Found nesting nowhere else in the world except the oak-juniper woodlands of Central Texas is the golden-cheeked warbler. This bird requires older growth forest with a denser tree canopy where they forage for a variety of insects, including caterpillars.

In early March, golden-cheeked warblers begin arriving in central Texas from their wintering ground in Mexico, Honduras, Nicaragua, and Guatemala. Their stay in Texas lasts until about the end of July, when they begin departing to take advantage of more abundant winter food supplies south of our border.

The males arrive first and can be seen and heard at the tops of the tallest oak and juniper trees. The characteristic Bzz Bzz Lay-Zee -Day-Zee (ending on a high note) song announces each male's territory, which is defended against other males. Territories are approximately 3-6 acres.  When the females arrive a few days to a week later, they choose males that sing the loudest and defend their territories most vigorously. Normally, pairs remain together throughout the nesting season. If one partner dies, the remaining partner may attempt to find a new mate. There is evidence from banding experiments that some birds return to the same territories year after year, and may even choose the same mate.

Nesting
Once a female has chosen a mate, she alone builds the nest. The nest is composed of strips of juniper bark, rootlets, grasses, cobwebs, cocoons, and may be lined with fur from animals. Although nests have been found in various trees, the one factor they have in common is the presence of strips of juniper bark. Once juniper reaches an advanced age, strips are easily taken from the bark and used in nest building. It appears that female golden-cheeked warblers are unable to build nests without this resource, which makes the presence of old-growth Ashe juniper vital to the species’ survival.

Golden-cheeked warblers lay 3-4 creamy-white eggs, less than 3/4 inch long and ½ inch wide. Incubation begins one day before the last egg is laid. For approximately the 12 days, the female warbler incubates the eggs. The male is for the most part inattentive at this time, joining the female only when she forages for insects away from the nest. Hatching occurs rapidly, including having all of the instances where all of the eggs hatch on the same day.

To avoid attracting the attention of predators, egg shells and fecal sacs of the young are either carried away or eaten by the adults. The nestlings fledge at nine days, but remain near the adults for approximately four weeks, begging for food. By the third week, the young bird are foraging for themselves and can fly as well as the adults. By mid-July they are ready for the journey south.

Threats to Survival
Habitat loss or degradation is the main reason the golden-cheeked warbler is endangered. The clearing of old juniper woodlands for livestock grazing and urban expansion has decreased the area available for nesting. When large tracts of woods are broken up with pastures, roads and development, a population increase among nest predators such as the blue jays and the brown-headed cowbird occurs. The quantity of woodlands on the small fragmented tracts often means adults cannot find enough food to feed the young, or the young have no areas on which to disperse.  About 27,000 warbler are estimated to survive today, a decline of about 25% in 28 years.

Habitat loss on the wintering grounds due to timber harvest and agricultural development is also a problem. Cooperation between conservation groups and government agencies in Latin America is progressing to set aside important wintering areas.