This study was on nest and its site, measurement and building time of Common Kingfisher (Alcedo atthis) and White-throated Kingfisher (Halcyon smyrnensis) in Bangladesh. After pair formation, both species chose nearly 90 0 sloppy sandy-loam areas for nesting. The nests were tunnel-like, the length of which were 31 to 48 cm (median 36.5 cm, n = 8) for Common Kingfisher and 44 to 86 cm (median 59.25 cm, n = 10) for White-throated Kingfisher. The horizontal diameter of the outer opening of the hole of White-throated Kingfisher was almost double (6.5 to 14 cm, median 9.5 cm, n = 10) than Common Kingfisher (3.8 to 5 cm, median 4.25 cm, n = 8), whereas the vertical diameter was almost same (Common: 7.7 to 10 cm, median 4.25 cm, n = 8; and White-throated: 7.5 to 12 cm, median 10.5 cm, n = 10). The average horizontal and vertical diameters of ovalshaped egg chamber of Common Kingfisher were, 11 to 15 cm, respectively (median 12.7 cm, n = 8) and 11 to 13 cm (median 11.6 cm, n = 8) and Whitethroated Kingfisher 11 to 21 cm (median 17 cm, n = 10) and 10 to 16 cm (median 12 cm, n = 10). Both species reused old nests through cleaning (37.5% in Common Kingfisher and 50% in White-throated Kingfisher) and the nest building periods were 12 to 20 days (16.1 ± 2.5 days, n = 8) and 8 to 18 days (13.2 ± 3.5 days, n = 10), respectively.

Tenualosa ilisha is a popular anadromous and significant trans-boundary fish. For sustainable management and conservation of this fish, drawing an appropriate picture reflecting population status of this species is very essential based on their all-strategic habitats in Bangladesh. In this study, 139 samples from 18 sites were collected and cross-species gene enrichment method was applied. Like most of the Clupeiforms, nucleotide diversity of this shad was very low (0.001245–0.006612). Population differences between most of the locations were low and not significant (P > 0.05). However, P values of a few locations were significant (P < 0.05) but their pairwise FST values were very poor (0.0042–0.0993), which is inadequate to recognize any local populations. Our study revealed that the presence of a single population in the Bangladesh waters with some admixtured individuals, which may contain partial genes from other populations. Most of the individuals were admixed without showing any precise grouping in the ML IQtree and Network, which might due to their highly migratory nature. Fishes from haors and small coastal rivers were not unique and no genetic differences between migratory cohorts. The hilsa shad fishery should be managed considering it as a single panmictic population in Bangladesh with low genetic diversity.

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