Nest position, breeding success and diet of the Black-crowned Night Heron, Nycticorax nycticorax in the Anzali Wetland, Northern Iran (Aves: Ardeidae)

Abstract

Breeding ecology of the Black-crowned Night Heron (Nycticorax nycticorax) was studied in a mono-specific colony in the Anzali wetland, Northern Iran during the breeding season of 2016. The breeding period lasted from mid-May to late July. The average clutch size was 3.1±0.6 eggs and the breeding success 77.6%. No significant differences were found between nests built on trunks and those built on branches of trees. The clutch size and breeding success appeared to be independent of the structural variables of the nesting site (diameter of trees, height from the ground, height of nests from the canopy, nest number per tree, location of nests on trunks and branches). No significant difference was found between the timing of the start of incubation and the height of nests above the ground. The average vertical and horizontal distances between nests was one metre. Fish, particularly Carassius gibelio, dominated the diet of the nestlings.

Keywords:

• breeding ecology
• breeding success
• nest variables
• diet
• Anzali wetland

Acknowledgements

We are grateful to Gilan Provincial Office of the Department of the Environment. Dr Giorgos Catsadorakis and Dr Abolghasem Khaleghizadeh helped with review of the manuscript and to Crawford Prentice for language improvements. We thank Mr Mahiar Tahamoli, Mr Yaqoub Rakhsh-Bahar, and Mr Ebrahim Pourmojib for their assistance in field work. We are also grateful to Dr Keyvan Abbasi, Dr Mahdi Jalaeian and Mr Mostafa Sayad Rahim, experts in the Inland Waters Aquaculture Research Center, Iranian Fisheries Science Research Institute, Bandar Anzali and Rice Research Institute of Iran for identifying prey items.

Disclosure Statement

No potential conflict of interest was reported by the authors.