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Na­ture Talks Tues­day, No­vem­ber 20: Wet­land Birds in New Zea­land

Wet­lands — a gen­eral term for marshes, swamps, bogs and the wet mar­gins of rivers, streams, lakes and es­tu­ar­ies — have been de­scribed as the en­vi­ron­ment’s kid­neys.

They reg­u­late nutri­ent lev­els by tak­ing up ex­cess nu­tri­ents from the wa­ters that flow through them; fil­ter out or­ganic par­tic­u­lates in­clud­ing, in agri­cul­tural land­scapes, fae­cal ma­te­rial; detox­ify pol­lu­tants; se­quester heavy me­tals; and con­trol wa­ter flow. Apart from these func­tions, which im­prove the qual­ity of wa­ter flow­ing out of them, they also serve as vi­tal habi­tat for spe­cial­ist plants, in­ver­te­brates, fish and birds.

New Zea­land has lost pro­por­tion­ately more of its nat­u­ral wet­lands than al­most any other coun­try. Es­ti­mates of wet­land ex­tent prior to hu­man set­tle­ment, based on as­sess­ments of land­form, soils and the dis­tri­bu­tion of re­main­ing wet­lands, sug­gest that we have lost around 90 per cent of wet­lands through them be­ing drained and in­filled for agri­cul­tural and ur­ban de­vel­op­ment. Be­fore hu­man set­tle­ment, wet­lands cov­ered just un­der 2.5 mil­lion ha (9.2 per cent of the land), of which only around 250,000 ha sur­vive to­day. Many of these re­main­ing wet­lands are still at risk of be­ing drained or filled in, or be­ing de­graded by pol­lu­tion and re­duced wa­ter in­flows due to up­stream ab­strac­tion and com­mer­cial af­foresta­tion. Over­all, our wet­lands suf­fer from gen­eral ne­glect and ig­no­rance of their bio­di­ver­sity val­ues and eco­log­i­cal func­tion­ing.

In the last Na­ture Talks pre­sen­ta­tion for 2018, As­so­ciate Pro­fes­sor Phil Bat­t­ley from Massey Uni­ver­sity will ex­plore what this loss and degra­da­tion means for wet­land birds, fo­cus­ing es­pe­cially on the true swamp-dwellers — bit­tern, rails and crakes, fern­bird — species that live nowhere else. What are the spe­cial char­ac­ter­is­tics of wet­land birds and of their wet­land habi­tats? Which species orig­i­nally in­hab­ited our wet­lands, and which still sur­vive, na­tion­ally and lo­cally? What is their cur­rent sta­tus and what must be done to se­cure their fu­ture? The talk will be given in the Davis Lec­ture Theatre, Whanganui Re­gional Mu­seum (Watt Street en­trance), on Tues­day, No­vem­ber 20, start­ing at 7.30pm.

Na­ture Talks is a se­ries of monthly talks of­fered by three lo­cal en­vi­ron­men­tal groups — the Whanganui Mu­seum Botan­i­cal Group, the Whanganui branch of For­est & Bird, and Birds New Zea­land (Whanganui Re­gion), in con­junc­tion with the Whanganui Re­gional Mu­seum — on top­ics re­lated to New Zea­land’s en­vi­ron­ment and nat­u­ral his­tory, and their con­ser­va­tion. The talks are nor­mally held on the third Tues­day of each month. The talks are free although a gold coin koha is al­ways ap­pre­ci­ated from those who can af­ford it.

This lit­tle egret is an oc­ca­sional vis­i­tor to New Zea­land from Aus­tralia. Some of the va­grant species, over time end up breed­ing here, but not this species, so far.

PIC­TURES / PETER FROST

The New Zea­land dabchick is a char­ac­ter­is­tic species of the now much-di­min­ished dune lakes that were once wide­spread on the Manawatu¯ -Whanganui coastal plain.

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