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Friend or foe? Global megafauna study calls for con­ser­va­tion rethink

pub­lished 20 August 2017 | mod­i­fied 07 Decem­ber 2018

It’s hard to imag­ine an Aus­tralia ruled by hippopotamus-​sized wom­bats (Diprotodon) and three-​metre-​tall kan­ga­roos (Pro­coptodon golian). The con­ti­nent lost all native megafauna to the Pleis­tocene extinc­tions, tens of thou­sands of years ago.

Dromedary camelAus­tralia is home to the world’s only pop­u­la­tion of wild drom­e­dary camels.
Image credit: Arian Wal­lach, UTS Cen­tre for Com­pas­sion­ate Conservation.

Remark­ably, how­ever, eight species of intro­duced megafauna now call Aus­tralia home and some of them are “rewil­d­ing” mod­ern ecosys­tems, new research has found. These include ani­mals on the Red List of Threat­ened Species, com­piled by the Inter­na­tional Union for Con­ser­va­tion of Nature (IUCN), such as one of the largest pop­u­la­tions of endan­gered wild horses (Equus ferus cabal­lus) and the world’s only pop­u­la­tion of wild drom­e­dary camels (Camelus drom­e­dar­ius).

Dr Arian Wal­lach and Dr Daniel Ramp from the Uni­ver­sity of Tech­nol­ogy Syd­ney (UTS) Cen­tre for Com­pas­sion­ate Con­ser­va­tion, along with researchers from Ari­zona State Uni­ver­sity and Ore­gon State Uni­ver­sity, say the research chal­lenges fun­da­men­tal ideas sur­round­ing “inva­sive” species and conservation.

The global study, pub­lished in Ecog­ra­phy, iden­ti­fied that of the world’s 76 exist­ing megafauna species, 22 have intro­duced pop­u­la­tions. Of these intro­duced pop­u­la­tions, almost half are either threat­ened or extinct in their native ranges.

The global decline of megafauna is being dri­ven by habi­tat loss, changes in land use and over­hunt­ing. Despite this, some megafauna have found refuge in new habi­tats through introductions.

Dr Arian Wal­lach, chief inves­ti­ga­tor, Uni­ver­sity of Tech­nol­ogy Syd­ney, Cen­tre for Com­pas­sion­ate Conservation

The team, led by Ari­zona State University’s Erick Lund­gren, has also found intro­duced megafauna can con­tribute unique eco­log­i­cal func­tions, some of which may have been lost since the late Pleis­tocene. “As large her­bi­vores, these intro­duced species can con­sume plant mat­ter indi­gestible to smaller her­bi­vores, which may reduce fire fre­quency, accel­er­ate nutri­ent cycling and shape plant com­mu­ni­ties,” Lund­gren says.

In North America’s Sono­ran Desert, wild don­keys are now dig­ging ground­wa­ter wells more than a metre deep. These holes pro­vide a much-​needed water source for at least 30 species of mam­mals and birds, as well as ger­mi­na­tion nurs­eries for river veg­e­ta­tion. Crit­i­cally endan­gered in its native range, the wild don­key has clearly found refuge and is con­tribut­ing to ecosys­tems in its intro­duced range, says Lundgren.

(Source: Erick Lund­gren YouTube channel)

Many exist­ing pop­u­la­tions of megafauna are either endan­gered or extinct. Con­ser­va­tion his­tor­i­cally over­looks such pop­u­la­tions, assum­ing any­thing “intro­duced” is “alien” or “inva­sive”. Lund­gren and his team, how­ever, sug­gest such pop­u­la­tions are crit­i­cal buffers against extinc­tion and may have a pos­i­tive impact on their new homes.

What this study shows is that the world is much wilder than we often think,” says Wal­lach. “The ques­tion is whether we are will­ing to allow it to be.”

Lis­ten to lead researcher, Erick Lund­gren from Ari­zona State Uni­ver­sity explain­ing how intro­duced megafauna are ‘rewil­d­ing’ new regions and why we need to rethink tra­di­tional atti­tudes sur­round­ing conservation:

(Source: UTS news release, 15.08.2017; 2ser 107.3)

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