En­dan­gered but for­got­ten

New Zealand has more than 900 na­tive species ap­proach­ing ex­tinc­tion and an­other 2800 de­clin­ing or at risk – yet Ki­wis be­lieve we are do­ing a good job on con­ser­va­tion. In this For­got­ten Species series, Ged Cann asks are we sim­ply be­liev­ing our ow­nad­ver­tisi

The Timaru Herald - - FRONT PAGE -

Any­one who has ever en­joyed fish and chips at the sea­side wouldn’t be­lieve there was a threat­ened gull in New Zealand.

How­ever, the na­tive black­billed gull – the rarest gull on the planet – is in se­ri­ous de­cline.

The Depart­ment of Con­ser­va­tion (DOC) clas­si­fies the black­billed gull as na­tion­ally crit­i­cal, with a pop­u­la­tion of about 60,000 breed­ing adults, which is ex­pected to de­cline by up to 70 per cent over 10 years or three gen­er­a­tions, which­ever is the long­est.

That puts it in the same cat­e­gory as the black robin, but un­like the robin, the black-billed gull looks very sim­i­lar to a species most of us con­sider a pest – the red­billed gull.

Ap­pear­ance is where the sim­i­lar­ity ends be­cause, un­like other gulls, this species favours nests among the shin­gle of braided riverbeds to the coast­line, and is smaller, more timid, and far less likely to pinch a chip.

Edith Smith is in­volved with BRaid, a group ad­vo­cat­ing for sav­ing New Zealand’s braided rivers, and said the black-billed gull was fac­ing mount­ing pres­sures from pre­da­tion and a grow­ing risk of sud­den floods wip­ing away its nests.

The new year brought a re­minder of just how vul­ner­a­ble these birds are, with heavy rains all but wip­ing out a colony of 3000 gulls nest­ing near the State High­way 1 bridge over the Hakatere River near Ash­bur­ton, in Can­ter­bury.

Smith said up to 2500 chicks drowned in the floods.

‘‘The re­main­ing adults ap­pear to be quite un­set­tled, with many preen­ing or tuck­ing heads un­der their wings. Only one or two older chicks pos­si­bly from the ear­lier colony re­main. The colony has been washed clean with no sign of the nest­ing ma­te­ri­als or guano of a few days ago.

‘‘Some clus­ters of gulls have moved fur­ther down­stream and can be seen in the dis­tance.

‘‘While most of the younger chicks were too im­ma­ture to float down the river to higher ground, some may well have sur­vived.’’

A sec­ond, larger, colony at the mouth of the Hakatere River nested ear­lier than the SH1 group, mean­ing their young would have been ma­ture enough to fly or move to higher land.

Smith said the birds pre­ferred braided rivers for their in­ver­te­brate prey, but pol­lu­tion from in­ten­sive farm­ing meant even this food source could prove un­re­li­able.

Braided rivers were also more likely to re­main pol­luted for ex­tended pe­ri­ods, be­cause they don’t get the cleans­ing floods com­mon in alpine rivers.

The gulls formed colonies, and child­less gulls of­ten babysat nestlings while their par­ents were for­ag­ing, keep­ing them safe from any preda­tors.

‘‘If some­thing like a fer­ret or a stoat ... comes fer­ret­ing around, they fly up and so that sud­den noise and flap­ping of wings will of­ten scare the preda­tor away.’’

Smith said a study of black­billed gulls in South­land had found if the pop­u­la­tion con­tin­ued to de­cline at the same rate there could be a cri­sis point reached within the next gen­er­a­tion.

Black-bills rou­tinely mi­grate to the warmer North Is­land or up­per South Is­land, and re­turn to the braided rivers around Au­gust as they scout for nest­ing spots.

There is hope as the gull’s pro­file grows, re­flected in the num­ber of votes it re­ceived in For­est & Bird’s Bird of the Year com­pe­ti­tion, climb­ing from 72 to 900 in 2017.

‘‘Some­body Smith said. likes them,’’

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