By Ty Fitzmorris
September glows in golden light, rich with scents of late summer — its sunrises are heady with the fragrance of white Sacred Datura flowers, fading into the noontime butterscotch of sun-warmed Ponderosas, and then into the dusk sweetness of bricklebush. In much of North America, September marks the beginning of the colder part of the year, with last harvests and cold nights. But in the lower latitudes, such as the Mogollon Highlands of Arizona, September is still summer, though with hints and foreshadowings of autumn. The monsoon rains usually continue into the early part of the month, tapering off eventually into glorious sunny days, with extraordinary flowering of purple four-o-clocks, asters, and morning-glories, red penstemons and Scarlet Creeper, yellow sunflowers and daisies, and the tall, strange tree-like Wright’s Thelypody (Thelypodium wrightii), with its white flowers. Insect diversity, too, continues to grow and change, with some of the largest insects of the year making their debut. Look for the large brown Rhinoceros Beetle (Xyloryctes jamaicensis), the Great Ash Sphinx Moth (Sphinx chersis), and the gigantic leaf-mimic katydids of the genus Microcentrum, as well as the harmless (though somewhat alarming) Giant Crab Spider (Olios giganteus), which is often seen in houses as temperatures fall outside.
It is in this time of extraordinary plenty that many creatures begin to prepare for the coming cold season. Most of our woody plants are setting seed, which woodpeckers and squirrels are storing away in granaries; young of many mammal species are leaving home to establish their own territories; and insects are laying eggs, their unique adaptation to climatic stress. One of the most unusual egg-laying techniques in the insect world is the creation of galls, which are structures created by plants in response to an insect laying its egg in the plant’s tissue. Galls can look like pine cones (on juniper trees, which bear no visible cones), like apples on Emory Oak trees, like smooth, blushing tumors on Gambel Oaks, or like furry, curled leaves on Arizona White Oaks. Oaks, in fact, have the highest diversity of galls, with over 300 different types found on them. Many of these galls will appear now, as specialist wasps, moths, and flies lay their eggs in the growing tissue of their coevolved host-plant.
Our most water-dependent creatures, such as snails and mushrooms, abound now — species that one rarely associates with the desert Southwest. Arizona is home to at least 200 species of native snail, most of whom are completely unstudied, though they can easily be seen consuming riverside vegetation during this wet season. Our species of fungi number in the thousands (just in Arizona!) and, again, are substantially unstudied, but they present a bewildering diversity from now until the Fall, from brittlegills to puffballs to earthstars. Their fruiting bodies are the only part of a mushroom that we typically take note of, but this is a small part of the organism — the real fungus is a network of filamentous mycorrhizae interlacing (and often enriching) the soil. In fact the largest organism on Earth is thought to be a single mushroom 2,400 acres in size in Oregon, which may be 8,500 years old.
The mammals of the Central Highlands are, for the most part, at the peak of their year. Food is abundant, and most species are not under any real food or water stress, so it is now that the contests for mates begin. Mule and White-tailed Deer, Elk, and Pronghorn all begin their annual rut in September, after their antlers and horns are fully grown. This period is defined by male competition for females and territories, and fighting, scent-marking, and tree-marking are common. Coyotes, foxes and Porcupines are also finding mates and breeding. Other mammals, such as squirrels and chipmunks, sensing the shortening days, are stashing food for the coming cold season.
Some species of birds will start to migrate into our area from the north toward the end of the month, and we will see species that we haven’t seen in large numbers since spring. Violet-green and Northern Rough-winged Swallow, can be found in flocks during this time, though they will have continued their travels southward by mid-October. Teal, hummingbirds and warblers, mostly in fall plumage, will pass us as they fly south. Look, also, for the earliest migrant hawks from the north, including Ferruginous, Swainson’s and some very early Rough-legged Hawks.
A Very Brief Survey of What’s Happening in the Wilds
• Coyotes begin courting and can be seen running in pairs.
• Elk breeding season begins, and sometimes the resonant bugling of male elk can be heard in wilder areas.
• Porcupines begin their breeding season (with a substantial amount of care) in the Aspen groves in higher elevations.
Visit: Dandrea Trail, No. 285.
Ponderosa Pine Forests
• Black Walnut leaves begin to turn yellow as cold air flows down river drainages from the higher mountains, and the husks of walnut seeds litter the ground.
• Large patches of vegetation underneath Ponderosas turn bright red toward the end of the month. These wispy, near-leafless plants are Dysphania graveolens, a type of goosefoot that emits a pungent, resinous smell when touched. (Thanks to Lisa Zander at the Natural History Institute for the ID help).
• Some needles on Ponderosas start to turn orange, and are shed toward the end of the month, as new, soft green leaves replace them. Healthy Ponderosas lose nearly 40 percent of their needles every autumn, and even though this type of needle loss can be rapid it does not necessarily indicate health problems. Also, the wonderful vanilla-butterscotch odor of the Ponderosa is at its peak now — smell in furrows in the bark.
Visit: Aspen Creek Trail, No. 48.
• Emory Oak and Arizona White Oak bear their nutrient-rich acorns, providing one of the year’s biggest crops for Acorn Woodpeckers, Rock Squirrels, and Cliff Chipmunks.
• Mule Deer begin their rut. Males can sometimes be seen sparring, and territorial marking, such as rubbed spots on saplings, can be found easily.
• Mushrooms “flower”’ in great diversity, especially in areas with downed, wet wood. It is during this time that most wood decomposition takes place, with their aid.
• Fendler’s Ceanothus continues to flower. The Navajo use this plant as both a sedative and an emetic (to cause vomiting), and the berries are an important food source for many animals.
• Mountain Mahogany (Cercocarpus montanus) bears its seeds. The long, spiral seeds burrow actively into the soil when they fall, both as a method for self-planting and fire avoidance.
Visit: Miller Creek Trail, No. 367.
• Goldenrods (Solidago spp.) and bricklebush (Brickellia spp.) flower, the latter of which has arguably the best aroma of any of our flowering plants, which it releases at dusk to attract moths.
• Butterflies fly in great diversity, drawn to the flat, open flowers of the aster family, including the fleabanes, sunflowers, asters, and groundsels.
Visit: Juniper Springs Trail, No. 2.
• Pronghorns begin their short breeding season, with males entering their rut. During this time the males will fight for dominance, and winners will gather together a harem of females.
• Yellow and purple asters abound, along with sunflowers.
• The grasshoppers, our primary grass herbivores, reach their final, winged life-stage, and many species can be found in different microhabitats. Look especially for the massive, though wingless, Plains Lubber Grasshopper (Brachystola magna), which can often be found crossing roads such as Arizona Route 69, east of Dewey-Humboldt.
Visit: Mint Wash Trail, No. 345.
• Canyon Treefrogs (Hyla arenicolor) conclude their mating season and finish laying eggs, even as some eggs hatch into tadpoles.
• Young River Otters leave their parents and their home territories, dispersing into new habitats. This species is slowly reoccupying habitats from which it was extirpated by trapping, declining water quality, and habitat loss, and now can be found throughout the southwest.
• Monarch Butterflies appear toward the end of the month, beginning their long migration south, following creeks and drainages.
• Katydids, large-winged relatives of grasshoppers, fly in riparian galleries. These are some of the best leaf-mimics of the insects.
• The fruits of Coffeeberry (Rhamnus californica) continue to ripen and provide a valuable (and delicious) food source for many species of birds.
Visit: Bell Trail, No. 13.
• Paintbrushes (genus Castilleja) bear their bean-like seed-pods. These beautiful plants are unusual in that they are hemiparasites, which draw nutrients out of other plants but also perform some photosynthesis of their own.
• Seep Willow (Baccharis sarothroides) flowers in desert washes. This plant was used extensively by the Tohono O’odham to make arrows and brooms, as well as to brew a tea for coughs.
Visit: Algonquin Trail, No. 225.
Average high temperature: 81.8 F (+/-2.9)
Average low temperature: 48.9 F (+/-3.2)
Record high temperature: 98 F (1948)
Record low temperature: 26 F (1903)
Average precipitation: 1.71” (+/-1.51”)
Record high precipitation: 10.02” (1983)
Record low precipitation: 0” (7 percent years on record)
Maximum daily precipitation: 3.08” (Sept. 24, 1983)
Source: Western Regional Climate Center
Note: These statistics do not include 2017 data
Ty Fitzmorris is an itinerant and often distractible naturalist who lives in Prescott and is proprietor of the Peregrine Book Company, Raven Café, Gray Dog Guitars, and is a founder of Milagro Arts, a community arts nexus, all as a sideline to his natural history pursuits. He is also the Curator of Insects at the new Natural History Institute at Prescott College. He can be reached at Ty@PeregrineBookCompany.com with questions or comments.