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CROSS-PURPOSES ON GRAND MESA (AND THE GALAPAGOS)!

By Nic.Korte

Look at this photo. Is there something wrong with this bird’s beak?

   Nope. This bird is a red crossbill. Yep, it is a female. As with many species, the females are dull-colored so they can blend in with the vegetation during feeding and nesting. The males are brick-red. These are small birds, and typically rather common on Grand Mesa—especially some winters. (On our January 1, annual Grand Mesa Christmas Count, birders counted 68!)
   Why the funny bill? Well, it so happens these bills are designed to crack open pine cones—this species’ principal food. At other times of the year, they may eat some buds and insects.
   Crossbills, with a diet so dependent on conifers live at high elevations or high latitudes. What do they have in common with the Galapagos? The Galapagos are famous because much of what Charles Darwin observed there led to his Theory of Evolution. That’s why the finches that live on the various islands are called “Darwin’s Finches.” There are now 15 varieties. But, they look much the same. The principal difference is the size, shape and strength of the bills. The birds have separated themselves by eating various varieties of seeds. Painstaking work over many decades by researchers Peter and Rosemary Grant have shown how these birds have split into such specific niches. (Two wonderful books on this subject are: The Beak of the Finch, by Jonathon Weiner {winner of the Pulitzer Prize for non-fiction} and How and Why Species Multiply by the Grants. The former is an entertaining “read” for the lay-person, while the latter is for biologists and bird-geeks.}
    The red crossbill has not had as much attention as Darwin’s Finches. The attention that has been paid, however, has shown that up to 8 species may be present because of differences in the “size, shape and strength” of the bills. The "species" have separated by living in different mountain ranges or "islands in the sky."  Ornithologists agree that there are more than one distinct species, but how many is being debated.
   Crossbills have adapted to remove seeds from cones. They start at the bottom of a cone and spiral upward, prying open each scale and removing the seeds with their tongues. The bills can cross in either direction, and the direction of the cross dictates the direction that the bird spirals up the cone. Each crossbill type has a distinct cone as a favorite food and a distinct flight call.
    The breeding cycle of Red Crossbills is more closely tied to food availability than it is to season. They can breed at almost any time of year including mid-winter if there is an abundant source of seeds. They are monogamous, and pairs form within flocks. The parents continue to feed the young for about a month after they hatch. The bills of young birds are not crossed at hatching, but cross as they grow. By 45 days they are crossed enough for the young to extract seeds from cones.
   

Enough details! Do you want to see some crossbills?

    A good way would be to participate in the Grand Valley Audubon Society annual x-country ski field trip to be held Sunday January 12th. Leaders are Lee Stigen and Cecelia Barr. Call 241-3905 or email audubonvg@gmail.com for more information. Meet at 9AM at the Palisade High School Parking Lot. Everyone is invited. Cost is $5/person except for students who are free.
     The skiing will be easy. All you need to bring is binoculars, lunch, water, sunscreen and appropriate gear.


Other birds you may see include three-toed woodpecker, gray jay, red-breasted nuthatch and more.


Keep up with the activities of Grand Valley Audubon Society by checking our website (audubongv.webs.com), and by following us on Facebook. Email audubongv@gmail.com with any questions or comments.
 

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