BREEDING BIOLOGY OF NORTHERN RIVER TERRAPIN BATAGUR BASKA IN CAPTIVITY IN BANGLADESH

Abstract

Northern River Terrapin, Batagur baska, is an ecologically extinct species in
Bangladesh. The ‘Project Batagur’ has undertaken some important initiatives to
resuscitate the nearly deceased population through captive breeding at Bhawal
National Park, Gazipur, Bangladesh. We conducted a study on breeding biology
of B. baska from May 2016 to June 2017 in the project site. Four adult females and
three adult males comprised breeding pair in the study site. Male Batagur baska
developed black colouration on head and neck, with rich crimson on dorsal
portion of the neck during breeding season. During our study, we observed
paired basking behaviour rather courtship and parental care. We found three
nests from mid-March to first week of April. Females laid eggs at night and a
total of 67 eggs were extracted from three nests; eggs were elliptical and whitish
in colour. Clutch size varied from 18 to 28 eggs. There was significant positive
correlation between clutch size and nest diameter (p = 0.03). The relationship was
also positive and significant between egg weight and diameter (p = 0.01).The size
of the egg was not related with the size of breeding females (r = 0.143).Average
incubation period was (68.26 ± 5.23) days and there was significant negative
relationship with temperature (p= 0.000), clutch size (p = 0.001), and hatching
success (p = 0.004). Hatching success was also negatively co-related with
temperature (p= 0.001). Hatching started in May and ended in the first week of
June 2017 with mean hatching success of 91%. Simple linear regression showed
positive relationship between egg length and hatchlings’ carapace length,
plastron length, and height. We also found positive relationship between egg
diameter and hatchlings weight, and carapace width. This study can be used as a
protocol for captive breeding and rearing activities of threatened chelonians
around the world.