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California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 1
CALIFORNIA RED-LEGGED FROG WORKSHOP
Norman Scott & Galen Rathbun
ACKNOWLEDGEMENTS
California Department of Transportation
U. S. Fish and Wildlife Service
U. S. Geological Survey
California State Parks
Grey HayesElkhorn Slough Coastal Training
Program
Dana BlandGranite Rock Sand Plant
SCHEDULE
WEB SITE
DOCUMENTS
IMPORTANT POINTS• Water regimes -- Mediterranean
climate• Population dynamics• Agriculture -- cattle and ponds• Manage larval survival• Manage populations, not individuals• Clear management objectives
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 2
Identification
Foothill Yellow-Legged
Frog
Rana boylii
Mountain Yellow-Legged FrogRana sierrae
Pacific Chorus Frog
Pseudacris regilla
BullfrogLithobates
catesbeianus
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 3
Bullfrog
California Red-Legged Frog
CaliforniaRed-Legged
Frog
California Red-Legged
Frogs
Variation
Light and Dark Colorful
Individuals
Colorful With Little Pattern
Male vs. Female
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 4
Egg MassesGOSNER
EMBRYO/TADPOLE STAGING SYSTEM
Stage 1 = Undivided fertilized eggStage 26 = Hind leg bud apparentStage 46 = Metamorphosis complete
Gosner 1960. Herpetologica 16:183-190.
California Red-Legged Frog California Red-Legged
Frog
Tadpole Identification
BODY PROFILES
Tree Frog Red-Legged Frog
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 5
Bullfrog Tadpole BULLFROG TADPOLES
Hatch April to SeptemberProbably overwinter at least onceAre usually greenish or yellowAlways have dots or “freckles”
Are almost never the same size as contemporaneous red-legged frog tadpoles
Red-Legged Frog and BullfrogTadpoles
Bullfrog
CALLIDENTIFICATION
(Davidson 1995)
DISTRIBUTION
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 6
TERMINOLOGYAdultAge
EmbryoFroglet
JuvenileLarva
MetamorphTadpole
RECENT TAXONOMIC CHANGES
Pacific Chorus Frog (Tree Frog)Hyla regilla >> Pseudacris regilla
Western ToadBufo boreas >> Anaxyrus boreas
BullfrogRana catesbeiana >> Lithobates
catesbeianusCalifornia Red-Legged Frog
Rana aurora draytonii >> Rana draytonii
RANA DRAYTONII PHYLOGENY
Rana aurora• males to 65 mm, females to 93 mm• males lack vocal pouches• often calls underwater• eggs often placed deep
Rana draytonii• males to 116 mm, females to 138 mm• males with vocal pouches• never calls underwater• eggs placed near surface
BIBLIOGRAPHY
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 7
MEDITERRANEAN
CLIMATE
Mediterranean Climate
Stream FlowExtremes
Flow Extremes
San Simeon - Summer San Simeon - Fall
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 8
San Simeon - Winter San Simeon - Spring
Calm and Stable Water
forEgg Laying BIOLOGY
ANNUAL CYCLEYear 1December-April.......................Calling and Egg LayingJanuary-September................Tadpole Stage*June-September......................Metamorphs Appear*June-November.......................Juvenile Period
Year 2.......................................Juvenile Period
Year 3December-April........................First Breeding
(males and some females)
Duration of Stages•Calling: 1-2 months•Egg: 2-3 weeks•Tadpole: 4-6 months usually,
some to 1 year•Juvenile: 20-32 months•Adult: maximum 7 years +
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 9
Fresh Egg Mass
Egg Clusters
Newly Hatched TadpolesCalifornia
Red-legged Frog
MetamorphosisJuvenile
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 10
AdultTADPOLE FOOD
“Aufwuchs”Algae, fungi, microscopic
animalsCarrion
FROG FOODArthropods
MolluscsAnnelid worms
Largest frogs include fish, other frogs, mice
SIZE AND WEIGHT
Age - Size Weight - Length
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 11
POPULATION
MODEL
EIGHT-YEAR STUDY
Populations in four coastal streams
San Luis Obispo County
SURVIVORSHIP
Stage Age Survival(months)
•Egg>>metamorph 0-5 1-5%**
•Metamorph>>juvenile 5-12 10%
•Juvenile>>adult 12-24 33%
•Adults 24-80+ 33%/year
Rana draytonii Survivorship
0100200300400500600
1 2 3 4 5 6
Year
Num
ber o
f Fro
gs
Roughly..........
The average female only breeds once
and
One egg mass (1000-4000 eggs) will produce 1 breeding pair
HABITATS
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 12
Habitats – Cattle are Important Habitat – Dams are Important
Cattle and Dam Cattle and Dam
Stock Pond Stock Pond
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 13
Spring Box
Treated Wastewater Storage
Percolation Pond Dunes Pond – No Cattle No Dam
Riparian Upland Habitat
MOVEMENTS
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 14
MOVEMENT STUDIES
Personal Observations (1993-9) San Luis Obispo Co.
Bulger et al. (2003) Santa Cruz Co.
Fellers & Kleeman (2007) Marin Co.
Tatarian (2008) Contra Costa Co.
INTERPRETING MOVEMENT STUDIES
Length & seasonality of study
Habitat characteristics
Adversity factors
MovementsBreeding, Dispersal, and Avoiding Adversity
Pico Creek Radio Tracking
San Simeon Creek Radio Tracking
Dispersing Juvenile Frogs
???
Establishing a Pattern?
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 15
SCOTT CREEKRADIO TRACKING
Scott Creek Valley
POPULATIONBIOLOGY
POPULATION TERMINOLOGY
•LOCAL POPULATION--Frogs in habitats linked by the regular exchange of propagules
•METAPOPULATION--Two or more local populations rarely linked by migrating individuals
•ISOLATED POPULATION--A local population not exchanging propagules with any other local population
THE GEOGRAPHY OF EXTINCTIONS
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 16
Extinction Sequence
•Metapopulation linkages are broken, creating isolated local populations
• Local populations lose mosaic of local habitats
•Local populations go extinct
Isolated populations will not
persist without managementTHREATS
Threats
• Urban Influences • Agricultural
Influences • Exotic Predators • Natural Predators• Disease 89 Winter Road Surveys
1994, 1995, 199739 Frogs, ~ 90% deadR. Seymour & M. Westphal unpubl. data
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 17
Urban Impacts
Bridges &Culverts
Water Regimes & Barriers
Disappearing Water
Barrier Mortality
Agricultural Impacts
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 18
Cattle & Vegetation Exotic Predators
IntroducedCentrarchidFishes –Bluegill &Largemouth bass
Native Predat
ors AGRICULTURAL CHEMICALS
CHYTRID FUNGUS
RANAVIRUS
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 19
MANAGEMENTFISH & BULLFROG
CONTROL
“Skinny legs!...I got skinny legs!”D’Amore et al. (2009)
Factor Bullfrog Red-Legged Frog
Higher temperature 0 +Higher pH 0 +Constructed pond 0 +Pond isolation 0 +Distance to agriculture 0 -Percent cultivated 0 +
CONSTRUCTION ANDMANAGEMENT
OF HABITATS
STOCK POND
MANAGEMENT
See Handout
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 20
ManagingFrog
Ponds
Cattle Fence
Constructed Breeding Pond - Failed Constructed Pond – Successful Breeding
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 21
Constructed Summer Habitat
Golf Course Ponds
Buffer Zones
SCORING PONDS AND
SMALL STREAMS AS
BREEDING HABITAT
TRANSLOCATION
Guadalupe Oil Field
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 22
HomingNo Home
RE-ESTABLISHING A POPULATION
Pinnacles National Monument
Bear Gulch Reservoir
BEAR GULCH RESERVOIR HISTORY
1934 Reservoir completed1960s-70s Red-legged frogs present
~1980 Catfish introduced1985 Drained, catfish removed198?-2000 Frogs absent2001 Re-establishment started
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 23
CHALONE CREEKWet Season
CHALONE CREEK RED-LEGGED FROG EGG
MASSES
1998 0
1999 >5
2000 7-8
•COLLECT 20% OF EGG MASSES FROMCHALONE CREEK
•HOLD TADPOLES IN HEADSTARTBOXES IN RESERVOIR
•RELEASE TADPOLES INTO RESERVOIR
RE-ESTABLISHMENTPROGRAM
NUMBER OF EGG MASSES AND
TADPOLES RELEASED
YEAR CHALONE CREEK TADPOLES EGG MASSES RELEASED
2001 5 116++2002 9 9142003 3 841
TOTALS 17 1871++
RESULTS (1)
YEAR TADPOLES METAMORPHS ADULTS ANDRELEASED JUVENILES
2001 116++ 17 0
2002 914 154 12
2003 841 427** 29
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 24
RESULTS (2)YEAR METAMORPHS ADULTS AND
JUVENILES2001 17 02002 154 122003 427 29------------------------------------------------2004 485 202005 317 122006 329 222007 68+ 15+2008 206 14
IMPORTANT POINTS• Water regimes -- Mediterranean
climate• Population dynamics• Agriculture -- cattle and ponds• Manage larval survival• Manage populations, not individuals• Clear management objectives
U.S. FISH AND WILDLIFE SERVICE
Site Assessment & Survey ProtocolRecovery PlanCritical Habitat
TECHNIQUES
BIBLIOGRAPHY
SURVEY EQUIPMENTMOST SURVEYS
WadersHeadlamps
Dip NetsData Recorder
SPECIAL CIRCUMSTANCESFloat tubesSpotlightsBinoculars
Tadpole Traps
“See, Frank? Keep the light in their eyes and you can bag them without any trouble at all”
California Red-Legged Frog Workshop 2009
Galen Rathbun and Norman Scott in cooperation with the Elkhorn Slough Coastal Training Program 25
LIGHT SOURCES FOR
EYE-SHINE SURVEYS
EQUIPMENT
SUPPLIERS
Questions?