For Birds – Water Bathing is Not Just a Matter of Cleanliness
Birds spend an average of 9.2% of a day in maintenance behavior and water bathing is an important element of it followed by preening and oiling. Researchers have attempted to decipher if this bathing affects their flight performance and have made some interesting observations.
As a part of their various experiments a group of researchers from UK noticed that, newly caught and handled birds tend to immediately bath in fresh water following the release into a cage. This observation prompted to believe that the bathing followed by preening was done to repair the feathers disrupted by the catching and handling. However proving that would be impossible, as analyzing the feather after the bathing and preening would again disrupt the repaired feathers. So, they tested to see the direct influence of bathing on the flight performance.
The group caught 32 European starlings and grouped them into three different groups based on the quality of (number of missing or broken) feathers, to help compare the performance more fairly. Each of these birds was then left in an aviary either with a water bath or without a water bath for three days. Following this, on the day of flight performance testing, the birds were moved to rooms with or without a water bath, and thus creating four different possible treatment groups.
The birds were then in a random order released into an obstacle course of hanging weighted strings (number of strings hit and speed of flight recorded). The room had obstacle free area for acceleration and the obstacles where distanced approximately 3/4th of the length of the wing span of the birds. The lighting and other setups (dead trees) were such that all birds flew in the same direction. Several video cameras were employed to facilitate later frame by frame analysis.
Statistical analysis indicated that bathing in water prior to a flight test had a significant impact on flight performance in starlings that had previously had their plumage disrupted by catching and handling. Birds that had bathed in the short-term tended to hit fewer strings and fly more slowly through the obstacle course. It also indicated that there is a trade-off between flight speed and flight accuracy. However, there was no definitive answer as to why the speed decreased.
Journal Reference: doi:10.1016/j.anbehav.2009.07.022
Image Credit: Flickr
