After years of lawsuits, court rulings, studies and allegations, the U.S. Fish and Wildlife Service (USFWS) this week declared the Mexican and narrow-headed garter snakes as threatened species.
The USFWS also listed about 240 miles of streams and 620,000 acres as critical habitat.
The areas considered essential to the survival of the two stream-dwelling, fish-frog-lizard eating snakes include portions of Tonto Creek and the Verde River.
In all, the once common snakes have lost about 90 percent of their range. On top of that, about 80 percent of the surviving populations probably can’t hold out much longer, the Fish and Wildlife Service concluded in listing the reptiles.
The listing doesn’t affect what people do on private property, but does require the federal government to consider the possible impact on the species of not only its own activities — but also any activity it permits on federal land. That would include things such as allowing Payson to build the Blue Ridge pipeline and granting grazing leases on federal land.
The decline of the two water-loving snakes is linked to the invasion of outside species like bullfrogs, crayfish and bass. They remain like a scaly canary in the coal mine when it comes to signaling the demise of the Southwest’s most endangered habitats — streams.
An estimated 90 percent of the riparian areas in Arizona have been destroyed or degraded as a result of dams, water diversions and groundwater pumping.
The listing announced this week proposed 421,000 acres of critical habitat for the northern Mexican garter snake, including 912 miles of stream. The listing included 210,000 acres of critical habitat for the narrow-headed garter snake, including 1,503 miles of stream.
Despite the dramatic declines in the populations and spread of the two snakes, it took a decade of struggle to force the USFWS to list the snakes and the critical habitat. The Center for Biological Diversity had to fight the USFWS in court since 2003 to force the listing.
After several lawsuits, USFWS designated the northern Mexican garter snake as a “candidate” species in 2008, which provoked another appeal from the Center. Then in 2011, the USFWS agreed to issue protection decisions for 757 species before the end of 2014, including the rare garter snakes, found in Arizona, New Mexico and Mexico. Many of the 757 species had for years lingered in the limbo of a “warranted but precluded” category, which means USFWS agreed the species were probably endangered but insisted it didn’t have the money to do the studies needed to make it official.
“These two snakes have been in trouble for years, so I’m glad they’re finally getting the protection they desperately need to survive,” said Collette Adkins Giese, an attorney for the Center. “Protecting these snakes and their beleaguered habitat in the Southwest will benefit every other animal that depends on these river systems.”
USFWS Arizona Field Supervisor Steve Spangle said “many Americans’ earliest outdoor recollections include memories of frogs and garter snakes at a family swimming hole. Taking care of these Southwestern critters and habitats today may guarantee our kids and grandkids can have such important experiences.”
The narrow-headed garter snake grows to about 34 inches long and lives mostly in clear, rocky, higher-elevation streams along the Mogollon Rim from northern and eastern Arizona into southwestern New Mexico. It feeds on native fish species and even trout, but struggles to compete against introduced species like bass, catfish and bullfrogs. The snake gives birth to 20-30 live young a year, but the tiny snakes quickly fall prey to introduced predators like bullfrogs.
The northern Mexican garter snake faces similar challenges, although it grows up to 44 inches long. The snakes live in wetlands and brushy riparian areas with pools and backwaters, including portions of Tonto Creek and the upper and middle Verde River. An unknown number of the snakes also live in Mexico, but USFWS concluded that almost everywhere their populations are “tenuous.”
The listing noted that stock ponds maintained by ranchers can easily provide critical habitat for the snakes, which hunt the fish and frogs drawn to those water sources. The listing included a special rule that will exempt landowners operating such stock ponds on federal land from getting in trouble if their federally permitted actions or the actions of their cattle result in the “harassment” or death of the snakes.
“Livestock operations do not pose a significant threat to either garter snake. In fact, many ranchers have created and maintain habitat for northern Mexican garter snakes,” said Spangle. “In 2002, we provided regulatory flexibility for livestock operators at threatened Chiricahua leopard frog waters. Their resulting stewardship has netted remarkable recovery advances for the frog — we anticipate similar results for the garter snake.”
However, studies have shown that cattle can have dramatic effects on riparian areas if their access is not limited — especially in the spring when the cattle eat the green shoots of keystone plants like cottonwood and willow saplings. Cattle also can trample and wallow in a stream, making it wider, warmer and full of silt.
Giese, with the Centers, said the listing will provide one more legal hook on which to hang protection of the state’s remaining riparian areas.
“The decline of these snakes is symptomatic of widespread declines in the aquatic fauna across the Southwest. These snakes depend on native fish and amphibians as prey and the widespread loss of these snakes and their prey reflects a severe collapse of the food web in Southwest rivers and streams.”
On the other hand, the presence of threatened and endangered species and their designated critical habitat can also produce headaches for landowners and local agencies.
For instance, Payson paid for an environmental assessment of its Blue Ridge pipeline project. The consultants found no endangered species in the East Verde River that would be affected, but noted that critical habitat for both Mexican spotted owls and Chiricahua leopard frogs lay within a mile of the stream. That resulted in a series of questions posed by a Tonto National Forest biologist that delayed the start of construction on the project for four months or more.