Urban Refuge

Male monarch resting in a mesquite tree       photo by Richard Halliburton

One of the greatest wonders of the natural world is the annual migration of millions of monarch butterflies from eastern North America to fir forests deep in southern Mexico each winter. But Michoacan, Mexico is not the only place that monarchs overwinter. Right here in central Phoenix, teams of butterfly scientists, or lepidopterists, have been tracking monarchs that overwinter along the Salt River, as well as along the Colorado River near Yuma and Parker, Arizona. Numerous "hot spots" around the state of Arizona, from Grand Canyon in the north to Patagonia in the south, also attract monarchs to feed and breed at various times of the year.

Monarchs are very selective about what species of plant they will lay eggs on, since the caterpillars are adapted to feed almost exclusively on milkweeds. However, the adults will gather nectar from a wide variety of flowers. Even though they are endemic to North America, monarchs are happy to feed on plants imported from the Mediterranean, such as lantana and rosemary, or Australia, such as eucalyptus and wattle trees.

Female monarch nectaring on a wattle tree

For roosting, though, they need just the right kind of canopy and just the right kind of leaves to hang onto with their tiny feet, says Gail Morris, director of the Southwest Monarch Study.  Gooding's willows, large trees native to Arizona, are their favorite at the riverside location in central Phoenix. At least that is where they have been noticed by people who pay attention to these sorts of things. It is quite possible that they are hanging out in the eucalyptus trees in your neighborhood, as they do along the coast of California. If you see monarch butterflies floating around your neighborhood this winter, people want to know, especially if you can see a tiny round tag with numbers on its wing. These tags are one way scientists are keeping track of butterflies that roam through Phoenix. You can report your sightings, with or without tags, to swmonarchs@yahoo.com.

Photos are excellent documentation too, since it is easy to confuse a monarch with the more abundant and closely related queen and occasional viceroy butterflies that also flutter around these parts. Learn the differences here: Identifying Monarch Butterflies.

Stalked Puffball

My greatest excitement today was finding this stalked puffball, Battarrea diguettii, on my morning walk. This is a new species for my "life list," and the second type of stalked puffball I've seen growing around Phoenix. It's a wonder that the neighborhood isn't covered with these strange fungi, as the spores must number in the billions from just this one specimen. This and other members of the genus Battarrea have lots of folk names: sandy stiltball, desert drumstick and donkey fungus are the most common. A close relative of this species, Battarrea phalloides, has been found all over the world, from Africa and Oahu to Uruguay, where none other than Charles Darwin collected specimens in 1833. Diguettii is distinguished by the pores on the cap that release the powdery spores, and is endemic to the Mojave and Sonoran deserts of North America.

Life and Death

Around here, if a scorpion doesn't get you, the ants will. This Arizona desert scorpion (Hadrurus arizonensis) I found on the sidewalk probably met its death by a crushing foot, but it did not take long for tiny Southern fire ants (Solenopsis xyloni) to swarm in for a feast.  At least the scorpions usually hunt solo. 

Also known as the Giant Hairy Scorpions for short stiff hairs along the sides of their legs, this species is reputed to be the largest in the U.S., measuring up to six inches long from the tip of their stinger to the small, sharp jaws or chelicerae. Add on all those legs plus the formidible claws, or pedipalps, and they are quite impressive. This one was about four inches long based on my calculations as sized up to my pen. (I need to add a small ruler to my pack for observations like this.) The ants are just a teensy fraction-maybe a sixteenth of an inch-or a couple of millimeters apiece if you prefer metric. Although scorpions can deliver a painful sting, they rarely cause a serious reaction in humans, and this one is actually one of the least toxic, despite its size. The dark back and pale legs also distinguish this species from the smaller, more dangerous and much more common bark scorpion (Centruroides exilicauda) that haunts the SW deserts. 

As gruesome as a scene like this may be, it is a reminder that all life thrives on death, humans included...unless you like your meat very fresh!

Exoskeletons

After a month or two spent mucking about in a pond for food, the aquatic larvae, or nymphs, of dragonflies crawl out of the water, crack open the skin on their back, and begin new lives as aerobatic adults. I found these exoskeletons, or exuvia, of roseate skimmers (Orthemis ferruginea) clinging to a cement wall along the Central Arizona Project canal, where a trough of still water serves as a year round breeding ground for dragonflies, as well as dozens of other insects. The exuvia are perfect casts of the fearsome jaws and giant eyes that make the larvae successful predators. I would like to have witnessed the magical hour when dragonflies emerged from these chitonous skins. Even more, I would like to be able to shed my own skin and fly! 

This trough on top of the CAP canal collects debris and mud,
creating a year-round pond that is brimming with aquatic life.

An adult Roseate Skimmer rests on a blade of grass.

Dragonfly larvae blend in with muck at the bottom of the pond.

Mussels and Clams

Quagga mussels (Dreissena rostriformis ssp. bugensis) and Asian clams (Corbicula fluminea) have claimed some territory along the Central Arizona Project canal, far from their native habitats in Ukraine and southeast Asia respectively. A small pile of shells is spread out across the trail after being scraped out of pipes in a water treatment plant in north Glendale, looking quite out of place in this arid scene.

Hitching rides on ships and then on smaller boats, both species have become naturalized in many freshwater systems in North America including the Colorado River and its system of reservoirs and canals. The clams are considered to be symbols of prosperity in Asia and have also been intentionally introduced through the aquarium trade and as a source of food.

Katydid

This Elegant Bush Katydid (Insara elegans) appeared on my window screen recently. Also called a Mesquite Katydid, they are distinguished from other katydids by the long narrow wings marked with white stripes. Katydids are nocturnal, so this one seemed content to let me photograph it mid-day as it rested. The males are the source of some of the rasping night sounds coming from high in the trees during the summer around here.  The name "katydid" is supposedly and onomatopoeia for this sound, but that's a real stretch, at least for this species.  Elegant, yes, for the slim wings and extraordinarily long  antennae. This was the first year in twelve that I've seen this species in our neighborhood, which makes me wonder: Have they always been around, and I just haven't noticed, or are they having an especially good year, so more abundant? 

Desert Shaggy Mane

The desert shaggy mane mushroom (Podaxis pistillaris) or "black powderpuff" is actually a type of puffball. Open it up and, depending on the ripeness, it will either be filled with thick white goo or erupt in a cloud of dark spores. These began popping up in gravel along Highway 17 after monsoon rains at the end of July this year. Sadly, they are reported as being inedible not due to toxins, but because they are just plain foul-tasting, as well as tough and woody. However, if you are truly desperate, or just curious, munching on an immature stalked puffball won't kill you.  This species is common in desert regions around the world. Australian aborigines have used the spores mixed with water for body paint and the dry spores for hair dye.