Surge in Seychelles White-eyes

By November 30, 2017 Nature

Over the past year the Seychelles White-eye population on North Island has grown by over 20%, with 115–127 individuals recorded in the 2017 survey, exhibiting both a higher average group size and number of groups compared to 2016. An incredible result, which is testament to the ongoing Noah’s Ark rehabilitation programme on North Island.

The White-eye population has steadily increased in size since its introduction in 2007, when just 25 of these endangered birds were reintroduced to the Island. Between 2014 and 2016, the population appeared to reach a plateau and stabilised between 89 and 105 individuals. However the current census has yielded positive results with another steep increase in 2017 – now over 5 times the original population size. The dramatic reduction in the Common Myna population, as well as continuing efforts to rehabilitate the vegetation on North Island are undoubtedly contributing to the continued increase in the Seychelles White-eye population.

At the time of the current survey, fewer than ten Common Mynas were believed to inhabit the island. The near-eradication likely released the Seychelles White-eyes from interspecific competition, resulting in improved reproductive success and survival rates of especially young birds. The systematic clearing of invasive plants and the simultaneous planting of indigenous plant species has proven successful. The White-eye population showed an increase in a year with below-average rainfall – a period when it may be expected that the population would remain stable or even decline due to resource limitations.

The population is healthy and self-sustaining and there is every indication that the Seychelles White-eye population will continue to expand in tandem with these rehabilitation efforts. The estimated population reported represents the minimum population size. Previous surveys suggest that 10–12 % of the population goes unrecorded during surveys, which translates to approximately 12–13 additional individuals, suggesting that the actual population size is in the region of 127–140 individuals, and may even be higher as some individuals and/or groups inhabiting the more inaccessible parts of the island may have been overlooked.

 

Reference:

PIETERSEN, D. 2017. Assessment of the Seychelles White-eye Zosterops modestus Newton, 1867 population on North Island, Seychelles: Report for the period 5 to 21 October 2017. North Island.