Each day I scan the sky for migrating broad-winged hawks. They return from a tropical winter in swirling flocks called kettles containing dozens to thousands of individuals. A really big kettle of a thousand or two flyers is one of nature's most awesome sights, and it's not seen every year. Each year, though, a pair of broadwings nests in the ravine, using only scalybark or bur oaks for its tree-canopy nests. Fledging is in late June. Before that the two or three chicks climb branches and make short hop-flights for a week or two, returning to the nest to be fed. They begin serious flying by mid-July and are mostly independent by late August.
When broadwing chicks hatch in May, their parents put red mulberry twigs with leaves in the nest. Such greenery characterizes the nestling stage of many hawks and eagles, but its function is uncertain. Sanitation, air freshener, camouflage, and sun or wind screen have been suggested. All local broadwing nests I've looked into have red mulberry leaves, which are among our largest. Bur oak leaves are large too, but the twigs are stout and perhaps harder to snap. Because the leaves are concentrated on the nest's west side, which is only partly shaded by the nest tree's growing leaves, I guess that they shade chicks when an adult can't.
Local broadwings represent a small, disjunct, western population of this eastern species. They were newcomers to the ravine in 1975, about a hundred miles removed from brethren in east Texas. Blue jays immediately began to imitate them, as they'd always done with redtailed hawks. Perhaps they learned the un-hawklike call, a plaintive "peer-ee," through cultural contact with east Texas cousins, who'd known broadwings for millennia. This hawk is the only local colonist among neotropical migrants, since the ravine forest grew vertically while shrinking horizontally. I'm not sure why they're here but I'm happy that we've gained one summer resident, because we've lost eight.