M. Farid Ahsan
Department of Zoology, University of Chittagong, Chittagong 4331, Bangladesh.
M. Tarik Kabir
Department of Zoology, University of Chittagong, Chittagong 4331, Bangladesh.
Population, Breeding ecology, Bank myna, Acridotheres ginginianus, Chapai Nawabganj
Chapai Nawabganj district of Bangladesh
Conservation and Biodiversity
Study area Chapai Nawabganj District (24º44´ N and 088º12´ E), an area of 1,744.33 km², is bounded by West Bengal of India on the north, south and west. Rajshahi and Naogaon Districts cover the east side. The District comprises five Upazillas: Chapai Nawabganj, Shibganj, Bholahat, Gomastapur, and Nachole. Part of the District lies in Barind Tract and consists of diaras and charland (sandbars develop in river beds). Main rivers of the area are the Ganges, Mahananda, Pagla, Maraganga, and the Punarbhaba. The description of these rivers may be found elsewhere (e.g., Baby 2003; Chowdhury 2003a; Chowdhury 2003b; Taru 2003). These rivers, especially their banks at some places, are important breeding grounds of bank myna. The study area experiences a tropical monsoon climate, characterised by hot, humid summer and dry, mild cool winter. There are three distinct seasons in Bangladesh (former East Pakistan) (Ahmad 1968): (1) pre-monsoon (hot)- March to May, (2) monsoon (rainy season)- June to October, and (3) winter season (dry)- November to February . Breeding colonies of bank myna were searched along the Rivers (Mahananda, Punarbhaba, and Pagla), adjacent roads and brickfields under Chapai Nawabganj District of Bangladesh during June 2007 to October 2009. Motorised boats were used to spot the breeding colonies of the bird. Later on, microbus and/or local transport were used to reach to the spots. Local assistants were engaged to collect information on the breeding spots, which we physically verified. Population count Population was estimated by transect methods through searching and counting active nests of the bank myna in the aforesaid areas, either on foot, boat, by boat or vehicle. The active nests were identified by seeing the pairs engaged in nest building and/or renovation. Breeding biology Twenty of 30 marked nests (e.g., Bar 1 [Barogharia 1], Bar 2, Bal 3 [Baliadanga 3] and so on) were visited on alternate mornings and afternoons to collect information about breeding biology (nest building, egg-laying, egg measurement, incubation, parental care, and feeding). Breeding biology was recorded in two sites: Baliadanga (24o 37.238 N, 88o 16.229 E) and Barogharia brickfields (24o 36.237 N, 88o 15.345 E). Nest measurement A long stick was pushed into the nest hole to measure the length of the tunnel. Circumference of the nest entrance was defined by a rope, which was then measured. In addition, five nests were dug out by kodal (spade) to get the actual shape of the nest tunnel. One long white paper was placed over the dug-out nest tunnel and sketched. Sketched paper drawn by marker was reduced to a suitable size by repeated photocopies. Nesting materials Observations on nesting materials were made by collecting them from damaged or broken nests (due to flooding) from Baliadanga, Nakkatitala, and Palsha brickfield sites. Statistical analysis Similar data were compared using either t-test or Mann-Whitney U-test depending on the nature of data. Relationships of two correlated samples were computed through Pearson’s correlation coefficient. Statistical analysis was done using SPSS version 13.
Proceedings of the International Conference on Biodiversity – Present State, Problems and Prospects of its Conservation January 8-10, 2011 University of Chittgaong, Chittagong 4331, Bangladesh
Report/Proceedings