Caspian Tern
The Caspian Tern (Hydroprogne caspia), known in Māori as Taranui, is the largest tern species globally and a striking presence along New Zealand’s coastlines. With a wingspan of up to 1.3 meters and a bright red bill, it resembles a gull in size but maintains the sleek elegance of a tern. Adults sport silver-grey or white underparts, with a black cap during the breeding season that becomes speckled in winter. Though globally widespread, the Caspian Tern is considered nationally vulnerable in New Zealand due to its relatively small and localized populations.
Two Caspian Terns, Waiorongomai stream
New Zealand hosts an estimated 1300–1400 breeding pairs, primarily concentrated in the northern North Island, including Northland, Auckland, and Waikato2. These birds nest in colonies or as isolated pairs, with breeding sites shifting over time due to environmental changes and human disturbance. Surveys from the 1970s to the 1990s showed a stable population, though colony locations varied, with some disappearing and new ones forming2. The species’ limited fossil record suggests it may be a relatively recent colonist to New Zealand, possibly confined to northern regions until the 20th century.
Breeding occurs from late September to December, with nests being shallow scrapes in sand or gravel, often sparsely lined. Caspian Terns typically lay 1–3 eggs, spaced a few days apart. Both parents share incubation and chick-rearing duties. Chicks fledge after several weeks but remain dependent on adults for food for some time. Nesting sites are vulnerable to flooding, predation, and human activity, making conservation of breeding habitats crucial.
Their diet consists mainly of small fish, which they catch by diving from the air into shallow waters. Caspian Terns are often seen patrolling estuaries, harbours, and lakes, flying with slow, deliberate wingbeats before plunging into the water. They may also consume crustaceans and aquatic invertebrates, depending on availability. Their loud, guttural calls are a common sound around feeding and nesting areas.
Caspian Tern in flight, Waiorongomai stream
In terms of habitat, Caspian Terns are found in sheltered coastal bays, estuaries, and inland lakes and rivers. While they favor coastal shellbanks and sandspits for breeding, they are also known to nest on braided riverbeds and lake margins, especially in Canterbury and Southland 3. Their adaptability to both coastal and inland environments is notable, but habitat degradation and disturbance remain ongoing threats. Conservation efforts focus on protecting nesting sites and monitoring population trends to ensure the species’ continued presence in New Zealand.
Collated from the following sources :
New Zealand Birds Online
Birds nz