If you read the news in Colorado, you could be forgiven for thinking that the
state was being invaded by moose. In recent years, dozens of news articles
have chronicled expanding moose populations in the Southern Rockies.
Most assert that moose are non-native, with local history beginning when
they were transferred by the Colorado Division of Wildlife in the late 1970s.

In December, Rocky Mountain National Park initiated a public comment
period for its National Environmental Policy Act application to begin
addressing high moose populations within the park, sparking a new blitz of
news coverage on moose. One article published this month included
interviews with RMNP staff and claimed “before the Colorado Division of
Wildlife introduced moose into the state in 1978, it was rare to see the
species. Moose would occasionally wander into Colorado from Wyoming,
but there were no sustained populations.”

This bold and oft-repeated assertion is not supported by evidence. As
scientists who study ancient animal populations, we believe such claims
demand rigorous scrutiny before they drive policy decisions that might be
hard to undo. Last fall, we conducted a review of historical records and
found dozens of moose encounters documented in diaries, newspapers, and
photographs. These records confirm moose have lived in Colorado as far
back as written records go. RMNP has now revised some of their public
messaging, suggesting that moose were rare rather than totally absent.
But this is still a misinterpretation of the historic record. Before systematic
wildlife surveys, written accounts only occasionally captured encounters
with solitary, backcountry animals like moose – making them an unreliable
measure of actual populations. Our visit to the archives of former CDW
biologist Dick Denney revealed that state wildlife officials clearly
understood the 1978 translocations as reintroductions. And importantly, the
archives highlight the patchiness of the written record—Denney himself
recorded many verbal-only accounts of moose in the decades before
reintroduction.

Looking at records from across the Rockies (Montana, Idaho, Wyoming, and
Utah), we found that in each state, there was a scattered historic record of
moose before the mid-20th century, and confusion about the presence,
absence, or abundance of moose in earlier times. After our investigation,
Colorado now boasts among the largest tallies of early moose records west
of the Mississippi. These records unequivocally document reproductively
active, locally-residing moose, including cows, calves, and bulls.
Although the written records don’t extend much beyond the mid-19th
century, it is not clear how far back this history might go. Moose form an
important part of the stories and traditions of Colorado’s Native cultures,
and published identifications of moose appear in the state’s archaeological
record, from the ruins of Mesa Verde to the Paleoindian period thousands of
years ago.

As Colorado faces drought, climate change, and a host of difficult
challenges today, the expansion of moose populations in RMNP, and their
impact on the area’s willow and beaver habitat, is a real ecological problem
that deserves attention, and perhaps intervention. But the park’s framing—
that the problem is a moose invasion—is not supported by scientific
evidence. Large herbivores, willows, and beavers coexisted across North
America for millennia, because predation, disease, fire, floods, and human
hunting gave browsed areas time to recover. Park Service policies have
historically suppressed many of these forces, subjecting unfenced willow
stands to constant browsing pressure. But elsewhere in Colorado, moose
populations are being effectively managed by Colorado Parks and Wildlife
through hunting, with most growth occurring through range expansion, not
overpopulation.

Management choices available to the park range from culling and
extermination to cooperative partnerships with state wildlife officials and
Tribes. In Olympic National Park, a similarly questionable designation of
mountain goats as non-native has led to decades of helicopter-based
removal. Whatever Rocky Mountain National Park decides for the local
moose population, it is important that we get the facts straight: moose have
been in Colorado for centuries.

William Taylor is an archaeozoologist and Assistant Professor/Curator at
the University of Colorado Museum of Natural History. John Wendt is a paleoecologist and Assistant Professor of Rangeland
Ecosystem Management at New Mexico State University