The ice has melted and western chorus frogs are calling from the wetlands of mid Missouri. These small tree frogs, usually under 1.5 inches in length, are gray or brownish in color with faint dark stripes on their backs; a white line across the upper lips is one of their better fieldmarks. Now that you know what to look for, good luck!
While their calls echo across swamps and wet prairies from late winter to mid spring, it is very difficult to observe the frogs themselves. The males usually sing from mats of vegetation that collect on shallow pools or sloughs but fall silent at the slightest disturbance. Your best bet is to sit quietly at the edge of a pond or marsh, watching for their vocal sacs to expand and contract as they resume their distinctive call. The latter is a rising "prreeep," resembling the sound of a thumbnail plunking the teeth of a comb.
The males usually sing through mid May and, unlike most tree frogs, deliver their calls day and night. Attracted by their song, females arrive to lay up to 1000 eggs at various locations throughout the shallows; these will hatch into tadpoles and then mature to frogs by late summer. Adults spend the warmer months in moist woodlands, hunting for insects and spiders in the understory; they seldom climb far from the ground. As the cold returns and their prey dies off, chorus frogs hibernate in moist soil beneath marsh grass or plant debris.
