Adapted from Jim Conrad's online book A Birding Trip through Mexico, This excerpt from "Grassland-Mesquitenorthern Chihuahua state
Mesquite leaves are compound, looking like two green feathers joined at their bases onto a single stem. Each section of the compound leaf, or pinna, is divided into forty to fifty tiny leaflets, with the result that Mesquite leaves appear diffuse. In the present sunlight, every leaflet shows itself as adorned with a glistening dewdrop.
The Clay-colored Sparrows hop along a stem sideways until they come near a sparkling cluster of leaves, then in an instant flutter into them, land back on the stem, and more often than not shake their heads, possibly to jar dew from their nostrils or eyelids.
The dewdrop bath continues for ten minutes or so, and then Yellow-rumped Warblers arrive. It appears that the warblers have been watching and now want to join in the fun, for they land in the mesquite's crown and immediately begin excitedly flitting from spot to spot and flying about. However, they do not make contact with the wet leaves. They simply flit about the leaves and fly into the air a couple of meters or so above them. It's as if they want to share in the experience, but can't quite grasp the entire concept.
After three or four minutes, they seem to catch on.. They also begin fluttering into the leaves, dousing themselves with dewdrop spray. Have I watched one species teaching another how to take dew baths?
What a shame that in this Mesquite-grassland so many discoveries like this surely remain to be made, but I'm out of water, and have so many other places to go.