Roadside-nesting cliff bird Swallows is one of the birds which often dies while crossing roads. Recently, a new study suggests that these birds might be evolving shorter wings to avoid being killed.
Swallows often build nests under bridges or other well-trafficked areas. As Swallows have longer wingspans, it can’t get a rapid momentum while crossing roads and occasionally and very unfortunately they are hit by cars and other vehicles. Some researchers studied upon those dead Swallows and then compared them to other birds who accidentally died some other way. Researchers found some big difference in Swallows’ evolution.
Swallows used to have longer wingspans for which it could fly in air and turn very smoothly. But this longer wingspans were a negative point for them too. In comparison to other birds who have smaller wingspans, Swallows were not very fast in achieving momentum while trying to fly from any static situation. Surprisingly researchers found that the dead Swallows wingspans were comparatively shorter than usual. Then researchers discovered that in the last three decades, huge amount of Swallows had died, but not by hit or ran over by any car or vehicles.
Based on this vital clue, researchers surmised that long-winged birds die most of the time while crossing road and the shorter-winged birds may be able to turn and take off faster than their counterparts, avoiding oncoming traffic. After further analysis, scientists found that surviving birds’ wings have reduced in length by as much as four millimeters over the past 30 years.
Source: Daily Mail