Defense of Homopteran Honeydew by Birds in the Mexican Highlands and Other Warm Temperate Forests

Abstract

Nearctic migrants aggressively compete for the honeydew of scale insects (Margarodidae, Xylococcini) throughout the winter in oak forests of the highlands of Chiapas, Mexico. Yellow-rumped warblers (Dendroica coronata) defend territories around 3-7 infested oak trees. Aggression is directed primarily against adult male Townsend's warblers (Dendroica townsendi), which in turn defend the territory against conspecifics and other migrant warblers when the dominant yellow-rumped warbler is off territory. The white-eared hummingbird (Hylocharis leucotis) is the only resident species to commonly feed on honeydew. Birds have only rarely been reported to feed on honeydew. The reports are restricted to moist, equable temperate forests in Australia, New Zealand, the Brazilian highlands, the Andes, and the mountains of Mesoamerica