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

Embryos Larvae Juveniles Adults

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

simplifiedhydrograph

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

substratecomposition and sorting

water velocity

Human Influencese.g.,- regulated flows- reservoir construction and introduction of exotic species- road construction and erosion- timber harvest effects on woody debris

Upslope / Upstream / Reach+ Scale Influencese.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 NevadaButte Creek – eggs and tadpolesWB Feather - eggs and tadpolesSouth Fork Feather - eggsPit River – eggs Coast RangeSouth Fork Eel – tadpoles

Reasons Other Datasets Not Used

* Missing one or more of focalvariables

* 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 1991-2006

0.00

0.02

0.04

0.06

0.08

0.10

0.00 0.05 0.10 0.15 0.20 0.25

Mid-column Velocity of Water at Egg Mass, in m/sec

Observed

Linear

Quadratic

Velocity of Water at Egg Mass, in m/sec

2 3 7

2 = Butte Creek 3 = WBrNFFeather 7 = Pit

0.00

0.20

0.40

0.60

0.80

1.00

To

tal D

ep

th o

f W

ate

r, in

m

91

92

76

88

83

82

462

408

409

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

Suitability Water Depth Water Velocity

Substrate

0 values lower than lowest and greater than highest observed

values greater than the highest observed

substrate categories with no obs.

0.1 lowest depth greater than 0 to 5th percentile & 95th to 100th percentile

90th to 100th percentile of obs.

all remaining substrate categories with obs.

1 5-95th 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

Suitability Water Depth Water Velocity

Substrate

0 values lower than lowest and greater than highest observed

values greater than the highest observed

substrate categories with no obs.

0.1 lowest depth greater than 0 to 5th percentile & 95th to 100th percentile

90th to 100th percentile of obs.

all remaining substrate categories with obs.

1 5-95th 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

Suitability Water Depth Water Velocity

Substrate

0 values lower than lowest and greater than highest observed

values greater than the highest observed

substrate categories with no obs.

0.1 lowest depth greater than 0 to 5th percentile & 95th to 100th percentile

90th to 100th percentile of obs.

all remaining substrate categories with obs.

1 5-95th 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

Suitability Water Depth Water Velocity

Substrate

0 values lower than lowest and greater than highest observed

values greater than the highest observed

substrate categories with no obs.

0.1 lowest depth greater than 0 to 5th percentile & 95th to 100th percentile

90th to 100th percentile of obs.

all remaining substrate categories with obs.

1 5-95th 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....

Suitability Water Depth Water Velocity

Substrate

0 values greater than highest observed

values greater than the highest observed

substrate categories with no obs.

0.1 90th to 100th percentile of obs.

90th to 100th percentile of obs.

all remaining substrate categories with obs.

1 numerical 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 = 0.06-0.47 m0.1 = 0.02-0.05, 0.48-0.90 m

0 = <0.02,>0.90 m

velocities 1 = 0.0-0.09 m/sec0.1 = 0.10-0.25 m/sec

0 = >0.25 m/sec

Combined River Habitat Suitability Criteria – Tadpole Groups

depths 1 = 0.02-0.44 m0.1 = 0.45-1.00 m

0 = <0.02,>1.00 m

velocities 1 = 0.00-0.11 m/sec0.1 = 0.12-0.24 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 Type Narrow Broad

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)Suitability1

Mid-column Water Velocity (m/sec)

Suitability2

SubstrateSuitability2

River n 0 0.1 1 0 0.1 1 0 0.1 1

All Rivers Combined

223/192/248

<0.02, >0.90

0.02-0.05, 0.48-0.90

0.06-0.47

>0.25

0.10-0.25

0.0-0.09 Small or large woody debris, other

Silt/clay/ mud, sand, bedrock

Cobble, gravel/pebble, bedrock

Butte Creek 59 <0.02, >0.64

0.02-0.04 0.05-0.64

>0.07

0.06-0.07

0.00-0.05

West Branch Feather River

49 <0.09, >0.90

0.65-0.90 0.10-0.64

>0.17

0.13-0.17

0.00-0.12

South Fork Feather

28 na na na >0.25

0.14-0.25

0.00-0.13

Pit River 114/80

<0.06, >0.49

0.06-0.09, 0.32-0.49

0.10-0.30

>0.15

0.10-0.15

0.0-0.09

1 - 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)Suitability1

Mid-column Water Velocity (m/sec) Suitability1

SubstrateSuitability1

River N 0 0.1 1 0 0.1 1 0 0.1 1

All Rivers Combined

154/145/155

<0.02, >1.00

0.45-1.00

0.02-0.44

> 0.24 0.12-0.24

0.00-0.11

Small or large woody debris, other

Silt/ clay/ mud, boulder

Sand, cobble, gravel/pebble, bedrock

Butte Creek 114/105

<0.02, >1.00

0.45-1.00

0.02-0.44

> 0.23 0.09-0.23

0.00-0.08

West Branch Feather River

40 <0.05, >1.00

0.36-1.00

0.05-0.35

> 0.24 0.11-0.24

0.00-0.10

South Fork Eel River

184 <0.01, >0.70

0.21-0.70

0.01-0.20

> 0.08 0.04-0.08

0.03-0.08

1-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).

SubstrateCategory Egg Masses (%) Tadpole Groups (%)

Silt/Clay/Mud 0.4 2.6

Sand 0.8 10.3

Gravel/Pebble 10.9 22.6

Cobble 72.6 40.6

Boulder 13.7 7.1

Bedrock 1.6 16.8

Other 0.0 0.0

0.00 0.20 0.40 0.60 0.80 1.00

Total Depth of Water, in Meters

0

10

20

30

40

50

60

70

Fre

qu

ency

Mean = 0.2209Std. Dev. = 0.14084N = 223

"Egg Masses - Total Water Depth - All Rivers

0.00 0.05 0.10 0.15 0.20 0.25

Mid-column Velocity of Water at Egg Mass, in m/sec

0

20

40

60

80

100

120

Fre

qu

en

cy

Mean = 0.029Std. Dev. = 0.04265N = 192

Egg Masses - Mid-column Velocity - All Rivers

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

Example Histograms for Individual Rivers

Pit River – Egg Masses

0.0 0.2 0.4 0.6 0.8 1.0

Total Depth of Water, in Meters

0

5

10

15

20

25

30

Fre

qu

ency

Mean = 0.1973Std. Dev. = 0.07402N = 114

Egg Masses - Total Water Depth - Pit River

0.00 0.05 0.10 0.15 0.20 0.25

Mid-column Velocity of Water at Egg Mass, in m/sec

0

10

20

30

40

Freq

uenc

y

Mean = 0.0353Std. Dev. = 0.04066N = 80

Egg Masses - Mid-column Velocity - Pit River

0.00 0.20 0.40 0.60 0.80 1.00

Total Water Depth, in Meters

0

10

20

30

40

Fre

qu

en

cy

Mean = 0.2256Std. Dev. = 0.16372N = 154

Total Water Depth, in Meters - WB Feather and Butte Rivers

0.00 0.05 0.10 0.15 0.20 0.25

Mid-column Velocity at Tadpole Group, in m/sec

0

20

40

60

80

100

Fre

qu

ency

Mean = 0.0322Std. Dev. = 0.05365N = 145

Mid-column Velocity at Tadpole Group, in m/sec - WB Feather and Butte Rivers

Tadpoles – WB Feather and Butte Ck combined

Example Histograms for Individual Rivers

West Branch Feather River – Tadpoles

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

0.20

0.22

0.24

Velocity at Tadpole Group, in m/sec

0

5

10

15

20

Fre

qu

en

cy

Mean = 0.0087Std. Dev. = 0.01244N = 40

Velocity at Tadpole Group - West Branch Feather River

0.00 0.20 0.40 0.60 0.80 1.00

Total Water Depth, in Meters

0

5

10

15

Fre

qu

en

cy

Mean = 0.207Std. Dev. = 0.16948N = 40

Total Water Depth - West Branch Feather River

Mid-column velocity m/s