Daily roosting behaviour of the critically endangered White-bellied Heron Ardea insignis as a function of day length

ABSTRACT

The White-bellied Heron (Ardea insignis) is listed as a critically endangered bird species by BirdLife International due to the rapid population decline. Before this study, nothing was known about the night roosting behaviour of this imperiled species. Here, we report on the night roosting behaviour of the White-bellied Herons in Punatsangchhu and Mangdechhu river basins of Bhutan. There was a significant difference in landing and takeoff flights between the short- and long-day periods (P <0.05). Overall, the night roosting behaviour was dominated by sleeping (65 ± 11 min). We also documented two prominent behaviours that were thermoregulatory in function. The White-bellied Herons roosts solitarily on the tree branches in the night and makes extensive use of the night roosting trees. Therefore, night roosting trees are essential for consideration while assessing the home range size of the White-bellied Herons for their better conservation and management.

KEYWORDS:

• White-bellied Heron
• Ardea insignis
• night roosting rhythm
• behaviour
• conservation

Acknowledgments

The authors wish to thank the Nature Conservation Division (NCD) and Royal Society for Protection of Nature (RSPN), Bhutan for loaning the camera traps, Ugyen Wangchuck Institute for Conservation and Environmental Research for granting the research permit. We express our immense gratitude to Assoc. Prof. (Dr.) Kitichate Shridith of Prince of Songkla University, Dr. George Archibald of International Crane Foundation, Sonam Wangdi of NCD, Dr. Kinley Tenzin, Rebecca Pradhan, Sonam Tshering, Tshewang Lhendup, Tashi Phunthso, Indra P. Acharja of RSPN and lab members of small mammals, bats, birds and spiders unit of PSU for their constant inspiration as well as continuous guidance in this endeavor. We are forever grateful to Krishna, Sonam Dorji, Chencho Bidha, Namgay Younten, Phub Tshering and Pema Dorji for their help with the field works. Most importantly, we are immensely grateful to two anonymous reviewers for their critical comments in improving this manuscript.

Declaration of Conflicting Interests

The authors declared that there is no conflict of interest.

Additional information

Funding

The authors are immensely thankful to Prince of Songkla University for the thesis research grant, and the Rufford Foundation (grant number: 29460-2). Thailand’s Education Hub Scholarship for ASEAN Countries (THE-AC) also supported PK;Prince of Songkla University for the scholarship award on Thailand’s Education Hub for ASEAN Countries (TEH-AC) [contract no. TEH-AC 043/2017];Prince of Songkla University [Thesis Grant];Rufford Foundation [29460-2];