Developing the Relationship between Relative and Actual Abundance to Estimate Population Size of the Relict Leopard Frog

Rebeca Rivera and Jef R. JaegerSchool of Life Sciences, University of Nevada, Las Vegas

Colorado River Terrestrial and Riparian Meeting 2014, January 28-30

   

         

       

        

     

      

Background Known Historical Locations

1990s Frogs known from 3 areas

2001 Frogs known at only two areas

~ 1100 adults

2002 Petitioned for listing under ESA

From Bradford, Jaeger, & Jennings 2004

Monitor populations

Establish additional populations in existing or created habitat

Voluntary Conservation Agreement and Strategy

ESA Listing Revisited

2011 USFWS submitted a MDL plan

2016 Review of Relict Leopard Frog status

Population size

   

  

 

Conservation Agreement and Strategy

Sites: ~ 6 historical 11  Extant  Experimental

Upper & Lower Blue Point

Rogers

Black Canyon Sprs.

Bighorn Sheep

Salt Cedar

Historical Experimental Failed Experimental

Boy Scout & Dawn’s

Tassi Pupfish Refuge Goldstrike

Sugarloaf

Red Rock

Grapevine, NV

Perkins Pond

Lime

Bearpaw

Quail

Grapevine, AZ

Horse

Wetland Park

Union Pass

Double Sampling Technique Calibrate indices of relative abundance by finding the

relationship between 2 survey methods

Relative abundances from Visual Encounter Surveys (VES)

Estimates of true abundance from Mark-recapture Provides ratio estimates Applied to sites where only VES data is available

YEst=XMR Est

XRA

YRA

Ratio Estimate

( )Relative Abundance

PopulationEstimate

    

              

      

      

Sampling Conducted efforts during Fall 2011 and Spring 2012

Visual encounter surveys at all sites

Mark‐recapture sampling at 5 sites

Ratio estimates from 4 sites

Upper & Lower Blue Point

Rogers

Black Canyon Sprs.

Bighorn Sheep

Salt Cedar

Historical

Experimental

Boy Scout & Dawn’s

Tassi Pupfish Refuge

Goldstrike

Red Rock

Perkins Pond

Lime

Bearpaw

Quail

Grapevine, AZ

Horse

Union Pass

Occurred at night

Mark-recapture

Multiple site visits/events

(Schnabel approach)

2-5 surveyors using floodlights

PIT tags adult frogs (≥ 45mm SVL)

VES

Count observed frogs

2-3 surveyors using floodlights

Sampling

Red Rock Spring

Ratio EstimatesRed Rock Spring

Relative abundance of adults during sampling events

Fall 2011 Spring 2012

Period Marked N 95% CI CV(N) Average Ratio Estimate

Fall 2011 17 17.5 17.0-22.7 0.055 1.27 (1.23-1.64)

Spring 2012 18 18.6 18.1-24.3 0.058 1.49 (1.45-1.94)

Rel

ativ

e ab

un

dan

ce

Mark-recapture estimates

0

5

10

15

20

Sampling Events

Pupfish Refuge Spring

Ratio Estimates

Period Marked N 95% CI CV(N) Average Ratio Estimate

Spring 2012 66 67.9 66.4-75.2 0.027 2.31 (2.26-2.56)

Rel

ativ

e ab

un

dan

ce

Mark-recapture estimates

Relative abundance of adults during sampling events

Pupfish Refuge Spring

0

10

20

30

40

50 Spring 2012

Sampling Events

Grapevine Canyon Spring

Ratio Estimates

Period Marked N 95% CI CV(N) Average Ratio Estimate

Spring 2012 296 456 410-521 0.062 4.07 (3.66-4.65)

Rel

ativ

e ab

un

dan

ce

Mark-recapture estimates

Relative abundance of adults during sampling events

Grapevine Canyon Spring

Spring 2012

Sampling Events

0

50

100

150

200

Upper Blue Point Spring

Ratio Estimates

Rel

ativ

e ab

un

dan

ce

Mark-recapture estimates

Relative abundance of adults during sampling events

Upper Blue Point Spring

Period Marked N 95% CI CV(N) Average Ratio Estimate

Fall 2011 39 47.3 42-61.4 0.095 2.57 (2.29-3.34)

Spring 2012 48 51 48.8-59.1 0.044 2.43 (2.32-2.81)

0

10

20

30 Spring 2012Fall 2011

Sampling Events

Average Ratio Estimates – Used to estimate overall population in Spring 2012

MR Site N/VES

Red Rock 1.49

Pupfish Refuge 2.31

Upper Blue Point 2.43

Grapevine Canyon 4.08

  

        

            

        

                

           

Overall Population Estimate Selectively applied

Average Ratio Estimates to calibrate relative abundances at 11 other sites

Estimate in Spring 2012: 1,387 adult frogs (Range 1,318 – 1,595)

Bradford et al. 2004: 1,100 adult frogs (Range 693 – 1,833)

Upper & Lower Blue Point

Rogers

Black Canyon Sprs.

Bighorn Sheep

Salt Cedar

Boy Scout & Dawn’s

Tassi Pupfish Refuge

Goldstrike

Red Rock

Quail

Grapevine, AZ

Union Pass

Management zone

   

  

  

     

 

                        

 

Conclusion Relative abundance of adults and juveniles during VES from 2004‐2012 at all active sites

700

600

500

400

300

200

100

0 Spr Spr Spr Spr Spr Spr Spr Spr Spr 04 05 06 07 08 09 10 11 12

Storm event

Horse Lime Bearpaw Poppy Union Pass Perkins Pond Quail Tassi Red Rock Grapevine, AZ Pupfish Goldstrike Salt Cedar Dawns Cyn Boy Scout Black Cyn Sprs Bighorn Sheep Rogers Blue Point

Acknowledgements

Special Mention:

Michael Burroughs

Alejandra Cortes

D. Tyler Harrison

Alex Jones

Heidi McMaster

Mark Maynard

Simon Madil

Amelia Savage

Mike Sredl

Mitch Urban

Paul van Els

Michael Webber

Everyone on the Relict Leopard Frog Conservation Team…and many others…

Photo credits: Jef Jaeger & Rebeca Rivera

U.S. Fish and Wildlife Service