Communal nesting ecology of Little Tern (Sternula albifrons) and Small Pratincole (Glareola lactea) in two seasonally emerged riverine islands in Bangladesh

The nesting ecology of two wetland-dependent bird species, the Little Tern (Sternula albifrons) and the Small Pratincole (Glareola lactea) were studied in two seasonally emerged riverine islands, locally named as charlands in Padma River of Bangladesh. A total of 269 and 299 nests of Little Tern and Small Pratincole were found in the breeding season of 2022. We monitored 70 nests of the two species from two charlands, and the nesting success was 74.28% and 78.57%, respectively. No correlation was found between nesting success of both species in relation to clutch size, nest height, nest depth and presence of vegetation near nest. We found strong positive correlation between nesting success and nest distance to river for Little Tern. Nesting success was higher if the Little Tern’s nests were located far from the river channel. However, no such trends were observed for Small Pratincole in the study area. The main factor affecting Little Tern nesting success was nest predation by avian predator (n = 6) and tropical storms (n = 3). On the contrary, eight Small Pratincole nests were predated by avian predators and four nests were lost due to storm. However, in case of 12 deserted nests (with unhatched eggs) of both species, no apparent reasons were identified. The study suggests that these charlands, if protected from human interferences, can provide great breeding support for colonial ground nesting waterbirds.