Progress 10/01/10 to 09/30/15

Outputs
Target Audience:Efforts were targeted to California citizens interested in natural resource conservation, public school children, public and private agencies tasked with managing natural resources, and other scientists. Targeted groups included the US Bureau of Land Management, the US Fish and Wildlife Service, the US National Park Service, the National Park Trust, California Department of Fish and Wildlife, California Energy Commission, BrightSource Energy LLC, Chevron Environmental Management Corporation, and a local primary school from both Baker, CA and Henderson, NV, among other groups. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?I trained three doctoral graduate students, Melia G. Nafus, J. Mark Peaden, and Max Kern, and one master's graduate student, Jacob Daly, on the project. Melia Nafus completed her dissertation under my supervision in 2014 and currently works as a postdoctoral research associate for San Diego Zoo Global. The other three students continue to work with me. I also trained three Junior Specialists on the project, J. Mark Peaden, Lindsay Chiquoine, and Val Johnson. I hosted an outreach/educational event September, 2014, with the Mojave National Preserve and National Park Trust to educate 4th and 5th grade public school children. In February 2013 we hosted a fieldtrip to our study site and described our research to participants of the 38th Annual Meeting and Symposium of the Desert Tortoise Council. Additionally, I have taken part in workshops with the US Fish and Wildlife Service and shared results of our work at multiple professional development workshops/scientific conferences (see products, above). How have the results been disseminated to communities of interest?I, my graduate students, and my colleagues on this project have presented results of our work from this project to scientific audiences at numerous scientific conferences (see products above). I presented a webinar to the California Energy Commission that was attended by members of the California Energy Commission and the US Fish and Wildlife Service November 2013. I took part in an outreach activity to provide an overview of our project to a diverse group of shareholders in September 2014. This activity included a guided tour and speaking engagements and included members of the US National Park Service, Chevron Environmental Management Corporation, MolyCorp, 4th and 5th grade students from Baker, CA and Henderson, NV, the non-profit National Park Trust, interested local citizens in Southern California, and a few policy makers and regional politicians. I have also published several articles in scientific journals during this period, and provided a publicly-available final report of our research to the California Energy Commission (see products, above). What do you plan to do during the next reporting period to accomplish the goals?I have several manuscripts in review at the moment to continue sharing our work with the broader scientific community. Additionally, I have upcoming conferences with relevant stakeholders to continue disseminating our research findings to the appropriate natural resource management communities. Finally, we have made some changes to our research methods to test new hypotheses that could provide interesting/relevant results to better promote recovery of this threatened California species.

Impacts
What was accomplished under these goals? Project Purpose This project evaluated the effectiveness of head-starting as a mitigation tool for helping desert tortoise populations recover. Desert tortoises have low survival as juveniles, are long lived, slow growing, and can take 15-20 years to reach sexual maturity and begin reproducing. Methods that increase survival and growth rates of juveniles may enhance opportunities to recover declining populations and mitigate potential declines of tortoises from proposed development. This project also studied the habitat selection of free-ranging juvenile desert tortoises shortly after release to better understand their habitat and resource preferences on the landscape. This new knowledge would help locate new renewable energy projects (or any land disturbing activities) in a manner that avoids damaging this important habitat. Project Results Head-starting juvenile desert tortoises in semi-natural outdoor enclosures with added water from sprinklers and protection from predators greatly increased their growth and survival relative to free-ranging tortoises that were released and monitored in the field. Although predation is suspected to be high on young tortoises, the results suggest that the added benefit of head-starting at this site was from supplemental rain more than from protection from predators. Added water availability promotes greater plant growth and more opportunities for drinking, foraging, and other activity in outdoor enclosures. More deaths of free-ranging direct release animals were attributed to exposure or desiccation than predation. Previous research suggests that juvenile tortoise survival increases and approaches that of adults when their carapace (the upper shell) reaches a length of 105 mm. The current study suggests that animals could reach this size in as little as 5.5 years after hatching with supplemental rainfall and without additional food supplements. Nevertheless, there was some indication that releasing even smaller juveniles in captivity for at least six months maintained a size advantage and had greater survival than younger animals released immediately after hatching. Ultimately, however, if the goal is to promote high survival of captive-raised animals after release, the results suggest that animals should not be released in their first three years of life when their carapace is still shorter than 105 mm. Monitoring habitat selection by free-ranging juvenile desert tortoises identified several habitat characteristics important to juvenile tortoises. Juvenile tortoises strongly preferred areas where perennial plants (that live longer than one year) were nearer and covered more of the ground surface. Juvenile tortoises also selected areas that were closer to washes and had more washes within 5 meters of their locations. Juvenile tortoises were far more likely to use areas with more nearby small mammal burrows, and these areas tended to be associated with more creosote bush shrubs than white bursage shrubs. Creosote bush seeds are eaten by many small mammals, which in turn have extensive burrow networks that juvenile tortoises use to create their own resident burrows. Creosote bush is among the largest of the common perennial plant species in much of the Mojave Desert, providing shade from excessive temperatures and and cover from visual predators. They also support more annual plants beneath their canopies, which in turn may provide greater foraging opportunities for growing juvenile tortoises. Project Benefits This project successfully demonstrated the value of a US Fish and Wildlife Service-prescribed recovery action that can be used to recover and mitigate declines of desert tortoises. This work showed the effectiveness of head-starting to improve growth and survival of juvenile desert tortoises. This mitigation tool can be used to temporarily increase the population size of desert tortoises in areas that have been negatively affected or to offset losses expected from new energy development. Given the low survival of free-ranging juvenile desert tortoises, if populations are left alone and unaided, few juvenile tortoises will likely survive to adulthood, so recovery of depleted populations will be unlikely or, at best, take decades. Instead, prudent use of head-starting may facilitate recovery by producing larger or hardier juvenile tortoises that may better survive raven attacks or the harsh environment and so have a greater chance of reaching reproductive age when released at larger sizes. For the future, it is imperative to fully assess the long-term benefits and survival of juvenile tortoises released at larger sizes, but early results are promising. A second benefit of this project is the important information gained about juvenile desert tortoise habitat requirements. Juveniles are rarely encountered and so are poorly studied, creating an important knowledge gap in understanding tortoise ecology. Information about the habitat requirements of juveniles is essential to preserve the species as required by law. By focusing on habitat selection of desert tortoises, this study provides project planners and wildlife agencies with better information about targets for pre-construction clearance surveys and habitat restoration in mitigation efforts, and it is can also help identify sites for future release of head-started juvenile tortoises. Combining new knowledge about head-starting and habitat selection has direct potential benefits for facilitating renewable energy development. The project findings could potentially expedite the permitting of solar energy facilities, by enabling the siting of projects in lower value tortoise habitat and providing a tested mitigation option for remaining impacts. This could also improve the perception of renewable energy technology and lower project costs because of faster permitting.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2011 Citation: Todd BD. 2011. Public workshop on desert research projects funded by the Public Interest Energy Research Program, California Energy Commission, Sacramento, CA. January, 2011.
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Buhlmann KA, Tuberville TD, Nafus MG, Peaden JM, Todd BD. 2013. Desert tortoise head-starting project in Mojave National Preserve: an update. 38th Annual Meeting and Symposium of the Desert Tortoise Council, Las Vegas, NV. February, 2013.
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Nafus MG, Tuberville TD, Buhlmann KA, Todd BD. 2013. Differential habitat use by female desert tortoises (Gopherus agassizii) in relation to forage availability. 38th Annual Meeting and Symposium of the Desert Tortoise Council, Las Vegas, NV. February, 2013.
• Type: Conference Papers and Presentations Status: Published Year Published: 2013 Citation: Nafus MG, Todd BD, Tuberville TD, Buhlmann KA. 2013. Differential habitat use by female desert tortoises (Gopherus agassizii) in relation to forage availability. Annual Joint Meetings of Ichthyologists and Herpetologists, Albuquerque, NM. July, 2013.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Buhlmann KA, Tuberville TD, Nafus MG, Peaden JM, Johnson V, Todd BD. 2014. Movements and survivorship of hatchling and head-started desert tortoises. 12th Annual Symposium on the Conservation and Biology of Tortoises and Freshwater Turtles, Turtle Survival Alliance, Orlando, FL. August, 2014.
• Type: Conference Papers and Presentations Status: Published Year Published: 2015 Citation: Buhlmann KA, Tuberville TD, Nafus MG, Peaden JM, Chiquoine L, Daly J, Johnson V, Todd BD. Survivorship and growth of predator-protected vs free-ranging released juvenile desert tortoises in the Mojave National Preserve. 40th Annual Meeting and Symposium of the Desert Tortoise Council, Las Vegas, NV. February, 2015
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Nafus MG, Germano JM, Perry JA, Todd BD, Walsh A, Swaisgood RR. 2015. Hiding in plain sight: a study on camouflage and habitat selection in a slow-moving desert herbivore. Behavioral Ecology 26(5):1389-1394.
• Type: Journal Articles Status: Published Year Published: 2015 Citation: Nafus MG, Todd BD, Buhlmann KA, Tuberville TD. 2015. Consequences of maternal effects on offspring size, growth, and survival in the desert tortoise. Journal of Zoology 297:108-114.
• Type: Other Status: Published Year Published: 2015 Citation: Todd BD, Tuberville TD, Buhlmann KA. Innovative mitigation of solar energy impacts on desert tortoises: head-starting and habitat selection of juvenile desert tortoises. Final Project Report, Energy Research and Development Division, California Energy Commission, Sacramento, CA. April 2015.

Progress 10/01/13 to 09/30/14

Outputs
Target Audience: Efforts in this period were targeted to California citizens interested in natural resource conservation, public school children, public and private agencies tasked with managing natural resources, and other scientists. Such groups included the US Bureau of Land Management, the US Fish and Wildlife Service, the US National Park Service, the National Park Trust, California Department of Fish and Wildlife, California Energy Commission, BrightSource Energy LLC, Chevron Environmental Management Corporation, and local primary school from both Baker, CA and Henderson, NV. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? Melia Nafus successfully completed her dissertation under my supervision and training and transitioned to a new position as a researcher working for San Diego Zoo Global Conservation Institute. I continued supervision and training of a graduate student (J. Mark Peaden) on this project. One employee (Valerie Johnson) completed her training and employment on this project and is now pursuing other opportunities. A new employee (Lindsay Chiquoine) began training and working on this project in summer 2014 as a staff technician collecting data. How have the results been disseminated to communities of interest? I a graduate student (J. Mark Peaden) both presented overviews of work conducted on this project to scientific audiences at two international conferences in the summer of 2014. I presented a webinar to the California Energy Commission that was attended by members of the California Energy Commission and the US Fish and Wildlife Service November 2013. I took part in an outreach activity to provide an overview of our project to a diverse group of shareholders in September 2014. This activity included a guided tour and speaking engagements and included members of the US National Park Service, Chevron Environmental Management Corporation, MolyCorp, 4th and 5th grade students from Baker, CA and Henderson, NV, the non-profit National Park Trust, interested local citizens in Southern California, and a few policy makers and regional politicians. What do you plan to do during the next reporting period to accomplish the goals? We will analyze the data that we have collected to determine the efficacy of head-starting juvenile tortoises. We will also analyze data to better understand habitat selection by juvenile desert tortoises to inform conservation planning for potential development of desert habitats in the Mojave Desert Region of southern California.

Impacts
What was accomplished under these goals? We completed three years of working with hatchling and juvenile tortoises produced as part of our long-term study on captive rearing and headstarting of juveniles on this project. We completed collecting data from several years of habitat use of juvenile tortoises released on this project. We also completed collecting data on the growth and survival of juvenile tortoises both released and held captive in outdoor enclosures. We are currently analyzing these data to evaluate habitat use and selection by these animals and to evaluate survivorship and growth of these animals. This work was partly funded by the California Energy Commission and we will spend the next year writing reports for the funding agency and producing two publications to be submitted to peer-review scientific journals.

Publications

• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Todd BD, Peaden JM, Nafus MG, Buhlmann KA, Tuberville TD. 2014. Quantifying road effect zones for desert tortoises (Gopherus agassizii) to estimate benefits of mitigation and habitat protection. Joint Meetings of Ichthyologists and Herpetologists. Chattanooga, TN. July 30-August 3, 2014.
• Type: Conference Papers and Presentations Status: Published Year Published: 2014 Citation: Peaden JM, Todd BD, Nafus MG, Buhlmann KA, Tuberville TD. 2014. Quantifying road effect zones for desert tortoises (Gopherus agassizii) to estimate benefits of mitigation and habitat protection. Joint Meetings of Ichthyologists and Herpetologists. Orlando, FL. August 4-7, 2014.

Progress 01/01/13 to 09/30/13

Outputs
Target Audience: Efforts in this period were targeted to California citizens interested in natural resource conservation, public and private agencies tasked with managing natural resources, and other scientists. Such groups included for example the US Bureau of Land Management, the US Fish and Wildlife Service, the US National Park Service, the National Park Trust, California Department of Fish and Wildlife, California Energy Commission, BrightSource Energy LLC, and Chevron Environmental Management Corporation. Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided? I trained a doctoral student in analyzing, writing, and publishing scientific research. I also trained two technical specialists in the field methodology of our study, including radio-telemetry, statistical analysis, and data collection and management. I took part in a workshop (listed above) to share information with other researchers working in my arena on the head-starting and captive rearing of threatened desert tortoises. How have the results been disseminated to communities of interest? I have participated in a workshop with other stakeholders involved in similar research. I have also coauthored two talks given to national/international audiences that included many private and public stakeholders as well as other scientists (see above). I have provided written quarterly reports to one funding agency, the California Energy Commission. I have also provided an annual report to the California Department of Fish and Wildlife and the US Fish and Wildlife Service updating them on our research activity with this state- and federally listed species. What do you plan to do during the next reporting period to accomplish the goals? We plan to continue our field research and data collection. We also expect to analyze data and prepare several additional manuscripts for submission to peer-reviewed journals to disseminate our results to the broader scientific community.

Impacts
What was accomplished under these goals? In the activity period we continued to track adult females and produce another annual cohort of hatchlings for use in the study (now at three cohorts total). We released additional juvenile desert tortoises to track them in the wild for use in studying their habitat use, growth, and survival in the wild and for comparison with captive-held animals being reared at the head-starting facility. We determined that not only is survival significantly greater when animals are retained in the captive rearing facility, but the added supplemental water facilitates significantly greater growth in captive animals than in animals released directly into the wild upon hatching.

Publications

• Type: Journal Articles Status: Published Year Published: 2013 Citation: Nafus MG, Tuberville TD, Buhlmann KA, Todd BD. 2013. Relative abundance and demographic structure of Agassizs desert tortoise (Gopherus agassizii) along roads of varying size and traffic volume. Biological Conservation 162:100-106.

Progress 01/01/12 to 12/31/12

Outputs
OUTPUTS: During 2012 we hand-captured, tagged with VHF radio-transmitters, and followed 29 female desert tortoises in the Ivanpah Valley of the Mojave National Preserve. Of these 29 females, 2 were killed by predators during the year. A total of 25 tortoises were brought into our outdoor captive enclosures to nest, and of these, 23 successfully laid eggs before they had to be released at their original point of capture within 30 days of being brought into the enclosures. Of these 23 nests, 103 total eggs were laid and 81 of these eggs hatched. Of the 81 that hatched, 9 died shortly after hatching due to adverse environmental conditions and developmental problems, leaving 72 viable hatchlings in 2012. We outfitted 12 of these hatchlings with radio transmitters and released them in October 2012 to begin studying their habitat use and survival in the areas where their mothers live. We also released 6 one-year old animals that had been held captive since hatching in 2011. Thus, we are currently tracking the habitat use and survival of 6 one-year old hatchlings from 2011 and 12 new hatchlings from 2012. We currently have 33 one-year old animals from 2011 and 60 new hatchlings from 2012 that are being kept captive in outdoor enclosures and being provided with supplemental rainfall at high and low levels to study ways to increase their growth in their early years. We coordinate with the California Energy Commission (CEC) to share our progress on a quarterly basis. We also submitted a yearly report to the California Department of Fish and Wildlife, the National Park Service Mojave Preserve, and the US Fish and Wildlife Service to update them on our research and ongoing results. In October 2012 I met with Chevron Environmental Management Corporation, the National Park Service Mojave Preserve, and the National Park Trust Foundation to update them on the progress of our work. They filmed me, one of my students, and one of my technicians in a series of interviews that was then edited and shared online on YouTube.com. In February 2013 we shared our progress and current results with the broader community of biologists at the Desert Tortoise Council meetings in Las Vegas. This audience included many federal and state agency biologists, environmental consultants, academic biologists, and members of the public. PARTICIPANTS: (c) Brian Todd was the lead PI on the project. UC Davis Ecology Graduate Group doctoral student Melia Nafus received training in field research, experimental design, handling of a state- and federally-threatened species, and training in writing and grantsmanship on this project. UC Davis Junior Specialist John Mark Peaden received training in field research, experimental design, and handling of a state- and federally-threatened species on this project. We collaborated with University of Georgia Research Scientists Drs. Tracey Tuberville and Kurt Buhlmann on this project. We coordinated with the California Energy Commission, the US Fish and Wildlife Service's Desert Tortoise Recovery Office, the US National Park Service Mojave National Preserve's Science Advisor Debra Hughson, Chevron Environmental Management Company, BrightSource LLC, and the National Park Trust to conduct the work. TARGET AUDIENCES: (c) We work to produce high quality results that inform the California Energy Commission and renewable energy developers who want to minimize disruption/impacts to local populations and ecosystems when installing and operating desert renewable energies or who wish to mitigate for negative local effects by improving management of species and communities in unaltered systems elsewhere. Our results and data are also shared with the US Fish and Wildlife Service and California Department of Fish and Wildlife, both of whom are interested in the preservation and recovery of this threatened species, the Mojave Desert Tortoise. Finally, our target audience also includes members of the general public interested in the environmental issues of renewable energy and its impacts to local habitats and communities. I gave a radio interview that aired on Davis, CA local radio station KDVS in 2012. I, Mark Peaden, and Melia Nafus also gave interviews that were produced into a video segment that was uploaded to YouTube.com to provide an overview of our work. PROJECT MODIFICATIONS: a) Not relevant to this project

Impacts
Our work has continued to demonstrate that captive care of young tortoises in outdoor enclosures can contribute to high survival during the important vulnerable early years of a tortoise's life. These findings so far indicate that the use of head-starting, that is, protection of juvenile tortoises for release later as larger adults, may be a viable strategy for recovery of this declining and protected species. This is important given that the federal recovery plan has prescribed this method as one means of recovering declining tortoise populations to reach eventual delisting of the species from the Endangered Species Act. Our early results also suggest that greater supplemental "rainfall" in the form of sprinklers in the outdoor enclosures may facilitate quicker growth and thus earlier release and shorter captivity of these animals in an attempt to maximize their contribution to wild populations. Our work with nesting females in outdoor enclosures continues to demonstrate that this is a viable way to incubate eggs and produce hatchling tortoises for use in the research and for eventual use as a recovery tool for the desert tortoise.

Publications

• Publications are currently in preparation due to the research program still being in its early stages. 2012

Progress 01/01/11 to 12/31/11

Outputs
OUTPUTS: During 2011 we hand-captured, tagged with VHF radio-transmitters, and followed 15 female desert tortoises in the Ivanpah Valley of the Mojave National Preserve. We allowed them to nest in our outdoor captive enclosures and produced 25 hatchling tortoises that are being maintained in predator-proof outdoor enclosures. We are coordinating with the California Energy Commission (CEC) to share our progress and results with other researchers and we provided an overview of our project and it's relation to renewable energy development in California Deserts at a CEC meeting in Sacramento in January 2011. PARTICIPANTS: Brian Todd was the lead PI on the project. UC Davis Ecology Graduate Group doctoral student Melia Nafus received training in field research, experimental design, handling of a state- and federally-threatened species, and training in writing and grantsmanship on this project. We collaborated with University of Georgia Research Scientists Drs. Tracey Tuberville and Kurt Buhlmann on this project. We coordinated with the California Energy Commission, the US Fish and Wildlife Service's Desert Tortoise Recovery Office, and the US National Park Service Mojave National Preserve's Science Advisor Debra Hughson to conduct the work. TARGET AUDIENCES: We work to produce high quality results that inform the California Energy Commission and renewable energy developers who want to minimize disruption/impacts to local populations and ecosystems when installing and operating desert renewable energies or who wish to mitigate for negative local effects by improving management of species and communities in unaltered systems elsewhere. Our results and data are also shared with the US Fish and wildlife Service and California Department of Fish and Game, both of whom are interested in the preservation and recovery of this threatened species, the Mojave desert tortoise. Finally, our target audience also includes members of the general public interested in the environmental issues of renewable energy and its impacts to local habitats and communities (we gave a radio interview in 2011 that aired on local radio station KDVS in 2012). PROJECT MODIFICATIONS: Not relevant to this project.

Impacts
We identified that many of these adult tortoises frequently cross roadways and move along roads. We also identified recent remains of 2 tortoises that had been hit and killed on the main road running through the preserve. These findings indicate that future mitigation strategies aimed at improving long-term persistence of the tortoise population must consider adult mortality and possible ways of reducing road kills in addition to repatriating the population with head-started juveniles. Our findings so far also indicated that allowing females to nest in outdoor enclosures and allowing nests to incubate in situ as they were laid results in high juvenile hatching success (>90%), thus pointing out that it is a viable strategy moving forward in our work.

Publications

• No publications reported this period