One of New Zealand's iconic braided river birds, the black-fronted
tern, is in decline. To turn things around the Department of
Conservation and the University of Otago are co-operating in a
large-scale South Island wide project to learn more about this small
From September to January the terns breed in loose colonies in the braided
riverbeds of the Eastern South Island. Its breeding plumage is very
distinctive: A black cap contrasted by a narrow white cheek stripe and
slate-grey body plumage, its bill and short legs are bright orange.
To many fishermen, the elegant tern is a familiar sight as they like to
feed on hatching mayflies and are often seen near good trout fishing
spots. After the breeding season, the terns move to the coast of all three
main islands and have been observed feeding many kilometres off-shore.
It is estimated that about 10% of the total population breeds in the
Waitaki River, making it a significant stronghold for the species.
Unfortunately the tern's populations have been in decline and are
currently classed as Endangered. The biggest threat are introduced
predators - like cats, hedgehogs, rats, ferrets and stoats - as well as
weeds, such as lupins, broom and gorse invading their breeding habitat.
Not much is known about black-fronted terns and their movements: Do the
same birds return to the same river each year? Do the breeding colonies
mix during the winter? Do birds move from one river to another? This
information is though necessary to properly plan protection measures like
weed and predator control. The Department of Conservation (Dr Richard
Maloney) and the University of Otago (Dr Bruce Robertson and MSc student
Ann-Kathrin Schlesselmann) are working together on a South Island wide
project to learn about these relationships using genetics. As the birds
have very short legs, using coloured bands and simply observing birds is
not practicable - nor would it be possible to undertake this on a South
Island wide-scale. For the genetic analysis only a small blood sample from
a bird is required, which can be later analysed in a laboratory.
This research helps in developing predator and weed control at the right
level to protect all the birds within a population. It will allow us to
understand better how for example the birds breeding in the Waitaki River
are connected to the colonies in the Mackenzie Basin.