Dragonfly migration resembles that of birds, scientists say

Scientists have discovered that migrating dragonfliesand songbirds exhibit many of the same behaviors, suggesting the rulesthat govern such long-distance travel may be simpler and more ancientthan was once thought.

The research, published in the May 11 Biology Letters, is based on datagenerated by tracking 14 green darner dragonflies with radiotransmitters weighing only 300 milligrams -- about a third as much as apaper clip. Green darners are among the 25 to 50 species of dragonfliesthought to be migratory among about 5200 species worldwide.

The team of researchers that made the discovery, led by PrincetonUniversity's Martin Wikelski, tracked the insects for up to 10 days fromboth aircraft and handheld devices on the ground.They found that the dragonflies' flight patterns showed manysimilarities to those of birds that migrate over the same regions ofcoastal New Jersey.

"The dragonflies' routes have showed distinct stopover and migration days,just as the birds' did," said Wikelski, an associate professor ofecology and evolutionary biology. "Additionally, groups of both birds and dragonflies did not migrate on very windy days and only moved after two successivenights of falling temperatures. We saw other similarities as well, whichmakes us wonder just how far back in Earth's history the rules formigration were established in its animals."

According to fossil records, dragonflies appeared about 285 millionyears ago, predating the first birds by about 140 million years.

Wikelski said that the findings could also be an important demonstrationof how to track small animals over great distances, a technique thatcould be useful in agriculture and ecological management.

"These small transmitters could enable us to track animals from space all around the globe ifsatellites were available," Wikelski said. "Though nearly everyone hasheard of animal migration, we actually know very little about howanimals move. It could tell us a lot about the way speciesrespond to climate change and other disturbances. Becausethe economies of many nations are still largely agrarian, a betterunderstanding of how, say, locust swarms travel could assist us withmanaging both local agriculture and the world economy that hinges uponit."

Source : Princeton University