Golden-cheeked warblers are a migrating species, Jonny explained, that winter in southern Mexico and Central America, flying north in early spring to nest and raise their young exclusively in Central Texas. The males arrive first, generally in mid March. They set up and defend their territory by singing. Then the females arrive, select a mate and a nesting site, and build a nest. The female builds the nest in 4 or 5 days, and then rests for about a day before laying one egg every day for the next four days. The female incubates the eggs for about 11 days. Both parents feed the fledglings for the next 9 to 11 days before the fledglings leave the nest. In mid July, the warblers begin the flight south to their wintering grounds.
Golden-cheeked warblers have two songs, with variants. The male sings his “A” song, “bzz bzz lay zee day zeee,” when he is establishing or defending territory. When the female has begun incubating the eggs, the male sings his “B” song, “bzz zee dada,” or “bzz zee dabadaba.” When the fledglings hatch, the male will sing his “A” song again, sometimes with a beak-ful of worms for the hungry mouths in the nest.
Jonny also called our attention to the songs of blue-gray gnatcatchers, phoebes, and a red-eyed vireo. Continuously scanning the branches for nests, Jonny spotted and pointed out a fuzzy ball a little bigger than a hummingbird’s nest. Moments later, an adult blue-gray gnatcatcher entered the nest, bringing worms to the nestlings. We also spotted a golden-cheeked warbler male, perched in the top of an oak tree, singing his A song, preening, and politely posing for a full minute to be viewed and photographed.
Though the focus was mostly on listening and watching for birds, the plant species offered surprises as well. Robert spotted the uncommon seven-leaf creeper (Parthenocissus heptaphylla) on the fence by the entry. A drop of bright red at the side of the trail was in fact a scarlet leatherflower (Clematis texensis). The unusual green flower of the pearl milkweed vine (Matelea reticulate) caught our attention, and a lemony scent from underfoot turned out to be Drummond’s false pennyroyal (Hedeoma drummondii). Altogether a fine spring morning in the BCP.
Visit the Wildlands Conservation Division’s online calendar of events at http://www.austintexas.gov/department/wildland-conservation-division to learn about and register for future hikes and volunteer or training opportunities.