Karen H. Beard9 February 2008

Population density, diets, and growth rates of Eleutherodactylus coqui in Hawaii

Beard et al. (In Review) J. of Herpetology

2,954 adults in 8 study plots over 3 years

°N 19

°N 20

0 50 10025Kilometers

H A W A I I

Kailua

Hilo

OL

AK

PK

HSPP

LT

MPH a w a i i a n I s l a n d s

Hawaii

Maui

OahuKauai

KP

Population Estimates

Sex, SVL, Habitat, Color pattern, Individually mark5-9 nights, 60% recap

Woolbright (2005) Herp. Review

Year

2004 2005 2006

Abun

danc

e Es

timat

e (A

dults

/ha)

0

2000

4000

6000

8000

10000

12000

14000

16000

18000Akaka FallsHumane SocietyKalopa State ParkLava TreeManuka NARWaipio OverlookPuanaikoParadise Park

°N 19

°N 20

0 50 10025Kilometers

H A W A I I

Kailua

Hilo

OL

AK

PK

HSPP

LT

MPH a w a i i a n I s l a n d s

Hawaii

Maui

OahuKauai

KP

• Lava Tree had a 3-yr mean 3X higher than the highest long-term mean from Puerto Rico.

2x

3x

Beard et al. (Accepted) J. of Herpetology

Adult density estimates

2X

Preadult:Adult Total Density (Frogs / ha)2004 2005 2006 2004 2005 2006 Mean10.86 2.64 5.55 74,700 18,900 25,500 39,7002.00 2.27 1.35 21,600 23,500 20,400 21,800

-- 2.97 0.36 -- 2,400 2,000 2,2001.43 2.27 2.97 32,300 32,700 40,500 35,2005.62 0.57 2.21 91,400 8,500 -- 49,900*

0.24 1.17 0.20 2,600 3,100 3,000 2,9001.84 1.27 2.05 15,100 12,900 22,900 17,0002.76 -- -- 35,300 -- -- 35,300

Total density estimates Preadult:adult x adult estimate = preadult estimate

Site

AKHSKPLTMPOLPKPP

Before Hurricane Hugo 1989 After Hurricane Hugo 1990Woolbright (1996) Biotropica, Stewart & Pough (1983) Science

What limits coqui densities?

Positive relationship between total density and habitat structure across study sites

Habitat Structure in the Understory

10 20 30 40 50 60 70 80 90

Tota

l Fro

g D

ensi

ty /

ha

0

10000

20000

30000

40000

50000

60000

AK

HS

KP

LT

MP

OL

PK

R2 = 0.85 F = 28.42, P < 0.01

Waipio (OL)

Manuka (MP)Beard et al. (Accepted) J. of Herpetology

Weak positive relationship between invertebrate abundance and total density across study sites

Beard et al. (Accepted) J. of Herpetology

Invertebrate Abundance

20 40 60 80 100 120 140 160 180 200T

tlF

Dit

/h

0

10000

20000

30000

40000

50000

60000

AK

HS

LT

MP

OL

PK

PP

R2 =0.45 F = 4.04, P = 0.10

Sin et al. 2008 Biological Invasions

Ecological Effects of the Coqui in Hawaii

157°W

157°W

156°W

156°W

155°W

155°W

19°N 19°N

20°N 20°N

21°N 21°N0 50 10025

Kilometers

H A W A I I

M A U I

H a w a i i a n I s l a n d s

Hawaii

Maui

OahuKauai

MMG

MKN

OL

AKPK

KCPP

MP

HS

LT

KT

Frog Stomach Content Analyses

11 study sites, Summer 2004

Beard 2007 Copeia

Orders

Acarina

AmphipodaAraneae

Coleoptera

CollembolaDiptera

Frog eggs

Hymenoptera-antsIsopoda

Per

cent

of S

tom

ach

Con

tent

s by

Item

0

10

20

30

40

50

60

No:CulicidaeDespite:Tipulidae

Beard 2007 Copeia

696 frogs, 5310 invertebrates were identifiable. 7.6 ± 7.6 (SD) prey items per stomach.

Males: 0.008 ± 0.0007 vs. 0.02 ± 0.0003Females: 0.01 ± 0.001 vs. 0.08 ± 0.005

Controlled for SVLWoolbright (1985) Copeia

Growth rates

• Is fitness higher in Hawaii or Puerto Rico?

• Common environment• 4 Puerto Rico populations

and 2 Hawaii populations• Fitness measures:

– Number of eggs per clutch?– Egg size?– Offspring size?– Growth/survivorship of

offspring?

E.M. O’Neill

Range

Hawaii Puerto Rico0.000

0.005

0.010

0.015

0.020

0.025

0.030

RangeHawaii Puerto Rico

Ht

hliS

0

2

4

6

8

Range

Hawaii Puerto Rico

Ei

(

0

1

2

3

4

5

6

7

F1,27 =1.38, P = 0.25 F1,27 =12.68, P = 0.0014

F1,27 =6.89, P = 0.014

*

*

F1,27 =6.90, P = 0.015

*

RangeHawaii Puerto Rico

0

10

20

30

40

Velo-Antón et al. (2007) Molecular Phylogenetics and Evolution

Peters et al. (2008) Molecular Ecology Notes

• Thirteen microsatellite loci were isolated from the coqui frog

• The purpose for initiating this study was to determine the number of introductions in Hawaii and the primary source or mode of introductions

LT

Peters et al. (2008) Molecular Ecology Notes

Bayesian population assignment test

Hawai Data

LT

• Coqui densities vary across sites, but can be 3X higher than Puerto Rico

• Habitat structure is highly correlated with coqui densities

• Coquis are mostly consuming non-native leaf litter invertebrates, esp. ants, amphipods

• Two introductions• Extreme bottleneck

Conclusions

Funding Sources and Support: Jack Berryman Institute

US Fish and Wildlife ServicesHawaii Land and Natural Resources (Invasive Species Council)

USDA/APHIS/WS Hilo Field StationUtah State University

William C. Pitt for logistical supportMISC, KISC and OISC for sending frog samples

Graduate students: Hans Sin, Nathania Tuttle, Eric O’Neill,

Simon Bisrat, Emily PriceUndergraduate students:

Kody Crowell, Jesse Poulos, Dixon Grant, Michelle Higashi, Austin Huff, Ray McGuire, and others