As global temperatures shift dramatically, wildlife often is forced to find suitable habitats and relocate to far-flung areas. Scientists are constantly striving to understand better how many species will be affected by climate change and how they may struggle to find new hospitable homes.
Understanding the Effects of Climate Change on Hummingbirds
Animals that migrate to higher altitudes face two issues: the significantly colder temperatures and the thinner, oxygen-deprived air that makes it difficult to breathe normally. In a recent study published in the Journal of Experimental Biology, titled "Anna's hummingbird (Calypte anna) physiological response to novel thermal and hypoxic conditions at high elevations," researchers brought a group of Anna's hummingbirds on a trip to roughly 1,200 meters above the species normal habitat.
The study results show that the hummingbirds' metabolic rates decreased as they hovered. The birds were observed to fly for shorter durations with less efficiency, most likely due to the need for more oxygen.
Although future temperatures across the globe could be warmer, the experiments conducted in the cooler elevation show the chilling effects of climate change on the sleeping patterns of the birds. When the hummingbirds slept, they entered a hibernation-like state more often, which resulted in the depression of their metabolism by roughly 37%, reports ScienceAlert.
The study's authors say that, at least for the hummingbirds, migrating to higher elevations to escape the rapid temperature changes would pose a significant challenge for the species. In their paper, the team wrote that the results of their study suggest that lower oxygen availability and lower air pressure may be difficult challenges for the hummingbirds to overcome shifting upslope due to the rising temperatures, especially if there is minimal long-term acclimatization.
Studying the Upper Limit of Hummingbird Migration
Hummingbirds have already been seen moving their homes, responding to rising temperatures, to higher elevations between 10 to 2,800 meters. The distance and range of temperatures alone are astonishing, but researchers wanted to identify whether an upper limit exists for the migration of hummingbirds.
For the study, researchers relocated 26 hummingbirds across the current elevation range, which all struggled to adapt. On the other hand, the study suggests that those from higher elevations often have larger hearts for better oxygen circulation around the body. Austin Spence, an ecologist from the University of Connecticut and lead author, explains in the news release that this means that if the birds are from warm or cool spots, they use torpor when the temperatures decrease.
Hummingbirds were great test subjects in this case due to their high-energy lifestyle. These birds can cope with various weather conditions; however, it seems as though migrating to the higher ground might be well beyond the species unless it is down slow enough for the bird's bodies to adapt.
The researchers wrote that to fully understand the capacity of species to shift in response to the climate's rapid warming of the climate; it is vital to assess the physiological performance and compare it with the performance of the species beyond its current distribution.
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