AboutZoos, Since 2008


Loss of large car­ni­vores poses global con­ser­va­tion problem

pub­lished 11 Jan­u­ary 2014 | mod­i­fied 25 Decem­ber 2014

In ecosys­tems around the world, the decline of large preda­tors such as lions, din­goes, wolves, otters, and bears is chang­ing the face of land­scapes from the trop­ics to the Arc­tic — but an analy­sis of 31 car­ni­vore species that has been pub­lished on 10 Jan­u­ary in the jour­nal Sci­ence shows for the first time how threats such as habi­tat loss, per­se­cu­tion by humans and loss of prey com­bine to cre­ate global hotspots of car­ni­vore decline.

Puma-7fMore than 75 per­cent of the 31 large-​carnivore species are declin­ing, and 17 species now occupy less than half of their for­mer ranges, the authors reported. To offer a com­pre­hen­sive look at the state of car­ni­vores and their impacts on the world today the sci­en­tists reviewed over 100 pub­lished stud­ies on the matter.

South­east Asia, south­ern and East Africa and the Ama­zon are among areas in which mul­ti­ple large car­ni­vore species are declin­ing. With some excep­tions, large car­ni­vores have already been exter­mi­nated from much of the devel­oped world, includ­ing West­ern Europe and the east­ern United States. Many of the largest car­ni­vores are listed as threat­ened on the Inter­na­tional Union for the Con­ser­va­tion of Nature (IUCN) Red List, and most are still declin­ing in num­ber. These ‘top or apex preda­tors’ have one great com­peti­tor: humans.

Glob­ally, we are los­ing our large car­ni­vores, many of them are endangered
William Rip­ple, lead author, pro­fes­sor in the Depart­ment of For­est Ecosys­tems and Soci­ety, Ore­gon State University »

“Their ranges are col­laps­ing. Many of these ani­mals are at risk of extinc­tion, either locally or glob­ally. And, iron­i­cally, they are van­ish­ing just as we are learn­ing about their impor­tant eco­log­i­cal effects,” Rip­ple said.

Bill Rip­ple explain­ing the impor­tance of preda­tors in nature:

Large car­ni­vores are vul­ner­a­ble to extinc­tion because of their low pop­u­la­tion den­si­ties and their need to roam widely to search for food. These ani­mals are essen­tial to the health of an ecosys­tem and also pro­vide social and eco­nomic ben­e­fits for humans.

Rip­ple and col­leagues from the United States, Aus­tralia, Italy and Swe­den called for an inter­na­tional ini­tia­tive to con­serve large preda­tors in coex­is­tence with peo­ple. They sug­gested that such an effort be mod­elled on the Large Car­ni­vore Ini­tia­tive for Europe, a non­profit sci­en­tific group affil­i­ated with the Inter­na­tional Union for the Con­ser­va­tion of Nature.

The researchers reviewed pub­lished sci­en­tific reports and sin­gled out seven species that have been stud­ied for their wide­spread eco­log­i­cal effects or trophic cas­cades.” This includes African lions, leop­ards, Eurasian lynx, cougars, gray wolves, sea otters and dingoes.

Rip­ple and his Ore­gon State co-​author Robert Beschta have doc­u­mented impacts of cougars and wolves on the regen­er­a­tion of for­est stands and ripar­ian veg­e­ta­tion in Yel­low­stone and other national parks in North Amer­ica. Fewer preda­tors, they have found, lead to an increase in brows­ing ani­mals such as deer and elk. More brows­ing dis­rupts veg­e­ta­tion, shifts birds and small mam­mals and changes other parts of the ecosys­tem in a wide­spread cas­cade of impacts.

Stud­ies of Eurasian lynx, din­goes, lions and sea otters have found sim­i­lar effects, the authors reported. Lynx have been closely tied to the abun­dance of roe deer, red fox and hare. In Aus­tralia, the con­struc­tion of a 3,400-mile dingo-​proof fence has enabled sci­en­tists to study ecosys­tems with and with­out the ani­mals, which are closely related to grey wolves. In some parts of Africa, the decrease of lions and leop­ards has coin­cided with a dra­matic increase in olive baboons, which threaten farm crops and live­stock. In the waters off south­east Alaska, a decline in sea otters through killer whale pre­da­tion has led to a rise in sea urchins and loss of kelp beds.

The authors call for a deeper under­stand­ing of the impact of large car­ni­vores on ecosys­tems, a view that they trace back to the work of land­mark ecol­o­gist Aldo Leopold. The clas­sic con­cept that preda­tors are harm­ful and deplete fish and wildlife is out­dated, they said. Sci­en­tists and wildlife man­agers need to recog­nise a grow­ing body of evi­dence for the com­plex roles that car­ni­vores play in ecosys­tems and for their social and eco­nomic benefits.

Leopold recog­nised such rela­tion­ships between preda­tors and ecosys­tems, Rip­ple said, but his obser­va­tions on that point were largely ignored for decades after his death in 1948.

Lords of Nature
Top preda­tors may hold a key to life itself. Can peo­ple and preda­tors coex­ist? Can we afford not to?
Birds, but­ter­flies, beaver and ante­lope, wild­flow­ers and frogs — could their sur­vival pos­si­bly be con­nected to top preda­tors like the wolf and cougar? Nar­rated by Peter Coy­ote, Green Fire Pro­duc­tions has cre­ated a cap­ti­vat­ing doc­u­men­tary (58 min) that goes behind the scenes with lead­ing sci­en­tists to explore the role top preda­tors play in restor­ing and main­tain­ing ecosys­tems and biodiversity.

“Human tol­er­ance of these species is a major issue for con­ser­va­tion,” Rip­ple said. “We say these ani­mals have an intrin­sic right to exist, but they are also pro­vid­ing eco­nomic and eco­log­i­cal ser­vices that peo­ple value.” Among the ser­vices that have been doc­u­mented in other stud­ies are car­bon seques­tra­tion, ripar­ian restora­tion, bio­di­ver­sity and dis­ease control.

Where large car­ni­vores have been restored — such as wolves in Yel­low­stone or Eurasian lynx in Fin­land — ecosys­tems have responded quickly, said Rip­ple. “I am impressed with how resilient the Yel­low­stone ecosys­tem is. It isn’t hap­pen­ing quickly every­where, but in some places, ecosys­tem restora­tion has started there.” In those cases, where loss of veg­e­ta­tion has led to soil ero­sion, how­ever, full restora­tion in the near term may not be pos­si­ble, he said.

“Nature is highly inter­con­nected,” said Rip­ple. “The work at Yel­low­stone and other places shows how one species affects another and another through dif­fer­ent path­ways. It’s hum­bling as a sci­en­tist to see the inter­con­nect­ed­ness of nature.”

And Wildlife Con­ser­va­tion Soci­ety Exec­u­tive Vice Pres­i­dent of Con­ser­va­tion and Sci­ence John Robin­son said,

This impor­tant paper explores how car­ni­vores reg­u­late the struc­ture and func­tion­ing of ecosys­tems and what hap­pens when they are lost. For many peo­ple, it will be an eye-​opener and hope­fully bring about a change in atti­tudes and a deeper appre­ci­a­tion of these key species

For more won­der, rewild the world
Watch the TEDTalk (15 min) of George Mon­biot and learn how he, in a bold thought exper­i­ment, imag­ines a wilder world in which humans work to restore the com­plex, lost nat­ural food chains that once sur­rounded us.

(Source: Ore­gon State Uni­ver­sity news release, 09.01.2014; Wildlife Con­ser­va­tion Soci­ety press release, 09.01.2014; Uni­ver­sity of Mon­tana news, 09.01.2014)

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Tiger map” (CC BY 2.5) by Sander­son et al., 2006.

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