Testing the meta-population structure of the endemic lava heron (Butorides sundevalli) on the archipelago island system

The probabilities of species colonization and extinction rates of meta-populations on island system could be affected by fraction of islands occupied and size of each island. Meta-population models are relevant to understand the dynamics of endangered species which often persist in highly fragmented landscapes. The objectives of the study were to: (1) determine the meta-population dynamics of the endemic lava heron ( Butoridessundevalli ) on the archipelago island system through estimating the probabilities of colonization and extinction rates; (2) investigate the structure of meta-populations and their trends on the island system by using meta-population models. The results revealed that islands which are large in size showed a source-effect due to their positive internal rate of population growth, lower probabilities of extinction rates, and higher average abundance of population size. However, islands with small size had lower average abundance of population size and relativity lower (negative) internal rate of population growth so that they acted to play a sink-effect. In contrast to the prediction made by meta-population model, the results of the comparison across the twelve islands showed that both the probabilities of colonization and extinction rates of the small sized islands were relatively higher than those islands with large size. However, across time frame comparison showed that the extinction probabilities increased with the increase in fraction of occupied islands though colonization probabilities showed a slight decline when the fraction of occupied islands increased. This suggested that the meta-population structure of the endemic lava heron on the archipelago island system was found to be the combination of source-sink and core-satellite structure. Fraction of islands occupied, and the area of islands had a significant effect to predict the internal rates of population growth and the average abundance of population size for the endemic lava heron on the archipelago island system, respectively.