Ecology, behavior, and reproduction of an introduced population of Red-vented Bulbuls (Pycnonotus cafer) in Houston, Texas

Abstract

Results are reported from a citizen-science program to study the ecology, behavior, and reproduction of an invasive population of Red-vented Bulbuls (Pycnonotus cafer) in Houston, Texas. The most frequent behaviors are foraging (n = 69), resting (n = 45), and calling (n = 29). The entire population occurred in urban areas. Bulbuls consumed berries (n = 8 species), fruits (n = 5), flowers (n = 5), and buds (n = 4); some insects are also included in the diet. Nine of the 20 species of identified plants consumed are exotics found within the native range of the bulbul, six are exotics found outside the native range, and five are native Texas species. The most common of the 35 species of plants that bulbuls perched in are bamboo (Bambusa sp.), crape myrtle (Lagerstroemia indica), edible fig (Ficus carica), and tallow (Sapium sebiferum). Flock size averaged 2.3 birds/flock (range = 1–22) and the largest flocks (12–22 birds) are in late summer and early winter. Bulbuls are not migrants; peak observations are during spring and summer, with lower numbers during October. General biology is similar between Houston bulbuls, native populations in Asia, and other invasive populations in the Northern Hemisphere. This alien population is not a serious agricultural pest or disperser of weedy seeds, does not compete with native species, and has not expanded beyond the Houston region in the continental United States.