Mountain Bikers & Trail Runners: Slow Down for Snakes!

Here in Colorado, at least along the Front Range, we enjoy a variety of "wilderness" recreational opportunities from hiking to rock climbing. Sometimes differing modes of trail enjoyment come into conflict, and sometimes the wildlife suffers even worse consequences. Here I will relate why people traveling over trails at high speed (mountain bikers and trail runners specifically) need to understand their potential impacts on reptiles in particular.

Baby gartersnake basking on trail

I have been fortunate to encounter at least four species of snakes along popular trails in various parks and open spaces. Snakes make use of patches of earth unobstructed by vegetation in order to bask, warming their bodies for active hunting later, to help digest a meal, or otherwise regulate their metabolism. Trails are ideal for this purpose and it is not uncommon to find serpents stretched across the full width of a trail.

Obviously, venomous snakes such as the Prairie Rattlesnake also pose a threat to people using trails. Trail runners must be mindful of the potential to encounter rattlesnakes, especially in early morning or early evening hours, and on overcast days. I personally recall one afternoon when a trail runner passed me, and I almost tripped over a Prairie Rattlesnake shortly thereafter. I suspect the runner never saw it.

A handsome Prairie Rattlesnake stretched across a trail

When traversing terrain at a high rate of speed, it is essentially impossible to notice a snake or other small organism on the trail. If it is noticed it may be mistaken for a branch or other object. Snakes are generally well-camouflaged and overlooked even by those seeking to find them.

Besides the fact that a snake cannot move rapidly enough to avoid an oncoming bicycle tire, or running shoe, it is usually not programmed to do so behaviorally. A snake's primary defense against a perceived threat is to rely on camouflage and stillness in hopes the predator or danger does not detect it. So, snakes are, figuratively if not literally, "sitting ducks" when it comes to oblivious mountain bikers and trail runners.

Aw-w-w, a basking baby gophersnake

There is evidence that other types of small animals also suffer from collisions or other encounters with mountain bikers and trail runners. While my chief personal interest is in insects and spiders, and I find a great deal of carnage related to even regular bicyclists, most invertebrate species have robust, widespread populations that can withstand even heavy mortality. Not so with many reptiles, small mammals, ground-nesting birds, and other organisms. Remember that all animals are subject to many non-human mortality factors as well: Predators, parasites, disease, and infertility for example.

Gartersnake smile

What can you do to avoid conflict and still enjoy yourself? Consider recreating at a time of day when reptiles are not normally active. Yes, that means late morning through afternoon during the warmer months. Winter riding means little or no conflict with wildlife. Slow down, especially in open habitats such as prairies, meadows, and glades, south- or east-facing hillsides, and along rock outcrops. Ride only on trails designated for mountain biking (but you do that already, I'm sure). If there is a park headquarters, visitors center, or nature center, consult with personnel there to find out which trails are best, and whether there is frequent wildlife activity along them.

Thank you for reconsidering your riding and running habits and becoming more "wildlife-friendly" to other creatures. Those of us who share the trails but move at a slower pace and enjoy our encounters with animals will be grateful for your thoughtfulness.

Prairie Rattlesnake thanks you for your courtesy

Sources: Burgin, Shelley and Nigel Hardiman. 2012. "Is the evolving sport of mountain biking compatible with fauna conservation in national parks?," Australian Zoologist 36(2): 201-208.
Craver, Monica. 2009. "The Impacts of Mountain Biking on Amphibians and Reptiles, 2008," e-mail to Council ATdnv.org
Davenport, John and T. Adam Switalski. 2006. "Environmental Impacts of Transport, Related to Tourism and Leisure Activities," in Davenport, John and Julia L. The Ecology of Transportation: Managing Mobility for the Environment. Dordrecht: Springer. pp. 333-360.
Goode, Matthew J., Jeffrey M. Howland, and Michael J. Sredl. 1995. Effects of Microhabitat Destruction on Reptile Abundance in Sonoran Desert Rock Outcrops. Nongame and Endangered Wildlife Program Heritage Report. Arizona Game and Fish Department, Phoenix, Arizona.
Vandeman, M.J. 2011. "The Impacts of Mountain Biking on Wildlife and People - A Review of the Literature," ARPN Journal of Science and Technology 4(7): 418-426.

Cape May Point State Park

After spending time at Cape May State Park on October 15, 17, and 18 of this year, I can highly recommend this natural gem to any naturalist. There is literally something for everyone, from history to architecture to nature.

The most obvious landmark at the park is the lighthouse, 157 feet in height. It was erected in 1859, after erosion forced the dismantling of the previous lighthouse built in 1847. Many of the bricks from the older version were incorporated into the current tower.

An equally impressive structure is a World War II bunker, constructed as part of the Harbor Defense Project of 1942. The entire park is actually a former military base, and the bunker was originally 900 feet from the shore. Today, at high tide most of it is under water.

A pair of linear one-story buildings near the lighthouse houses the restrooms, park visitor’s center, and a small natural history museum that contains some live animals as well as typical taxidermy mounts and other old-style interpretive exhibits.

You might be better off simply exploring the trails that lace through 153 acres of wetlands and open woodland. The half-mile Red Trail is wheelchair-friendly, while the Yellow and Blue trails eventually end up at the dunes and beach. While watching for birds above, be sure to note what is underfoot on the boardwalks, too. We saw this ribbon snake on one of our treks.

Other animals may cross your path as well, like this male Blue-faced Meadowhawk dragonfly

The boardwalks also have several platforms, and even a few wooden blinds, from which to watch waterfowl on on the open water in the marshes. There are obviously continuing efforts being made at habitat restoration as well, with numerous plantings installed on drier ground.

Do take advantage of the many programs and guided nature walks offered here. There is even a hawk-banding demonstration from mid-September through October.

The official website for Cape May Point State Park offers more details than I can share here, but by all means consider a trip here.

Night of the Toads

I was fortunate enough to attend the annual Invertebrates in Education and Conservation Conference in Rio Rico late last month, and participate in a couple of the spontaneous field trips that happen, especially after dark. One such excursion, led by my good friend Zack Lemann of the Audubon Institute Insectarium in New Orleans. We were looking for certain beetles, and had success, but reptiles and amphibians were also in abundance. Chief among those were toads.

We drove north from the conference headquarters in Rio Rico toward Madera Canyon, stopping at a service station at an exit in Green Valley. There, right by the interstate, we found the cactus longhorn beetles Zack was after, but there were also several Couch’s Spadefoots (Scaphiopus couchi) dining on the many insects drawn to the lights of the gas station.

Spadefoots are technically frogs in the family Pelobatidae. They lack the large parotoid glands of true toads (located just behind the eyes and visible as large, elliptical bulges). What truly sets them apart from other amphibians, however, is the dark, hardened tubercle on the underside of the heel of each hind foot. These “spades” help the animal dig into and out of the mud.

Couch’s Spadefoot is exceedingly tolerant of long dry spells, emerging during the soaking monsoon downpours that typically begin in early or mid-July here in the Sonoran Desert. They erupt from low-lying areas as those ditches and depressions fill with water and soak into the soil, softening it. The spadefoots have been buried fairly deep in the soil awaiting the rains.

Males call to females with a voice that has been likened to a “bleating sheep with a cold.” Real attractive. It works, though, at least on female spadefoots. Females lay eggs in the temporary puddles and the ova hatch twelve to twenty-four hours later. The tadpoles, in a race against the evaporation of their aquatic niche, metamorphose to miniature adults in as little as eight days. Before the mud dries and cracks, the spadefoots dig in. Underground they are able to tolerate at least a year without food or water until the rains once again return.

From Green Valley, our party moved on to a retirement community in the small town of Continental. The lights in the parking lots of the community attract many insects, and not surprisingly toads are wise to this fact. Under one light I found this Great Plains Toad, Bufo cognatus.

I am grateful that the toad was quiet, for I have read that the calls of males are lengthy, extremely loud, and likened to a jackhammer. Unlike spadefoots, members of the genus Bufo are true toads in the family Bufonidae, characterized by “warty” skin and those prominent parotoid glands. Otherwise, the life cycle and habits of the Great Plains Toad closely resembles that of Couch’s Spadefoot. The tadpoles take longer to mature, but the adult toads likewise spend the bulk of their lives underground awaiting heavy rains. They make the most of their time aboveground, eating a huge amount of insect and arachnid prey to get them through lean times.

Conspicuously absent from the landscape on this particular night (July 28-29) were the enormous Sonoran Desert Toads, Bufo alvarius that usually dominate the scene. Formerly known as the Colorado River Toad, this species has apparently been rendered extinct in much of the Colorado River corridor (along with the water which now does not even reach the Gulf of Mexico). These are huge animals, mature adults often measuring seven inches….in just about any direction so great is their girth. Some specimens would find a dinner plate a somewhat confining perch. They are not easy to photograph, either, as they turn away from flashes. I imaged this one in Picture Rocks.

Sonoran Desert Toads are nothing to trifle with, especially if you are a dog. They have incredibly toxic skin secretions. The hallucinogenic properties of those toxins are well-known to the medical community, too. Stupid people who engage in “toad-licking” get what they deserve. Pets that don’t know better can die from ingested toad toxins.

A really great online article about the Sonoran Desert Toad can be found here at The Firefly Forest website. Information about the other anurans (science-speak for “frogs and toads”) treated here can be found on the website of the Arizona-Sonora Desert Museum.

Sources:
Brennan, Thomas C. & Andrew T. Holycross. 2006. Amphibians and Reptiles in Arizona. Phoenix: Arizona Game & Fish Department. 150 pp.
Hanson, Jonathan and Roseann. 1997. Fifty Common Reptiles & Amphibians of the Southwest. Tucson: Southwest Parks and Monuments Association. 63 pp.

Spring Peepers

One of the many things I love about Facebook is that my nature-loving friends will note harbingers of the changing seasons. Lately, I have begun reading that some folks are already hearing spring peepers, a type of treefrog. Given the harsh winter this year, a more appropriate reaction might be “It’s about time.”

Spring peepers bear the scientific name Pseudacris crucifer, in reference to the “X,” or cross-like pattern usually evident on the backs of these diminutive amphibians. Mature adults are only two or three centimeters in length, but they make up for their small size with a big voice.

Males broadcast in synchronized choruses from a variety of wetland situations throughout most of North America east of the Mississippi River. The sound can carry up to a quarter of a mile. What you normally hear is the courtship song designed to attract females. The males are quite protective of their small territories, however, and another intruding frog will elicit a short trill of aggression.

Making a racket is risky, though, as you can also attract predators. So, there is something of a ventriloquistic element. Just try finding one in the act of calling, even when it is in close proximity, on the ground or on vegetation.

After mating, females lay clusters of eggs in a gelatinous mass under water, attached to aquatic vegetation or at the bottom of a small pond. In fact, a favored habitat of this species is vernal pools, temporary wetlands in an otherwise forested habitat.

Egg-laying can continue into the summer months, but the tadpoles hatch in 7-10 days, taking from five to eight weeks to metamorphose into tiny versions of the adult. The larvae are highly vulnerable to aquatic predators including turtles, salamander larvae, and even large insects like dragonfly nymphs.

You would think that tiny frogs known as “spring peepers” would be found in….spring. Apparently they are not limited to that season, since Dave Small, Lynn Harper and myself found one in a meadow in the neighborhood of the Quabbin Reservoir on the fourth of October, 2009. Prior to that, my initial encounter with Pseudacris crucifer had been at Dave’s home, where at least one frog sat patiently beneath the mercury vapor light, awaiting any errant insects that were attracted to it.

Here’s wishing that you hear your own springtime serenade any day now.

Pickerel Frogs

Never in my life as a naturalist have I ever seen as many frogs as I have here in western Massachusetts. They seem particularly abundant right now around ponds, rivers, even dry areas fairly far from water. Among the most common are pickerel frogs, Rana palustris.

I’ve been privileged to encounter several cooperative photographic subjects in the field at places like the High Ledges Wildlife Sanctuary and the Westfield River. One shy specimen hid under the shed at Dave Small’s house in Athol and happily gobbled up moths and other insects that, attracted by his mercury vapor light, fell to the ground beneath.

Pickerel frogs are easily mistaken for leopard frogs, Rana pipiens, the amphibian we all dissected in biology lab. Leopard frogs are identified by their round spots, while pickerel frogs have larger, nearly square blotches. Leopard frogs are in severe decline over much of their geographic range, however, due not to scalpels but to many environmental factors impacting most frogs. Acid rain, draining and filling of wetlands, and fungal disease are among the suspected reasons for their disappearance.

Pickerel frogs seem to be thriving by contrast, at least in my own experience this summer. Western Massachusetts did have an abnormally wet season, though, the wettest on record by some accounts, and there was certainly no shortage of areas for frogs to breed. It was difficult to avoid wet places in fact. Even so, I found many pickerels in perfectly dry (even downright hot) conditions at High Ledges Wildlife Sanctuary.

Male pickerel frogs call for mates by inflating a pair of vocal sacs in beneath their throat. Most references describe the sound they produce as a “snore,” but not having heard one I cannot say for myself. They started breeding from March to early May, before I arrived here.

The female frog lays her eggs in vernal (temporary) pools, usually near rivers or streams, and she is prolific. One egg mass can have from 700 to 3000 ova. Tadpoles can become frogs by the end of the summer, but it takes two years from egg to sexually mature adult.

I have to thank the people of Massachusetts for preserving a great deal of amphibian habitat; and thank the frogs themselves that were kind enough to not hop away too quickly while I fumbled with my camera. They are very photogenic, but perhaps they know that….

Bullfrogs

I haven’t been to the Campus Pond at the University of Massachusetts in many weeks now, but back on June 8 I was treated to a large, very cooperative amphibian as a photo subject during my lunch hour. The bullfrog, Rana catesbeiana, is native here, but elsewhere in North America, where it has been introduced, it might better be called the “bully” frog.

The species is named for the early English naturalist Mark Catesby who explored the southeast United States in the early 1700s, documenting his findings in words and illustrations published as Natural History of Carolina, Florida, and the Bahama Islands. Just like its human namesake, the frog has had “legs” to parts of the world far removed from its native eastern U.S. haunts.

It has, in fact, been those meaty hind legs that have caused the dispersal of the bullfrog around the globe. Prized as a delicacy, frog legs are a staple appetizer on many a restaurant menu. It is far less expensive to harvest the amphibians locally than to import them, so consequently the bullfrog was introduced to various new territories including the western U.S. and British Columbia, Cuba, Jamaica, Mexico, South America, Europe, Asia, even Hawaii.

That humans prey on bullfrogs, along with herons, raccoons, snakes, and other animals, is not enough to mitigate the effects of what the bullfrogs themselves eat: which is nearly anything and everything. Where bullfrogs have been introduced, native wetland fauna can suffer dramatically.

Bullfrogs have been at the least implicated in the decline of the western pond turtle in the Pacific Northwest (they eat the hatchling turtles), the Mexican garter snake in parts of Arizona, New Mexico, and Mexico, and native frog populations in California.

Any animal smaller than the bullfrog is fair game, though, and even tarantulas are on the menu, along with various large insects, small rodents, and birds.

I have a hard time now hearing that deep bass call of “jug-o-rum” without cringing a bit. Every organism surely has its place, but when Homo sapiens extends the boundaries of place for an animal like the bullfrog, all hell can break loose in the aftermath.