Migratory Pollinators & How to Help
Three groups of pollinators travel astonishing distances across the Americas each year. Here's how they migrate, what threatens them, and what you can actually do about it.
Monarch Butterfly
Monarchs are the best-known migratory pollinator in the Americas, and the only butterfly known to make a two-way migration similar to birds — except no single monarch completes the full round trip. It takes three to five generations to finish the cycle each year.
Eastern population: breeds east of the Rocky Mountains across the U.S. and southern Canada, then migrates as far as 3,000 miles to overwinter in the oyamel fir forests of the Monarch Butterfly Biosphere Reserve in Michoacán and the State of Mexico, a UNESCO World Heritage Site.
Western population: breeds west of the Rockies and overwinters in a shorter migration along the California coast, in groves of eucalyptus, Monterey pine, and other trees.
Caterpillars can eat only milkweed (Asclepias species) — their sole host plant — while adult monarchs need nectar from a variety of blooming plants along the entire route.
Migratory Hummingbirds
Several hummingbird species pollinate wildflowers, agaves, and garden plants as a side effect of feeding on nectar during enormous seasonal journeys.
Rufous Hummingbird makes the longest documented migration of any hummingbird — a looping, roughly 3,900-mile route from wintering grounds in Mexico to breeding grounds as far north as Alaska, and breeds farther north than any other hummingbird species. Its "nectar corridor" is vulnerable wherever it crosses vast, sparsely vegetated stretches such as the Sonoran Desert or the Gulf of California coastline.
Ruby-throated Hummingbird, the only hummingbird regularly found in the eastern United States, crosses the Gulf of Mexico in a single non-stop flight between wintering sites in Mexico and Central America and breeding grounds across the eastern U.S. and Canada.
Multiple Selasphorus species (Allen's, rufous, broad-tailed) and the ruby-throated hummingbird have shown population declines since the 1970s–2000s, with the rate of decline accelerating in the most recent decade studied.
Lesser Long-Nosed Bat
This threatened, nectar-feeding bat is a primary pollinator of agave and columnar cactus across the U.S.–Mexico borderlands.
Each spring, lesser long-nosed bats migrate roughly 1,000 miles north from Mexico into the Sonoran Desert of the southwestern U.S., following a connected chain of blooming agaves known as the nectar corridor. Northbound bats follow two routes — a Coastal Lowland Route and an Inland Montane Route — over as long as three and a half months, while the fall southbound migration follows a single Inland Agave Corridor.
Bat Conservation International's Agave Restoration Initiative, launched in 2018, has planted more than 185,000 native agaves along this corridor, with a goal of 500,000 agaves and 95,000 hectares of restored/protected habitat by 2030.
What They Have In Common
Shared threats along the corridor
Habitat Loss & Fragmentation
Agricultural intensification, development, and roadside mowing have removed milkweed, nectar plants, and agave stands from huge stretches of the migratory route.
Pesticides
Systemic insecticides such as neonicotinoids, herbicide drift that kills host and nectar plants, and treated "pollinator-friendly" nursery stock all take a toll.
Deforestation of Overwintering Sites
Illegal logging and land-use pressure threaten the oyamel fir groves in Mexico where eastern monarchs cluster all winter, and the coastal groves used by western monarchs.
Climate Change
Shifting bloom times, more extreme storms and droughts, and changing temperature bands disrupt the timing that migratory species depend on to find food along their route.
Light & Noise Pollution
Artificial light disrupts night-flying moths and other nocturnal pollinators, while border infrastructure can fragment habitat corridors outright.
Disease & Parasites
Pathogens such as Ophryocystis elektroscirrha (OE) in monarchs and pathogens affecting bee and bat populations add additional pressure to already-stressed migrations.
Take Action
How you can help — wherever you live
- Plant native milkweed. Choose species native to your ecoregion (e.g., Asclepias incarnata and Asclepias tuberosa in much of the eastern U.S.) rather than tropical milkweed, which can disrupt migration timing and harbor disease.
- Plant a season-long nectar buffet. Include early, mid, and late-blooming native flowers so monarchs, hummingbirds, bees, and moths have food throughout the growing season and migration window.
- If you live in agave/cactus country, plant agave. Especially in Arizona, Sonora, and along the nectar corridor, native agave supports the lesser long-nosed bat directly.
- Avoid pesticides — especially neonicotinoids. Check that milkweed and nectar plants you buy have not been pre-treated with systemic insecticides.
- Certify your garden. Register a Monarch Waystation (Monarch Watch), a pollinator garden (Pollinator Partnership / National Wildlife Federation), or nominate your town for Bee City USA/Canada.
- Leave the leaves. Skip fall cleanup where you can — leaf litter and dead stems shelter overwintering native bees, moths, and other insects.
- Provide water. A shallow dish with wet sand or pebbles gives butterflies and bees a safe place to drink.
- Join citizen science. Report sightings to Journey North, tag monarchs through Monarch Watch, log bumble bees on Bumble Bee Watch, or submit hummingbird observations through eBird.
- Reduce mowing along roadsides and rights-of-way. Delayed or reduced mowing lets milkweed and nectar plants bloom and set seed.
- Support habitat protection in Mexico. Donate to organizations funding forest communities in the Monarch Butterfly Biosphere Reserve, such as the Monarch Butterfly Fund or WWF Mexico.
- Advocate locally. Ask your city, school, or Rotary club to adopt pollinator-friendly landscaping policies and reduce pesticide use on public land.
- Spread the word. Share this site and the Organizations Directory with anyone who gardens, farms, or manages land.