Ghosts of species past

New Zealand’s ma­jes­tic moas are long gone, but their essence lingers on in the is­lands’ ecosys­tems.

Australian Geographic - - Wild Australia - JOHN PICKRELL is a for­mer AUS­TRALIAN GEO­GRAPHIC ed­i­tor. Fol­low him on Twit­ter: @john_pick­rell

MOAS WERE nine huge flight­less bird species – related to the emu, cas­sowary and kiwi – that once stalked the lush beech forests, shrub­lands and sub­alpine mead­ows of New Zealand. The big­gest of these im­pos­ing avians was up to 3.6m tall, dwarf­ing even the largest kiwi species still found on

New Zealand to­day.

When sea­far­ers first ar­rived in NZ from Poly­ne­sia about 700 years ago, there may have been nearly 60,000 of these mag­nif­i­cent crea­tures, but within just 200 years all moa species had been hunted to ex­tinc­tion, along with more than 40 per cent of the is­lands’ other na­tive bird species.

To­day, most of what we know of moas comes from bones, feath­ers, skins and other dried remains, some­times found in re­mark­ably good con­di­tion in cave en­vi­ron­ments. In re­cent years, ex­perts have also been able to re­con­struct the diet of gi­ant moas from gut con­tents and many well-pre­served co­pro­lites – par­tially fos­silised drop­pings.

The lat­est of these stud­ies was pub­lished re­cently in the Pro­ceed­ings of the Na­tional Academy of Sci­ences, by re­searchers in­clud­ing Alexander Boast of the Aus­tralian Cen­tre for An­cient DNA at the Univer­sity of Ade­laide, and Jamie Wood at Land­care Re­search in Can­ter­bury, NZ. From caves and rock shel­ters at eight South Is­land sites, the sci­en­tists col­lected 23 co­pro­lites from four moa species and also the kakapo (a crit­i­cally en­dan­gered flight­less par­rot that’s been ex­tir­pated from most of NZ’s is­lands). These fos­sil drop­pings ranged in age from

124 to 1557 years old.

“Co­pro­lites were ac­tu­ally more com­mon than we’d thought, once we started look­ing for them,” Jamie says. “And it turns out they con­tain a huge range of im­por­tant in­for­ma­tion about past ecosys­tems.”

The sci­en­tists were able to get moa DNA from the dung, in­for­ma­tion on pathogens and specialised par­a­sites that af­flicted these species, and clues to the birds’ long-lost be­hav­iour. One fas­ci­nat­ing find­ing was that both the moa and the kakapo ate a wide va­ri­ety of fungi and mush­rooms that re­main an es­sen­tial com­po­nent of NZ’s beech forests to­day and have close sym­bi­otic re­la­tion­ships with tree roots.

Many of these so-called ec­to­my­c­or­rhizal fungi are brightly coloured, pos­si­bly to mimic fruits and berries and look ap­petis­ing to ground-dwelling birds. This would have en­cour­aged moas to eat them and help dis­trib­ute their spores across the is­lands’ forests.

Colour­ful fruits and berries have of­ten evolved to be eaten by birds or pri­mates, be­cause many other mam­mals don’t have full colour vi­sion and only see the world in muted shades.

These fungi also have fruit­ing bod­ies that never open fully to re­lease their spores, re­ly­ing in­stead on an­i­mals – such as moas and kakapo – to eat and spread them.

The sci­en­tists re­port in their pa­per that “we pro­vide ev­i­dence that moa and pre­his­toric kakapo con­sumed ec­to­my­c­or­rhizal fungi, sug­gest­ing these birds played a role in dis­pers­ing fungi that are key to NZ’s nat­u­ral for­est ecosys­tems. We also pro­vide the first DNA-based ev­i­dence that moa fre­quently sup­ple­mented their broad di­ets with ferns and mosses.”

With the loss of these birds, the critical role they played in their ecosys­tems has also gone, with po­ten­tial implications for the on­go­ing health of NZ’s beech forests. This isn’t the first time a lost eco­log­i­cal re­la­tion­ship in NZ has been found us­ing fos­silised dung. In 2012 Jamie was part of a team that used kakapo co­pro­lites to prove these birds had once been an im­por­tant pol­li­na­tor for the par­a­sitic ‘flower of Hades’ (AG 128).

Dur­ing re­cent mil­len­nia, the ex­tinc­tion of many of our planet’s large an­i­mals has left bro­ken food chains, dis­rupted ecosys­tems and empty niches. But clever new meth­ods, such as analysing DNA in co­pro­lites, are al­low­ing re­searchers to re­con­struct lost bi­o­log­i­cal re­la­tion­ships like never be­fore.

Ex­tinct moas may have eaten colour­ful fungi such as this pur­ple pouch fun­gus (right) found to­day in NZ beech forests.

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