By Ty Fitzmorris
Highlands. The cold has crawled from the cracks of night into the light of day changing how all of the creatures of the region live. The coming season brings scarcity of food and water along with low, sometimes killing temperatures, and every species, plant and animal, has their set of adaptations to these challenges. These adaptations are sometimes physiological and sometimes behavioral, though for most species there is a little of both. Mammals (including humans) and some non-migratory birds begin to undergo cold acclimatization now, which includes redirection of blood flow away from skin, accumulation of insulative body fat and fur, and metabolic and chemical changes, all resulting in an overall increase in tolerance for low temperatures. Insects undergo a wide variety of changes — some, including bumblebees, generate propylene glycol (antifreeze) in their blood, which prevents them from freezing, while others develop the ability to raise their body temperatures far above that of the surrounding air, proving themselves anything but “cold-blooded.” Reptiles and amphibians are able to tolerate very low body temperatures without any injury, though some snakes, such as rattlesnakes, gather together in large numbers in caves to avoid killing frosts. Many birds, including the swallows and warblers, migrate south both for food and to avoid the cold, while mammals such as Black Bears, Rock Squirrels, and Beavers, create dens in which to shelter.
The winter adaptations that are often less discussed, however, are those that are evolutionary in nature, such as the development of life stages suitable for extreme conditions. The most conspicuous are plant seeds and insect eggs, which are excellent for dispersal but also are capable of extraordinary feats of survival. Seeds might remain dormant for decades in soil, waiting for perfect germination conditions, while some invertebrate eggs are tough enough to withstand the harshest of conditions and still hatch. It was this hardiness that led NASA to take the eggs of fairy shrimp far outside of our atmosphere, holding them with mechanical arms outside of spacecraft for long periods, and then hatching them with no apparent injury back on Earth.
These quiet months are a challenge to the naturalist after the bewildering panoply of the growing season, but some of the more neglected aspects of the natural world remain for us to explore. Winter is a great time to study the rocks and landforms of the Mogollon Highlands, which form the basis for our ecoregion as a whole. Formerly called the Central Highlands, the Mogollon Highlands are defined as the broad band of mountains and valleys between the Mogollon Rim of the Colorado Plateau and the deserts of the South, from the Chihuahua to the west to the Sonora to the south to the Mojave to the east. The Mogollon Highlands, as a result, have plants and animals from all of these regions, though intermingled in ways that have remained largely unstudied.
The three geologic processes that have affected our region most are the volcanism that has provided the extrusive igneous basalt cap of the Colorado plateau as well as the intrusive igneous granite that formed the Granite Dells and Granite Mountain; the spreading of the geologic plates, which have pulled the highlands apart, causing dropped blocks of crust to form valleys; and the movement of rock materials by gravity, water and wind, which carve the majestic valleys such as Sycamore Canyon, the Agua Fria, Walnut Canyon, and Oak Creek Canyon.
A Very Brief Survey of What’s Happening in the Wilds
• Young Ravens gather into large groups (called “congresses of Ravens”), sometimes as many as 50-70 individuals, and can be seen at sunrise and sunset flying from communal roosts to feeding sites.
• Though Black Bears finished mating in the summer, they delay implantation until now and begin their pregnancy as they enter hibernation.
Visit: Spruce Mountain Loop, No. 307.
Ponderosa Pine Forests
• Mule Deer and White-tailed Deer ruts reach their peak now as bucks finish rubbing the velvet from their full-grown antlers. Look for bare spots on saplings where male deer have rubbed off their velvet.
• Arizona Black Rattlesnakes (Crotalus cerberus), along with the other five rattlesnake species in our area, begin looking for hibernacula in which to spend the winter, sometimes with many other rattlers. Rattlesnakes are much maligned, but are typically very interested in avoiding humans, and will not bite unless harassed.
Visit: Schoolhouse Gulch Trail, No. 67.
• Young Western Screech Owls find temporary territories. These beautiful small owls, which weigh from 3.5 to 10 ounces, will prey on worms, insects, rodents, birds, or even crawdads. Some have been observed catching rabbits and, rarely, ducks.
• Galls on oak trees and shrubs are very visible now. The most common is the Oak-apple Gall, which looks like a red-orange peach, but is really an incubation site for an immature wasp. The wasp stings the plant, laying its egg in the growing tissue of the oak, and the plant grows this specialized structure around the developing larva. Oaks have over 300 types of galls, including some that look like furry animals, curled leaves, and gnarled twigs.
Visit: Little Granite Mountain Trail, No. 37.
• Javelinas switch to eating large amounts of prickly pear along with whatever protein-rich plant food, such as acorns and pinenuts, still remains.
Visit: Tin Trough Trail, No. 308.
• Pronghorn change their diets to shrubs and tough evergreen plants now that grasses have died back. Pronghorn can digest many plants that are poisonous to cattle, and thereby graze grasslands evenly. This, in turn, allows for a greater diversity of plants to thrive where Pronghorn graze since no one species can outcompete others.
Visit: Mint Wash Trail, No. 345.
• Many of the creeks in the Prescott area dry up until the snows of winter arrive and melt.
• The leaves of trees in lower-elevation riparian areas change now, reaching a riotous diversity of color before dropping.
• Hermit Thrushes, one of the last of the songbird migrants to migrate through our region, stop over only long enough to regain lost body fat and drink water. These relatives of American Robins migrate according to the magnetic field of the Earth and keep a straight, unwavering path, flying night or day. The only time they change course is when they pass near lightning storms, in which case the Hermit Thrushes fly directly toward the storm.
• Ducks and other waterfowl begin to arrive at our man-made lakes, such as Watson and Willow near Prescott. These lakes have become important migratory stop-over points for many species and will host thousands of individuals of many different species from now until February.
• Beavers cut branches from Aspens and riparian trees, pushing them into river-bottom mud to store for midwinter food. Because Beavers slow down the flow of rivers and distribute nutrients in riparian areas, they are very important for maintaining river health in the Southwest.
Visit: Lower Wolf Creek Falls, No. 384
• The leaves of Ocotillos (Fouquieria splendens) change color and fall. This species, along with Yellow Palo Verde (Parkinsonia microphylla), has photosynthetic bark and only grows leaves during times when water is abundant. They then drop them as drought periods return.
• Phainopeplas, the sole member of their family (the Silky-flycatchers) in North America, return to the desert from the uplands. These pitch-black birds would seem to be incongruous in the hot desert, but thermal studies have shown that their black plumage actually functions to decrease their skin temperature, in much the same way that the black robes of the Bedouins of North Africa diffuse incoming solar heat.
Visit: Agua Fria National Monument.
Average high temperature: 60.6 F (+/-4.2)
Average low temperature: 27.4 F (+/-3.2)
Record high temperature: 83 F (1933)
Record low temperature: -1 F (1931)
Average precipitation: 1.22” (+/-1.35”)
Record high precipitation: 8.68” (1905)
Record low precipitation: 0” (15 percent of years on record)
Maximum daily precipitation: 4.3” (Nov. 27, 1919)
Source: Western Regional Climate Center
• Nov. 3: Full Moon at 10:23 p.m. This is the second of three “supermoons” this year, the other two being in the preceding and following months. During a supermoon the Moon is slightly closer to the Earth,and may appear slightly larger and brighter than other lunar cycles and also exert a stronger gravitational pull on the Earth causing greater tidal swings.
• Nov. 4: Taurid Meteor Shower Peak. This is a long-running shower, from Sept. 7 to Dec. 10, which occurs as we pass through two separate dust trails — one from Comet Encke and one from an asteroid that broke off of the comet at some point in the past, called Asteroid 2004 TG10. Meteors from this shower are typically not very bright, and the full Moon will wash out all but the brightest.
• Nov. 13: Conjunction of Venus and Jupiter. The two brightest planets in the night sky will be within a half degree of one another in the morning sky. The planets will rise at 6 a.m. and will only be visible in the eastern sky until the Sun rises at 7 a.m.
• Nov. 17: Leonid Meteor Shower Peak. The Leonids are among the brightest and most reliable showers of the year, producing as many as 15 meteors per hour at its peak. This shower is caused by dust particles from the tail of Comet Tempel-Tuttle, which last passed through our solar system in 1998, and will return next in 2031. The 33-year period of this comet results in a 33-year cyclonic peak for the shower, during which meteors are extremely abundant. The last of these was in 2001, during which time more than 30 bright meteors were visible per hour in dark locations. As with all meteor showers, best viewing is after midnight, as our position moves onto the side of the Earth facing into our rotation around the Sun, which is the side that collides with the most meteors. The dark skies around the New Moon will provide perfect viewing conditions for this major meteor shower. This is one of the best of the year, so don’t miss it.
• Nov. 18: New Moon at 4:42 a.m.
Ty Fitzmorris is an itinerant and often distractible naturalist who lives in Prescott and is proprietor of the Peregrine Book Company, Raven Café, and Gray Dog Guitars, 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. Contact him at Ty@PeregrineBookCompany.Com with questions or comments.