Thursday, March 22, 2018

Cactus flowers, bees and rattlesnakes - spring in Arizona

Spring has sprung. Some Hedgehog cacti are blooming and the related, but non-native ladyfinger cactus on our patio. Cactus bees immediately spotted it, and pose. Little green sweat bees like it too, but are difficult to catch on camera. 

Our big rattler made a first appearance, I guess he was sleeping under the barbecue when Mecki charged into him - some rattling, lots of barking until I banned the dogs into the house. The dogs may need a refresher of their snake avoidance training, they were too close for my comfort, but at least their obedience rapport is firm.

Rattler proceeded to explore the entire patio. Seemed to be tracing something (a partner?) judging from his careful tongue-testing of the path. 

Tuesday, January 16, 2018

Javelinas in our Backyard

Our backyard gets visitors periodically, even though it's fenced as a dog run. They (the Javelinas) systematically uproot dozens of mamillaria cacti and eat the roots. So we pick up the buds and put them into sand-filled pots to reroot, then plant them for the next invasion. To get at least something out of it, I made the whole party pose for a painting.

 Even though they look deceivingly similar to wild boars Javelinas or Peccaries are only distant relatives of pigs. Taxonomically they are members of the same suborder, Suina, but are in their own family, Tayassuidae (New World pigs). They sport two pairs of big canines as opposed to just one in Oldworld Pigs.
But like pigs, they live in family groups, and root for their food with very similar snouts. As ours live in the desert, I never saw them enjoy mud baths, but our Arizonan, New Mexican and Texan Javelinas  live at the northern most tip of their distribution area which reaches all the way south to Argentinia. So they must use  many different types of habitats.
They are territorial and use skunk-smelling secretions of their  scent glands (below each eye and  on their backs) for marking and communication. If hunted for food, these glands have to be carefully and immediately removed or the meat is spoiled. I have eaten jerky and fresh, grilled tenderloin as guset of Mexican gold miners and it was very good.
Javelinas are rather nearsighted and also quite fearless, which results in frequent close encounters between them and human and caninen Arizona residents. Often the Javelinas just go quietly about their business. While house-sitting in the Tucson foothills at First Avenue, I once found myself surrounded by a herd  between garage and patio. They were so peaceful that I reached out to touch the big patriarch when he walked close to me. He screamed with indignation and bristled. Other people have been less lucky,  and those big canines leave bad wounds. My 40 pound Healer-type dog Bilbo got into a fight with a single Javelina last year, and he came away from it with a big, gaping chest wound. But at other times my dogs have cornered the entire resident herd including young ones and nothing happened. With Javies, you just never know.  So don't ever feed them, not even inadvertently by  keeping garbage or compost in accessible containers. The more the 'desert pigs' get habituated to humans and their houses, the more confrontations happen, and those usually end with killing or removal of the javelina herd, and our desert is all the poorer for it.

Sunday, January 7, 2018

Why is the sting of Velvet Ants so painful?

Dasymutilla  erythrina, D. gloriosa, D. sicheliana, all female
 First of all, though I have picked up many fast-running, wingless female Velvet Ants (Mutillidae, a family of wasps, not ants) to photograph them, my experience with their sting is all hear-say, as none of them ever tried to sting me. I've  also often swatted at males of nocturnal species that love to buzz around my reading light, but of course those males are stingless (the sting is the ovipositor)

Dasymutilla sicheliana male

Dasymutilla occidentalis (Cow Killer) from Eastern US, photo Barry Marsh
But the name cow-killer (a total exaggeration) and the bright aposematic colors of these insects that usually lead very unobtrusive lives on the ground, among sand and rocks, do hint at a potent weapon.  Justin Schmidt ranks their sting high in his sting index. High on the pain scale, but very low in duration or tissue damage.

Social wasps, Polistes sp. colony
 Among wasps and bees, most painful and harmful stings evolved in species that prey on very big, active and potentially dangerous prey that they send into an extended period of paralysis (tarantula hawk), or in social insects with lots of resources to defend. Nests of social wasps, bees and ants are sought after by many enemies because those nests offer a quite unique accumulation of proteins and carbs. Where else could a bear or a human village harvest  honey, pollen and larvae by the bucket? Of course, those social hymenopterans defend their riches with whole armies of rather expendable workers. The sting of these amazons is painful and often even harmful (tissue damage and central nervous effects) making sure that lessons are taught and remembered. Pogonomyrmex sp. Harvester ants, Fire Ants, Honey Bees, Yellow Jackets and Hornets are examples that most people know.

Mutillids are neither social nor do they store larval food or even have their own nests. Their larvae develop as Ectoparasitoids of immature insects, esp. bees and solitary wasps (also flies, limacodid moths, beetles, and cockroaches). So the mutillid wasp is not guarding or defending those nests or larvae. There are many other solitary wasps like Scoliids, Cicada Killers, and Mud Daubers etc. with comparable developmental histories that are not known for an especially painful sting.

Male nocturnal Mutillid
 And there is even more to the defense system of Mutillids: Velvet Ants squeak (stridulate) when grabbed or otherwise trapped - I know that from a male that crawled into my husbands ear while we were reading in bed - To me it sounded like Micky mouse and Donald duck got into an intense  argument in his ear-canal.  
Some species of mutillids also release chemical defenses when caught. In addition, all of them, winged males and fast-footed females, are so heavily armored that they survive unharmed when swatted at or stepped on - even when chewed on by a naive predator I assume. This extra strong exoskeleton must be costly to build and heavy to carry.  Justin Schmidt also mentions that the legs of a female mutilid are about as strong and muscular as insect legs can get. That's easy to believe when you see them running. So these wingless wasps have a defensive arsenal that is not equaled by many other insects.
Dasymutilla cirrhomeris
So why? Schmidt suggests a reason in his book The Sting of the Wild: Longlevity as a strategy.
The majority of insects has a very short adult life span. After mating, females of many species lay hundreds of eggs in one big clutch on a host plant and then die. Even big wasps like Cicada Killers that provide food for their offspring don't live much longer than 40 days. Mutilid wasps are parasitoids of solitary bees or wasps. Their arid habitats are bare and thinly populated by any host species. Mutilids procreate by placing single eggs into late instar larvae or pupae of their host species. So even if the female Mutilid finds a leafcutter nest with a series of larval chambers, there might only be one or two that fits her requirements. So her egg production may be strung out over a long time and depends on her searching for just the right situation to lay one egg or a few.  This is possible because her adult life span, amazingly, is longer than a year. This longlevity ensures that the female has time to place enough eggs to guaranty the survival of the species.  The arsenal of defensive weapons provides the means necessary to survive that long.

With Justin Schmidt and his family: searching for mutillids and other arthropods in the dunes along Blue Sky Road in Willcox, AZ in July of 2017
Thanks to Justin O. Schmidt for his excellent book 'The Sting of the Wild' John Hopkins University Press 2016,  for including my Mud Dauber, and for great company in the field!

Sunday, November 26, 2017

Beetle Talk for the Butterfly Society

On Tuesday, November the 28th at 7 PM, I am giving a talk about the Beetles of Arizona for the Tucson Butterfly Society at the Lutheran Church in the Foothills. Given that I am working on a book with that title together with Arthur V. Evans for years now, the topic is obviously one of my faves. I hope that the lep folks get excited about it too!

My 5 posters will be available after the talk: Butterflies, Moths, Arachnids, True Bugs and Beetles.

Sunday, October 22, 2017

We need Connections, not Walls!

Ocelot and Mexican Amberwing, watercolor October2017
 I live in Tucson, Arizona. 30.7 miles, or 50 kilometers, or 44 min by car from the US/Mexico border. In my dual role as artist and biologist I spend much of my time in the field. Tucson is surrounded by the Sonoran Desert. As deserts go, the lower Sonoran is beautiful and rich in geological formations and fauna and flora. But also hot and dry most of the year. The long drive to the Colorado Plateau and Grand Canyon in northern Arizona  would take me through the endlessly sprawling metropolis of Phoenix. So I turn south instead. The borderland to Mexico, studded with sky islands and the first hints of the Sierra Madre Occidental has become my favorite hunting ground.  I regularly join  excursions to study the biodiversity south of the border wit groups of US and Mexican naturalists and biologists. More often, and on my own, I spend time just north of the border. Long dirt roads connect the Canelo Hills and the San Rafael Grasslands, Parker Lake and Copper Canyon, Sycamore Canyon and Arivaca. Many side roads take me directly to the border fence. There are often heavy truck barriers, but they are low enough to step over. In other places, tall metal beams, set too close to each other to squeeze through, form a more impressive interruption of the landscape, but it still seems penetrable for small wildlife and cougars have been shown to jump it. In Lochiel, an old, nearly abandoned border town south of Patagonia, AZ, I used to pet Mexican horses grazing on the other side of an old chain link fence with big holes.  It's a quiet area, somehow suspended in time, and full of natural beauty.
It's not all paradise. In many areas along the fence, there is a wide gash in the vegetation, where border patrol erased every living thing to create a corridor for easy surveillance. There are strange contraptions that the agents can pull behind their trucks to sweep the ground so new tracks of border crossers show up clearly.   There is thrash that crossing people abandoned and sometimes clearly the packing material from drug transports. There are water stations that good Samaritans established because the harsh desert claimed so many lives. Very occasionally I meet people who approach me for help - who ask for water or need a charge for their phones. Or even a connection to the next agents of 'la migra'. The white, green-barred  SUVs of the border patrol agents are usually not far away, always cruising, waiting, watching ... but also often the last resort for people in need. The agents keep up the immigration restriction that US law dictates, but  so far, the situation is very different from what we experienced in the Europe of my childhood along the Iron Curtain and most of all the Wall and Death Stripe of Berlin. I can only hope that it stays that way.  

Saturday, October 21, 2017

Under a full Moon

Ringtail (Bassariscus astutus) watercolor, available
When you spend as many summer nights as I out in the canyons of Arizona and Mexico, you will sometimes hear rustling in the trees above, bumping noises on a roof or little chittering voices. Little faces with dark eyes under big ears peer at you from behind branches. They jump and climb with ease, trailing a long, luxurious tail, banded in black-and white. But since it's usually dark when ringtails show themselves, I never caught more than a glimpse.
At Carr house in the Huachucas we saw a regular visitor high on the roof, slipping in and out of the beam of our flash lights. Similar fleeting impressions were left by a couple of them very high up in a tree during a black lighting session in Ida Canyon further south. At my friend Pat Sullivan's and Lisa Lee's house I wanted to check the black light at the bug room one more time before sun rise and found myself face to face with the resident Ringtail who had had the same idea. We both jumped and he retreated.  Once I slept under the stars at the Madrone Ranger station in the Rincons - when I got up a Ringtail had just tucked himself into a crucked branch above my head to spend the day. Most encounters where ghostly and swift. No photos.
But during our August trip to the Sierra Juriquipa in Sonora Mexico one of our group, Steve Minter, wasn't giving up so easily. At nightfall, he saw a little guy watching him from a tree branch, so Steve climbed after the ringtail, up into the tree, camera and all. One name for Ringtails is Miner's  Cat, but in fact, the little racoon relatives are better acrobats than even cats. So why did it not run?  Steve was wearing a bright headlight - so maybe it was the 'deer in the headlights' effect or maybe the ringtail knew that the thinner branches would not support even the most daring human - anyway, the miner's cat stayed put and Steve got a number of nice photographs. This painting was inspired by them.

Ringtails are omnivores that feed on everything from bird eggs to berries, lizards and bugs. They like rocky areas with crevices  and cavities for their dens and they tend to live close to water. I keep thinking of them as typical southwestern animals, but they can be found from southwestern Oregon, south through California, southern Nevada, Utah, Colorado, Texas, Arizona, New Mexico, Oklahoma, eastern Kansas, Baja California and northern Mexico. I have sometimes seen a couple of them together, but those may have been litter mates or a female with a sub-adult kid. Normally ringtails live solitary in small territories. 

Wednesday, October 18, 2017

She loves me, she loves me not ...

'She loves me, she loves me not'   Peachfaced Lovebird Watercolor, October 2017
Finally back at the easel - no actually, I just made some room for my stretched paper next to my computer. Watercolors need to lie rather flat if you want to use any wet-in-wet technique.

The little gregarious parrots in the genus Agapornis were brought over from Africa for the pet trade. Escaped or released by unconscientious breeders, they found backyards and parks in the Phoenix area quite hospitable. Humans like them because they are pretty and their antics are entertaining. So the Love Birds find feeders and bird baths filled.  As cavity breeders, they appreciate the work of Gila Woodpeckers and Gilded Flickers. A peachy head poking out of a Saguaro cavity delights many valley (Phoenix) photographers. As a biologist I cringe, though. There is no telling yet what the impact of this invasive species will be. Can they adapt to real desert conditions and seriously compete with native Saguaro breeders? I got the impression that house sparrows (from Europe) manage to do so to a degree, while the European Starlings seem to stay around urban and agricultural neighborhoods and golf courses. This does not mean they are not depriving our endemic birds of prime 'oasis' living space. So far, the Peach-faces seem to stick to the Phoenix area and some backyard bird watchers in Tucson are clamoring to see them here. Tucson, with its proximity to the southeastern sky islands could be the jump-off point for the birds to colonize the sky islands. To me, a night mare.  So I love them (in Africa) and love them not (in Arizona).