatures in Canada have been increasing faster than in most other places and have already risen by 1.7 degrees Celsius since 1948. It’s rainier, too.
The impact of climate change on Tanzania and neighboring countries has been hard, and they lack resources to cope with the worsening droughts and flooding.
"There are a variety of bird species that are in warming places that are declining rapidly," Freeman told Haaretz. "For example, burrowing owls (Athene cunicularia), a are a nationally endangered owl in Canada that are declining quite rapidly. Similarly, we also see corncrakes (Crex crex) declining rapidly in Central Europe."
In Asia, the decline of the mountain sheep is marked. "Red colobus monkeys in Uganda are endangered and we see them declining rapidly with associated warming, he says.
It is hard to say from the ZSL study which specific aspect of warming is to blame for the declines, Freeman says: It could be that the timing of seasons is changing while daylight isn't, temperature extremes, or some other factor.
"We have found that in places where warming is rapid, declines are faster but the mechanism of this remains unclear. It may be that, as others have found, with climate change, peak food availability is earlier that usual and therefore less associated with peak breeding times. This makes it harder for annual breeders to maintain their populations," Freeman says.
The data is not clear-cut but it seems that larger mammals, for example, may be declining less rapidly, Freeman says. For the time being.
Sometimes, the effects of climate change aren’t exactly what we expected. Australia brings us an example of a completely different type of problem. Among the bearded dragon, in temperatures between 34 to 37 degrees Celsius (93 to 99 degrees Fahrenheit), male embryos turn female. The outcome can be a gender ratio of 16 females to one male. That is unfortunate.
Bizarrely, the converted male lizards produce more eggs than genetic females, the paper reports. This “super-female” (as the scientists called the bearded lady lizard) goes more boldly to places where other regular bearded lizard males go. Go figure.
In any case, the real problem isn’t sexual frustration in the female bearded lizard, but that temperature dependency of sexual determination will ultimately lead to an all-female population, which will then promptly go extinct.
“Our research shows that in areas where the rate of climate warming is worse, we see more rapid bird and mammal population declines. Unless we can find ways to reduce future warming, we can expect these declines to be much worse,” said Freeman.
The ZSL also made news in April for reporting on the approaching extinction of a turtle that grows algae on its head and has gills in its cloaca. Which means, it breathes through its genitals. The Mary river turtle also sports bumps that look like proto-tentacles under its chin and lives exclusively in the waters of the Mary river in Queensland, Australia.