The San Luis Valley as a Critical Stopover During Bird Migration

Updated: Apr 16

Prepared by the San Luis Valley Ecosystem Council, Spring 2021

All photos by NPS/Patrick Myers

Cinnamon Teal by NPS/Patrick Myers

Introduction

Each spring and fall, thousands of feathers slice through the brisk San Luis Valley (SLV) sky, alerting resident wildlife, local farmers, and eager birders to the change of season. Ranging from shorebirds to songbirds, a myriad of avian species visit this high-elevation desert as they migrate along the Central Flyway to their breeding and wintering grounds. Nurtured by the Valley’s mosaic of wetlands, riparian corridors, and agricultural fields, the SLV is a critical stopover for these determined travelers.


Foundational to the health of any stopover habitat is the presence of water. As local hydrology continues to be threatened by high agricultural demands, persistent drought, mining of the aquifer, and water export proposals, the future of the San Luis Valley as a migratory stopover is unknown. By protecting both ground and surface water reserves, we honor the miraculous winged creatures that bring energy, life, and color to the San Luis Valley.


The Importance of Migratory Stopovers

From distributing nutrients, seeds, and pollen, to balancing local food chains, animal migrations enhance ecosystem health. Spanning hundreds to thousands of miles in distance, these impressive voyages speak to the beauty, intelligence, endurance, and collective determination of species worldwide. Coming at tremendous energetic costs, migrations also highlight the importance of maintaining healthy habitat along migratory corridors.


Jenny Nehring and Cary Aloia, SLV biologists and partners at Wetland Dynamics, explain that many people “overemphasize the importance of wintering and breeding grounds,” when in fact, a successful migration also requires the presence of intact, resource rich habitats along the way (Interview, 2021). Without areas to rest and refuel like the SLV, birds would arrive to their destinations underweight and undernourished. For this reason, birds navigate not by the arbitrary borders and boundaries designed by humans, but by the geographical landmarks, such as rivers and wetlands, that represent feeding and resting opportunities.


Connected by threads of wetland and marsh habitats, the Central Flyway offers safe passage to thousands of birds during their biannual migrations. From the thick boreal forests of Canada to the Gulf Coast of Texas, this flight path is believed to support the movement of over 400 bird species each year (Bode, 2020). The San Luis Valley, a vast high desert shrubland in Southern Colorado, is a critical stopover for many migratory species. Blessed with interspersed wetlands, it is an especially important stop for Central and Pacific Flyway ducks, water birds, shorebirds, and the iconic Sandhill Crane (Ducks Unlimited).


SLV Significance to Migratory Birds

According to soil scientist and field ornithologist John Rawinski, the SLV’s drastic range in elevation, and therefore climate, creates a variety of distinct habitats for birds. Cradled by the impressive San Juan Mountains to the west and Sangre de Cristo’s to the east, the semiarid San Luis Valley ranges in elevation from 7,600 feet on the valley floor to over 14,000 feet in the Sangre de Cristo Mountains. From the harsh alpine tundra to the tranquil grasslands of the lowlands, this diverse habitat in the SLV yields impressive avian biodiversity. Over 360 species have been recorded in this Valley and surrounding mountains (Rawinski, Interview, 2021). Over 250 bird species have been identified at the Great Sand Dunes National Park and Preserve alone. Of this count, many are migratory species including the Great Blue Heron, American Avocet, Snowy Plover, Burrowing Owl, Black-chinned Hummingbird, Lewis’ Woodpecker, and Cedar Waxwing, (GSDNPPC,pgs. 1-8).


The SLV Wetland and Wildlife Conservation Assessment identifies the San Luis Valley as being the “southernmost significant waterbird production area in the Central Flyway and the most important waterfowl production area in Colorado…” (Wetland Dynamics, 2019, pg. 19). For birds that winter in Mexico and South America, the area is ideal for breeding. In fact, it is one of North America’s most critical breeding grounds for various species of duck and colonial wading birds, specifically the Cinnamon Teal (Ducks Unlimited). Similarly, priority duck species, such as Mallard and Northern Pintail depend on the Valley’s flooded wetlands and densely vegetated habitats for migration, nesting, and wintering (Wetland Dynamics, 2019, pg. 19).


For bigger bird species and waterfowl, the Valley functions as a vital rest-stop to regain stamina for the journey onward. For example, the SLV is an important destination for nearly the entire Rocky Mountain Population of Greater Sandhill Cranes as they fly along the Central Flyway. Due to their spectacular numbers and continued presence, this iconic wading bird highlights the value of the SLV’s high quality habitat.


Sandhill Cranes in the SLV

Sandhill Cranes West of Dunes by NPS/Patrick Myers

Human Connection

Dynamic, loud, and majestic, the Rocky Mountain Sandhill Greater Sandhill Crane migration has attracted perhaps the most attention out of any bird to visit the Valley. These grey, long-bodied creatures have flocked to the San Luis Valley for ages, inspiring ancient Native American petroglyphs that date back up to 3,000 years (Rawinski, Interview, 2021). Spanning nearly 6 feet in length, the “Big Bird” petroglyph located outside of Del