Moose Pop­u­la­tion Has Swelled At Rocky Moun­tain Na­tional Park


COLORADO SPRINGS, Colo. — The Holzwarth His­toric Site in the Kawuneeche Val­ley on the west side of Rocky Moun­tain Na­tional Park is un­usu­ally quiet for a mid-Au­gust night. At the height of sum­mer tourist sea­son, the park at­tracts hordes of visi­tors — more than 4 mil­lion in 2017. But the only noises are the flutter of the wind pass­ing through the leaves of the as­pens, the crunch of the gravel un­der de­lib­er­ate foot­steps and the oc­ca­sional muted mur­mur of a park em­ployee’s ra­dio.

Si­lence was what land­scape ecol­o­gist Hanem Abouelezz needed as she peered through a stand of as­pens at a 4-year-old fe­male moose feed­ing on a bounty of wil­low trees in the marshy area just south of the his­toric site’s build­ings.

If all went well, Abouelezz would shoot the moose with a dart con­tain­ing slow-re­lease anes­the­sia. The moose would slowly fade into a light slum­ber as a team of bi­o­log­i­cal tech­ni­cians em­ployed by the Na­tional Park Ser­vice took blood sam­ples, mea­sured heart rate, checked for ticks and per­formed a rec­tal biopsy.

About an hour after Abouelezz re­leased the dart, she would in­ject the moose with a rev­er­sal drug. The cow will grad­u­ally awaken, stand up and re­turn to her night of munch­ing, sleep­ing and roam­ing.

Yet, if a crunch be­came a crack or a mur­mur be­came shout, this moose might head for the hills. Abouelezz and her team would leave emp­ty­handed, with­out the per­fect can­di­date for her study, the first of its kind in­volv­ing moose, but with im­pli­ca­tions that could im­pact the health of ri­par­ian ar­eas through­out the park.

In 1980, only one moose was re­ported in the Kawuneeche Val­ley. In 2017, the park re­ported 30 to 50 on the west side and an in­creas­ing num­ber on the east side. They’ve been sighted in ev­ery drainage, lead­ing park sci­en­tists to ask what types of changes were driv­ing such pop­u­la­tion growth and what the long-term ef­fects would be.

Last sum­mer, a re­search team led by Abouelezz trans­formed their ques­tion into an ex­per­i­ment with the goal of fit­ting up to 40 moose — 20 on the west side and 20 in the north­east side — with col­lars ad­justed to each an­i­mal’s neck. The GPS col­lars al­low them to col­lect data on moose pop­u­la­tion size, pop­u­la­tion growth, car­ry­ing ca­pac­ity and habi­tat use. The moose are also mon­i­tored for chronic wast­ing disease, which has af­flicted elk in the park, but not yet moose, as well as other base­line health.

Though park sci­en­tists have col­lared elk in the past, this is the first time the track­ers have been fit­ted to moose.

Thus far, the col­lars have not left no­tice­able rubs or marks and don’t ap­pear to be in­ter­fer­ing with the moose’s daily ac­tiv­i­ties. The hour un­der anes­the­sia, also, has had lit­tle if any im­pact on the moose.

“We do what we can to make the moose as com­fort­able as pos­si­ble,” Abouelezz said. “When we’re tak­ing the sam­ples, we make sure it’s spine is in align­ment, blind­fold it so it has no aware­ness of hu­man con­tact and, just in case, hook it up to an oxy­gen tank.”

In iso­la­tion, an uptick in the moose pop­u­la­tion isn’t a prob­lem. But moose don’t live in a vacuum, just like ev­ery other or­gan­ism in the park, in­clud­ing the hu­mans that visit it.

More moose means more mouths to feed. That means more stress on wil­low trees, which are 93 per­cent of a moose’s 55-pound-a-day diet in Rocky Moun­tain Na­tional Park. Again, in iso­la­tion, this might not have caused much con­cern, the team said, since wil­lows evolved with browsers like moose, adapt­ing to their feed­ing habits to find ways to re­grow once their leaves were chomped off, said John Mack, the branch chief of nat­u­ral re­sources for the park.

Add disease, specif­i­cally Cy­tospora fungi which is car­ried by birds, and the equi­lib­rium of the ecosys­tem is no­tice­ably dis­rupted. Sud­denly, cer­tain ar­eas that used to be pop­u­lated with a dense mass of tall wil­low trees are mead­ows stud­ded with stumpy wil­low bushes. Their branches, which are now only about 3 to 4 feet long, are naked and dy­ing, even though their core still tries to pro­duce leaves at the base.

With­out griz­zly bears and wolves — pri­mary preda­tors of moose — the wil­lows have few de­fenses.

“The in­fec­tion it­self is not out of the or­di­nary, but it kills the leaves at the per­fect level for browsers, which moose are, and we have a lot of it cur­rently,” Abouelezz said.

Wil­lows serve as soil sta­bi­liz­ers in ri­par­ian zones, which serve as the in­ter­face be­tween land and a river or stream and are crit­i­cal to water­shed health, wildlife habi­tat and over­all ecosys­tem health. With­out such veg­e­ta­tion, the ri­par­ian zone can wash away, im­pact­ing the aquatic and ter­res­trial land­scape.

“Once you see the whole ecosys­tem starts to suf­fer, the red flags go up,” Mack said, prob­ing the empty branches atop a wil­low.

Ear­lier in the night, about 5 p.m., a sec­tion of Trail Ridge Road just west of the Bowen Brown Trail­head was in what park em­ploy­ees like to call “an an­i­mal jam.”

A visi­tor with an eye at­tuned to wildlife had spot­ted a moose about a quar­ter mile off the road and pulled over for a closer look.

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