Wednesday, July 16, 2008

Springs in the Desert

Out in the desert, you come to expect miles and miles of dry land. Every once in awhile you come across some water, and that water is a welcome sight.

The water provides water to drink, a resting spot for waterfowl, and home to fish, frogs, and other aquatic organisms.

The green in the foreground of this picture is watercress (Nasturtium officinale). Watercress only grows where water is present year round and in specific water conditions. In some desert springs, it is an important substrate for snails.

This tiny springsnail (Pyrgulopsis species) is one found on the watercress. It doesn't look like much, but it shows that the spring may have been around for thousands of years. I explain a little more about the life of a springsnail in this post.

Viewed from above, springs stand out in stark contrast to the surrounding bleak desert vegetation. Desert animals learn where the springs are and know how far they can go from their water sources and still survive.

Perhaps even skunks! Skunk Spring is located in an especially dry area.

Sometimes springs are developed to provide a water source for wildlife and livestock. To develop a spring, an area with greasewood is usually dug up, a collecting area and pipe installed, and the water flows downhill into a tub or other collector.

Not all desert springs are totally isolated. This spring helps feed a creek that leads into a lake.

Desert springs are hotspots of diversity. After all, who wouldn't like to live by a little water? They are also particularly vulnerable to changes in the water table. If these little green patches dry up, it could be many, many miles to the next water source. That's a scary thought when it's a hot, dry summer day and you've run out of water!

Tuesday, July 15, 2008

Desert Boy and Henry Learn about Harvester Ants

While we were taking a walk the other day, I noticed the large number of harvester ant mounds among the bushes. Desert Boy and Henry went over to investigate.
Harvester ant mounds are easily distinguished, with a small hill of sand and gravel rising from the ground, sometimes as much as two feet high. Harvester ants belong to the genus Pogonomyrmex, and their predilection to make these mounds make them easy to identify. In our area we have more than 30 species of ants, but just two are Pogonomyrmex ants.
Desert Boy thought it was great to take a look, but because harvester ants have an extremely toxic poison, it's not good for him to get too close. Harvester ants are some of the most venomous animals in the world, with a venom 3 to 12 times as strong as a bee. Or in other words, one ant bite is equivalent to up to 12 bee stings. Ouch! Fortunately harvester ants have tiny mouths and don't bite often, as long as you stay out of their colony.
Henry takes a look at the harvester ant mound. The ants have dug deep into the earth so that they can take the seeds they find. In addition to seeds, they also eat small insects and other invertebrates. In turn they are eaten by horned lizards and some birds.
Here we can see ants coming and going out of the mound entrance. They turn over and aerate as much soil as earthworms.
The ants will stay inside the mound during the hottest part of the day. Then they go out to find seeds and insects and bring them back.
Here's a closeup of a harvester ant. It's a little blurry because the ants move fast! By the way, the head is the square end with the antennae sticking out.
One of the things that caught my eye as I walked past several harvester ant mounds was the entrance. It was always on the south or east side of the mound. One hypothesis about this entrance location is that it warms up faster in the morning than if it was located on the north or west side.
Harvester ants clear the vegetation directly around the mound. Although it might be tempting to try and kill the harvester ants, they are a natural part of the ecosystem, found throughout the western United States. In Texas and Arizona, the red imported fire ant is slowly taking over harvester ant territory, and these fire ants are much worse for humans than the fairly benign harvester ants.
One ant in this photo is carrying part of a plant that is bigger than himself. Ant watching turns out to be a fun sport: which ant is carrying the biggest thing? Which ants go in straight directions and which ones meander?
Desert Boy is enjoying his experience as an ant watcher. Ready to join him?

Monday, July 14, 2008

Desert Destination: A Marshmallow Cave

Over the weekend I went on a fun adventure to a cave. Full disclaimer: I love caves. I go in a cave whenever I can. Usually the caves involve lots of mud and/or lots of crawling. To my great surprise, this cave didn't involve either.

That little hole way up on the mountainside is Goshute Cave, but it's more fun to call it Marshmallow Cave because much of the interior is filled with giant white mammilaries that look like marshmallows! You'll see in a minute.

The trip was sponsored by the Northern Nevada Grotto. Grottoes are caving clubs, and they're located all over the country. They are part of the National Speleological Society, which has lots of great information about caves. One of the best parts about the Northern Nevada Grotto is that it has no dues. And it meets online. So all in all, it's a rather convenient organization to be a part of. The downside is that to actually see other members, you have to turn off the TV, get off the couch, and go somewhere. It worked out that I could go on this trip at the last minute because my wonderful hubby agreed to come along and watch Desert Boy. Desert Boy doesn't love caves, at least not yet, and my hubby can't get very excited about crawling so he didn't mind skipping the cave. 

Here's a view from the trail up to the cave. (It was a steep trail, so I had to do something while I was gasping for air.) You can see the Great Basin desert stretching out into the smoke-filled hazy horizon. The California wildfires are definitely having an impact on much more than California.
Here's the rock scramble below the entrance. Actually the entrance is a smaller hole to the left of the big, gaping one, but you can't see it until you're up there.
In case I didn't know where I was. Rooms throughout the cave had been named, apparently by a group back in 1912.
Here are those marshmallows I was talking about! These are mammillaries, which formed under water. Although they look sort of soft, they are hard calcite.
In some places the mammilaries have been eroded away, showing rings. These indicate that the mammilaries formed one layer of calcite at a time.
Another white, intriguing formation was the folia, layer upon layer of honeycomb looking calcite.
This is a closeup of the folia, where you can see that the layers aren't quite parallel. One suggestion as to their formation is that bubbles created the slightly sloping edges.
The main cave passage descended steeply, and we had to slide down some sections.
The proper caving gear of helmet, headlamps, sturdy clothing and boots, and kneepads, made the caving trip much more enjoyable and safe.
These aragonite crystals were tucked away in a little alcove. It is amazing to see such a delicate-looking formation and marvel how it has survived for thousands of years.
Here is a cave shield, a fairly rare speleothem. Its color contrasted with the wall behind it, suggesting that the water percolating into the cave to form the shield is picking up minerals along the way.
We climbed into an upper passage to go down a tight little hole called The Toilet Bowl. It is so small that your whole body completely fills the hole, and you can't see where you're going.
Eventually even your head disappears, and you are flushed into another part of the cave. (Sorry, I couldn't resist.)
These colorful draperies were part of the attraction of the cave. I was impressed with the diversity of formations and the large walking passages. The entire group seemed to enjoy the cave trip.
After reading this post, you're either ready to head down into the nearest hole or you're saying that cavers are a weird group of people, for who in their right mind would want to descend into the bowels of the earth? If you're in that second group, this photo helps explain why it's great to go into a cave. When you see a weird formation like this helictite, which grew upward and curving in spite of gravity, you realize that caves are one of the last frontiers, where we don't understand exactly how they formed and don't know what their bounds are. It might just be possible that you're sitting on top of a cave right now! 

Sunday, July 13, 2008

Henry Finds a Treasure

Henry loves going out on runs and walks because he can explore the smells of the neighborhood. We go out everyday, and yesterday Henry found gold. Okay, it wasn't real gold, but to him it was probably even better than the doggy equivalent of gold.
He found a deer leg, including the hoof. And he decided to bring it home. Oh, lucky me. It seems normal for dogs to chew on things, but that hoof just gets me. Why is that part so attractive to a dog?
Henry doesn't waste any time getting down to business. He's chewing away.
But he senses that I'm close, and puts a protective paw over that deer hoof. After all, I might want to steal away his treasure. 

Saturday, July 12, 2008

Desert Boy Rides a Horse

It's summertime, which means it's time to move the cows around different meadows and pastures as the feed allows. Aunt Tana helps move the cattle, and we saw her yesterday on her beautiful horse Jewel. She offered to take Desert Boy  for a ride.
Here's Aunt Tana with her dogs, Heidi and Tippy. They don't get along well with Henry. I think they sense that he's just a play dog and they know that they are work dogs, able to do important things like getting cattle to go where they want.
Aunt Tana starts by giving Desert Boy a lesson. She's an excellent rider, unlike me. In my dreams I'm an excellent rider, but in reality I get fairly nervous if we go faster than a walk.
Desert Boy quickly catches on and sows no fear being on top of the big horse by himself.
Desert Boy sees the cattle coming. Aunt Tana had ridden ahead to open the gate so they could come through. The horse has miraculously sprouted two more legs in this photo.
Desert Boy gets ready for the action.
He reaches for the other rein. He doesn't have much time to act, there's a storm coming in.
He's got the reins now and is ready to go. Maybe next time we'll put some shoes on him.
And there they are, a bunch of cattle in the background. They're moving in the right direction and all is well with the world.
Mission accomplished, Desert Boy scans the horizon, looking for his next task.
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