Status Assessment and Population Trends of the Madagascar Pond-Heron (Ardeola idae) from 1993-2016

Abstract

The Madagascar Pond-heron (Ardeola idae) is a migratory species that breeds exclusively in Madagascar and nearby islands (Europa, Aldabra and Mayotte). Changes in the population of this species were investigated over the last 23 years through literature reviews, field monitoring, and surveys undertaken from 1993 to 2016. Data from 111 sites were collected and analyzed for population assessment, including 11 known breeding sites in Madagascar (n = 6), Mayotte (n = 4), and Europa (n = 1). Trend analyses were done with surveys from 1993-2016 (omitting 1996) and population estimates from the last 5 years of surveys, 2012-2016. The species occurred in all types of wetlands including lakes, ponds, marshes, rivers, mangroves, pasture wet meadow, and rice fields. During the non-breeding season (May-September), many pond-herons migrate to eastern and central Africa; however, some birds (911 records) remained in Madagascar and Mayotte during austral winter. Data show the current population estimated at ∼1100 breeding birds in the total breeding area. The population has declined significantly, with 41.6% and 52.9% declines, respectively, at the two colony sites in Tsimbazaza and Tsarasaotra parks with the longest history of breeding. Main threats to the species are habitat destruction, collection of eggs and fledglings, predation, and human disturbance at all breeding sites.