Bats New Migration Cycle Due to Climate Change
By: Raquel Zuniga
Little has been known of how bats migratory cycle is affected by climate change, until Phillip Stepanian and Charlotte Wainwright, meteorologists from Rothamsted Research, conducted a 22-year study on the bats in the Bracken Cave, which is located on the outskirts of San Antonio. "Our initial goal was just to show that the populations could be monitored remotely without disturbing the colony. We weren't expecting to see anything particularly noteworthy. The results were surprising," Stepanian said to www.phys.org.
This is the first long-term study of animal migration using radar and the findings are just as revolutionary. Each night during the span of 22 years, a nightly population count was conducted—the first climate-scale phenological analysis. Using quantitative radar monitoring, the pair of meteorologists found that spring migration and summer reproductive cycle has started earlier by two weeks since the start of the study. "We found that the bats are migrating to Texas roughly two weeks earlier than they were 22 years ago. They now arrive, on average, in mid-March rather than late March," Wainwright said to www.phys.org.
The pair’s theory is that the bats have established an overwintering population as an environmental change, and to the presence of insect prey earlier in the year. While most bats tend to have left by the end of November, the pair discovered that about 3.5% of the summer population are now staying for the winter, compared with less than 1% 22 years ago and, from written cave surveys, no overwintering bats at all in the mid-1950s.
Their observations reveal that the bats are able to adapt due to the changing resource availability of prey, with clear implications for pest management across wider regional agriculture systems. These observations provide the first long-term quantification of bats response to a changing climate.
Thanks to this study, we now have a new perspective of bats adaptation to global change. This study answers many questions all the while raising many more. The pair has also said to www.phys.org, "weather radar networks are key infrastructure around much of the world...and hold the promise of providing continental surveillance of bat populations, as well as their ongoing responses to global change."
And read the published study at http://onlinelibrary.wiley.com/doi/10.1111/gcb.14051/abstract;jsessionid=613C408686EC1312907F40A9538BC845.f02t01