Courtesy Kenn Kaufman
In the U.S., the Mexican Chickadee is restricted to the higher elevations of two mountain ranges—the Chiricahuas in Arizona, and the Animas in New Mexico. However, the species is common and broadly distributed in the mountain forests over much of Mexico.
This bird prefers coniferous mountain forests, except in the southern part of its range in Mexico where it also occurs in oak-pine forests. In Arizona's Chiricahua Mountains, Mexican Chickadees are found in ponderosa pine (Pinus ponderosa
) forests and in spruce-Douglas fir forests; winter habitat here includes pine-oak, Arizona cypress (Cupressus arizonica
), sycamore (Platanus wrightii
), and alligator juniper. In Mexico, these chickadees are less restricted to coniferous forests than in the U.S. In northwestern Mexico (southern Durango), they are found mainly in oak-pine woodlands. In central Mexico's Valley of Mexico, they occupy a wider range of habitats, including dry oak woodlands, humid fir forests, and pine-alder forests.
The insectivorous Mexican Chickadee's major food items include small caterpillars, beetles, and other insects. These birds usually capture prey by foraging through foliage. Techniques commonly used are gleaning, and hanging upside down from leaves, twigs, and open pine cones. Bark, pine cones, lichens, and galls are searched as well. The chickadee may also grab an acorn or gall and hammer on it with its bill until it is broken and the insect larvae within can be removed. Unlike other chickadees, the Mexican Chickadee does not store food.
In the Chiricahua Mountains, Mexican Chickadee nests have been found up to 40 feet high—on the undersides of ponderosa pine limbs, in the forks of oak trees, or in natural cavities. Mexican Chickadees also nest in human-made boxes placed up to five meters high, with sawdust and wood shavings lining the floor. The male stays close to the female during nest building, while the female excavates the nest cup and gathers nest material. Natural nests may be lined with mammal hairs, soft catkins, bark fibers, and moss. Inside nest boxes, dry fibrous material may be topped with moss and fur. The nest cavity may be filled with material to a depth of 13 centimeters.
Females generally lay a clutch of five to nine dull white eggs marked at the larger end with small, pale reddish brown spots. Smaller clutches and smaller eggs may be laid by younger birds. Only females incubate the eggs and brood the young. Upon leaving the nest, females may cover the chicks with nesting material. Upon returning, the female often applies crushed beetles to the outside of the nest cavity in a sweeping motion; these chemicals may repel predators. Males are known to feed females near the nest during incubation, and to co-feed the young after hatching. Males bring beakfuls of tiny arthropods to nestlings, or one large caterpillar per visit. They may bring food about every 20 minutes, sometimes more frequently in early morning.
Mexican Chickadees are primarily permanent residents. In Arizona's Chiricahua Mountains, some individuals move down into lower canyons in the winter; others remain at higher elevations. In Mexico, there are local movements from higher to lower elevations in winter, but differences in these movements may be due to differences in vegetation. Since winters are milder there than in more northern areas, local movements may be less pronounced.