Branch of­fice

The species’ re­mark­able abil­ity to adapt is epit­o­mized by a lone bird hard at work – and prey – at City Park. A come­back is tak­ing flight.

The Denver Post - - FRONT PAGE - By Bruce Fin­ley

A bald eagle is us­ing cen­tral Den­ver as a hunt­ing ground, scan­ning from perches over City Park lakes for fish, ducks and small geese – ev­i­dence of re­silience in ea­gles’ strug­gle to come back from the brink of ex­tinc­tion. But com­pared with wild prairie, this 330-acre park pro­vides mar­ginal habi­tat: loud en­gines and the beeps of park-crew ve­hi­cles back­ing up, the Den­ver Zoo com­plex con­struc­tion, dog-walk­ers cir­cling frozen shores and talk­ing into smart­phones, and the 82-deci­bel or­ange robot “Goosi­na­tor” to haze geese.

The eagle in City Park shows bald ea­gles’ re­mark­able abil­ity to adapt, said Kevin Kritz, a fed­eral bi­ol­o­gist mon­i­tor­ing rap­tors and ea­gles for the Di­vi­sion of Mi­gra­tory Bird Man­age­ment.

“Bald ea­gles are a species that has proved to be a lot more flex­i­ble in their nest­ing and habi­tat than we ever thought pos­si­ble, and bald eagle pop­u­la­tions are ex­pand­ing,” Kritz said. “Some bald eagle pairs are able to come into cities and make a liv­ing.”

The na­tion­wide bald eagle pop­u­la­tion — once threat­ened by the DDT pes­ti­cide, re­quir­ing En­dan­gered Species Act pro­tec­tion un­til 2007 — has grown to an es­ti­mated 143,000. That num­ber in­creased be­tween 2003 and 2013 by an av­er­age 12 per­cent a year, fed­eral of­fi­cials say.

How­ever, bald ea­gles’ less-adap­tive cousin, the golden eagle, re­mains in often-com­pro­mised ru­ral habi­tat. Golden ea­gles’ pop­u­la­tion has stayed flat around 40,000 (31,000 in the western United States).

The num­ber of ea­gles in Colorado is un­cer­tain. Colorado Parks and Wildlife of­fi­cials say they no longer es­ti­mate golden and bald eagle pop­u­la­tions. A re­cent fed­eral re­port says bald eagle nests in the state in­creased from 51 in 2009 to more than 125 nests in 2015. Golden eagle data is lim­ited.

“While the U.S. Fish and Wildlife Ser­vice re­mains cau­tious con­cern­ing golden eagle pop­u­la­tions, the con­tin­ued in­crease in bald eagle num­bers is a great suc­cess story,” agency spokesman Steve Se­gin said.

Last year, a fully grown fe­male bald eagle landed near Longmont on power lines

and was elec­tro­cuted while her young were still in a nest, ac­cord­ing to Brian Smith, the USFWS re­gional chief of mi­gra­tory bird man­age­ment. But an­other adult fe­male paired up with the male, adopted the young ea­gles and raised them to where they could fly and hunt.

There’s com­pe­ti­tion all around for de­cent habi­tat for nest­ing and hunt­ing. In­side metro Den­ver, de­vel­op­ers’ push for denser de­vel­op­ment — blocks of con­do­mini­ums and apart­ments — com­bined with rapid hu­man pop­u­la­tion growth strains the ex­ist­ing open space. In once-quiet ru­ral Colorado, a boom in oil, gas and wind en­ergy pro­duc­tion edges out ea­gles and other wildlife.

Bal­anc­ing the en­ergy de­vel­op­ment with bird con­ser­va­tion has be­come a bat­tle, es­pe­cially with record­fast in­stal­la­tion of wind tur­bines that man­gle and kill hun­dreds of ea­gles a year in the 170 mph whirling blades. While not en­dan­gered, golden and bald ea­gles are pro­tected un­der the Mi­gra­tory Bird Treaty Act and the Bald and Golden Eagle Pro­tec­tion Act, which pro­hibit killing ea­gles with- out a per­mit.

Fed­eral wildlife reg­u­la­tors are hon­ing their ap­proach. The feds say they will ne­go­ti­ate per­mits in ad­vance, spec­i­fy­ing lim­its on how many ea­gles can be killed over 30 years – “in­ci­den­tal take” — at en­ergy in­dus­trial sites. Fish and Wildlife Ser­vice of­fi­cials told The Den­ver Post that 4,200 bald ea­gles a year could be killed with­out harm to the species.

“What we’re try­ing to do is man­age the on­go­ing take, and make that le­gal, and then get con­ser­va­tion ben­e­fits in re­turn,” said Kritz, who is help­ing to ne­go­ti­ate a per­mit for the pro­posed $5 bil­lion Chokecherry and Sierra Madre Wind Project near Rawl­ins, Wyo.

The idea is that com­pa­nies run­ning wind, high­way, oil and gas, and other projects that cause harm to ea­gles, for which they re­ceive “take” per­mits to cover ac­ci­den­tal killings, “will have to do things: con­ser­va­tion mea­sures, sur­veys, things that pro­duce con­ser­va­tion ben­e­fits for the species,” Kritz said. “With a per­mit­ting sys­tem, you have a chance to be proac­tive.”

The Cokecherry wind project in Wy­oming ini­tially would de­ploy 500 wind tur­bines, project doc­u­ments show. A per­mit cov­er­ing five years hasn’t been is­sued yet pend­ing dis­cus­sions over is­sues such as the size of tur­bine blades (big­ger blades kill and maim more ea­gles). Fed­eral reg­u­la­tors es­ti­mate the Cokecherry wind farm tur­bines would kill one or two bald ea­gles and 10 to 14 gold­ens a year.

Yet it’s un­clear ex­actly how dis­rup­tions of tra­di­tional eagle habi­tat may be re­lated to the rise of ea­gles adapt­ing to liv­ing in cities. Most ea­gles in Den­ver parks prove to be short­time vis­i­tors. The one in City Park this month was alone. Parks staffers say ea­gles have not made nests in City Park. Lone ea­gles have hunted there since 2012.

City of­fi­cials re­gard the sit­u­a­tion as frag­ile, urg­ing a hands-off ap­proach to min­i­mize ur­ban dis­tur­bances.

“Some peo­ple find it sur­pris­ing that wildlife can be found in and around the ur­ban ar­eas of Colorado’s fast­grow­ing Front Range,” Parks and Recre­ation ad­min­is­tra­tor Vicki Var­gasMadrid wrote in an e-mail. “As our state con­tin­ues to be­come more pop­u­lated, more wildlife species are be­ing dis­placed and forced out of their nat­u­ral habi­tat, re­sult­ing in them hav­ing to adapt to our way of life, in an ur­ban set­ting. Cer­tain species of wildlife, of course, are more re­silient than oth­ers.”

Joe Amon, The Den­ver Post

A bald eagle keeps a watch­ful eye on a brave mag­pie at Den­ver’s City Park on Wed­nes­day. The na­tion­wide bald eagle pop­u­la­tion – once threat­ened by the DDT pes­ti­cide – has grown to an es­ti­mated 143,000.

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