An Ancient Path
San Luis Valley, Migratory Stopover Approximately 23,000 - 27,000 Sandhill Cranes migrate biannually through the San Luis Valley (SLV). Most of the Rocky Mountain Population of Sandhill Cranes breed in the greater Yellowstone area and winter along the middle Rio Grande Valley on the Bosque del Apache NWR near Socorro, New Mexico and in Northern Mexico.
Sandhill Crane Natural
Three sub-species of Sandhill Cranes visit the SLV: Greater, Lesser, and Canadian. It is very difficult to differentiate between the three sub-species. The Greater is larger and lighter gray than the Lesser and Canadian. The Greater Sandhill has a head/bill shaped similar to a Canvasback while the Lesser Sandhill has a head/bill similar to a Redhead duck.
Lesser and Canadian Sandhill Cranes frequent the valley, however, only about 3,000 - 5,000 of each subspecies. Most Lesser and Canadian Sandhill Cranes migrate through the interior of the United States staging on the Platte River in central Nebraska, but a few move through the SLV before moving onto wintering grounds. The Lesser Sandhill Cranes nest in the arctic of Alaska and northern Canada. The Canadian Sandhill Crane nests in the pothole region of prairie Canada.
Cranes live from 20-30 years and breed at about 2-5 years old. Sandhill Cranes mate for life, pair bonds are formed with a “dancing” behavior that can be seen in the spring.
Fall Cranes in Private farm field near Monte Vista NWR
Sandhill Cranes build large ground nest primarily in wet meadow habitat and both sexes incubate eggs. As with most cranes, Sandhill Cranes lay two eggs but usually only one chick will fledge (leave the nest).
In the fall, crane family groups, two adults and one juvenile, leave the breeding grounds. The juvenile stays with the parents through the summer, fall, and winter and will accompany the parents on the northward migration. En route, in the SLV, breeding adults begin renewing pair bonds and the juvenile leaves (or is forced out of) the family group.