NESTING ECOLOGY, TERRITORIALITY AND BROOD CARE IN RED-VENTED BULBUL, Pycnonotus cafer stanfordi DEIGNAN AT LUMAMI, ZUNHEBOTO DISTRICT, NAGALAND

Abstract

In the present study we have examined nesting ecology, territorial integrity and brood care strategy in red-vented bulbul, Pycnonotus cafer stanfordi Deignan at Lumami (26oN). Observations recorded on 300 nests from 2017-2021 showed that birds prepared loose textured cup-shaped nests between spring equinox and autumnal equinox with a seasonal peak appearing during May/June. Nests were made using locally available grasses within 4.50±0.25 (Table 1) days lurking into deep foliage of host plants/trees. Prior to fixing their nest, mates were seen ascertaining suitability of the site by eliciting motions of building a nest without nesting material. Entry and egress routes to the nesting sites were not common. Clutch size consisted of 2-3 pinkish-brown eggs which appeared to be regulated during nest construction. At rim level, an average diameter of nest with 3 eggs measured at 67.62±0.42 mm (n=240) which was significantly more (p<.001) as compared with nest with only 2 eggs (62.83±0.24 mm; n=60). Conversely, mean depth of nest with 3 eggs measured at 37.39±0.11 mm (n=240) and was significantly less (p<.001) as compared with nest holding only 2 eggs (42.40±0.23 mm; n=60). Basement area of nest with 2 eggs measured at 117.80±1.05 cm2 which was significantly less (p<.001) as compared to basement area of nest with 3 eggs (150.34±3.15 cm2). The bird was noticed to exhibit a strong tendency to safeguard its nest and brood against predators. Brood care began with deposition of first egg which grew progressively with completion of clutch size, incubation and hatching. Persistent predation pressure amidst incubation has led to the heightening of security concerns of mates and a consequent decline in foraging timings had triggered rejection of eggs and hatchlings appearing late. Fledglings were nourished and cared by parent birds until they had learnt to fetch nourishment for themselves and evade predation. It is suggested that red-vented bulbul is highly territorial and has a strong tendency to defend its brood vis-à-vis extending its territorial boundary.