3 wolves left at Isle Royale: sci­en­tists

The China Post - - LIFE - BY JOHN FLESHER

The gray wolves of Isle Royale Na­tional Park, which sci­en­tists have stud­ied closely for more than half a cen­tury along with the moose on which they feed, are on the verge of dis­ap­pear­ing as the most re­cent cen­sus showed that only three re­main, sci­en­tists said Fri­day.

In­breed­ing and ill­ness ap­pear to have caused a sharp drop-off in wolf num­bers on the Lake Su­pe­rior is­land wilder­ness, where vis­i­tors thrill at hear­ing their qua­ver­ing howls. The count stood at 24 in 2009 but has fallen ev­ery year since, ac­cord­ing to Michi­gan Tech­no­log­i­cal Uni­ver­sity re­searchers who lead what they de­scribe as the world’s long­est-run­ning study of a preda­tor-prey re­la­tion­ship in a closed ecosys­tem.

They have urged the Na­tional Park Ser­vice to bring more wolves to the is­land to rein­vig­o­rate the gene pool. But it may be too late to res­cue the cur­rent pop­u­la­tion, which likely con­sists of one mat­ing pair and a pup — all heav­ily in­bred, bi­ol­o­gist John Vucetich said.

“Th­ese are the last dy­ing gasps,” he said.

Sci­en­tists have held out hope that the wolves, whose num­bers stood at nine a year ago, would re­bound. But fed­eral of­fi­cials prob­a­bly will have to choose be­tween start­ing over with a new group or leav­ing the park with­out a top preda­tor, Vucetich said. In that case, the moose pop­u­la­tion — al­ready 1,250 and climb­ing — could get so high that trees will suf­fer as that much more fo­liage gets eaten, he said.

“One thing we know with great cer­tainty is that wher­ever there are large her­bi­vores like moose, elk or deer you have to have a top preda- tor to main­tain ecosys­tem health,” Vucetich said.

Moose made their way to Isle Royale around the turn of the 20th cen­tury, pos­si­bly by swim­ming from main­land Canada or Min­nesota, roughly 15 miles away. The first wolves crossed an ice bridge in the late 1940s.

As wolf num­bers grew, moose pro­vided a steady diet. Wolves kept their prey species from over­pop­u­lat­ing.

The wolf pop­u­la­tion has av­er­aged a cou­ple dozen. Sci­en­tists say new­com­ers ar­rived at least twice dur­ing icy win­ters, breed­ing with ex­ist­ing wolves.

But ice bridges have be­come less com­mon, although they formed dur­ing the past two win­ters. A pair of wolves wan­dered over from Canada in Fe­bru­ary but didn’t stay.

Mean­while, six is­land wolves dis­ap­peared in the past year. One, fit­ted with a ra­dio col­lar, is known to have died, bi­ol­o­gist Rolf Peter­son said. The oth­ers ei­ther died or mi­grated to the main­land.

So few wolves re­main that they no longer even limit the moose pop­u­la­tion, Peter­son said. Dur­ing their an­nual win­ter study on the is­land, he and Vucetich ob­served just one moose kill. They usu­ally spot 20 to 30.

Park Su­per­in­ten­dent Phyl­lis Green an­nounced last year that of­fi­cials would not in­ter­vene as long as a breed­ing wolf pop­u­la­tion re­mains. She said Fri­day the park ser­vice soon will in­vite public par­tic­i­pa­tion in a study of op­tions for wolf, moose and veg­e­ta­tion man­age­ment.

The agency prefers let­ting na­ture take its course but ac­knowl­edges that hu­mans have left a big foot­print on the is­land en­vi­ron­ment, Green said. Wolves have fallen down mine shafts and died from par­vovirus spread by pet dogs. Cli­mate change also could make fu­ture ice bridges rare.

“We’re go­ing to do the best job we can to man­age for the kinds of changes we ex­pect to hap­pen,” Green said.

AP

This photo re­leased by Michi­gan Tech­no­log­i­cal Uni­ver­sity taken on Feb. 15 shows the last three wolves known to live in Isle Royale Na­tional Park at Lake Su­pe­rior.

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