Is there a competition between endemic pink pigeon (Nesoenas mayeri) and invasive Madagascar turtle-dove (Nesoenas picturata) in lowland Mauritius?

Abstract

Mauritius, one of the Mascarene islands in the Indian Ocean, was identified as a biodiversity hotspot by IUCN and as an Important Bird Area by BirdLife International, mostly because of its endemic species richness. Habitat destruction and introductions of many alien invasive species already caused extinctions and reduction of populations to critical low levels. The endemic pink pigeon (Nesoenas mayeri), one of Mauritius emblematic species, has recovered from less than 20 birds in the mid 1970s to 343 free-living individuals in 2014 among which the subpopulation established on Ile aux Aigrettes, a Nature Reserve offshore islet. This study investigated if pink pigeons were competing with exotic Madagascar turtle-dove (Nesoenas picturata), a sister species widespread on the island, for food and nesting sites. The reproductive success of both species was also investigated by nests monitoring. Significant differences in the diet, foraging behaviour and nesting preferences of pink pigeon and Madagascar turtle-dove were found on Ile aux Aigrettes. Pink pigeon was predominantly eating leaves and favouring areas of mature canopy forest, preferring tall ebony trees Diospyros egrettarum for nesting. Madagascar turtle-dove was mostly a fruit eater and was nesting at lower levels, with no big preference in the plant species choice, and in open areas or forest edges. Proportion of successful nests was 3 times higher for the exotic N.picturata. Differing ecological requirements indicate that divergence between these congeners may be sufficient for them to coexist and exploit contrasting resources on this restored islet. Nevertheless, we discuss the implications of such coexistence in relation to pathogen Trichomonas gallinae transmission which can affect pink pigeon long-term recovery programme.