Denali’s microwilderness: the arthropods behind the bears and how they are cataloged

Denali is known for grizzly bears, moose and wolves, but arthropod species make up more than 90 percent of its wildlife. National Park Service entomologist Jessica Rykken wrote about the park's invertebrates, and this page paraphrases the article. Hidden in the shrubs, trees, wildflowers, gravel bars, alpine tundra and snow patches, the article says, is a diverse multitude of creatures, many of them not yet discovered. They pollinate, decompose, scavenge, eat plants, hunt and serve as prey.

Grizzly bears gorge on blueberries pollinated by bumble bees. NPS Photo / Jacob W. Frank.

Why small animals matter

A single species or group can have large effects. Outbreaks of spruce bark beetle can kill vast swaths of spruce in the boreal forest, with long-term consequences for the forest's other inhabitants. Blueberries, an iconic plant in the park, rely on bumble bees for most of their pollination, and Denali grizzlies feed on blueberries in the fall to fatten up for hibernation, so the bees matter to the bears.

At outbreak levels, bark beetles can kill millions of acres of trees. U.S. Fish & Wildlife Service.

What the surveys have found

Denali has documented its arthropods through several projects. A major one, with entomologists and students from the University of Alaska Fairbanks, sampled beetles, spiders, bees and flower flies along an elevation gradient, in low spruce forest, mid-elevation shrubs and high tundra. Each habitat had a distinctive group of species. Five of the park's 17 bumble bee species occur almost exclusively in alpine tundra, true Arctic and high-elevation species adapted to harsh climates, while forest specialists include rove beetles and dwarf spiders that hunt insects in logs and moss. As climate change moves trees and shrubs upslope, the author asks whether the specialists will follow, and whether tundra species will decline with nothing but rock and ice above them.

Prickly rose attracts a variety of flies, including flower flies and muscoid flies. NPS Photo / J. Rykken.

Another project looked at the pollinators visiting common plants in Denali and seven other Alaskan parks, including fireweed, invasive dandelions and prickly rose. A surprisingly high diversity of insects came, among them bees, wasps, butterflies, beetles, true bugs, thrips and springtails, and flies are extremely diverse and abundant pollinators at northern latitudes. It also tracked the timing of leaf-out, flowering and fruiting, to learn how earlier spring thaw affects plants and pollinators.

A century of collecting

Recent projects are documenting hundreds of arthropod species in the park for the first time, but insect collecting there goes back nearly a century. In 1924 H.C. Fall discovered a minute brown scavenger beetle, Corticaria arctophila, which feeds on microfungi. Almost one hundred years later the team collected a single individual in a shrubby thicket at mid-elevation on Mount Healy, the first documented sighting since the discovery.

Most of the specimens collected are kept at the University of Alaska Museum Entomology Collections in Fairbanks, whose insect cabinets can hold millions of specimens. The many thousand Denali specimens there give information on the distribution, habitat preferences and host plants of Alaskan arthropods. After the park's species database, NPSpecies, was updated with all the museum's records, the list reached almost 800 invertebrate species, 791 to be exact, against 199 terrestrial vertebrate species, which are mammals, birds and one frog. Spiders and beetles make up more than half of the invertebrates, and flies, wasps, bees and butterflies most of the rest. There are many more discoveries to be made, the article says.

Sources

• National Park Service, Denali National Park & Preserve, Exploring & Cataloging Denali's Microwilderness, by Jessica Rykken, entomologist; two photographs credited to individuals outside the Service are left out; rewritten in hubnx's own words.