There are many sky islands in Arizona. Madera Canyon was one of them. Madera Canyon is located on a sky island. We went there after the debacle of Tucson’s Festival of Books. Sky islands are incredible mountain ranges that rose up abruptly out of the desert lowlands without foothills. The mountains seemed to be emerging out of the earth as if by magic.
Later I learned more about this phenomenon. I learned that such mountains usually had an elevation of between 6,000 and 8,000 feet. I also learned that these mountains which looked like islands in a sea of grass or sea of desert scrub actually had an abundance of wild life. These islands include most of Arizona’s biotic communities. They are among the most bio-diverse ecosystems on the planet. They are often the meeting place between desert and forest and everything in between. It is precisely that diversity that attracts wild life, especially birds. That is why these sky islands contain well over half the bird species in all of North America. Not just Arizona. They also contain 29 bat species, more than 3,000 species of plants, and 104 species of mammals.
Sky Islands are havens of biodiversity. That is really their most important feature. When you move into these “islands” in the desert there is an astounding range of biodiversity. As Gary Paul Nabhan said, “In fact the “sky islands” of southeastern Arizona and adjacent Sonora are now recognized by the national Union for the Conservation of Nature as one of the great centers of plant diversity north of the tropics.”
The reason for that diversity is of course the great variety of topography in the state. That produces a wonderful variety of life, both flora and fauna. As Nabhan said, “When we compare our desert with others, the contrast is striking. Overall, the Sonoran Desert has the greatest diversity of plant growth forms–architectural strategies for dealing with heat and drought–of any desert in the world.”
The Sonoran Desert is certainly not the bleak and barren place that many expect–and sky islands are the apexes of diversity.
What makes Madera Canyon so special is the creek at the bottom. It traverses 4 life zones and many habitats between the desert floor and the mountain tops. It has become world famous for its diverse flora and fauna. According to the Friends of Madera Canyon, “the variety of climates within 10 miles is similar to that found in driving from Arizona to Canada!”
Southwestern Arizona and this canyon are spectacular places for people who love wildlife and wild plants. This area is ranked the third best birding area in the US! It contains some 400 birds species and especially 14 of Arizona’s 15 hummingbird species. That is more hummingbirds than any where else in the United States. But today we saw none at all.
It was interesting that the more we gained in altitude the more deciduous trees appeared and the less cactuses. I have learned that usually in Arizona the higher the altitude the higher the precipitation so the more diverse the vegetation. Trees need the added the moisture on the higher elevations. Of course, if the mountain is too high, as in the San Francisco Peaks then there are no trees at all. Just snow. Trees, like all life is finicky. Like Goldilocks, things have to be just right.
The landscape of southern Arizona seems dry—it is dry. But it does get rain. In fact this region gets about 11 inches (280 mm) of rain per years. This is enough rain to allow a surprising amount of vegetation to flourish. Even wild flowers abound. That seems impossible. It looks so dry and nearly barren. But the land is not barren—far from it.
On the day we were there an enthusiastic birder showed me a photograph of an Elegant Trogon (Trogon elegans) one of the rarest birds in the United States. A couple of years ago my brother-in-law Harv and I went in search of it but did not find. He has seen it a few times. Me never. Darn! The birder showed me a photograph he had taken of it. I was really jealous. Later I went in search of it. I found another birder who had found it and he told me exactly where to go, but I missed it. I am an incompetent fledgling birder. We spent some time sitting on a bench with camera and binoculars in hand. We saw a lot of birds of different species, but surprisingly no hummingbirds. Usually in the past we saw a large variety of hummingbirds here. I was puzzled by their absence.
House Finches are interesting birds because they were released in the eastern part of North America by people who brought them from Europe in the 1940s and now they have spread over most of North America including Arizona and Manitoba.
Acorn Woodpeckers often drill small holes in trees in the autumn to insert their acorns. Often their “granary trees” are used over and over again and contain thousands of acorns. Aren’t birds weird?
Mexican jays have co-operative breeding where the young from previous years help the parents to raise the new young. Nature is not just competition, sometimes it involves cooperation.
2 thoughts on “Sky Islands”
House Finches are endemic to the West Coast, not Europe.
Thanks for correcting me