By Mark Gutglueck
More than 12,000 ravens living in San Bernardino County’s desert area are most likely doomed if the U.S. Military gravitates, as it seems on a trajectory to do, toward the most efficient method of protecting the Desert Tortoise on and around the six military posts located in the Mojave.
As part of the arrangement the Army, the Navy, the Marines and the Air Force have to utilize land in Southern California, the services individually and collectively have been committed to protecting, to the extent possible, the ecology and environment around their various bases.
One of the most vulnerable species in the Mojave Desert is the desert tortoise. The gravest, most direct and lethal threat to the tortoises are ravens, which are present throughout the desert in massive numbers far in excess to those of the tortoise. Given that there are few other viable remaining habitats for the tortoise, the proliferation of the ravens in the Mojave Desert represents an existential threat to the tortoise.
A report relating to how desert tortoises in the Mojave Desert can be safeguarded was commissioned by the Naval Facilities Engineering Systems Command as well as U.S. Marine Corps Major General A. E. Renforth, the commanding general of the Marine Air Ground Task Force Training Command Marine Corps Air Ground Combat Center headquartered in Twentynine Palms; Captain Troy Searcy, the director of environmental affairs at the Combat Center; Kristina Brown, the deputy director of governmental external affairs at the Combat Center; Captain Jacob Spaulding, the deputy director of the Marine Corps Logistics Base; Stephen Watts, the chief of environmental resources and planning at Edwards Air Force Base; David Housman, the National Environmental Protection Act planner at Fort Irwin; Julie Hendrix, the natural resources specialist/installation biologist at the China Lake Naval Air Weapons Station; Bill Berry, the regional conservation program manager at the Marine Corps Installations West; Thomas Leeman, a wildlife biologist with the United States Fish & Wildlife Service; and Dennis Orthmeyer, the state director of wildlife services with the U.S. Department of Agriculture.
In response, a document was prepared by Stella Acuna along with Jackie Clark, Stephanie Clarke, J. Scott Coombs, Josh De Guzman, Michael Dungan, Doug Gilkey, Paul Radley, Clint Scheuerman, Lisa Woeber and contributors Jesse Martinez, Aaron Hebshi, Ph.D., Vanessa Shoblock and Albert Owen, Ph.D. Their study of the circumstance pertaining to the desert tortoise population, which was released yesterday, November 18, is entitled Programmatic Environmental Assessment for Integrated, Adaptive Management of the Common Raven on Department of Defense Lands in the California Desert.
The six major U.S. Military installations in the Mojave Desert are the Marine Corps Air Ground Combat Center, the Marine Corps Logistics Base, Fort Irwin, the Naval Air Weapons Station China Lake, Edwards Air Force Base and the Chocolate Mountain Aerial Gunnery Range. Those installations fall within parts of or overlap among Kern, Inyo, Imperial, Los Angeles, Riverside, and San Bernardino counties.
The assessment circumscribes the issue and lays out two alternatives for dealing with the threat the ravens pose to the desert tortoise. The first of those calls for a continuation of the existing primarily non-lethal and mostly ineffective raven management strategy, consisting of the flushing of the birds from their coveys and stepping up the level of stress on the birds to discourage and disrupt their nesting and breeding. The second more aggressive and much more likely efficient plan entails the lethal removal of 11,830 to 13,293 ravens initially and 1,477 to 1,715 ravens annually.
According to the assessment, “Over the last three to five decades, raven numbers have increased in much of Southern California and by a factor of 15 in parts of the California desert. In a recent study of bird populations in the Mojave Desert, the raven was the only species shown to have a significant population increase since the early Twentieth Century, while every other native species has shown a decrease. In general, as human communities increase, raven populations increase, taking advantage of resource subsidies that humans inadvertently provide. In 2008, the United States Fish & Wildlife Service and cooperating agencies, including the Department of Defense installations in the western Mojave Desert that are identified in this assessment, prepared an environmental assessment to implement a desert tortoise recovery plan to reduce common raven predation on the desert tortoise. At the time of the 2008 environmental assessment, the United States Fish & Wildlife Service estimated the California desert raven population at 37,500. As of 2021, the United States Fish & Wildlife Service estimates that there are over 100,000 ravens in the California desert. The current raven population in the U.S. is roughly 2.5 million.”
The assessment document continues, “The overpopulation of ravens in both the built and undeveloped areas of the California desert has had several detrimental impacts on the Department of Defense installations within the region. For instance, increased raven numbers result in higher incidences of predation on juvenile desert tortoises. The desert tortoise is the only federally listed species that occurs within the boundaries of all six Department of Defense installations in the California desert, and the Department of Defense is legally obligated by federal law to ensure the species is protected. Ravens are also causing property damage and pose a human health hazard in the built environment, particularly in and around areas where vehicles and aircraft are parked and where Department of Defense personnel must work directly underneath high-use roosting sites.
“One of the primary threats to desert tortoises is extensive raven predation of juvenile tortoises, which are vulnerable to raven predation until they are at least 8 years old,” the assessment document continues. “Ravens had the greatest impact on the mortality of juvenile (less than 2 years old) tortoises released from Department of Defense Headstart programs in the western Mojave Desert.”
The Headstart program consists of an effort by biologists attached to the various military bases in the Mojave Desert to assist in the survival rate of tortoise hatchlings. Since desert tortoises do not reach full maturity until they are 12 years old and remain vulnerable to predation at least until they are nine years old, the Twentynine Palms Combat Center created one of several tortoise research and captive rearing sites. Another was established at the Fort Irwin National Training Center near Barstow. Another was set up at Edwards Air Force Base. Within the captive sites, the young tortoises are protected from the vast majority of threats to their survival.
“In a study of desert tortoises released from the Headstart program at Fort Irwin NTC, of the 23 small juveniles (less than 2 years old) that died, two were confirmed as having been depredated by ravens (shells showed characteristic raven damage or carcasses were located beneath raven nesting or roosting sites), and 16 others were strongly suspected to have been taken by ravens (e.g., tortoise transmitter found under known raven perching sites or near fresh raven footprints),” the assessment document states. “Of 15 tortoises released from the Edwards AFB Headstart Program between 2005 and 2006, the probable cause of death of 8 tortoises was predation, with 7 by ravens that lived in the area. The Edwards AFB Headstart Program also released an additional 120 juvenile tortoises between 2013 and 2018. Of the known mortalities for these 120 juveniles, 45 occurred where the remains were found, and a likely cause of death could be determined with a high degree of certainty. Of these 45 mortalities, 15 (33%) were attributed to ravens based on peck marks and other evidence indicative of raven predation. In total, the Edwards AFB Headstart Program has conducted seven major releases for a total of 299 juveniles released into the wild. Of these 299 juveniles, only 57 are known to be alive (all others are dead or missing). As the numbers above show, raven predation has been a major factor in the mortality rates of small head-started tortoises.”
According to the assessment document, “Unlike ravens, which occur throughout most of the western U.S. and California, the geographic range of the Mojave population of desert tortoise is limited to portions of the Mojave and Sonoran deserts and their population is in decline.”
Beyond their threat to the tortoise, ravens have demonstrated themselves to be an all-around nuisance, the assessment document noted.
“Ravens can have negative economic impacts to agriculture and property,” the document states. “Ravens will eat crops such as grains, nuts, and fruits, and have been implicated in the killing or maiming of small livestock. On Department of Defense installations in the California desert, it is commonly acknowledged that ravens detrimentally impact places they are attracted to, such as: landfills, trash dumpsters, vehicle shade structures, hangars, parking decks, and barracks.”
The birds disingratiate themselves by shitting on everything beneath them, according to the assessment.
“In locations where ravens form large communal roosts in and around built structures on Department of Defense lands, the accumulation of excrement causes economic impacts from damage to military equipment (including but not limited to utility supply equipment, radar equipment, mission testing equipment, and parked vehicles and aircraft) and the personhours that are required to clean these areas,” the assessment document states. “Overpopulation of the raven in the California desert has resulted in human health hazards and potential disease vectors associated with significant build-up of raven excreta in shade structures and hangars and on buildings, dwellings, and other public locations where ravens roost and nest.”
Two paths for dealing with the ravens present themselves, according to the document.
“Under the no-action alternative, current raven management actions, primarily ad hoc and non-lethal, would continue to be conducted piecemeal at the identified Department of Defense installations in the California desert,” the document states. “These current management actions would continue if the proposed action is not selected. Non-lethal management techniques alone do not meet the purpose and need, and Department of Defense installations would continue to experience negative, and increasingly detrimental, impacts to ecological, economic, and health and safety resources from elevated and increasing raven populations. All of these impacts would continue to hinder military readiness.”
On the other hand, according to the assessment document, “Under the proposed action, the Department of Defense would integrate the identified raven management actions on lands owned or used by the Department of Defense in the California desert. Raven management would include non-lethal (subsidy management and unoccupied nest removal) and lethal (age-class specific removals informed by current density estimates and a desert tortoise-common raven conflict threshold) raven management actions to reduce raven populations and activities. Management under the proposed action would be integrative and adaptive. Adjustments in management strategy would be made based on changing numbers and effectiveness of efforts in achieving the purpose and need.”
The pro-active alternative calls for the “lethal removal of 11,830 to 13,293 ravens initially, followed by up to 1,477-1,715 ravens removed annually,” the document states. The birds would be killed by shooting them and by poisoning them with bait left proximate to their nesting grounds. The poisons to be used would consist or a 97 percent concentration of RC-1339, 3-chloro-p-toluidine hydrochloride or carbamylcholine chloride blended into meat or egg baits, without exceeding a maximum single application rate of 5,200 meat or egg baits/acre.
Another lethal means to be contemplated would be to douse eggs in nests with oil, which would have the dual impact of preventing the eggs from hatching while monopolizing the nests, as the parent birds will not dislodge unhatched eggs, such that subsequent laying of eggs producing offspring will be unlikely, lessened or compromised.
According to the assessment document, the non-lethal means consist of using “lasers for hazing” and salting foods the birds naturally gravitate to with substances unpalatable to birds to achieve “conditioned taste aversion.” Other non-lethal means include reduction of the ravens’ food and water availability, removal of perching, roosting, and nesting sites, as well as trapping and removing the birds.
According to the document “both non-lethal and lethal management actions would be implemented by trained personnel, following all applicable requirements and guidelines and per resource protection measures.”
According to the document, the most aggressive protocol contemplated, killing the birds, would result in a “less than significant adverse impacts to the raven population, because the species is overpopulated in the California desert and, at most, four percent of the California population would be removed.” The document states that “Less than significant, and overall, beneficial impacts to desert tortoise and other wildlife species that ravens threaten” would occur.
The Department of Defense and the command of the six military bases in the Mojave Desert are to ultimately determine whether to implement the no-action alternative or the proposed action in whole or part; whether to adopt additional discretionary monitoring and/or discretionary mitigation; whether the analysis presented in the programmatic environmental assessment supports a finding of no significant impacts or requires further analysis in an environmental impact statement; and/or whether to adopt the programmatic environmental assessment in support of the agency decision.
Members of the public have been invited to comment on the environmental assessment and its alternatives, consisting of the plan to kill thousands of ravens at the six military installations in the Mojave Desert or to essentially allow the status quo to persist.
An electronic copy of the draft assessment can be accessed at: www.29palms.marines.mil/Staff-offices/Environmental-Affairs After reaching that page, search in Environmental Assessments to find the document.
The 30-day public review period began yesterday, November 18, 2021, and electronic or written comments concerning the proposed action will be accepted through December 18, 2021.
Comments may be submitted via email to jesse.w.martinez1@navy.mil or by mail c/o Cardno Government Services, Attention Jesse Martinez, 3888 State Street, Suite 201, Santa Barbara, CA 93105.