Abundance and breeding habitat of Noddies and White Terns on a relatively unmodified island in the Kingdom of Tonga

Abstract

Islands in the Kingdom of Tonga have undergone severe modification since human colonisation and, as a result, the availability of optimal habitat for breeding seabirds has decreased. We collected data on the abundance of breeding Black Noddies (Anous minutus), Brown Noddies (A. stolidus) and White Terns (Gygis alba) during a short visit to Maninita Island, one of the few relatively unmodified islands in Tonga. The island was surveyed and quadrat plots were used to count trees, birds and nests, from which we described vegetation composition and structure, and obtained population estimates of the Noddies and White Terns on the island. The island's vegetation is dominated (96.8% of total basal area) by Pisonia grandis, which is used for nesting by the noddies and terns. At the time of our visit the seabird population on Maninita consisted of an estimated 2664 ± 110 noddies and 233 ± 14 White Terns. Our work illustrates the importance, to breeding seabirds, of conserving those few relatively unmodified islands that remain in the Kingdom of Tonga.