Fall Leaves and Winter Queens
By: U.S.Fish Wildlife Alaska
Tags: Alaska, Conservation, Garden, Winter, Pollinators

Pollinators (the creatures that carry pollen from flower to flower, allowing plants to reproduce) come in all shapes and sizes. They use many different strategies to survive Alaska’s cold, harsh winters.

HUMMINGBIRDS

A female rufous hummingbird 📷 USFWS/Peter Pearsall

Some pollinators just aren’t built to survive Alaska’s winter… so they get out of town. Fast.

Each year, Alaska’s fast and furious rufous hummingbirds leave the state at the end of peak flower season. The males leave first, heading south on the Rocky Mountain flyway where alpine flowers are still in bloom. Females and juvenile hummingbirds follow soon after.

Not all pollinators are capable of leaving the state. Some tough it out all winter long.

BUTTERFLIES

Did you know Alaska’s various butterfly species overwinter in all the different phases of their lifecycle? A quick refresher: Butterflies grow from an egg, into a larva (caterpillar), a chrysalis (hard-shelled pupa), and finally to a four-winged fluttery butterfly.

Alaskan blue butterfly. 📷 BLM/Luise Woelflein

The small, charismatic Alaskan blue (Plebejus idas alaskensis) winters as an egg on a variety of plants such as Labrador tea and lupine. When the weather warms in the spring, it undergoes the metamorphosis to become a butterfly. Though guidebooks describe the Alaskan blue as “not a particularly strong flier,” it is widespread across the state.

Fritillary butterfly. 📷 USFWS/Kristine Sowl

Fritillary species (Boloria spp.) are found across Alaska and share the common trait of hibernating as larvae. Some are known to use flower species such as violets and dryas as winter hosts, while others use willows.

Canadian tiger swallowtail. 📷 USFWS/Sabrina Farmer

Canadian tiger swallowtails (Papilio canadensis) inhabit the boreal forest and spend the long winter months as chrysalises in trees including aspen, ash, and willow.

A mourning cloak butterfly basks in the sun after the long winter. 📷 USFWS/Sabrina Farmer

Mourning cloaks (Nymphalis antiopa) survive winter as adult butterflies nestled in willows across much of the state. They are some of the earliest butterflies seen each year, ready to fly in the warm spring sun.

BEES

Alaska’s 100 bees use different strategies to survive the winter months.

Bumble bees

Bumble bees (Bombus spp.) are social bees native to North America with a similar life-history to the European honeybee. Queens lay eggs and establish colonies in spring, often in abandoned rodent burrows.

A foraging bumble bee. 📷 Derek Sikes

The worker bees of these colonies forage on the pollen and nectar of Alaska’s diverse summer flowers. As summer wanes, male drones and a new generation of queens are born. These queens mate as summer fades to fall and eat to build up their nutrient reserves for the long, solo winter ahead.

Bumble bee queens are the only colony members to survive through the long Alaskan winter. In the fall, they find locations to burrow into the ground and enter a deep hibernation. This is the part of the bee’s life cycle that scientists know the least about, but the survival of these overwintering queens is essential for the success of future bee populations.

A bumble bee queen crawls out of her nest. 📷 Siaron James

Solitary bees

The vast majority of North America’s bee species are solitary and in Alaska they represent about 80% of the diversity of species. There are many types of solitary bees, which means there are various strategies for surviving winter.

Female Clark’s miner bees excavating nests. 📷 Matthew Carlson

Some species of solitary bees, such as Clark’s miner bee (Andrena clarkella), overwinter as adults. This allows them to emerge early in spring to take advantage of Alaska’s short growing season. Other species overwinter in a larval stage and emerge later in the summer after pupating. Solitary bees are generally active for two to three weeks and provide food to support only a dozen or so offspring. Female solitary bees defend their nests from intruders and feed offspring by themselves.

A solitary bee emerging from a ground nest. 📷 Nigel Jones

Adult bees must select a place to spend the winter. Solitary bees fall into two general nesting categories: ground nesters and cavity nesters. Ground nesting bees burrow into the soil to stay warm in the winter months. Cavity nesters use dead stems, hollow wood, or piles of brush to nest.

FLOWER FLIES

A pollen covered flower fly. 📷 Judy Gallagher

Remember Alaska’s Wannabees? Like butterflies and solitary bees, flower flies can overwinter in different life stages. In general, there are two strategies: Survive as larvae or as adults.

Hibernating adults find cubby holes in old trees, fallen logs, or piles of rocks. Species that survive winter as adults will be some of the first flies you see each spring. Larvae survive winter by hiding in the soil, preparing for the long-awaited warm season where they will feed, pupate, and emerge as adults.

Alaska’s various pollinators each have specific needs but they all require high-quality habitat to thrive. As you embark on the process of preparing your space for winter, keep pollinators in mind: