Reproductive performance of the great cormorant (Phalacrocorax carbo sinensis) in three Greek colonies

Abstract

Several breeding parameters of the great cormorant (Phalacrocorax carbo sinensis) were studied in Greece in 2001 and 2002 and were found to be generally higher at Lake Kerkini than in the other colonies. Fledging success (proportion of hatched eggs that led to fledged nestlings) was significantly higher at Lake Kerkini and in the Axios Delta in both years than at Lake Mikri Prespa in 2002. Mean fledgling production (the number of young fledged per initiated clutch) was significantly higher at Lake Kerkini than at Lake Mikri Prespa in 2002. The high fledgling production (2.15–2.75 fledglings on average in this study), the high food availability and the low initial population density allowed the total Greek breeding population to grow at a fast rate (19.0% per annum) in the 1990s. Given the scarcity of information on great cormorant nesting in Greece, basic breeding parameters are important for modelling population dynamics.

Keywords:

• great cormorant
• clutch size
• egg size
• breeding success
• population dynamics
• Greece

Acknowledgements

We are very grateful to the following people for their assistance in the field and provision of information: P Chatzigiannidis, S Kazantzidis, P Menounos, T Naziridis, F Passios, K Poirazidis and P Vafeidis. We also thank two anonymous reviewers whose useful comments and suggestions helped greatly improve the manuscript.