Hummingbirds Face Possible Extinction Due to Global Warming

Hummingbirds may face extinction as a result of global warming, Newsweek reports on a new study. Scientists predict that the avian species will have to migrate north in search of cooler climates or possibly perish completely.

As hummingbirds have the most difficult type of flight in the whole animal kingdom, hovering requires far more energy and oxygen than regular flight, as Study Finds reports.

The bird species, however, are unaffected by the thin air. From Alaska to South America, they thrive in high mountain ranges.

Studying Anna's Hummingbirds Species

According to the study, the hurdles of shifting may be too much for the agile, tiny aeronauts.

Austin Spence, the stated lead author of the study and a Ph.D. student at the University of Connecticut, explains that overall, the presented data implies that low air pressure and oxygen availability may impair hovering performance in hummingbirds when subjected to the acute challenge of high-elevation.

In the study, Spence explains that when there is less oxygen available, thinner and colder air is especially challenging for species trying to stay warm.

The study focused on the species Anna's hummingbirds (Calypte anna), which may live up to 2,800 meters above sea level.

They enticed the bird species into net traps from locations around California, including Sacramento, which is 10 meters above sea level, and Mammoth Lakes, which is at 2,400 meters.

The researchers then relocated them to a 1,215-meter aviary in western California.

After a few days in their new habitat, the birds were given a little funnel into which they could stick their heads while hovering and sipping delectable syrup.

The metabolic rate of the small organisms was recorded overnight since they let their metabolism drop as they slept.

During sleep, this type of mini-hibernation conserves energy. Hummingbirds can cool their bodies to below 4°C at night, the lowest temperature ever recorded in any bird.

They have wings that beat at a rate of more than 10 times per second, and they use their hovering abilities to drink nectar from thousands of flowers during the day.

Hummingbirds have a small heart that roughly 1,000 times each minute to stay up, but only 50 times during rest. The birds were transported by Spence and colleagues to a nearby research site 3,800 meters up near Mount Barcroft's top, where the air is thinner, with around 39% less oxygen and a temperature of about 5°C.

The hovering hummingbirds should have been working harder to remain aloft in the thin air 1000 meters above their natural range, but they experienced a 37 percent drop in metabolic rate.

When the researchers examined the energy expended on the mountain top by birds that began around sea level and those from the higher end of their range, they found that they all labored similarly.

Read also: For At Least 50 Years, Bird Population Kept on Falling in Tropical Rainforest 

Furthermore, the hummingbirds began to lower their metabolic rate for longer periods during the night. They were in torpor for more than 87.5% of the freezing high-altitude night.

Spence explained that the birds employ torpor when it's extremely cold.

The researchers also looked at the size of the animals' lungs to see if they grew larger in those that came from higher altitudes to compensate for the lack of oxygen.

The team's findings show that although the birds' lungs were not larger, their hearts were.

The findings in the Journal of Experimental Biology have implications for the future of hummingbirds as the avian species seek more comfortable conditions due to climate change.

The findings presented by Spence and his team show that decreasing oxygen availability and low air pressure may be challenging difficulties for hummingbirds to overcome.

Related article: Bizarre 'Behavioral Change' Observed in Birds Linked to Climate Change