Waterfowls habitat modeling: Simulation of nest site selection for the migratory Little Tern (Sterna albifrons) in the Nakdong estuary

This paper aims to find patterns in nest site selection by Little Terns Sterna albifrons, in the Nakdong estuary in South Korea. This estuary is important waterfowl stopover and breeding habitat, located in the middle of the East Asia-Australasian Flyway. The Little Tern is a common species easily observed near the seashore but their number is gradually declining around the world. We investigated their nests and eggs on a barrier islet in the Nakdong estuary during the breeding season (May to June, 2007), and a pattern for the nest site selection was identified using genetic programming (GP). The GP generated a predictive rule-set model for the number of Little Tern nests (training: R2 = 0.48 and test: 0.46). The physical features of average elevation, variation of elevation, plant coverage, and average plant height were estimated to determine the influence on nest numbers for Little Tern. A series of sensitivity analyses stressed that mean elevation and vegetation played an important role in nest distribution for Little Tern. The influence of these two variables could be maximized when elevation changed moderately within the sampled quadrats. The study results are regarded as a good example of applying GP to vertebrate distribution patterning and prediction with several important advantages compared to conventional modeling techniques, and can help establish a management or restoration strategy for the species.

► This paper aims to find patterns in nest site selection by Little Terns Sterna albifrons, using an empirical modelling algorithm; genetic programming (GP). ► Nest distribution was surveyed for the species, and physical environment data were used as forcing functions. ► The developed model provided useful information for the explanation of Little Tern nest distribution patterns. ► Monospecific colony of Little Tern exhibited different patterns (sensitivity to mean elevation from sea level) from mix colonies of multi-species. ► The results of this study are challenging due to the importance of estuarine areas globally as refuge sites and because of the limited effort in modeling research based on animal species in these areas.