Main Points. Elkhorn Freshwater Working Group. Pursuing Ecological Research: A Case Study in Conservation Research for the California red-legged frog

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1 Pursuing Ecological Research: A Case Study in Conservation Research for the California red-legged Photo: Darrell Steely Valentine Hemingway UCSC Department of Ecology and Evolutionary Biology hemingway@biology.ucsc.edu Main Points How did I get involved? Why increase the conservation effort for this? Questions to answer for conservation Research methods What we know now and where we are headed Introducing the California red-legged (Rana draytonii) Threatened, declining native Largest native CA Uses freshwater ponds and upland habitat Elkhorn Freshwater Working Group Elkhorn Slough National Estuarine Research Reserve CA DFG Elkhorn USFWS Docents & Slough Volunteers Foundation Nina D Amore Is the Reserve population isolated? What environmental factors are positively associated with healthy CRLF populations? D'Amore, A., V. Hemingway and K. Wasson (2009). Do a threatened native amphibian and its invasive congener differ in response to human alteration of the landscape? Biological Invasions: 12(1): 145

2 Total CRLF Adults and Juveniles Per Year Year Declines in California Red-Legged Frogs at Elkhorn Slough Reserve Total CRLF Adults and Juveniles Determined by the greatest weekly maximum count for all Reserve ponds per year. Possible Culprits Increased predation Novel pathogen or increased virulence New or increased contaminant load Change in hydrology Combination of factors Other unknown factor Question and Approach Which habitat characters predict distribution, abundance, and reproduction for our pond-breeding s? Within 5km radius, distribution, relative abundance, and reproduction of each species Comparative method: Successful invasive vs. declining native Common native vs. declining native Study Species American bull Rana catesbeiana Invasive Declining Native Sierran tree Pseudacris sierra Common native

3 Amphibian Surveys Three years of surveys: ponds total, 38 ponds all three years Each site 3+ times per year Listening for breeding calls Larval surveys Nocturnal surveys Habitat Characteristics Pond Level Perennial or Ephemeral Manmade or Natural % Vegetation Cover Aerial Extent Depth Landscape Pond Proximity Agriculture Proximity % Agricultural Cover Road Proximity Comparison: Native vs Invasive Habitat Characteristic American bull Perennial Manmade Ponds within 500m; within 100m Agriculture within 50m Cultivation within 1km buffer 500m Road Proximity Comparison: Native vs Invasive California red-legged American Bull Year 0 Year 1 Year 2

4 Comparison: Declining vs Stable Habitat Characteristic Perennial Manmade Ponds within 500m; within 100m Agriculture within 50m Cultivation within 1km buffer 500m Road Proximity Pacific chorus If we improve some or all of these factors, will efforts ensure popn s long-term viability? Population Viability Analysis (PVA) Gather survivorship estimates and their variances Published values Better are estimates from your population Make a model reflecting the life history of your species Ex: Annual survivorship of each life stage, likelihood of reproduction of each life stage, fecundity Run your model and interpret Making Survivorship Estimates Define population Mark & recapture individuals, take data Mark them with Passive Integrated Transponders Enter and analyze data Hemingway, V., D'Amore, A., Doak, D., Scott, N., Rathbun, G., Smith, R., Bloom, P., Fisher, R., Backlin, A., Cook, D., Tartarian, T., Setka, J., Newcomb, T., and Mulchaey, B. Comparative demography for species conservation: A range-wide examination of the survivorship of a threatened species, Rana draytonii.(in prep.) PVA Process Gather survivorship estimates and their variances Published values Better are estimates from your population Make a model reflecting the life history of your species Ex: Annual survivorship of each life stage, likelihood of reproduction of each life stage, fecundity Run your model and interpret

5 S(egg) * S(tad) * Frog Life Cycle Next Year Population Size = This Year Population Size * S(meta) * S(juve) * S(ad) * R(ad) * Likelihood of popn persistence after 50, 100, 1000 years? Sensitivity to perturbations? F Egg Tadpole Metamorph Juvenile/Adult Through Models We Can: 1) Predict relative risk of multiple threats 2) Ask how environmental factors mediate various threats, such as introduced pathogens 3) Explore management options Predicting & quantifying the outcome of chytridiomycosis Emerging infectious disease Global amphibian declines Is it impacting the California red-legged population? Can we mitigate? Test marked individuals Recapture multiple years Estimate mortality attributable to chytrid (mean & variance) for each life stage Incorporate into popn model to estimate longterm impact