n29:13

ENDANGERED SPECIES RESEARCH

Endang Species Res

Vol. 29: 13–21, 2015

doi: 10.3354/esr00696

Published online November 4

INTRODUCTION

Wildlife rehabilitation is the process of treating in -

jured, sick or orphaned animals and releasing them

back into the wild. As conservation has moved to the

forefront of ecology, releasing rehabilitated animals

as a way of enhancing wild life populations is becom-

ing more frequent (Ka resh 1995, Cardona et al. 2012,

Mestre et al. 2014). These actions have the potential

to play significant roles in stabilizing or augmenting

wildlife populations, especially those in conservation

peril (Karesh 1995). Rehabilitation based on sound

conservation and biological principles (Tribe &

Brown 2000, Ferraro & Pattanayak 2006) ensures that

available resources can be allocated towards the

most effective conservation measures (Tribe & Brown

2000, Ferraro & Pattanayak 2006, Wimberger et al.

2010, Feck & Hamann 2013). In some cases, however,

the high costs of rehabilitation or low success rates

may be too great to warrant widespread implementa-

tion. Thus, understanding the success rates of reha-

bilitation and how they vary with species biology

(e.g. body size, sex) will enhance our ability to gauge

how these activities can contribute to conservation.

The primary objective behind wildlife rehabilita-

tion is the welfare of individual animals (Moore et al.

Attribution Licence. Use, distribution and reproduction are un -

restricted. Authors and original publication must be credited.

Publisher: Inter-Research · www.int-res.com

*Corresponding author: [email protected]

Sea turtle rehabilitation success increases with

body size and differs among species

Linda Baker

1,2

, Will Edwards

1,2

, David A. Pike

2,3,

College of Marine and Environmental Sciences, James Cook University, Cairns, Queensland 4878, Australia

Centre for Tropical Environmental & Sustainability Science, James Cook University, Cairns, Queensland 4870, Australia

College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia

ABSTRACT: Wildlife rehabilitation can contribute to species conservation by releasing healthy

individuals back into the wild and educating the public about threatening processes. Rehabilita-

tion has substantial financial costs, however, and thus it is important to understand the success

rates of these potential conservation management actions. We quantified the success rates for

1700 sea turtles admitted to rehabilitation facilities in Florida (USA) between 1986 and 2004.

Rehabilitation success was low: 61.5% of turtles died in rehabilitation and only 36.8% were

released back into the wild. A further 1.6% of turtles were maintained in captivity permanently

due to the severe nature of their injuries. Most mortality occurred early during the rehabilitation

process (within a few weeks), and successful rehabilitation often took several months to more than

3 yr. Loggerhead turtles Caretta caretta were most likely to survive rehabilitation, followed by

Kemp’s ridleys Lepidochelys kempii and green turtles Chelonia mydas; for all 3 species, larger

individuals had an increased chance of successful rehabilitation. At face value, the low rates of

rehabilitated turtles successfully released back into the wild may contribute only modestly to con-

servation in terms of contributing to population viability. However, many rehabilitation facilities

provide important educational experiences that increase public awareness of the threats facing

animals and highlight potential conservation solutions. Media coverage highlighting the release

of rehabilitated animals further extends the conservation value of these efforts. Wildlife rehabili-

tation provides important direct benefits that, combined with social benefits, together may justify

the expense and difficulty of rehabilitating individual animals.

KEY WORDS: Animal hospital · Endangered species · Human intervention · Injury · Marine turtle ·

Public engagement · Sea turtle stranding · Survival · Veterinary care · Wildlife rehabilitation

PEN

CCESS

Endang Species Res 29: 13–21, 2015

2007), which are often accepted into rehabilitation

without prioritizing rare or endangered species (Ka -

resh 1995, Tribe & Brown 2000). During catastrophic

events, there may be insufficient resources to care for

all affected individuals, and decisions may need to be

made about which animals to rehabilitate. The finan-

cial costs of rehabilitation are large (Karesh 1995,

Tribe & Brown 2000, Moore et al. 2007, Feck &

Hamann 2013), and in some cases those resources

could be more effectively directed towards conserva-

tion measures aimed at preventing wildlife injury

(Moore et al. 2007). This presents a conflict between

public support behind rehabilitating injured wildlife

as a conservation measure (reviewed by Feck &

Hamann 2013), and how effective rehabilitation

actually is for maintaining or increasing population

size, compared to the actual costs of other conserva-

tion efforts. An added benefit of treating animals in

captivity is the potential for positive educational

interactions between humans and wildlife, which

could contribute to conservation by garnering public

support (Tribe & Brown 2000, Moore et al. 2007, Car-

dona et al. 2012, Feck & Hamann 2013).

The efficacy of rehabilitation programs for mam-

mals and birds has been well reviewed (Karesh 1995,

Tribe & Brown 2000, Moore et al. 2007), but evalua-

tions of other fauna are limited (Dodd & Seigel 1991).

Sea turtle populations are in decline globally, and

integrated conservation efforts are required to pre-

vent extinction (Wallace et al. 2011). Sea turtle reha-

bilitation is usually achieved through medical man-

agement of sick or injured animals by veterinary

surgeons in wildlife hospitals (Casal & Orós 2009,

Feck & Ha mann 2013). The majority of animals in

rehabilitation are taken there because of some previ-

ous negative interaction with humans (Tribe & Brown

2000, Feck & Hamann 2013), including entanglement

in fishing gear (Allen 2000, Dutton & Squires 2008,

Bagarinao 2011), being hit by a boat or propeller and

a wide range of other causes (Shaver & Teas 1999,

Dutton & Squires 2008, Bagarinao 2011). Current

information on the success rates of sea turtle rehabil-

itation is limited, but suggests that the proportion of

animals released back into the wild is low (Haines et

al. 2000, Haines & Limpus 2001, Greenland et al.

2004, Greenland & Limpus 2006, 2008, Biddle & Lim-

pus 2011). Records from Queensland, Australia (1999

to 2010) suggest that only 26% of stranded sea turtles

found washed up on beaches were successfully reha-

bilitated and released back into the wild (Table 1).

The survival rate of rehabilitated animals once

released back into the wild could be lower than that

of wild turtles, further reducing overall success rates

in terms of the potential for individuals to contribute

to the population (Cardona et al. 2012). Widespread

rehabilitation of sick or injured turtles currently sup-

plements other conservation efforts (IUCN 1995,

Casal & Orós 2009, Goldberg et al. 2011, Mestre et al.

2014), but we still have a poor understanding of the

conservation potential of rehabilitation in terms of

numbers of healthy animals released (even without

knowing their longer-term individual survival; Car-

dona et al. 2012, Mestre et al. 2014).

To fill this knowledge gap, we analysed data on

injured sea turtles admitted into rehabilitation facili-

ties from 1986 to 2004 in Florida (USA) to determine

Year Died during Successfully Unknown Total Success 95% confidence limits

rehabilitation or rehabilitated rehabilitation turtles rate Lower Upper

euthanized and released outcome (proportion)

1999 77 97 0 174 0.557 0.483 0.630

2000 75 61 0 136 0.449 0.366 0.533

2001 29 2 3 60 0.059 0.011 0.188

2002 39 20 1 60 0.333 0.221 0.466

2003 55 16 8 79 0.203 0.122 0.308

2004 26 14 21 61 0.230 0.134 0.350

2005 53 19 11 83 0.229 0.147 0.330

2006 89 25 14 128 0.195 0.134 0.272

2007 145 45 33 223 0.202 0.153 0.259

2008 104 33 52 189 0.175 0.125 0.234

2009 128 40 66 234 0.171 0.127 0.225

2010 92 41 39 172 0.238 0.179 0.307

Total 912 413 248 1573 0.263 0.241 0.285

Table 1. Yearly data on rehabilitated sea turtles stranded along the Queensland, Australia, coast between 1999 and 2010. Data

are summaries from the Queensland marine wildlife stranding and mortality database (StrandNet; compiled from Haines et al.

2000, Haines & Limpus 2001, Greenland et al. 2004, Greenland & Limpus 2006, 2008, Biddle & Limpus 2011). Raw data were

unavailable for analysis

Baker et al.: Sea turtle rehabilitation

the overall success rates of rehabilitation, and whether

body size, sex or species identity influenced rehabili-

tation outcome. Understanding the outcomes of reha-

bilitation is essential because the public often views

these as conservation efforts (Feck & Hamann 2013,

Mestre et al. 2014).

MATERIALS AND METHODS

Sea turtle standing and rehabilitation

We used standardized data collected by the Sea

Turtle Stranding and Salvage Network (STSSN) in

Florida from 1986 to 2004 (Shaver & Teas 1999, Foley

et al. 2005), available online at http://ocean.florida

marine.org/mrgis/Description_Layers_Marine.htm #

turtle. The STSSN documents marine turtle strand-

ings along the Gulf of Mexico and Atlantic coastlines

of the United States. Information about each turtle

stranding event, when known, is recorded on a form

(e.g. date, location, species, sex, body size; see

STSSN Stranding Report at www.sefsc.noaa.gov/

species/turtles/strandings.htm), and all live turtles

are transported to rehabilitation facilities. Follow-up

details entered into the dataset often included the

fate of each turtle (died in captivity, euthanized,

released, or maintained in captivity indefinitely) and

the date of death or release back into the wild (as

appropriate).

From 1986 to 2004, a total of 2462 live-stranded sea

turtles were taken into rehabilitation, representing

all live stranding events recorded in Florida. The

dataset did not include sufficient information about

the type of injuries that potentially caused the turtle

to become stranded to include this variable in the

analysis. We used curved carapace length (CCL;

measured upon arrival at rehabilitation) as a meas-

ure of turtle body size; when straight-line carapace

length (SCL) was the only measurement available,

we converted this to CCL using Teas’ (1993) equa-

tion: SCL = 0.294 + (0.937 × CCL).

Rehabilitation success rates

We calculated the proportion of turtles that died in

rehabilitation, were euthanized, were successfully

released into the wild, and deemed to have injuries

too severe for release and thus were maintained in

captivity permanently. Proportional values and their

95% confidence limits were generated using the

Agresti-Coull approximation (Agresti & Coull 1998).

To estimate the average amount of time a turtle spent

in rehabilitation, we calculated the mean and stan-

dard deviation of the number of days spent in reha-

bilitation. For this analysis, we used the 1700 turtles

for which the outcome of rehabilitation (died or sur-

vived) and the number of days spent in rehabilitation

were known. We used a Mann-Whitney U-test to

compare the distribution of the number of days spent

in rehabilitation between turtles that died versus

those that survived.

Impacts of phenotype on rehabilitation outcome

We used generalized linear models (GLMs) imple-

mented in the program R (version 2.15.0; R Develop-

ment Core Team 2012) to estimate the influence of

multiple variables on sea turtle rehabilitation success

rates. The response variable, survival, is binomial

and describes whether each turtle lived or died. Ex -

planatory variables included species identity, sex,

body size, and the duration of rehabilitation (number

of days). Because the species we included differed in

body size by orders of magnitude, we converted raw

CCL measurements of turtles in our study to Z-scores

to allow us to compare distributions among species

(using n = 1622 turtles for which body size data were

available; Table 2). Z-scores ranged from −3 to +3,

with a value of 0 representing a turtle of average size

for the species (i.e. a Z-score represents the stan-

dardized deviation from a mean of zero), negative

values indicating smaller turtles, and positive values

indicating larger turtles. This approach also allowed

us to test for potential effects of individual body size

on survival, such as whether larger turtles were more

likely to be successfully rehabilitated.

For analysis of the influence of multiple variables

on rehabilitation outcomes, we used the subset of

records for which all data were available; common

omissions included sex and the outcome of rehabili-

tation efforts, as well as 2 turtles that were re leased

by vandals and another that escaped during rehabil-

itation (Table 2). This approach ensures that po ten -

tially competing models were refitted with the same

sample size each time. Within the subset of re cords

for which all data were available, sample sizes were

too low for analysis for 3 species (hawksbill Eretmo-

cehlys imbricata, n = 9; leatherback Dermo chelys

coriacea, n = 6; and olive ridley Lepidochelys oli-

vacea, n = 2). This resulted in a final dataset of 374

individuals, representing green Chelonia mydas (n =

184), loggerhead Caretta caretta (n = 170), and

Kemp’s ridley turtles Lepidochelys kempii (n = 20).

Endang Species Res 29: 13–21, 2015

Information theoretic approaches acknowledge

that a range of different models may display similar

abilities to describe true data. The process thus

requires fitting a range of competing models, which

are then compared in terms of their explanatory abil-

ities. Akaike’s information criterion (AIC) is a meas-

ure of information lost in fitting a given model, with

the lowest values indicating the best approximation

of data. This approach can, however, reveal that mul-

tiple models are equally supported descriptions of

the true pattern. Final model selection is thus based

on the magnitude of the difference in AIC values

between models. The best-supported models (i.e.

ΔAICs) are those that make up the top 90% of Akaike

weights and have relative deviations from the best

model of less than 2 (Burnham & Anderson 1998).

We first developed a global GLM that fitted all

explanatory variables: the full model. To determine

which variables were required to generate the best

approximating model, we used the dredge function

in the R package ‘MuMIn’ (Barto 2012) to produce

likelihood estimates for all possible nested models

(models including subsets of variables in the global

model) and chose the most parsimonious model (or

combination of models) based on ΔAIC for small sam-

ple sizes (ΔAICc). The response variable was logit-

transformed to ensure linearity. Thus, the coefficients

associated with the explanatory variables included in

the model are returned as log-odds ratios. To pro-

duce intuitive results, we transformed coefficient

value log-odds to simple odds ratios.

RESULTS

Rehabilitation success rate

Of the 1700 sea turtles with known rehabilitation

outcomes, 626 individuals (36.8%) survived and

were subsequently released back into the wild, 1047

individuals (55.3%) died in rehabilitation and 27 in -

dividuals (1.6%) survived but remained in captivity

(Table 2). The mean number of days spent in rehabil-

itation differed between turtles that died and those

that survived (Z = −24.59, p < 0.001). Turtles that

were successfully rehabilitated and released back

into the wild spent a greater mean time in rehabilita-

tion than those that died (Fig. 1).

Impacts of phenotype on rehabilitation outcome

The most parsimonious model (GLM2) included

the terms body size, time in rehabilitation and spe-

Species Total no. of Outcome Sex and Time and Size and All variables

turtles known outcome known outcome known outcome known known

Green 1218 860 241 750 828 184

Loggerhead 931 628 215 565 592 170

Kemp’s ridley 186 123 29 108 113 20

Hawksbill 113 76 10 72 76 9

Leatherback 12 11 6 11 11 6

Olive ridley 2 2 2 2 2 2

Total (%) 2462 1700 (69) 503 1508 1622 391 (15.9)

Table 2. Summary of known variables and associated sample sizes for the standardized data on stranded sea turtles gathered

by the Florida Sea Turtle Stranding and Salvage Network between 1986 and 2004

Died Survived

Outcome of rehabilitation

400

800

1200

Time in rehabilitation (d)

Fig. 1. Number of days spent in treatment by stranded turtles

that died during rehabilitation (n = 884) or survived (n = 624).

All turtles were found stranded alive along the Florida coast

by the Sea Turtle Stranding and Salvage Network and taken

to rehabilitation facilities between 1986 and 2004. Shown are

box plots (in grey) with outliers (filled circles and lines)

Baker et al.: Sea turtle rehabilitation

cies identity (Table 3). GLM2 had a smaller AIC

(139.5) compared to the global GLM (GLM1; AIC =

141.5). The difference in AIC between these 2 mod-

els is equal to 2, and thus both are equally plausible

(Burnham & Anderson 1998). We chose to focus on

the model with the lowest AIC. The 14 other possible

competing models did not fit our data as strongly (i.e.

ΔAICc > 2) (Table 4).

Body size (χ

= 61.5, df = 1, p < 0.001), time in

rehabilitation (χ

= 26.629, df = 1, p < 0.001) and

species identity (χ

= 39.174, df = 2, p < 0.001) sig-

nificantly influenced rehabilitation success. All coef-

ficients were positive, indicating positive influences

of these variables on rehabilitation success (GLM2;

Tables 3 & 5). Larger turtles of every species were

more likely to survive than smaller ones. For every

Model Explanatory Coefficients df Deviance AIC χ

p-value

variables (odds ratio)

GLM1

AIC = 141.5 Species 2 167.70 175.70 38.188 <0.001

Sex 1 129.51 139.51 0.000 0.987

Time 1 156.08 166.08 26.573 <0.001

Standardized size 1 189.75 199.75 60.243 <0.001

GLM2

AIC = 141.9 Kemp’s ridley 1.756139 2 168.68 174.68 39.174 <0.001

(5.790618)

Loggerhead 3.810844

(45.18856)

Time 0.005280 1 156.14 164.14 26.629 <0.001

(1.005294)

Standardized size 2.244386 1 191.06 199.06 61.500 <0.001

(9.434621)

Table 3. Plausible models for estimating the influence of species, body size (standardized curved carapace length), sex (male

or female) and time in rehabilitation (d) on sea turtle rehabilitation success rates. The dataset contains details of turtles

stranded in Florida and taken to rehabilitation between 1986 and 2004 (n = 374). Akaike’s information criterion (AIC) indicated

that the most parsimonious generalized linear model (GLM) was GLM2. Odds ratios were transformed from the coefficients

(log-odds) calculated by GLM2

GLM Intercept Sex Species Time Standardized df AICc ΔAICc

(coefficients) size (coefficients)

1 (Global) −6.983 + + 0.005281 2.245 6 141.7 2

2 −6.985 + 0.005280 2.244 5 139.7 0

3 −5.135 + 1.890 4 164.2 25

4 −5.160 + + 1.876 5 166.2 26

5 −3.385 0.003181 1.569 3 174.7 35

6 −3.558 + 0.003145 1.543 4 175.8 36

7 −2.962 1.492 2 190.2 51

8 −3.160 + 1.461 3 190.8 51

9 −4.261 + 0.003905 4 199.2 60

10 −4.411 + + 0.003848 5 199.9 60

11 −2.847 + 0.002850 3 221.0 81

12 −3.632 + + 4 221.5 82

13 −3.390 + 3 222.2 83

14 −2.543 0.002924 2 222.4 83

15 −2.589 + 2 236.4 97

16 −2.240 1 239.0 99.29

Table 4. Candidate generalized linear models (GLMs) used to assess the influence of species, body size (standardized curved

carapace lengt), sex (male or female) and time in rehabilitation (d) on sea turtle rehabilitation success rates. The dataset con-

tained details of turtles stranded in Florida and taken to rehabilitation between 1986 and 2004 (n = 374). Models with a

difference in Akaike’s information criterion (with correction for finite sample sizes; ΔAICc) greater than 2 were not well

supported

Endang Species Res 29: 13–21, 2015

increase in the CCL equivalent to 1 SD from the

mean, the odds of survival increase by 9.4 times

(Fig. 2). Additionally, the longer a turtle spent in

rehabilitation, the more likely it was to be released

(Fig. 3), with the odds of survival increasing by a

factor of 1 for each additional day spent in rehabili-

tation. The significant species effect in our model

revealed that loggerhead turtles were more likely

than the other 2 species to survive rehabilitation,

with green turtles the least likely and Kemp’s

ridleys intermediate (Figs. 2 & 3).

The power of our model could be

improved if the stranding dataset

had more complete records, which

greatly limited sample sizes in our

full analysis. Only 15.9% (n = 391) of

the 2462 records had complete infor-

mation (Table 2). Sex was the most

com mon variable missing, known for

only 503 (29.6%) turtles with known

rehabilitation outcomes (Table 2).

Complete details were recorded for

only 8% of hawksbill turtles (Table 2),

and the low sample sizes for other

species reflect their relative live

stranding rates (e.g. leatherback and

olive ridley turt les were generally

found dead rather than alive).

DISCUSSION

Any study on the success of reha-

bilitation efforts should be placed in

context; we have summarized find-

ings from a study spanning all stran -

ded turtles documented in Florida

over a period of 2 decades. We found

that 63% of sea turtles admitted into

rehabilitation facilities were never

released back into the wild, and those

animals that were released (37%) of-

ten required extended periods in re-

habilitation — ranging from months to

over 3 yr. Most mortality occurred

early in the rehabilitation process

(within a few weeks), but many ani-

mals died even after substantial peri-

ods in care (e.g. over 3 yr). We found

strong differences among species in

terms of rehabilitation success; log-

gerhead turtles were most likely to

survive rehabilitation, followed by

Kemp’s ridleys and green turtles, and larger individu-

als of all species were more likely to survive than

smaller individuals. Underlying these patterns, how-

ever, is unexplained variance that includes the causes

of mortality and severity of injuries, the treatments

provided to individual turtles, and the likelihood of

sick or in jured turtles becoming stranded and found.

Therefore, the results of our study do not necessarily

apply to other contexts in which different parameters

may be known about injured turtles. Low success

rates are typical of many rehabilitation programs

Species Body size (cm) Time (d) Sex (n)

Mean (SD, range) Mean (SD, range) Female Male Unknown

Green 44.0 72.4 122 62 184

(14.12, 23.5−108.1) (206.91, 0−1323)

Hawksbill 44.9 15.0 6 3 9

(19.11, 24.1− 76.6) (23.0, 0−60)

Kemps ridley 40.2 54.5 14 6 20

(14.79, 16.5−71.9) (77.22, 0−294)

Loggerhead 84.7 84.7 93 77 70

(16.18, 48.7−119) (151.75, 0−1119)

Table 5. Attributes of sea turtles admitted into rehabilitation centres in Florida

between 1986 and 2004 (n = 374), including body size and sex ratios of 4

species and the duration that each spent in rehabilitation prior to successful re-

lease back into the wild

–2 –1 0 1 2 3

Curved carapace length (standardized)

0.0

0.2

0.4

0.6

0.8

1.0

Probability of survival

Green

Kemps ridley

Loggerhead

Fig. 2. Size (standardized curved carapace length, CCL) versus probability of

survival for sea turtles taken for rehabilitation in Florida between 1986 and

2004 (n = 374). A standardized CCL value of 0 represents a turtle of average

size (i.e. a Z-score represents the standardized deviation from a mean of zero),

negative values indicate smaller turtles, and positive values indicate larger

turtles. Solid line: fitted values obtained by the binomial generalized linear

model (GLM) for each species; open circles: observed values for all species. As

the size of a turtle increases, so does the probability of survival

Baker et al.: Sea turtle rehabilitation

(Tribe & Brown 2000), but our findings indicate that

Florida sea turtle rehabilitation success rates are

higher than those in Australia (26%; Table 1).

Euthanasia is an option for some stranded turtles

whose injuries are severe enough to indicate that re-

habilitation may be unsuccessful (Karesh 1995, Tribe

& Brown 2000, Moore et al. 2007). For turtles that ap-

pear capable of making a full recovery, however, the

longer they survive in captivity the more likely they

are to be released back into the wild (Fig. 1). This

pattern emerges because those individuals that have

the most severe injuries die very quickly in the reha-

bilitation process, and as individuals are successfully

nursed through the first several weeks of rehabilita-

tion (when the health complications are most severe)

their odds of surviving dramatically increases (Fig. 1).

Individuals that require long periods in rehabilitation,

however, could present potential risks to wild sea

turtle populations. During rehabilitation, animals may

be exposed to pathogens to which they do not have

immunity (Tribe & Brown 2000, Moore et al. 2007).

These individuals may transmit diseases, which have

been acqui red or modified in rehabilitation, to the

wild population upon release (Tribe & Brown 2000,

Moore et al. 2007).

Although many individual turtles are successfully

released following extended rehabilitation, we know

very little about whether these animals ultimately sur-

vive. In general, reptile repatriation

projects are not very successful, and

thus long-term monitoring of sea turtle

survival after release from rehabilita-

tion is important (Dodd & Seigel 1991,

Karesh 1995, Tribe & Brown 2000).

Such stu dies are scarce because of the

ex pense associated with monitoring

re habilitated individuals in the open

ocean after release (Cardona et al.

2012, Mestre et al. 2014). Satellite

tracking of rehabilitated loggerhead

turtles has revealed that their move-

ment behavior is more variable than

wild turtles; released turtles travel at

higher speeds, turn back more often,

spend more time on the continental

shelf and at the surface during the

night compared to healthy turtles

(Cardona et al. 2012). Although this

suggests that reha bilitated loggerhead

turtles can survive for at least several

months after release back into the

wild, the behavioral anomalies they

have exhibited casts uncertainty upon

whether these individuals will survive and reproduce,

and thus contribute to the population over the longer

term (Cardona et al. 2012). Another study on logger-

head and green turtles suggested that rehabilitation is

promising, since turtles migrated towards known for-

aging areas following release (Mestre et al. 2014).

Understanding the capacity for released turtles to

breed and thus contribute directly to population re -

cruitment is also limited (Karesh 1995, Cardona et al.

2012, Mestre et al. 2014). The majority of information

about rehabilitated sea turtles has been gleaned from

animals that have been incidentally hooked or netted

by fishing gear and released immediately after hook

removal or untangling from netting aboard the fish-

ing vessel. The survival outcome for these animals

may differ from individuals that require long and

complicated rehabilitation in captivity for more seri-

ous illness or injury (Cardona et al. 2012). Thus, fur-

ther investigation into post-release survival rates of

rehabilitated sea turtles is necessary to better assess

rehabilitation success and its effects on behavior

(Cardona et al. 2012, Mestre et al. 2014).

The conservation value of animals during rehabili-

tation, and those that remain in captivity indefinitely

due to the serious nature of their injuries may be es-

pecially important as a mechanism to educate the

public about wildlife conservation (Feck & Hamann

2013). In our study, 1.6% of surviving sea turtles re-

0 200 400 600 800 1000 1200 1400

Time in rehabilitation (d)

0.0

0.2

0.4

0.6

0.8

1.0

Probability of survival

Green

Kemps ridley

Loggerhead

Fig. 3. Days spent in rehabilitation versus probability of survival for sea turtles

taken for rehabilitation in Florida between 1986 and 2004 (n = 374). Solid line:

fitted values obtained by the binomial generalized linear model (GLM) for each

species; open circles: observed values for all species. As the number of days

a turtle spends in rehabilitation increases, so does the probability of survival

Endang Species Res 29: 13–21, 2015

mained in captive facilities such as aquariums and

public education centres. Rehabilitation facilities play

a major role in providing environmental education

and raising public awareness about conservation is-

sues (Tribe & Brown 2000, Moore et al. 2007, Cardona

et al. 2012, Feck & Hamann 2013). For example, a live

turtle in rehabilitation can facilitate effective outreach

programs about habitat conservation (Moore et al.

2007, Feck & Hamann 2013). Allowing people to in-

teract directly with injured animals develops a sense

of stewardship for wildlife which may foster commu-

nity involvement in local habitat protection and con-

servation (Tribe & Brown 2000, Feck & Hamann

2013). Additionally, the release of rehabilitated turtles

can have important public educational benefits (Tribe

& Brown 2000, Cardona et al. 2012, Mestre et al.

2014) because such opportunities are often advertised

widely as media events to raise awareness of the

threats facing wildlife. Although this may not con-

tribute to conservation directly (in terms of population

growth), continuing to rehabilitate these animals in

facilities that are open to the public likely contributes

to conservation in other ways, by facilita ting a wide-

spread understanding of the cau ses and nature of

wildlife injuries. The public can also use this knowl-

edge to place political pressure on decision- makers in

a context where conservation measures are known,

feasible and available, but not implemented because

of lack of will by those responsible.

Our results provide decision-makers with a greater

understanding of the relatively low success rates of

sea turtle rehabilitation and the phenotypic attrib-

utes that influence rehabilitation success, enabling

prioritization of animals when the number of turtles

exceeds resource availability. When resources are

limited, we recommend focusing efforts on larger

adult turtles, which are more likely to survive

re habilitation. When possible, priority care should be

provided to species that are easier to success fully

rehabilitate (e.g. loggerhead turtles in Florida) or

rare species for the area. Key future studies should

include more thorough collection of data on stranded

and rehabilitated animals and post-release monitor-

ing of released individuals to determine survival

rates and reproductive potential. This information

can then be used to model the po tential conservation

outcomes of rehabilitation ef forts on population

dynamics. Overall, decision-makers should continue

to promote legislative protection efforts that seek to

reduce strandings, provide funding support for facil-

ities that rehabilitate threatened animals, and pro-

vide funding for research that investigates the causes

and consequences of strandings.

Acknowledgements. We are grateful to the Florida Marine

Research Institute and Florida Sea Turtle Stranding and Sal-

vage Network for making data accessible. We thank A.

Foley, director of STSSN, for permission to use the dataset

for our research, and R. Jones and S. Blomberg for statistical

advice.

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Editorial responsibility: Paolo Casale,

Rome, Italy

Submitted: August 18, 2014; Accepted: August 15, 2015

Proofs received from author(s): October 12, 2015

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