Birds of the Western Slope November 11, 2015
By Evelyn Horn
Published Thursday, November 12, 2015 9:10 am
Where are the Cranes?
I wish I knew! The senior biologist for our Rocky Mountain Flock of Greater Sandhill Cranes, Rod Drewien, shared with me that the number of cranes at the Monte Vista Wildlife Refuge was much lower than it has been in the past. And at the Bosque del Apache in New Mexico (the wintering grounds) the numbers were also down. Speculation includes poor water supply for the summer food crops, longer growing season of weeds, and warmer summer and autumn days. As I find further information, I'll include it in my future columns. But winter arrived last night, and the birds are on the move, who knows where!
It's been a long time since I've seen crane silhouettes against the evening sky, but I thrill at the mere memory of it! Maybe next spring?
In the spring migration they come to Hart's Basin by the thousands: safety is in numbers as the birds make their way to the nesting grounds to our north. After they leave Hart's Basin, they begin to leave the huge flock, and the pairs move on to their nesting site. So we think of cranes in terms of the gregarious birds that we see in spring. But they soon become solitary, with each pair claiming a territory to sustain them and their chicks for the summer. So our cranes have two distinct life-styles.
During the spring migration, when the reservoir is filled, the water's depth is just right for roosting (six to twelve inches). The birds stand in the water, often on one leg to sleep, with their favored spots in the shallow ponds along the north shores. This is where we can see huge flocks as they prepare to take off, usually between 9:30 and noon. But now in autumn, the water has been drawn down for irrigation (the basic purpose of the reservoir). So no roosting water and few cranes. In the past we've had fewer than 500 during fall migration and so far this year we've had about 200. But some of these birds will become our wintering flock. If you see or hear them, please leave a message on my phone, 835-8391. Thanks!