Ecology, Environment and Conservation Paper

NESTING TREE SELECTION AND TEMPORAL VARIATION IN THE NESTING OF LITTLE EGRET (EGRETTA GARZETTA) IN A HERONRY NEAR NEENDAKARA HARBOUR, ASHTAMUDI WETLAND, KOLLAM, KERALA, INDIA

Dilraj C.P., S. Jisha and B. Hari

Abstract

Birds often act as a biosensor in a disturbed wetland ecosystem. Their activities such as feeding, roosting, breeding, etc. are more confined to wetland areas. The heronry is a communal nesting place of waterbirds of the orders Ciconiiformes, Pelecaniformes, Suliformes which comprise Egrets, Herons, Storks, Darters, Cormorants, and Ibis. The present study was focused on the number of nests of the Little Egret (Egretta garzetta), nesting tree species, and a number of nests on different trees near the Neendakara fishing harbor, Ashtamudi Wetland (Ramsar site No: 1204), Kollam, Kerala, during June 2018 to March 2020. Bird counting was done with the aid of binoculars, a digital camera, and a spotting scope following the direct observation method. Little Egret nests were recorded as highest in July (108) and lowest in March (34) during the 2018- 19 period. During 2019-20, the highest number of nests were observed in July (93) and the lowest in March (15). Six tree species such as Cocos nucifera, Tectona grandis, Alstonia scholaris, Terminalia catappa, Acacia nilotica and Casuarina equisetifolia were utilized by the water bird for nest building. Relative abundance data revealed Cocos nucifera (50%) was the most utilized tree species. Tectona grandis (46%) harbours the highest proportion of nests. A one-way ANOVA followed by a Tukey’s HSD test showed a significant difference (P<0.05) in the relative nest abundance per tree species. Higher number of nests and adult birds residing in the heronry was reported during the wet season (June to November) when compared to the dry season (December to May). Survival of the heronry was threatened by several factors such as natural disasters, predation, poaching, and logging prevailing in the study site. However, there were no significant differences (P>0.05) in the year-wise cumulative nest number.