• A reservoir species for the emerging amphibian pathogen Batrachochytrium dendrobatidis thrives in a landscape decimated by disease.

      Reeder, N.M.M.; Pessier, Allan P.; Vredenburg, V.T. (2012)
      Chytridiomycosis, a disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is driving amphibian declines and extinctions in protected areas globally. The introduction of invasive reservoir species has been implicated in the spread of Bd but does not explain the appearance of the pathogen in remote protected areas. In the high elevation (>1500 m) Sierra Nevada of California, the native Pacific chorus frog, Pseudacris regilla, appears unaffected by chytridiomycosis while sympatric species experience catastrophic declines. We investigated whether P. regilla is a reservoir of Bd by comparing habitat occupancy before and after a major Bd outbreak and measuring infection in P. regilla in the field, monitoring susceptibility of P. regilla to Bd in the laboratory, examining tissues with histology to determine patterns of infection, and using an innovative soak technique to determine individual output of Bd zoospores in water. Pseudacris regilla persists at 100% of sites where a sympatric species has been extirpated from 72% in synchrony with a wave of Bd. In the laboratory, P. regilla carried loads of Bd as much as an order of magnitude higher than loads found lethal to sympatric species. Histology shows heavy Bd infection in patchy areas next to normal skin, a possible mechanism for tolerance. The soak technique was 77.8% effective at detecting Bd in water and showed an average output of 68 zoospores per minute per individual. The results of this study suggest P. regilla should act as a Bd reservoir and provide evidence of a tolerance mechanism in a reservoir species....
    • Assessing California's Relocation Guidelines for Burrowing Owls Impacted by Renewable Energy Development.

      Hennessy, Sarah McCullough; Wisinski, Colleen; Ronan, Noelle; Gregory, Chris; Swaisgood, Ronald R.; Nordstrom, Lisa A. (California Energy Commission, 2020)
      Once common and widespread throughout the western United States and Canada, the western burrowing owl (Athene cunicularia hypugaea) population has declined to the point where the species is now designated as a Species of Special Concern in California. Their presence in development areas, including renewable energy facilities, necessitates an effective strategy for protecting them. This study is the first of its kind to test both passive and active relocation techniques with burrowing owls and evaluate their relative effectiveness with and without the addition of conspecific cues (such as acoustic playback of owl calls and imitation whitewash to attract the owls)....
    • Beyond masking: Endangered Stephen's kangaroo rats respond to traffic noise with footdrumming

      Shier, Debra M.; Lea, Amanda J.; Owen, Megan A. (2012)
      ... Roads and road margins on and off reserves serve as dispersal corridors and refugia for SKR and other semifossorial taxa; these areas may therefore function as ecological traps if anthropogenic roadway noise negatively affects population persistence.
    • Building a new burrowing owl subpopulation through collaboration and translocation

      Wisinski, Colleen L.; Hennessy, Sarah M.; Marczak, Susanne A.; Mayer, D.; Nelson, T.; Nordstrom, Lisa A.; Rice, K.; Sin, H.; Stevens, Michael T.; Swaisgood, Ronald R. (Virtual, 2021)
      The western burrowing owl (BUOW, Athene cunicularia hypugaea)–a California species of special concern–has experienced range-wide declines, including in San Diego County where only one breeding population remained by the 2010s. As such, local conservation goals include increasing the number of breeding sub-populations to guard against extirpation of BUOW from the county. A working group including government agencies, non-profit organizations, and biological consultants was created to carry out adaptive management and conservation planning in support of these goals. Through a systematic and collaborative effort, we identified Rancho Jamul Ecological Reserve (RJER) as the first site for expanding the BUOW population. Site preparation techniques included vegetation management, targeted enhancement of the California ground squirrel (Otospermophilus beecheyi) population, and retrofitting/installation of artificial burrows. Population viability analysis utilizing 3 years of local demographic data predicted positive population growth from a small initial translocation population, and in 2018, we began translocating BUOW to RJER using a soft-release technique. Over three successive breeding seasons, we documented reproduction and retention of translocated owls, recruitment of their offspring, and recruitment of non-translocated owls. Here, we detail our methodologies and success metrics, and discuss leveraging our collaborative efforts to achieve conservation goals with limited resources.
    • Do postfire mulching treatments affect plant community recovery in California coastal sage scrub lands?

      McCullough, Sarah A.; Endress, Bryan A. (2012)
      In recent years, the use of postfire mulch treatments to stabilize slopes and reduce soil erosion in shrubland ecosystems has increased; however, the potential effects on plant recovery have not been examined. To evaluate the effects of mulching treatments on postfire plant recovery in southern California coastal sage scrub, we conducted a field experiment with three experimental treatments, consisting of two hydromulch products and an erosion control blanket, plus a control treatment….
    • Evaluating the performance of captive breeding techniques for conservation hatcheries: A case study of the delta smelt captive breeding program

      Fisch, Kathleen M.; Ivy, Jamie A.; Burton, Ronald S.; May, Bernie (2013)
      The delta smelt, an endangered fish species endemic to the San Francisco Bay-Delta, California, United States, was recently brought into captivity for species preservation. This study retrospectively evaluates the implementation of a genetic management plan for the captive delta smelt population....
    • Fitness costs associated with ancestry to isolated populations of an endangered species

      Wilder, Aryn P.; Navarro, Asako Y.; King, Shauna N. D.; Miller, William B.; Thomas, Steven M.; Steiner, Cynthia C.; Ryder, Oliver A.; Shier, Debra M. (2020)
      ... The endangered Pacific pocket mouse (Perognathus longimembris pacificus) persists in three isolated populations in southern California. Mitochondrial and microsatellite data indicated that effective population sizes were extremely small (Ne< 50), and continued declines prompted a conservation breeding program founded by individuals from each population....
    • Gopherus agassizii (Desert Tortoise) cohabitation with American badger

      Germano, Jennifer M.; Perry, Lindsey (2012)
      American Badgers (Taxidea taxus) are known predators of juvenile and adult Desert Tortoises as well as their nests (Berry and Duck 2010. Answering Questions About Desert Tortoises: a Guide for People Who Work with the Public. Desert Tortoise Council, Ridgecrest, California. Available online at ). Despite this fact, on 8 August 2011, we observed a badger sharing a caliche cave retreat with an adult male Desert Tortoise in southern Nevada. The badger was seen peering out of the cave before retreating, upon which time some “shuffling” was heard and the tortoise appeared at the cave entrance, apparently unharmed, and proceeded to sit just inside the mouth of the cave. As the tortoise was part of a radio-tracking study, we re- located it a week later and it remained alive and healthy. Though badgers will occasionally kill Desert Tortoises, this observation suggests that they may, at least temporarily, share desert retreat sites with tortoises without antagonistic or predatory behavior. This research is supported by financial assistance from the U.S. Fish and Wildlife Service, Desert Tortoise Recovery Office (Reno, Nevada, USA).
    • Hypothalamic–pituitary–adrenal (HPA) axis function in the California mouse (Peromyscus californicus): Changes in baseline activity, reactivity, and fecal excretion of glucocorticoids across the diurnal cycle

      Harris, Breanna N.; Saltzman, Wendy; de Jong, Trynke R.; Milnes, Matthew R. (2012)
      The California mouse, Peromyscus californicus, is an increasingly popular animal model in behavioral, neural, and endocrine studies, but little is known about its baseline hypothalamic–pituitary–adrenal (HPA) axis activity or HPA responses to stressors. We characterized plasma corticosterone (CORT) concentrations in P. californicus under baseline conditions across the diurnal cycle, in response to pharmacological manipulation of the HPA axis, and in response to a variety of stressors at different times of day....
    • Lead poisoning and the deceptive recovery of the critically endangered California condor

      Finkelstein, M. E.; Doak, D. F.; George, D.; Burnett, J.; Brandt, J.; Church, Molly; Grantham, J.; Smith, D. R. (2012)
      ...California condors were brought to the brink of extinction, in part, because of lead poisoning, and lead poisoning remains a significant threat today. We evaluated individual lead-related health effects, the efficacy of current efforts to prevent lead-caused deaths, and the consequences of any reduction in currently intensive management actions....
    • Proactive conservation management of an island-endemic bird species in the face of global change

      Morrison, Scott A.; Sillett, T. Scott; Ghalambor, Cameron K.; Fitzpatrick, John W.; Graber, David M.; Bakker, Victoria J.; Bowman, Reed; Collins, Charles T.; Collins, Paul W.; Delaney, Kathleen Semple; et al. (2011)
      Here, we discuss conservation management of the island scrub-jay (Aphelocoma insularis), the only island-endemic passerine species in the continental United States, which is currently restricted to 250-square-kilometer Santa Cruz Island, California. Although the species is not listed as threatened by state or federal agencies, its viability is nonetheless threatened on multiple fronts. We discuss management actions that could reduce extinction risk, including vaccination, captive propagation, biosecurity measures, and establishing a second free-living population on a neighboring island....
    • San Clemente loggerhead shrike (Lanius ludovicianus mearnsi) 2010 Studbook

      Grant, Tandora D. (San Diego Zoo Institute for Conservation Research, 2011)
    • Serologic and molecular evidence for testudinid herpesvirus 2 infection in wild Agassiz's desert tortoises, Gopherus agassizii

      Jacobson, Elliott R.; Berry, Kristin H.; Wellehan, James F. X.; Origgi, Francesco; Childress, April L.; Braun, Josephine; Schrenzel, Mark D.; Yee, Julie; Rideout, Bruce (2012)
      Following field observations of wild Agassiz's desert tortoises (Gopherus agassizii) with oral lesions similar to those seen in captive tortoises with herpesvirus infection, we measured the prevalence of antibodies to Testudinid herpesvirus (TeHV) 3 in wild populations of desert tortoises in California. The survey revealed 30.9% antibody prevalence….
    • Social learning in captive African elephants (Loxodonta africana africana)

      Greco, Brian J.; Brown, Tracey K.; Andrews, Jeff R. M.; Swaisgood, Ronald R.; Caine, Nancy G. (2013)
      …Social learning is assumed to be important for elephants, but evidence in support of that claim is mostly anecdotal. Using a herd of six adult female African bush elephants (Loxodonta africana africana) at the San Diego Zoo’s Safari Park, we evaluated whether viewing a conspecific’s interactions facilitated learning of a novel task….
    • The Frozen Zoo

      Ryder, Oliver A. (2012)
      Wildlife gene banks provide a tool for studying species and monitoring conservation efforts
    • Validating methods to determine walking rates of elephants within a zoological institution

      Miller, Lance J.; Andrews, J; Anderson, Matthew J. (2012)
      ...The purpose of the current research was to validate methods for examining the walking rates of elephants in a zoological facility. This included testing GPS units, examining walking rates of eight elephants at the San Diego Zoo Safari Park using collars and conducting trials on a subset of elephants wearing both a collar and anklet outfitted with GPS devices to determine reliability....