Nesting Ecology and Helping Behavior in the Azure-Rumped Tanager in Mexico

Abstract

Tanagers are among the most conspicuous birds throughout the Neotropics. In spite of this, only a few of the 240 species of tanager have been studied. The nests of less than half of the 51 species of Tangara have been described, and published observations on breeding biology exist for only 10 (Isler and Isler 1987). One of the poorly known species is the Azure-rumped Tanager Tangara cabanisi, which occupies a very small range in the Sierra Madre de Chiapas in Mexico and adjacent Guatemala. Distributional records consist of only five specimens from four localities and sight records from five additional areas (Heath and Long 1991). Its humid forest habitat is rapidly being destroyed, mainly for expansion of coffee plantations (Heath and Long 1991) and consequently it is listed as threatened (Collar et al. 1992). The Azure-rumped Tanager is a social species, usually seen in flocks of six to eight individuals in the canopies of trees (Hilty and Simon 1977, Isler and Isler 1987, Heath and Long 1991). It does not usually join mixed-species bird parties. The sexes are alike, but subadult birds have a duller plumage (Isler and Isler 1987). Here, we present information on nest-site selection, duration of incubation and nesting periods, parental care, and helpers at the nest. These data augment the breeding data in Isler and Isler (1987), which were based on observations of one nest.