As autumn approaches in Colorado, many species of birds from farther north begin their annual migrations south to warmer climates for the winter. Colorado’s diverse habitats along the Rocky Mountains and eastern plains provide important stopover sites for feeding and resting during these incredible journeys.
Why do birds migrate?
Birds migrate to move between their breeding grounds in the north and their wintering grounds in the south. The main reasons birds migrate include:
- Food availability – Birds migrate to regions with ample food supplies necessary to meet higher energy demands during breeding season and survive the winter.
- Nesting grounds – Northern regions provide ideal nesting locations free from predators and full of resources to raise young. But cold winters make it necessary to move south.
- Weather – Birds escape harsh winter conditions, including freezing temperatures and snow, by migrating south to warmer climates.
- Day length – Increasing day length in spring triggers hormonal changes and prompts northern migration for breeding. Decreasing day length in fall prompts southern migration.
What migratory flyways pass through Colorado?
Colorado lies along three major migratory flyways used by birds in the Americas:
- Central Flyway – Runs north to south between the Rocky Mountains and Great Plains, used by birds like ducks, geese, cranes, and shorebirds.
- Pacific Flyway – Runs along the Pacific Coast between Alaska and Patagonia, used by waterfowl, shorebirds, raptors, and songbirds.
- Mississippi Flyway – Follows the Mississippi River valley between central Canada through the Great Lakes region and Gulf Coast, used by ducks, geese, swallows, and blackbirds.
Colorado’s diverse topography allows it to host migrants from all three flyways as they pass through during seasonal movements.
What are some key migrant hotspots in Colorado?
Some top birding sites to spot migrants in Colorado include:
- Barr Lake State Park – Important stopover for waterfowl in the Front Range along the Central Flyway.
- Colorado National Monument – Diverse migrants along the canyons and plateaus in west Colorado.
- Pawnee National Grassland – Northeast plains grasslands harboring migrating sparrows, longspurs, and raptors.
- Ridgway State Park – Reservoirs and riparian habitat near the Uncompahgre Plateau used by waterbirds, raptors, and songbirds.
There are many excellent birding trails, refuges, parks, and nature preserves throughout Colorado to catch spring and fall migrants.
When do birds migrate through Colorado?
Different species migrate through Colorado at various times as they move between their breeding and wintering grounds. Here is an overview of when major migrant groups pass through:
Migration Period | Types of Migrants |
---|---|
Early March to May | Sandhill cranes, swallows, shorebirds, hummingbirds, warblers |
Mid-March to May | Ducks, loons, songbirds, sparrows |
April to early June | Neotropical songbirds like tanagers, grosbeaks, orioles, vireos |
Late September to November | Shorebirds, sparrows, hummingbirds, swallows, waterfowl |
October to mid-December | Raptors such as hawks, eagles, falcons |
Peak spring migration occurs from mid-April to early June. Fall migration peaks from late August through October. But there are excellent opportunities to spot migrants in Colorado year-round.
What are some key migratory bird species in Colorado?
Colorado hosts a diversity of migratory birds along the flyways. Some species to watch for include:
Waterfowl
- Snow Goose
- Canada Goose
- Wood Duck
- Mallard
- Canvasback
- Redhead
- Ring-necked Duck
- Lesser Scaup
- Bufflehead
- Common Goldeneye
- Common Merganser
Shorebirds
- American Avocet
- Spotted Sandpiper
- Solitary Sandpiper
- Greater Yellowlegs
- Willet
- Long-billed Dowitcher
- Wilson’s Snipe
Raptors
- Bald Eagle
- Northern Harrier
- Sharp-shinned Hawk
- Cooper’s Hawk
- Northern Goshawk
- Red-tailed Hawk
- Rough-legged Hawk
- Ferruginous Hawk
- Golden Eagle
- American Kestrel
- Merlin
- Peregrine Falcon
- Prairie Falcon
Upland Gamebirds
- Ring-necked Pheasant
- Greater Sage-Grouse
- Wild Turkey
Cranes
- Sandhill Crane
Hummingbirds
- Broad-tailed Hummingbird
- Rufous Hummingbird
- Calliope Hummingbird
Songbirds
- Tree Swallow
- Violet-green Swallow
- Swainson’s Thrush
- Yellow Warbler
- Yellow-rumped Warbler
- Wilson’s Warbler
- Western Tanager
- Black-headed Grosbeak
- Lazuli Bunting
- Chipping Sparrow
- Vesper Sparrow
- Savannah Sparrow
- Fox Sparrow
- Lincoln’s Sparrow
- White-crowned Sparrow
- Dark-eyed Junco
- Bobolink
- Western Meadowlark
- Bullock’s Oriole
- Baltimore Oriole
Conclusion
Colorado provides critical migratory habitat for a wide array of bird species traveling through the Central, Pacific, and Mississippi flyways each spring and fall. From waterfowl filling wetlands to songbirds flitting through mountain forests, there are incredible opportunities to witness these remarkable migrations across the state. Paying attention to the timing of different migrations and knowing key sites and species to watch for can help birders maximize their chances of spotting these seasonal avian visitors.