Effects of weather on parrot geophagy in Tambopata, Peru

Geophagy is widespread and well documented for mammals, but avian geophagy has only recently become the subject of serious scientific investigation. I analyzed data from 606 mornings of observations at a large avian geophagy site or "clay lick" in the southwestern Amazon Basin to examine the effects of weather on bird lick use. Birds used the clay lick on 94% of the mornings without precipitation or fog. Parrots dominated the site in both numbers of species (17) and individuals (>99%). Weather conditions were significantly correlated with total lick use: there was greater use on sunny mornings and less on rainy mornings. Fog and overnight rain were correlated with low lick use. Sun, rain, fog, and overnight rain were recorded on 47, 25, 20, and 8% of the mornings, respectively. I estimated that inclement weather caused an annual 29% reduction in geophagy for all bird species combined. When early morning rain prevented species from using the lick, they did not return later in the day nor did they compensate for rainy mornings by increasing lick use on subsequent days. The timing of lick use and the lack of compensation suggest that neutralization of toxins could be driving lick use in this system.