Nest construction scenario of Sri Lanka yellow-eared bulbul (Pycnonotus penicillatus) in tropical montane cloud forests of Horton Plains

Abstract

Sri Lanka yellow-eared bulbul (Pycnonotus penicillatus) is an endemic threatened bird occupying higher elevations above 900 m. The study aimed to determine nest construction strategies of P. penicillatus in the Tropical Montane Cloud Forests. The research was conducted at Horton Plains National Park (HPNP) of Sri Lanka from September 2015 to August 2018. Nests of P. penicillatus were located by following breeding pairs and searching the vegetation. Measurements of the nests were taken using a Vernier Calliper. Volume of the nest cup and material volume in the nest was calculated and nest orientation within the nesting tree was measured using a compass. To identify and quantify nesting materials, three nests were collected after the breeding season. In this study, 38 nests were recorded. P. penicillatus abstained 5 to 7 days to complete the nest. Both sexes participated to build the nest. External diameter of the nest was 12.01 ± 0.55 cm (Mean ± SD). Nest cup volume and nest material volume were 101.72 ± 15.63 cm3 and 527.90 ± 74.60 cm3 respectively. Maximum numbers of nests were located in North and East directions (8 nests in each direction). They used leaves (35%), moss (20%), lichens (10%), small twigs (10%), roots (10%), and threads (15%) as nest building material. The nest was comprehensively different from other bulbul nests with distinctive nest size and peculiar preference of nest materials. There were no synthetic nesting materials observed within HPNP. Moreover, they have used materials from endemic plants. This research will guide the management approaches to protect breeding habitats of P. penicillatus correspondingly.