Raptor Migration in Full Swing

Migrating turkey vulture

Migrating turkey vulture

The annual Raptor (aka Birds of Prey — eagles, hawks, falcons, owls and vultures) migration is in full swing. The birds of prey are migrating north to their summer nesting grounds. The raptors fly up the hog back for several reasons. First, it is an easy marker for them to follow —  a constant ribbon of rock from New Mexico into Wyoming. Second, the sun warms the rocks and provides up drafts. These up drafts give a little extra lift that the heavy birds of prey use to gain altitude. With the gift of lift, the raptors can soar for more miles every day.

Scientists take advantage of the concentration of raptors. There is a monitoring station perched on top of the Dakota Hogback at Raptor Ridge, just on the east side of Co Hwy 93, just south of the I-70/ Co Hwy 93 interchange. There is a parking lot at the base of the hog back, across from Mathews-Winters Open Space. http://jeffco.us/open-space/parks/matthews-winters-park/

Migrating Cooper's Hawk

Migrating Cooper’s Hawk

Migrating red-tailed hawk

Migrating red-tailed hawk

Scientists from the Denver Museum of Nature and Science initially manned the observation station, but budget cuts took their toll, and the job was passed on to Hawk Watch volunteers from the Rocky Mountain Bird Observatory. http://rmbo.org/v2/web/getInvolved/hawkWatch.aspx These hardy folks volunteer to count the raptors as they fly overhead. Not a bad gig when it is nice out, but in wind or cold, it takes true dedication.

But their work pays off, and you can see it in their reports. Since they started watching at the beginning of April, almost 400 birds of prey have been spotted cruising over the hogback. https://groups.google.com/forum/?fromgroups#!topic/cobirds/N7YwWW90D3k

Hawk Watch will continue counting raptors  through May. Go up and see them and spot some hawks flying by.

 

Minature Upslope Storm

My husband and I took a quick trip to the San Luis Valley of southern Colorado last week to see the largest migration left in North America — The Sandhill Cranes! Up to 20,000 Cranes and 20,000 other ducks, geese, coots, plovers and any other type of waterbird that you can imagine migrate through the San Luis Valley from February to April. They stop to fuel up in the rich salt marshes for their trek to Canada, Alaska and even Siberia. When they move on depends on the weather.

Unfortunately, by the time we got there, the Cranes had left the Valley.

But the San Luis Valley is such an interesting place that we found plenty of other things to keep us interested. One of the most interesting that we saw was purely by chance — a cloud getting caught on the top of Blanca Peak.

 

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Warm moist air runs into 14,345 foot Blanca Peak. See how the cloud gets higher as it gets closer to the Peak? It is probably snowing at the summit. Then, once it’s over the top, POOOF! The cloud is gone.

 

This is actually a small upslope storm created as warm moist air coming up from the south (right) is forced to rise to get over the mountain. As the air rises, it cools. As it cools, it forms a cloud. Once the moist air is over the top, it can expand again and it evaporates. Climate people call this orthographic lift.

March through May is the season of upslope storms in Colorado, as warmer temperatures begin to pump air up from the Gulf of Mexico onto the Great Plains and from the Pacific into the Four Corners and San Juan Mountains. The process is exactly the same as what you see here, in miniature. These spring storms bring Colorado most of our moisture, and account for most of our snowpack.

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