Exploring & Cataloging Denali's Microwilderness

By Jessica Rykken, Entomologist

This colorful ground beetle lives up in the tundra

Ryan O’Donnell CC BY-NC-ND

Grizzly bears gorge on blueberries pollinated by bumble bees

NPS Photo / Jacob W. Frank

While most visitors don’t come to Denali to see bumble bees or spiders, arthropod species make up more than 90% of wildlife in the park. Grizzly bears, moose, and wolves may get the attention of bus travelers on the park road, but hidden from view in the shrubs, trees, wildflowers, gravel bars, alpine tundra, and snow patches are an amazingly diverse multitude of invertebrate creatures, many of which have yet to be discovered.Not only are arthropods far more diverse than vertebrates, they also provide essential services to Denali’s ecosystems, as pollinators, decomposers, scavengers, herbivores, predators, and prey.

A single species, or group of species, can have significant impacts on an ecosystem. For example, spruce bark beetle outbreaks can kill off vast swaths of spruce trees in the boreal forest, with long term consequences for many forest inhabitants. Another iconic plant in the park, blueberry, relies on bumble bees for most of its pollination. Denali grizzly bears feast on blueberries in the fall to fatten up for their long winter hibernation, so bumble bees are critical for the survival of hungry bears (and humans!).

A dwarf spider in the genus Ceraticelus

Solomon Hendrix  CC By-NC

Prickly rose attracts a variety of flies, including these flower flies and muscoid flies.

NPS Photo / J. Rykken

Denali has taken on the challenge of documenting arthropod wildlife through a number of projects over the last several years. One of the biggest efforts has been a collaborative study with entomologists and students from the University of Alaska Fairbanks, documenting arthropods along elevation gradients in the park. Beetles, spiders, bees, and flower flies were sampled in low elevation spruce forests, mid-elevation shrubs, and high elevation tundra. Each of the habitats had a distinctive group of species that was different from the other two.

For example, five species of bumble bees (out of 17 species in the park) occur almost exclusively in alpine tundra. This group of bees are true Arctic and high elevation species, well-adapted to the harsh climate of these extreme environments. Forest specialists include several rove beetles and dwarf spiders that prey on insects in logs and moss. As climate change causes trees and shrubs to move upslope in Denali, will these arthropod specialists follow their shifting habitats up the mountain? Will tundra specialists decline in number as shrubs encroach into their habitat from below and there is nothing but rock and ice above? These are the kinds of questions we hope to answer in the future.

Frank Morand with his butterfly net and park ranger Lee Swisher

Swisher family collection No. 33. Courtesy of the Swisher family and used with permission

The lively clouded sulphur was first collected in Denali by Frank Morand in 1930.

Nick Block CC BY

Another recent project looked at the pollinator diversity associated with several common plants in Denali (and seven other Alaskan parks), including fireweed, invasive dandelions, and prickly rose. A surprisingly high diversity of insects were recorded visiting the different plant species, including bees, wasps, butterflies, beetles, true bugs, thrips, and springtails. Flies, in particular, are extremely diverse and abundant pollinators at northern latitudes. This project also tracked the phenology (timing of seasonal life cycle events like leaf out, flowering, and fruit production) of the host plants. As a warming climate brings earlier spring thaw to Alaska, how will this change affect both plant and pollinator phenology?

Although our recent projects are documenting hundreds of new arthropod species in Denali for the first time, the history of insect collecting and discovery in the park goes back nearly a century. For example, Frank Morand collected some of the first known specimens of the lively clouded sulphur butterfly (Colias philodice vitabunda) in Denali in 1930. In 1924, H.C. Fall discovered a new species of minute brown scavenger beetle (Corticaria arctophila) in the park. These tiny beetles feed on microfungi. Almost one hundred years later, we collected a single individual of this beetle in a shrubby thicket at mid-elevations on Mount Healy, the first time it had been documented since the original discovery!

Tiny pseudoscorpions (several could fit on your fingertip) are found on the underside of rocks next to creeks and rivers. This female is carrying her eggs while they develop.

Adam Haberski

Alex Wenninger CC BY-NC

Tiny spruce bark beetles can have a huge impact on boreal forests

The majority of the arthropods we’ve collected in Denali are stored at the University of Alaska Museum Entomology Collections in Fairbanks. The museum insect cabinets have space to hold millions of specimens, and the many thousand insect specimens from Denali contribute valuable information about the distribution, habitat preferences, and host plant associations of Alaskan arthropods.

Recently, we updated the National Park Service species database (NPSpecies) with all the records stored in the museum, resulting in an impressive list of almost 800 invertebrate species known from Denali! In comparison, only 199 terrestrial vertebrate species (mammals, birds, and one frog) are listed for the park. Among the 791 invertebrates, spiders and beetles made up more than half the species; flies, wasps, bees, and butterflies composed most of the remainder.

While Denali sets a great example among national parks in exploring and documenting its microwilderness, one thing is for certain: there are many, many more discoveries to be made!

At outbreak population levels, bark beetles can kill millions of acres of trees

U.S. Fish & Wildlife Service