HABITAT SUITABILITY CRITERIA FOR THE FOOTHILL YELLOW-LEGGED FROG (RANA BOYLII) IN THE NORTHERN SIERRA NEVADA AND COAST RANGE OF CALIFORNIA I. Background II. Data Set Evaluation and Preliminary Analyses III. Development of Criteria IV. Conclusions and Applications Amy Lind, Sarah Yarnell, and Technical Workgroup Goal: To develop habitat suitability criteria for the Rana boylii which can be used for instream water flow modeling and habitat availability evaluations.

Acknowledgements Technical Workgroup: C. Champe, M. Gard, A. Herman, S. Kupferberg, J. Lynch, M-L. Lynch, R. Peek, D. Smith, K. Turner, S. Wilcox Data Contributions From: PG&E, SMUD, South Feather Water & Power Agency, Devine-Tarbell & Assoc., Garcia & Assoc., Ibis Environmental, Inc., Stillwater Sciences, Spring Rivers Ecological Services, Clara Wheeler, Tom VanWagoner

EmbryosLarvaeJuvenilesAdults Adaptation to Flow Fluctuation  low velocity sites  channel shapes w / stable depth and velocity  egg adhesion clutch shape deforms to be hydrodynamic  burst swimming  interstitial refugia  mouthparts to hold on to substrate  move to over-wintering refuges ?  strong swimmers  move to over- wintering refugia (e.g. tribs, seeps, caves, etc.) Immobile Mobile Life cycle in synchrony with predictable flood / drought regimes Spring Summer Fall simplified hydrograph

Local Physical Environment e.g., - water temperature - local geomorphology - erosion / sediment regime Biological Influences e.g., - native predators - invasive exotic species - prey availability - algae availability - riparian canopy cover and seral stage - woody debris inputs FYLF oviposition and rearing habitat water depth substrate composition and sorting water velocity Human Influences e.g., - regulated flows - reservoir construction and introduction of exotic species - road construction and erosion - timber harvest effects on woody debris Upslope / Upstream / Reach+ Scale Influences e.g., - climatic regime - tributary proximity - valley width - stream gradient - base geology - proximity to off-channel waterbodies Influences on FYLF Habitat Conditions and Context for HSC Development

* Developed List of Key Habitat Variables – 3 Categories - variables related to instream hydrodynamic models (e.g. 2D model) - variables influenced by flow regime, but not typically part of hydrodynamic models - variables not influenced by flow regime but at reach-scale and greater * Focused On Three Characteristics of Instream Environments - water velocity - water depth - substrate use /composition * Rationale - found to be important descriptors of oviposition and rearing habitat conditions in natural history studies and recent research - can be readily used in hydrodynamic models Habitat Variables

* 2 lifestages analyzed egg masses & tadpoles Focal Lifestages * Rationale - eggs and tadpoles highly aquatic - strongly influenced by changes in flow regimes - application to hydrodynamic model more appropriate - lack of habitat data on post-metamorphic lifestages

Final Dataset Selection Selected Datasets by River and Lifestages Analyzed Northern Sierra Nevada Butte Creek – eggs and tadpoles WB Feather - eggs and tadpoles South Fork Feather - eggs Pit River – eggs Coast Range South Fork Eel – tadpoles Reasons Other Datasets Not Used * Missing one or more of focal variables * Missing or limited information on focal lifestages * Not available electronically * Final habitat data compiled for: individual egg masses, n = 251 tadpole groups (not individual tadpoles), n = 405 * Developed habitat suitability criteria for each river and overall (combined data) * Evaluated 31 datasets from 15 rivers; data collected from

Total depth by river Analyses of Habitat Variables * Compared water velocities at egg masses or tadpole groups, at mid-column, and surface * Compared water depths at egg masses or tadpoles and total. * Compared water depth and velocity values among rivers. * Final focal variables: mid-column water velocity, total depth, and substrate (egg attachment or dominant in tad group)

Criteria Development * Considered both continuous curves and categorical / rank approaches * Decided on categorial as best first approximation given limited data * 3 Categories: 0 = not suitable, 0.1 = marginal suitability, 1 = high suitability SuitabilityWater DepthWater Velocity Substrate 0values lower than lowest and greater than highest observed values greater than the highest observed substrate categories with no obs. 0.1lowest depth greater than 0 to 5 th percentile & 95 th to 100 th percentile 90th to 100th percentile of obs. all remaining substrate categories with obs th percentile of obs 0.0 m/s to the 90th percentile of obs. most frequent substrate categories totaling 90% of obs. Egg Masses

Criteria Development * Considered both continuous curves and categorical / rank approaches * Decided on categorial as best first approximation given limited data * 3 Categories: 0 = not suitable, 0.1 = marginal suitability, 1 = high suitability SuitabilityWater DepthWater Velocity Substrate 0values lower than lowest and greater than highest observed values greater than the highest observed substrate categories with no obs. 0.1lowest depth greater than 0 to 5 th percentile & 95 th to 100 th percentile 90th to 100th percentile of obs. all remaining substrate categories with obs th percentile of obs 0.0 m/s to the 90th percentile of obs. most frequent substrate categories totaling 90% of obs. Egg Masses

Criteria Development * Considered both continuous curves and categorical / rank approaches * Decided on categorial as best first approximation given limited data * 3 Categories: 0 = not suitable, 0.1 = marginal suitability, 1 = high suitability SuitabilityWater DepthWater Velocity Substrate 0values lower than lowest and greater than highest observed values greater than the highest observed substrate categories with no obs. 0.1lowest depth greater than 0 to 5 th percentile & 95 th to 100 th percentile 90th to 100th percentile of obs. all remaining substrate categories with obs th percentile of obs 0.0 m/s to the 90th percentile of obs. most frequent substrate categories totaling 90% of obs. Egg Masses

Criteria Development * Considered both continuous curves and categorical / rank approaches * Decided on categorial as best first approximation given limited data * 3 Categories: 0 = not suitable, 0.1 = marginal suitability, 1 = high suitability SuitabilityWater DepthWater Velocity Substrate 0values lower than lowest and greater than highest observed values greater than the highest observed substrate categories with no obs. 0.1lowest depth greater than 0 to 5 th percentile & 95 th to 100 th percentile 90th to 100th percentile of obs. all remaining substrate categories with obs th percentile of obs 0.0 m/s to the 90th percentile of obs. most frequent substrate categories totaling 90% of obs. Egg Masses

Criteria Development and similarly for Tadpole Groups.... SuitabilityWater DepthWater Velocity Substrate 0values greater than highest observed values greater than the highest observed substrate categories with no obs th to 100 th percentile of obs. all remaining substrate categories with obs. 1numerical range from 0.01 m to the 90th percentile of obs. 0.0 m/s to the 90th percentile of obs. most frequent substrate categories totaling 90% of obs.

Combined River Habitat Suitability Criteria – Egg Masses depths 1 = m 0.1 = , m 0 = 0.90 m velocities 1 = m/sec 0.1 = m/sec 0 = >0.25 m/sec

Combined River Habitat Suitability Criteria – Tadpole Groups depths 1 = m 0.1 = m 0 = 1.00 m velocities 1 = m/sec 0.1 = m/sec 0 = >0.24 m/sec

Criteria Application * Criteria developed through methods such as these can be used to quantify areas of habitat suitability via instream flow models such as 2-dimensional hydrodynamic models. Habitat Suitability Criteria River TypeNarrowBroad Small, shallow, slower water velocities Model should predict moderate suitability; probably okay Model should show lots of suitable areas; not very refined Large, deep, faster water velocities Model should predict less suitable habitat than reality Model should predict moderate suitability; probably okay stay tuned for next talk for more on 2-D model applications…… Consequences of narrow and broadly ranging HSC’s….

Next Steps * Further exploration of differences in habitat suitability for different developmental (e.g., Gosner) stages of eggs and tadpoles. * Data on habitat associations for post-metamorphic lifestages. * Validation of suitability criteria in different river systems, including incorporation of habitat data for areas not used by Rana boylii. * Research on relative role and importance of habitat conditions in determining overall distribution and abundance, especially where populations are small or isolated.

Table 2. Rana boylii egg mass habitat suitability criteria. n = valid sample size for depth/velocity/substrate if they differed among variables; 0 = not suitable, 0.1 = marginally suitable, 1 = suitable. See text for detailed description of how criteria were derived. Total Depth (m) Suitability 1 Mid-column Water Velocity (m/sec) Suitability 2 Substrate Suitability 2 Rivern All Rivers Combined 223/ 192/ , > Small or large woody debris, other Silt/clay/ mud, sand, bedrock Cobble, gravel/pebble, bedrock Butte Creek > West Branch Feather River > South Fork Feather 28na > Pit River114/ , > All Rivers for total depth = Butte, West Branch Feather, Pit. 2 - All Rivers for mid-column water velocity and substrate = South Fork Feather, Butte, West Branch Feather, Pit.

Table 3. Rana boylii tadpole habitat suitability criteria. n = valid sample size for depth/velocity/substrate if they differed among variables; 0 = not suitable, 0.1 = marginally suitable, 1 = suitable. See text for detailed description of how criteria were derived. Total Depth (m) Suitability 1 Mid-column Water Velocity (m/sec) Suitability 1 Substrate Suitability 1 RiverN All Rivers Combined 154/ 145/ 155 <0.02, > > Small or large woody debris, other Silt/ clay/ mud, boulde r Sand, cobble, gravel/pebble, bedrock Butte Creek114/ 105 <0.02, > > West Branch Feather River 40<0.05, > > South Fork Eel River 184<0.01, > > All Rivers = Butte, West Branch Feather (South Fork Eel not included).

Table 4. Frequency data for Rana boylii egg mass attachment substrate and tadpole group habitat substrate derived from 248 egg masses and 155 tadpole groups. Highlighted (yellow) cells represent the ranked (highest to lowest) substrate types used to reach a total of 90% of the observations. Data are from the following rivers: Egg Masses - Butte, West Branch Feather, South Fork Feather, Pit; Tadpoles - Butte, West Branch Feather (South Fork Eel not included). Substrate CategoryEgg Masses (%)Tadpole Groups (%) Silt/Clay/Mud Sand Gravel/Pebble Cobble Boulder Bedrock Other0.0

Eggmasses – WB Feather, Butte Ck, SF Feather, Pit Rivers combined

Example Histograms for Individual Rivers Pit River – Egg Masses

Tadpoles – WB Feather and Butte Ck combined

Example Histograms for Individual Rivers West Branch Feather River – Tadpoles Mid-column velocity m/s