Thursday, March 16, 2017

Animals and their habitat: Harris Antelope Squirrel

 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.

Animal Habitat: Cattleranch for Dung Beetles

Photo collage of my watercolor Longhorn Ranch and a digitally created inset of Canthon imitator rolling a dung ball.

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:

Wednesday, March 15, 2017

Animals in their Habitat: Mountain Lion

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

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

Animals and their habitat: Sphinx Moths and Sacred Datura

Watercolor and photo collage by M. Brummermann
The Moon Flower or Sacred Datura opens its flowers in the late evening. During the night, the main pollinators, Manduca spp. and other big Sphinx Moths, visit. In the morning there are still white-faced bees and other little insects crawling into the wilting flowers, but they are mostly too small to be effective pollinators.
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

Animals in their Habitat: Regal Horned Lizard

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 in their Habitat: Foothills Kestrel

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.