I did a little research on these interesting trees with green bark.
The Yellow, or Little Leaf, Palo Verde tree has green bark. Palo means wood or stick. Verde is spanish for green. This variety of Palo Verde has tiny, little, leaves and the spring blossoms are yellow. It can photosynthesize through its green bark, an important adaptation for a tree that will drop its leaves during the warm season and in response to fall cooling. The tree will also drop stems and branches during a drought so it doesn’t waste what water it does get.
Palo Verde trees serve as nurse plants for Saguaro cacti by providing a canopy – in effect, a microhabitat – which offers warmth in winter and shade in summer. The slower-growing, longer-lived cactus will eventually replace its one-time protector.
Burros were brought to this area in the late 1800’s by the miners. They were used as pack animals. Some burros escaped captivity and others were abandoned by the miners when they moved on to other areas to mine. They have adapted well to the Sonoran desert and continue to multiply faster than the environment can feed them. In order to keep the wild herds healthy, the BLM rounds up a certain number of them each year and allows people to bid on them to adopt them. Bidders have to meet certain criteria in order to adopt them (to make sure they have the means and the land to house and feed the burros).
We watched them for a while. Then, as we started walking away, another one startled. He was the scrappy one (Zoro). He held back from the other 3 and huffed at us. I’m pretty sure he was trying to scare us off. Don, as usual, imitated his threat back at him. I don’t think the burro was impressed. They kept their safe distance from us though. When we got back to the computer to look at the pix, we could see that Zoro has one short ear. Maybe he got huffy with a puma? I bet he feels even braver now, since he survived whatever he tangled with. Zoro is the one in front. If you can zoom in, it’s his right ear that’s damaged.