Abstract
To understand the breeding habitat requirements of the small, highly threatened migratory population of Eastern Sarus Crane (Grus antigone sharpii) in Cambodia and Vietnam, we assessed nest site selection at two different spatial scales: at the scale of individually occupied wetlands within the deciduous dipterocarp forests of Kulen Promtep and Chep Wildlife Sanctuaries, and at a landscape scale covering all such forested areas in northern Cambodia. To model the likelihood of nest occupancy within the landscape, results of aerial surveys for Sarus Crane nests, conducted in 2001, were combined with topographical and environmental spatial data. A second model incorporated deforestation and road development in the landscape between 2001 and 2016.
We found that Sarus Cranes in Cambodia typically nested in remote rain-fed wetlands that formed on flat terrain in the upper reaches of drainage basins. Within these small, forested wetland units, nests were often placed in deeper, well-defined ponds, although three-quarters of all nests were placed randomly in relation to water level. Nest locations were further from roads and agricultural areas than random points. Most of the best nesting habitat, including Kulen Promtep and Chep Wildlife Sanctuaries, was located on Cambodia’s Northern Plains (247 km2 of habitat with a predicted occupancy likelihood of >75 % inside pro- tected areas and 77 km2 outside), with smaller patches of highly suitable areas scattered across the Eastern Plains (15 km2 inside protected areas and 11 km2 outside).
Between 2001 and 2016, 14,215 km2 (15 %) of the original deciduous dipterocarp forest cover was cleared for agriculture, 1,605 km of road was constructed and the area of habitat with a predicted occupancy likelihood of >75 % shrank by 69 % in the Northern Plains (66 % inside protected areas and 79 % outside) and 73 % in the Eastern Plains (80 % inside and 64 % outside). In Kulen Promtep and Chep, cranes continued to nest but in areas modeled as having lower suitability. We recommend (i) strengthening protection of Kulen Promtep and Chep Wildlife Sanctuaries in the Northern Plains and of remaining nesting habitat in other protected areas; (ii) surveying for active nesting in areas having the highest suitability classes based on the 2001 model but not currently protected, particularly south of Kulen Promtep; (iii) in the meantime, take immediate steps towards protecting as much remaining habitat as possible, that was modeled as highly suitable, to allow for population recovery or in case subsequent surveys find it occupied
We found that Sarus Cranes in Cambodia typically nested in remote rain-fed wetlands that formed on flat terrain in the upper reaches of drainage basins. Within these small, forested wetland units, nests were often placed in deeper, well-defined ponds, although three-quarters of all nests were placed randomly in relation to water level. Nest locations were further from roads and agricultural areas than random points. Most of the best nesting habitat, including Kulen Promtep and Chep Wildlife Sanctuaries, was located on Cambodia’s Northern Plains (247 km2 of habitat with a predicted occupancy likelihood of >75 % inside pro- tected areas and 77 km2 outside), with smaller patches of highly suitable areas scattered across the Eastern Plains (15 km2 inside protected areas and 11 km2 outside).
Between 2001 and 2016, 14,215 km2 (15 %) of the original deciduous dipterocarp forest cover was cleared for agriculture, 1,605 km of road was constructed and the area of habitat with a predicted occupancy likelihood of >75 % shrank by 69 % in the Northern Plains (66 % inside protected areas and 79 % outside) and 73 % in the Eastern Plains (80 % inside and 64 % outside). In Kulen Promtep and Chep, cranes continued to nest but in areas modeled as having lower suitability. We recommend (i) strengthening protection of Kulen Promtep and Chep Wildlife Sanctuaries in the Northern Plains and of remaining nesting habitat in other protected areas; (ii) surveying for active nesting in areas having the highest suitability classes based on the 2001 model but not currently protected, particularly south of Kulen Promtep; (iii) in the meantime, take immediate steps towards protecting as much remaining habitat as possible, that was modeled as highly suitable, to allow for population recovery or in case subsequent surveys find it occupied
| Original language | English |
|---|---|
| Article number | 120703 |
| Journal | Forest Ecology and Management |
| Volume | 529 |
| Early online date | 10 Dec 2022 |
| DOIs | |
| Publication status | Published - 1 Feb 2023 |
Bibliographical note
Funding Information:We are grateful to: the General Department of Administration for Nature Conservation and Protection under the Ministry of Environment for granting us permission to conduct various aspects of this study; to the Convention on Conservation of Migratory Species of Wild Animals and International Crane Foundation for enabling 2001 aerial surveys and the Wildlife Conservation Society (WCS) and BirdLife International for their participation; to WCS for facilitating and assisting research in Kulen Promtep and Chep Wildlife Sanctuaries during the 2014-2015 period, especially Alistair Mould, Rours Vann and Thong Sokha. The latter two for leading their teams of community biodiversity monitoring rangers that participated in collecting data on nest site selection in Kulen Promtep and Chep Wildlife Sanctuaries. The overall collection of data on nest site selection within wetlands was facilitated by Kit Sokny. The Charles Darwin University (CDU) and the Critical Ecosystem Partnership Fund (Grant #7736-000 CEPF-005) funded the research activities of RNvZ in 2014-2015. The Critical Ecosystem Partnership Fund, administered for the Indo-Burma hotspot through the IUCN-Asia Regional Office, is a joint initiative of l'Agence Française de Développement, Conservation International, the European Union, the Global Environment Facility, the Government of Japan, the MacArthur Foundation and the World Bank. We thank Mirjam Kaestli at CDU for statistical support.
Funding Information:
We are grateful to: the General Department of Administration for Nature Conservation and Protection under the Ministry of Environment for granting us permission to conduct various aspects of this study; to the Convention on Conservation of Migratory Species of Wild Animals and International Crane Foundation for enabling 2001 aerial surveys and the Wildlife Conservation Society (WCS) and BirdLife International for their participation; to WCS for facilitating and assisting research in Kulen Promtep and Chep Wildlife Sanctuaries during the 2014-2015 period, especially Alistair Mould, Rours Vann and Thong Sokha. The latter two for leading their teams of community biodiversity monitoring rangers that participated in collecting data on nest site selection in Kulen Promtep and Chep Wildlife Sanctuaries. The overall collection of data on nest site selection within wetlands was facilitated by Kit Sokny. The Charles Darwin University (CDU) and the Critical Ecosystem Partnership Fund (Grant #7736-000 CEPF-005) funded the research activities of RNvZ in 2014-2015. The Critical Ecosystem Partnership Fund, administered for the Indo-Burma hotspot through the IUCN-Asia Regional Office, is a joint initiative of l’Agence Française de Développement, Conservation International, the European Union, the Global Environment Facility, the Government of Japan, the MacArthur Foundation and the World Bank. We thank Mirjam Kaestli at CDU for statistical support.
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