Drought and Birds: Dew Bathing
Verbeek attributed this rarely observed or reported behavior to the local drought conditions prevailing at the time, “with only a little over a centimeter [0.39 inches] of rain recorded in the 50 days preceding the day of observation.” While July and August are typically the driest months of the year in Vancouver, an average of 7.87 centimeters (3.1 inches) of rain normally falls during that period, nearly 8 times the amount recorded in 1961.
While others have reported instances of dew bathing in the wild (see Nichols 1921, Abbot 1954, Douglas 1968, and Baptista 1973), Verbeek is the only one who has suggested a connection between this behavior and drought. It seems likely that dew bathing would be more common amongst species that inhabit arid regions. In fact, Jim Conrad reported his observation of Yellow-rumped Warblers Dendroica coronata and Clay-colored Sparrows Spizella pallida bathing in the dew that had collected on mesquite leaves in northern Chihuahua.
Verbeek’s article, as well as the other references, can be read in full by clicking on the highlighted titles below (all are in .PDF format).
Abbot, Waldo G. 1954. Leaf bathing of the Mockingbird. Condor 56: 163-164.
Baptista, Luis F. 1973. Leaf bathing in three species of emberizines. Wilson Bulletin 85: 346-347.
Dow, Douglas D. 1968. Dew bathing and related behavior of the Cardinal. Bird-Banding 39: 227-228.
Nichols, J. T. 1921. Coereba bahamensis at Miami, Fla. Auk 38: 461-462.
Verbeek, Nicolaas A. M. 1962. On dew bathing and drought in passerines. Auk 79: 719.