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Image of a Sonoran desert tortoise
Credit: By U.S. Fish and Wildlife Service [Public domain], via Wikimedia Commons

This week, a story by Elizabeth Perez in Pulse Headlines caught my eye. In her piece, Sonoran Desert Tortoise is no longer listed as Endangered Species, she reported the following:

The U.S. Fish and Wildlife Service (USFWS) announced on Monday, October 5th, 2015 that the Sonoran Desert Tortoise is no longer on the Endangered Species List. What this means is that the USFWS has determined (based on seven years of monitoring) that the risks and threats to the tortoise "are not serious enough" to classify them endangered or threatened for a span of 10 years.

The New York Times article Desert Tortoise No Longer Candidate for Federal Protection by The Associated Press quoted USFWS spokesman Jeff Humphrey:

"We and our federal and state partners will continue to monitor the tortoises. However the current modeling in science demonstrates that there's virtually no probability of extinction over the next decade."

Current estimates put the number of adult desert tortoises (in the U.S. and Mexico) between 470,000 to 970,000.

But endangered species advocates and environmentalists were not pleased with this decision. And Taylor Jones, M.S., Endangered Species Advocate with WildEarth Guardians promised to "look closely at this decision" and whether local and federal organizations will continue to protect the desert tortoise. They haven't ruled out taking legal action.

Obviously, it's crucial that voluntary conservation agreements provide adequate protection for formerly endangered or threatened species. And, it's important that any guidelines or agreements are enforceable.

Desert Tortoise
Credit: Ken Bosma (kretyen on flickr) / Licensed under Creative Commons Attribution 2.0 Generic

Questions and Answers

The 2015 12-month Finding For the Sonoran Desert Tortoise

I decided to take a look at the press release from the USFWS Arizona Ecological Services Field Office. And here's the gist:

The Sonoran desert tortoise has been a candidate for ESA protection since December 2010, however its candidate status is being withdrawn.

Six risk factors were addressed regarding the tortoise’s status to arrive at this decision. I wanted to understand how they arrived at this conclusion, so I added additional information beside each one listed:

Altered Plant Communities or Habitat: Since Sonoran desert tortoises are herbivores, they eat fresh, dried or remnant plants (annuals, perennials, and plant litter).

Altered Fire Regimes: In order to understand this, I looked at Invasive Plants that Alter Fire Regimes in the Deserts of North America. In short, fire regimes are patterns of "burning" in relation to time (seasonality), space, and magnitude (severity). It's key to note that plant invasion changes how fires are fueled and native species usually suffer as a result.

Habitat Conversion of Native Vegetation for Development (such as agriculture, residential, and – I assume – commercial use).

Habitat Fragmentation: It's obvious that the more humans encroach on a formerly protected region, the more likely a habitat will become sparse. In turn, it becomes more difficult for species to find mates and reproduce (as well as difficulty in finding food and shelter). Often, species are more at risk to be killed by predators (or even vehicles), since their protective environments have been eroded or altered.

Human-tortoise Interactions: Roadways, housing, buildings, traffic and humans (in general) can cause a host of problems to numerous species and their native habitat.

Climate Change: Unfortunately, there isn't a lot that can be done about this. However, protecting terrain that provides shade or protection from the elements is probably key to the survival of species most at risk.

Desert Tortoises (presumed)
Credit: shankar s. (shankaronline on flickr) / Licensed under Creative Commons Attribution 2.0 Generic

Concerns and Additional Information

Initially, I felt not enough was known about these lovely tortoises. Another reason is that their population estimates seem rather broad (which tells me it's been difficult to follow and document these wonderful creatures). Notably, the Arizona Ecological Services Field Office report states:

"Geospatial analysis estimates there are presently 470,000 to 970,000 adult desert tortoises rangewide on approximately 38,000 square miles (24 million acres or 9.8 million hectares) of potential tortoise habitat (64% in the U.S. and 36% in Mexico)."

I'm also worried that precious habitat will be lost to commercial, agricultural, or housing developments. And these tortoises rely on the protection of burrows, rocky dens or crevices. 

Fortunately, I read the following in their Questions and Answers section (end of page 3):

"The Sonoran desert tortoise continues to be classified as a Species of Greatest Conservation Need by the Arizona Game and Fish Department and is listed under the Mexican equivalent to the Endangered Species Act as threatened. The collection of wild Sonoran desert tortoises in the United States remains prohibited."

And even though a lot can happen in 10 years, it's comforting to know that information regarding any potential threats to these tortoises can be submitted to Arizona's Ecological Services Office Field Supervisor at 2321 West Royal Palm Road, Suite 103, Phoenix, AZ 85021–4951.

Up next is The Arizona Game and Fish Department's study site (northeast of Phoenix) where Sonoran desert tortoises have been monitored since 1991. More recently, their "Turtles Project" is conducting a "first of its kind" study on juvenile tortoises. The video producer was David Majure.

I found it amusing and brilliant how the researchers used a simple tin can to check out the tortoises and prevent them from walking away. NOTE: If for some reason, the video isn't displayed below, here is a direct link to it: Tracking Tortoises

Tracking Tortoises by Arizona GameAndFish

Published on October 2nd, 2013

Sonoran desert tortoise
Credit: By U.S. Fish and Wildlife Service [Public domain], via Wikimedia Commons
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