1. The Critically Endangered gharial (Gavialis gangeticus) residing within Bardiya National Park (BNP) in Nepal constitutes the sixth major sub-population of this unique lineage; however, this population is not well studied. A 46 km protected stretch of the Babai River and a 60 km stretch of the Karnali River in and around BNP were surveyed for gharials in early 2017 and in 2019.
2. Gharial counts in 2017 – 17 from the Babai and one from the Karnali rivers – consisted of 10 adults, five sub-adults and three juveniles. In 2019, 19 gharials were counted – 18 for the Babai and one for the Karnali – comprising 11 adults, six sub-adults and two juveniles. In the Babai River within BNP, four breeding groups were identified. Gharials in BNP prefer sandy vs. rocky banks for basking and completely avoid sand-grass and clay banks. Habitat preference did not vary with size class.
3. Protected stretches of both rivers inside BNP (76 km) have resident gharial, intact habitats and few human threats. In contrast, the unprotected stretch of the Karnali (30 km) is threatened by boulder quarrying, sand mining and unlicensed fishing, and is avoided by gharials despite the availability of habitat.
4. This study established baseline data, including indices of population size, distribution and habitat preferences, and documented resident gharials that are breeding in the Babai River in BNP. The conservation of this Babai population is crucial for the species’ survival in BNP.
5. Based on this study, we recommend the following conservation actions on the Babai stretch: (a) determine hatching success; (b) assess juvenile recruitment; (c) consider supplementation by releasing captives; (d) study riverine features important as baselines; (e) accommodate upstream movements on the protected Babai stretch; and (f) protect the downstream Babai outside the boundary of the BNP.

中文翻译：

---

尼泊尔巴迪亚国家公园的 Gharials (Gavialis gangeticus)：人口、栖息地和威胁

1. 居住在尼泊尔巴迪亚国家公园 (BNP) 内的极度濒危加利尔 ( Gavialis gangeticus ) 是这一独特血统的第六个主要亚种群；然而，这一群体并未得到很好的研究。2017 年初和 2019 年，对 BNP 及其周围 46 公里受保护的巴拜河和 60 公里的卡尔纳利河进行了 gharials 调查。
2. 2017 年的 Gharial 计数——17 名来自 Babai，1 名来自 Karnali 河——包括 10 名成年、5 名亚成年和 3 名少年。2019 年，统计了 19 只 gharials——Babai 18 只，Karnali 1 只——包括 11 名成年、6 名亚成年和 2 名少年。在 BNP 内的八白河中，确定了四个繁殖组。BNP 的 Gharials 更喜欢沙滩而不是岩石岸边晒太阳，完全避免沙草和粘土岸边。栖息地偏好不随大小等级而变化。
3. BNP（76 公里）内的两条河流受保护的河段都有常驻的长吻鳄、完整的栖息地，几乎没有人类威胁。相比之下，卡尔纳利（Karnali）未受保护的一段（30 公里）受到巨石采石、采砂和无证捕鱼的威胁，尽管有栖息地，但加里尔人却避开了。
4. 这项研究建立了基线数据，包括人口规模、分布和栖息地偏好的指数，以及在 BNP 的巴拜河中繁殖的记录的常驻长吻鳄。这个 Babai 种群的保护对于该物种在 BNP 中的生存至关重要。
5. 根据这项研究，我们建议对八拜河段采取以下保护行动：(a) 确定孵化成功；(b) 评估少年招募；(c) 考虑通过释放俘虏来补充；(d) 研究作为基线重要的河流特征；(e) 在受保护的 Babai 段适应上游运动；(f) 保护 BNP 边界外的下游八百。