Chiricahua leopard frog (Lithobates chiricahuensis)
Cassidi Cobos, Carter Kruse, Magnus McCaffery
Ladder Ranch, NM
US Fish & Wildlife Service
New Mexico Department of Game & Fish
Dr. Jamie Voyles (UNR)
Range-wide decline of CLF is due to a suite of factors, including disease, invasive species, habitat degradation and loss, and increased severity/ duration of drought.
- Listed as threatened under ESA in 2002
- Listed as a Species of Greatest Conservation Concern in New Mexico
We aim to work in partnership with the CLF Recovery Team to achieve range-wide recovery that results in the delisting of the species from the ESA.
Population Objective – Over the next 10 years, we will ensure CLF occupancy of at least 70% of suitable lentic habitats in at least two major drainages on the Ladder Ranch to maintain a minimum of two CLF populations (comprised of >1 subpopulations) on the Ladder Ranch. At least one subpopulation in each drainage will exhibit a geometric mean growth rate over a five-year period of λ ≥1.0.
Habitat Objective – To indefinitely monitor and manage natural wetlands, stock-water pond habitats, and stream channels in at least two major drainages on the Ladder Ranch (e.g. Seco and Las Palomas creeks) to provide high quality and secure overwintering, breeding, foraging, and dispersal habitat that meets the life history requirements of all life stages of CLFs in to support viable populations on the Ladder Ranch.
Captive Breeding Objective – Over the next 10 years, and in coordination with the USFWS, we will hold adult CLFs from up to nine populations from across the species’ range in the captive Ladder Ranch ranarium facility. Adults from each population will be held in isolated population-specific cages and managed to promote breeding. All viable egg masses produced will be managed to optimize successful tadpole emergence, and tadpoles will be reared to late tadpole stage (Gosner 30+) prior to transference to suitable habitat or other captive holding facilities in coordination with the USFWS to assist with this agency’s range-wide species recovery objectives.
Captive Holding Objective – Over the next 10 years, we will coordinate with the USFWS to hold captive CLFs from any location within the species’ range in up to five artificial refugia sites on the Ladder Ranch (i.e. stock tanks, that will conserve genetically or geographically unique stocks of CLFs in peril (i.e., habitat destruction and disease), or CLFs that require a temporary relocation for their survival (e.g. during a drought that dries a stock tank, a population threatened by ash or sediment flow). Refugia may also serve as a source of egg masses, tadpoles, and adult CLFs for translocation to recovery sites, for augmentation, or to repopulate habitats after environmental disasters. Surplus CLFs from these facilities may also be used for research purposes.
Research Objective – Over the next 10 years, we will work collaboratively with state, federal, and/or academic partners to design and carry out work on at least one research/monitoring project on the Ladder Ranch per year, to inform and support CLF recovery actions and adaptive management. Results from these studies will be used in reports and/or submitted for peer-reviewed publication.
Supporting Rationale for Objectives
The 62,950 ha Ladder Ranch in Sierra County, NM is recognized in the federal CLF recovery plan as an area with a high potential for successful recovery actions, and as such is designated as a CLF Management Area within Recovery Unit (RU). The ranch supports a large CLF population in both natural wetlands and artificial stock water sites. For the frog to be considered for delisting, the recovery plan mandates that each RU has: (1) at least two CLF metapopulations located in different drainages and at least one isolated population, that exhibit long-term persistence and stability; (2) aquatic breeding habitats that are protected and managed; (3) the additional habitat required for population connectivity, recolonization, and dispersal is protected and managed, and that (4) causes of decline have been reduced or eliminated, and commitments to long-term management. Specific actions to achieve recovery include: (a) protecting remaining populations; (b) identifying and managing currently unoccupied sites and establishing new populations; (c) augmenting populations; (d) monitoring populations; (e) implementing research to support recovery actions and adaptive management
TESF has worked in partnership with the USFWS, and the NMDGF to conserve the CLFs on the Ladder Ranch since 2001. The conservation value of the Ladder Ranch’s 62,950 ha of diverse habitat in New Mexico cannot be overstated. As home to the last, large CLF population in New Mexico, the Ladder Ranch plays a crucial role in the survival of this species. The ranch is one of four CLF Management Areas within the Mimbres-Alamosa CLF Recovery Unit. From a broader conservation perspective, the Chihuahuan Desert Ecoregion is a WWF Global 200 Priority Ecoregion, conservation of which will help maintain a broad diversity of Earth’s ecosystems, and the Ladder Ranch itself is recognized as a Key Conservation Area by The Nature Conservancy. Numerous factors are involved in the range-wide decline of this species, including: disease, nonnative species invasions, habitat degradation, and an increase in the severity and duration of drought events. Perhaps in response to reduced natural habitat availability and drying climatic conditions, CLF have been found to naturally colonize man-made livestock water tanks. This behavior motivated us to adapt these tanks for use as escape-proof CLF refugia. These serve the purpose of temporary holding facilities for small, putatively unique populations that are at high risk of extirpation in the wild.
Project Activities in 2018
Wild population monitoring: We monitored all known sites occupied by wild CLF during 2018. Minimum count data from this survey work suggests that the Ladder Ranch population remains robust. However, this population continues to be largely confined to a single drainage (Seco Creek). Our long-term strategy is to improve the likelihood of CLF persistence on the Ladder by augmenting existing populations and expanding the species’ distribution through the creation of a network of natural and artificial wetlands. In 2014, we improved wetland habitat in Las Palomas drainage, and translocated CLF into one of these sites. However, since the sites were created Plains leopard frogs have colonized the area and frogs have tested positive for Bd.
Habitat actions on the Ladder Ranch
• Full pond renovation at Artesia; removed all cattail and installed pond liner
• Removed the majority of cattail from Johnson
• Removed some cattail from N. Seco
• Tested herbicide on cattail at LM Bar
Captive refugia program: In 2018, we translocated CLFs into the captive refugia tanks designated for use by the USFWS. Additionally, we took South Well offline. All frogs were captured and moved to Wildhorse. Overall, refugia tanks designated for both Ladder Ranch and USFWS use produced 63 viable egg masses in 2018.
Captive ranarium program: In 2018, the ranarium housed adults from eight off-ranch source populations, spanning three CLF Recovery Units, as well as adults from three on-ranch populations. Egg masses produced in adult cages were transferred to the integrated tadpole rearing facility. There are ten tadpole rearing tanks in the ranarium, which can hold around 1,000 tadpoles each. In 2018, 44 viable egg masses were transferred from adult cages to tadpole tanks. Tadpoles from these masses were released into the wild, or into captive refugia holding tanks in consultation with the USFWS. In 2018, the Ladder ranarium produced over 9,000 tadpoles. These tadpoles were released to wild or captive sites across New Mexico on both public and private lands.
Drought Study: We collaborated in an ongoing study with Jamie Voyles (UNR) on a federally funded project to investigate climate and disease dynamics in amphibian chytridiomycosis. At the Ladder ranarium, we maintained 9 mesocosm tanks with 40 tadpoles in each that simulated different drought treatments. Once these tadpoles metamorphose, they will be sent to UNR for Bd exposure. We had hoped that all tadpoles would metamorphose by October 2018 but that did not occur. In November, we raised the mesocosm water levels back up to the starting level of 40cm to overwinter the tadpoles.
Sperm Cryopreservation: In May of 2018, a team from Mississippi State University and the Ft. Worth Zoo came out to collect sperm from both wild and captive frogs (Fig. 4.3). The goals were to see if (1) Sperm can be collected and preserved from CLF, and (2) whether the collected sperm may be used to conduct successful IVF in captive females. Overall everything was a success: we achieved good fertilization rates using the frozen/thawed sperm, however, many tadpoles died during development. We hope to continue working with the group to refine the methods.