White-fronted Tern

Identification

The white-fronted tern is described as an average-sized bird. Its dimensions are 35–43 cm (14–17 in) in length, with a wingspan between 79 and 82 cm (31 and 32 in); the male weighs on average 130 g (4.6 oz). Females are marginally smaller, but this is difficult to determine when observing individuals in the wild.<p>Breaking down their monochromatic colouring, the white-fronted tern's lightest features are its all-white body, tail and underwing, with the upper side of the wings a light silvery grey hue. Through the breeding season there can be a faint pink coloration on the breast, but this is not always visible. The darkest features are the beak, black cap, eyes, feet and the shadowing on the outermost edge of the wingtips. The long ebony-like bill is slender and comes to a sharp point that dulls in colour at the tip. The crown is jet black, interrupted by a variably narrow white band between forehead and bill. The black cap continues over the crown and finishes at the nape. Inky black round eyes sit within the cap. The legs are stumpy with a deep burgundy black tone. A defining feature of the white-fronted tern is its forked tail, most recognisable when in flight and commonly drawing comparisons with a swallow's tail. In the breeding season, the outermost feathers of the tail lengthen, accentuating the already deep fork. <p>The black cap of non-breeding adults retreats towards the top of the forehead and above the eyes, while at the same time losing some of its intensity. Immature white-fronted terns are similar but have speckles of white through the cap. Along with a slight coloration on the wings and tail, which appear as a brownish cream.The juvenile plumage is very pronounced with flecks of light to dark grey and warm milky browns on the upper side of the wing, back, and mantle. the cap is incomplete and mottled, having dark black markings in front of and behind the eyes.<p>A very dull "crek" is used in courtship when the male is flying above groups, individuals may respond with the same noise. When descending upon intruders, they will let out a continuous "keark". Generally calling between individuals is a high-pitched "siet" used frequently during flight, it will be repeated over and over in particular intervals.

Taxonomy

The white-fronted tern was formally described in 1789 by the German naturalist Johann Friedrich Gmelin in his revised and expanded edition of Carl Linnaeus's Systema Naturae. He placed it with the terns in the genus Sterna and coined the binomial name Sterna striata. Gmelin based his description on the "striated tern" that had been described and illustrated in 1785 by the English ornithologist John Latham in his book A General Synopsis of Birds. The naturalist Joseph Banks had provided Latham with a drawing of the tern from New Zealand. The drawing had been made by William Wade Ellis from a specimen collected in 1777 off the southeast coast of New Zealand's North Island on James Cook's third voyage to the Pacific Ocean. The genus name Sterna comes from the Old English word for a black tern. The specific epithet is from Latin striatus meaning "striated". The species is monotypic: no subspecies are recognised.<p>The species is closely related to the common tern (Sterna hirundo), roseate tern (Sterna dougallii), black-naped tern (Sterna sumatrana), South American tern (Sterna hirundinacea), Antarctic tern (Sterna vittata) and Arctic tern (Sterna paradisaea).

Scientific name

Sterna striata

Authority

Gmelin, JF, 1789

Order

Charadriiformes

Family

Laridae

Genus

Sterna

Range and habitat

White-fronted terns are found in New Zealand and Australia. Juveniles will occasionally migrate across to south-east Australia and the Northern parts of Tasmania. Breeding populations in Australia are only observed in the Bass Strait, on Flinders and Cape Barren Islands. <p>They are the most abundant tern in New Zealand and live along the entire coastline. In the North Island, there are significant populations from Auckland to the Bay of Plenty including the Coromandel Peninsula and they are widespread along the coast from Wellington, up towards Manawatu. In the South Island, they are a familiar sight in the Marlborough Sounds and along the east coast into Canterbury, Otago and Southland, where they can be seen year-round. Stewart Island also has flocks and breeding pairs throughout the year. Apart from the main coastline of New Zealand they also populate many of the smaller islands, with large numbers of breeding pairs observed on both the Chatham and the Auckland Islands. They seldom head inland, but there have been recordings of them in the Canterbury area, where they travel up the large braided rivers to feed and nest.<p> White-fronted terns can be found in a variety of coastal habitats. With large flocks preferring coastal waters, harbours, bays and estuaries where they are content to live on either sand, shell or shingle ground. Occasionally living on the stony banks of Canterbury's braided rivers.<p>Not confined to just main coastal areas, white-fronted terns frequent coastal cliffs, offshore rock-stacks and small islands.White-fronted terns can also be found on human-made structures. as in Tauranga Harbour, where breeding pairs have taken up residence on disused concrete support structures.

Breeding range

AU : coasts and satellites of North, South, Stewart, Chatham (e of South I.) and Auckland is. (s of South I.; New Zealand); also (few) Furneaux group, e Bass Strait is. (Australia)

Non-breeding range

coastal e SA, Tasmania to se QLD (s, e Australia)

Migration

Complete migrants

Behavior

Migration pattern: Complete migrants.

Conservation

Population trend: declining.

Population trend

declining