Black-fronted Tern

Black-fronted terns are considered medium-small in size. Adults measure 28–30 cm in length, with a 65–72 cm wingspan and an average weight of 95 g. They have short orange bills, short orange legs, and a body that is dark grey above and light grey below with a white rump and a distinctive black cap. During the non-breeding season, the black cap recedes and becomes flecked with white.

Within New Zealand, black-fronted terns are found from the southern tip of the North Island, and along much of the eastern South Island from Marlborough to Southland, and to Stewart Island. There is an outlying population along the Buller and upper Motueka Rivers in southern Nelson. Black-fronted terns frequent coastal areas, including estuaries, harbours, and farmland (up to 3 km or 1.86 mi inland), where they will forage for insects and small fish. They will forage up to 10 km (6.21 mi) out to sea particularly in calm weather.

Black-fronted terns are particularly vulnerable to a number of threats including predation by introduced mammals, habitat loss (land use changes and weed encroachment), resource abstraction (gravel and water), human disturbance, and climate change. Conservation methods involve predator control, habitat enhancement (modification of river islands and weed control), and the use of chick shelters.

Predation. Black-fronted terns at all stages of life are vulnerable to exotic mammals that have been introduced to New Zealand. Due to the country's long isolation from other land masses, endemic New Zealand species have not evolved alongside mammalian predators and therefore have no effective defences against them. Predation is considered the leading cause of nest failure, though the predators responsible depend on the location of the colony. The following species have been recorded predating black-fronted tern adults, chicks, and eggs:

Mustelids (Mustela spp.), including stoats (M. erminea) and weasels (M. nivalis) Feral cats (Felis catus). There have been multiple known instances wherein a lone feral cat has depredated a significant number of tern nests in a single visit. …