In a recent study of hummingbird behavior, The Company of Biologists, a UK-based company, recently found that certain species of hummingbirds experience torpid behaviors more frequently and a drop in metabolic activity at elevations ranges of around 3800 meters. The results of their study are published in the Journal of Experimental Biology.
These findings come amid tumultuous times for animals in their environments. Climate change is pushing several species outside their current habitats, forcing them to new homes that can accommodate their needs. This often includes living at higher altitudes or in cooler climates.
Hummingbirds are no expectation. Certain species of hummingbirds are already comfortable at higher altitudes (for example, Anna’s hummingbirds can live in elevated habitats up to 2800 meters). However, this elevation ceiling may not be enough for hummingbirds fleeing the effects of climate change, as many may need to go higher. As a result, researchers wanted to know how (or whether hummingbirds) can thrive in environments higher than 2800 meters and decided to study how higher altitudes impact hummingbird activities.
To conduct the study, researchers captured hummingbirds from habitats at the bottom end of a hummingbird’s living range (sea level) and the max living range (up to 2400 meters). The birds were then brought somewhere halfway (about 1200 meters) where they remained for a few days. Researchers then set up a way for the birds drink nectar while also measuring O2 and CO2 levels to gauge metabolic processes. CO2 was specifically measured at night when hummingbirds were in a torpid state, a sort of hibernation used to preserve energy.
After a few days at 1200 meters, researchers moved the birds to about 3800 meters and continued to measure metabolism as well as the nature of their torpid state when asleep.
Researchers found that despite the fact the hummingbirds should have been working overtime in the thinner air, metabolism dropped by over 30%, with birds from sea level and the 2400 meter elevation experiencing equal drops. The hummingbirds also remained in a torpid state for far longer than normal. Ultimately, low oxygen levels and air pressure seemed to have a negative effect on hummingbird metabolism and activity.
These findings suggest that as climate change impacts habitats, hummingbirds may be one animal that will have a harder time adapting to a new environment.
Sources: EurekaAlert!; Journal of Experimental Biology
