With temperatures around the world changing so dramatically, wildlife is often forced to move to find suitable habitat – and scientists are working hard to try to understand how many species may struggle as they try to find new homes.
Animals that go higher up face two problems: colder temperatures and thinner, oxygen-rich air (making it harder to breathe). In a new study, a group of Anna’s hummingbirds (Caleb Anna) on flight at an altitude of 1,200 meters (4,000 ft) above its natural habitat.
Surprisingly, the hummingbird’s metabolic rate decreased as they flew. They also fly for shorter times with lower efficiency, most likely due to lack of oxygen.
While future temperatures may be warmer, cooler elevations have a chilling effect on hummingbird sleep patterns. When the birds sleep, they are more likely to engage in a kind of mini-hibernation, which also reduces their metabolism by an average of 37 percent.
The team behind the study say that at least in the case of hummingbirds, getting to higher ground will be a big challenge.
In their report, the researchers wrote: “Our results suggest that low oxygen availability and low air pressure may be a difficult challenge to overcome for hummingbirds moving from top to bottom as a result of rising temperatures, especially if there is little long-term acclimatization. long. .” published papers.
These birds were forced to relocate in response to rising temperatures, and they can currently be found at altitudes between 10 and 2,800 meters (33-9186 ft). It covers distances and temperature ranges, but the research team is interested in seeing if there is an upper limit.
In the study, 26 hummingbirds were flown from across the current altitude range, and they all struggled equally to adapt. However, the study found that those from high altitudes tended to have larger hearts to improve the distribution of oxygen throughout the body.
The researchers used a variety of methods to measure sleep levels and metabolic rates in hummingbirds, including a funnel filled with syrup to make the birds eat while simultaneously monitoring their oxygen consumption.
Carbon dioxide production during sleep, which is another indicator of metabolic rate, was also recorded. Hummingbirds spend at least 87.5 percent of the night in a small, energy-efficient hibernation, compared to the usual 70 percent. Again, this is consistent no matter what height the hummingbirds are taken from.
“This means that even if they’re from a warm or cold place, they go into hibernation when it’s really cold, and it’s cold.” Ecologist Austin Spence says: from the University of Connecticut.
Hummingbirds make good study subjects in this regard because of their high-energy lifestyle. They are capable of handling a wide range of weather conditions, but it seems that moving to higher ground may be too far for them – unless they do so slowly enough for their bodies to adapt.
However, species don’t have to go to higher altitudes to find cooler temperatures, because they can also change latitude—and researchers think these hummingbirds may eventually have to venture north.
The study’s authors also suggest that future studies and models should not only look at temperature as a trigger for changing species location. Other factors, including the availability of water and oxygen, must also be considered.
“To fully understand a species’ ability to change in response to global warming, it is necessary to assess its physiological performance within its current range and compare it to performance outside of its current distribution.” write researcher.
Search published in Journal of Experimental Biology.
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