Tern (New Zealand Fairy tern) Sternula nereis davisae
Species: S. nereis
Subspecies: S. n. davisae
Trinomial name: Sternula nereis davisae
Common name: New Zealand fairy tern. tara-iti
Sternula nereis davisae is a small, critically endangered tern which breeds on the lower half of the Northland Peninsula of the North Island of New Zealand. It is the smallest tern breeding in New Zealand and is a subspecies of the fairy tern (Sternula nereis). Adults measure around 250mm in length and weighing a mere 70 grams.
Breeding is limited to four regular sites: Waipu, Mangawhai, Pakiri and the South Kaipara Head. The wintering range of the birds extends over the Kaipara Harbour.
The number of birds plummeted to three pairs in 1983 but intensive conservation efforts were put in place and numbers increased so that in 1998 the population totalled some 25 to 30 birds with 10 to 12 breeding pairs spread over three breeding sites. Numbers have continued to increase and by 2006 had reached 30 to 40 individuals including 12 breeding pairs. Five years later, numbers have increased again to 40 to 45 individuals and around 10 breeding pairs. The usual lifespan of a New Zealand Fairy Tern is less than 10 years, however, there are a few approaching their 16th year.
A New Zealand government source considers that this bird is "probably New Zealand's most endangered indigenous breeding bird." Their nests are a shallow depression in the shell-covered sands, usually above the spring high tide mark. The eggs have camouflaged blotches on the shell to help them blend into the background and be less visible to predators. New Zealand fairy tern is highly vulnerable to introduced predators, domestic animals, storms, very high tides, strong winds and disturbance by humans on foot and in vehicles on the beach. The bird’s predators are rats, dogs, cats, hedgehogs and mustelids (stoats, weasels and ferrets) all of which prey upon eggs, chicks and adult birds.