Thursday, March 16, 2017
Cacti of the lower desert are important to the Harris Antelope Squirrels. They feed on the fruit of Barrel Cacti that are available all year round, ad generally stuff their big cheeks with anything from seeds to insects to even carrion. They are so dainty that they are able to jump into and hide in the most thorny Jumping Chollas. My dogs, and probably most hunting coyotes can only watch in deep frustration as the squirrel chitters only inches from their noses in relative safety. Besides coyotes, bobcats and hawks they have snakes to worry about. I have seen the little guys actively and aggressively take a stance against anything rattlesnake-related, even attacking and biting my snake stick that only smells of snakes. At this time (Feb. March) the squirrels raise their pups in underground (under cactus) burrows. All summer long, the day-active critters will brave the heat - one adaptation is their unusually high body temperature, also their little umbrella-tail and the habit of spread-eagling in shady places to dissipate heat to the cooler ground. During cold periods they seem to stay in their burrows, but during the last mild winter, a few were usually out and about.They are true denizens of the Sonoran Desert.
Animals in their habitat: For some few animals human activity improved the environment. Cattle ranches must be paradise for many dung beetles, even in areas where historically no big grazing herds occurred. Of course it's not quite that simple: http://
Wednesday, March 15, 2017
Animals in their habitat: Mountain Lions in the Tucson Mountains. With the exception of humans, the mountain lion has the largest range of any large terrestrial mammal in the Western Hemisphere. They are found from Canada to Argentina. They are also able to utilize the low desert as well as the higher elevations of the Catalina Mountains and the territories of individuals are huge. Although they may snack on prey a...s small as mice, their main target in the Tucson Mountains are Javelinas and mostly Mule Deer. A female lion with two grown kittens pretty regularly shows up at a water feature in the backyard of a friend who lives around Gates Pass (SE Tucson Mountains). Sadly, one was killed on Picture Rocks Road some years ago - that's only a couple of miles from our house, but I've never seen tracks on our property. While I often see mountain lion footage of trail cameras at places where I do field work in AZ and Sonora Mexico, I've only seen one during the day in the wild. So the model for my painting was the female at the Phoenix Zoo - and if she was out here, she'd probably prefer a more seclude resting spot, maybe above my head in an old Mesquite Tree .. but hey, it's my painting ...
Tuesday, March 14, 2017
Animals in their Habitat: Salt River Horses. This is a difficult topic. There is a community of horse lovers here who love this herd passionately and in a way defensively. Federal agencies have made weak attempts to remove them. When you observe the animals enjoying their free, rather secure live, splashing through the year-round running river, fighting for mates, forming bachelor groups and harems, raising foals, and all this trustingly in viewing distance of photographers and other admirers, you are apt to agree that they are a rare treasure.But any ecologist sees a growing herd of feral, not wild, horses that propagate unchecked by any meaningful predation in a very delicate desert environment. It seems difficult to find common ground. Even attempts to control birth-rates by chemical sterilization are vehemently decried by the human friends of the horses. The river so far is the saving grace - the members of the growing herd look well-fed and healthy and do not seem to stray too far into the real desert. I have not seen any impact studies concerning river banks or nitrate loads ...
Sunday, March 12, 2017
|Watercolor and photo collage by M. Brummermann|
The throat of Datura flowers is extraordinarily deep. When completely unrolled, the proboscis of Manduca rustica is long enough for the moth to hover over the flower and reach the nectar. Still, most moths land and crawl laboriously into the depth. They stay surprisingly long wiggling among anthers and stigma, and when they emerge, they head directly for another one of those white funnels. It is assumed that chemicals in the nectar may be slightly addictive and keep the moths faithful - thus assuring that precious pollen reaches its goal and does not get wasted. Datura (like many plants) is a known chemical powerhouse that produces potent Alkaloids. These may protect the plant tissue from many herbivores, but not from the caterpillars of several Manduca species who seem immune. So the pollinating moths can lay their eggs right on their favorite plant to produce a new generation for this symbiotic relationship.
Wednesday, March 8, 2017
When photos of this lizard are posted on social media sites, the predictable comments usually are that people used to 'always' see them in the past, but not anymore. Is this true, or is this anecdotal perception just that? On our property west of the Tucson Mountains I do see them occasionally and I'm not sure that I see fewer than 15 years ago when we moved here.
Of course they are very secretive and tend to bury themselves under loose sand whenever it is either too cool or to hot - after all they are ectotherm reptiles and need to regulate their body temps by appropriate behavior. They also depend mostly on certain ants for their diet, and these, too, are limited in their activity by the ambient temperature - meaning that extremely hot summers drive these harvester ants deeper under ground to live on their stored food. Extended droughts like the current one probably eventually diminish their numbers. So even in areas like our property, where the ants are save from insecticides and their food source (weeds) is not destroyed by herbicides or artificial ground cover, desert harvester ant populations may have been shrinking over the lat 10 years and with them the number of Regal Horned Lizards. My (also anecdotal) observations of the Greater Short-horned Lizard in the mountains seem to suggest the those are still faring better, as are grassland populations in Cochise County. It seems however that in areas where Harvester Ant colonies are under attack by introduced Fire Ants (Texas, but not Arizona) the effect on the local horned lizard species is quite negative and the numbers are in alarming decline.
The range of the Regal Horned Lizard in Arizona is within Arizona Upland Sonoran Desertscrub, Chihuahuan Desertscrub, and Semidesert Grassland communities. It inhabits valleys, rocky bajadas, and low foothills. It is usually encountered in relatively level areas with low shrubs, and open, sunny patches.
Tuesday, March 7, 2017
Animals and their habitat: Sometimes I take liberties when I paint: In the background of this watercolor from 1992 are the Catalina Mountains as seen from Tucson. But the Kestrel I had seen close to the Mule Mountains in Cochise County, and I liked his perch on the old Yucca stalk. Tucsonans will realize: those Spanish Bayonets do not grow in the southern foothills of the Catalinas (there are some on the north side, in the grassland towards Oracle though) Having lived here now for over 20 years, I would never again falsify a landscape like that. The Kestrel, however, would not care too much. The little falcons make their territories in grasslands, agricultural areas and in the saguaro desert, wherever there is open space around perches to hunt and nesting cavities to raise their offspring. We had a pair in our backyard for years, in an old woodpecker nesting cavity in a saguaro. They took a great toll on our lizard population which is the main menue the small male serves for the female and the chicks while he is the sole provider. Whne the larger female took to the wing again, she also served sparrows and finches.
Monday, March 6, 2017
Animals in their habitat: For some birds, their habitat requirements seem very variable. The Northern Cardinal seems to be fine where he has access to big, oily seeds, brush for nesting and some water. Still, the species' distribution puzzles a lot of human 'snowbirds'. They come from the Northeast to Arizona and find their statebird already established in their winterdigs. Did he migrate, too? No. He is a breeding resident. Was he introduced by transplanted humans who felt l...onely for their pretty red bird? I often hear that idea, sometimes vigorously defended and supported by the remark that Arizona 'really' is the territory of the 'Desert Cardinal', the pyrrholoxia. Not so. If you look at the distribution map of the Northern Cardinal you see that the bird indeed mostly lives in eastern Canada and US areas: from Maine to Texas and in the provinces of Ontario, Quebec, New Brunswick and Nova Scotia. The distribution maps of many birding books end at the souther US border. But in the south its distribution covers Mexico to the Isthmus of Tehuantepec, northern Guatemala, and northern Belize. An allopatric population is found on the Pacific slope of Mexico from Jalisco to Oaxaca; the Arizona population seemlessly extends from the north Mexican distribution. Most likely, the long north south extension of the Rockies in North America and northern Ice Ages are the reason for the peculiar distribution pattern of the 'Northern' Cardinal.
Sunday, March 5, 2017
Animals in their habitat: Bighorn Sheep in the Catalina Mountains. When I came to Tucson in the early nineties, there were still occasional sightings of Bighorn Sheep mainly on Pushridge. Massive developments like SaddleBrook soon encroached on their area and the growing influx of hikers everywhere caused more disturbance than the sheep could take. A huge forest fire took the brush cover of the mountainside, and eventually predation as well as livestock diseases killed of the last sheep. Now, a few years ago, the forest service and game and fish (?) began an ambitious reintroduction program, releasing several truck loads of sheep over a couple of years. At first, the animals did not seem to thrive. They dispersed into unexpected areas and mountain lions killed several of them. In reaction to that predation, a number of mountain lions were hunted down, which caused a public outcry. Many in Tucsonans believed that the whole release program had been done not to bring back an established resident of the mountains, but just an attraction for trophy hunters. But I think the Bighorn population is stabilizing by now, lambs are born, young bucks still stray all the way to the Tucson Mountains and the remaining many mountain lions are probably very happy. To depict the situation, I moved a Bighorn Ram from an old painting digitally into a landscape painting of Pima Canyon on the south side of the Catalinas. While the result is artistically somewhat lacking - the landscape is overwhelmingly busy - I think this digital collage fits the situation very well, showing the introduced, wandering ram just a little too low on the mountain in the upper part of the Saguaro zone.
Saturday, March 4, 2017
Roadrunners are one of the icons of the deserts Southwest. They are most often depicted running through open spaces of sun-bleached sand with maybe some cactus, or, cornier, an even more bleached cow skull in the background.
But our huge raptorial cuckoo-birds would not really like that cliché landscape too much. While they are tough enough and very adaptable and often run rather than fly, they still appreciate the low trees of the thornbush chaparral just as much or even more than the wide open desert.
Their nasal wouw-wouw-wouw calls are most often heard from the height of an ironwood or mesquite tree, and later I see our resident bird up there all fluffed up, turning exposed patches of his black skin towards the morning sun to absorb the warmth. I know he is perfectly able to regulate his bodytemperature by autonomous means (shivering, panting) - much better than for example the tiny hummingbird - but he seems to prefer those primitive behavioral ways.
To me, that makes him seem even more like some ancient saurian velociraptor that his sharp profile and strong running legs remind me of. Fast, fierce and insatiable and smart. Even the tiniest, blind nestlings can swallow whole lizards that the parents provide. Adults catch everything that moves, from tarantulas to House Finches to rattlesnakes. One was filmed while catching hummingbirds at a feeder. Roadrunners are probably the greatest menace in the young lives of baby quail. When our cat got out last summer, he came racing back with a Roadrunner in angry pursuit.
And yet - I'm delighted each time I catch a glimpse of a speedy runner or hear their fast, clacking ratchet noises in our backyard.
Friday, March 3, 2017
Animals in their habitat: for many beetles all the habitat they rely on seems to be a single plant species. They are so faithful to their hostplants that they show up on the flowers as adults, may it be to feed on pollen, nectar or the petals themselves or to meet their mating partners. The female then lays her eggs so the larvae can feed on the stems or roots of the plant. Next year, there will then be a new generation of beetles just in time for the flowers of the plant. For the sake of exchange of genetic material, I hope the beetles at least cruize the whole local population of their plants. The example here is the longhorn beetle Crossidius coralinus on Burrow Weed (Isocoma sp.?). Beetles of this genus frequent similar asteraceae all over the western US.
Thursday, March 2, 2017
Animals in their habitat: Black-throated Sparrows are character birds of our SW desert. All during spring their metallic song can be heard around our house in the bajada of the Tucson Mountains, but I've also found a nest in the grasslands around Cochise Stronghold on a friend's property. True to style, even that nest was hidden in a cholla cactus. But one of the five eggs in it was bigger and whiter than the other four. A cow bird had smuggled in a little parasitic guest. Th...e nest was very well protected with spiny jumping cholla branches, but my friend, being an entomologist in search of dung beetles, was armed with very long forceps. So he removed the cow bird egg. I was ambiguous about this interference, but he did the math: minus one cowbird means plus 4 sparrows, because the early hatching CB chick would have pushed the sparrow eggs out of the nest.
Wednesday, March 1, 2017
Finally! The first wildflowers and the first seasonal insects are gracing the Arizona deserts. After a relatively wet winter, poppies are popping up (ugh, sorry!) under Creosotes and around saguaros. We don't see great fields of them yet, but it's early yet. While I've never found specific pollinators on those periodic spring blooms, there are beetles that feed on pollen as well as petals of lupines, scorpion weed and poppies: several species of blister beetles, most of them in the genus Lytta. They are not the much maligned threat to life stock that some of their relatives (genus Epicauta) have become thanks to industrial hay harvesting methods. Our horses usually don't feed on poppies after all. So just enjoy those shiny little jewels! Read more about their biology in another blog chapter