February 19, 2010

The Cottonwoods of Pima Canyon

With a rain storm expected to roll in on Saturday, we decided to get in one more hike in the Santa Catalina mountains while the temperatures remain in the low 70's. We sort of unexpectedly came across Pima Canyon. Far less busy than the famous Sabino Canyon, this wonderful canyon with perennial water has a beautiful riparian stretch of cottonwoods, cholla cactus vines that climb tress, and cucumber vines that make for a completely unexpected jungle-like environment.

The trail access is only about 5 miles from Catalina State Park in northern Tucson. We were actually heading somewhere else to hike when I saw the sign on Oracle Road for the trailhead and looked up to see the canyon in the distance. So, we said, what the heck, let's go for it.

Notice the "No Tresspassing" Sign. There is still room for more homes up to the wilderness boundary!

The trail starts at the edge of a ever-expanding neighborhood and the first 1/2 mile of the trail is a county easement that snakes between houses. There is a sign that mentions the ever dwindling bighorn sheep population and how they will probably disappear from these mountains as the sprawl continues its climb into the foothills and the increasing numbers of dogs and other disturbances to their reproductive season.

On the sign discussing things we can do to help the last remaining bighorn sheep, someone write in marker; Don't buy a home in Tucson!

Once the trail enters the Pusch Ridge Wilderness Area, the route enters the canyon and you can leave the humanity of Tucson behind and enjoy the beautiful Sonoran desert environment and look ahead to the mesquite bosque that surrounds the riparian zone of Pima Creek at the bottom of the canyon.

The trail then drops down to the bottom and crosses the creek and next thing you know there are enormous old-growth cottonwoods and dense stand of vegetation. I was surprised, despite the warm weather, that the cottonwoods were already leafing out in February! At the size of some of those trunks, I am guessing they are reaching their maximum age of 150-200 years old.

These riparian stretches can only survive where adequate sediment has accumulated, so you go in and out of these patches as the terrain varies and the gradient changes. Where the stream is too steep, no sediment accumulates and the creek bottom tends to be bare rock and thus no riparian vegeation develops.

We hiked up perhaps 2.5-3.0 miles until finding a nice little "beach" for Hilina to play on. Further up stream, you could see that the creek flows for about 2 more miles until the ridge rises almost vertically up to Pima Saddle and eventually to the 7600 foot Mount Kimball above.

The Pima Saddle is visible at the end of the canyon

We ran across some scientists on the trail who were looking for "signs of spring" and indicated we should look for the yellow-tipped butterfly (which actually has a more orange color to it) as one of those signs. Once we got up to the riparian zone, we started seeing tons of those butterflies.

We saw a small unidentified accipiter hawk nesting up on this cottonwood. There is also a next in the tree in the distance.

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