Download Planning for Species Reintroductions (with some examples for large

Planning for Species
Translocations and
Reintroductions
Reed F. Noss
University of Central Florida
Why Translocate or
Reintroduce Populations?
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Many regions have suffered local extinctions
Missing species sometimes played critical roles in
their ecosystems, so reintroduction can restore
those functions
Reintroductions can increase the range and overall
population size of species, enhancing probability of
persistence (so, reintroduction usually part of
recovery plans)
Many extant populations are small and inbred, so
translocations can restore genetic integrity and
fitness
Translocation can potentially save individuals that
would otherwise be lost to development
Humans have an ethical obligation to restore what
we have degraded
Be Cautious!
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Many translocations and reintroductions are failures
(e.g., 56% - 89% of translocations failed; Griffith et
al. 1989, Beck et al. 1994)
A review of 91 herpetile translocations from 19912006 found that 42% were successful, 28% failed,
and 29% had unknown success (Germano and
Bishop 2008).
Translocations to established populations can lead
to outbreeding depression or disease transmission
(to the same or related species)
Long-term studies are required before deeming any
translocation a “success” – at least several decades
for long-lived species
Steps in Translocation
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Feasibility study
Preparation phase
Release phase
Monitoring and evaluation phase
Ask critical questions: Why is
reintroduction needed? Will the
reintroduced population be viable?
Factors that Influence
Reintroduction Success
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Rigorous planning, including consideration of
habitat suitability, landscape context, and longterm population viability
Demographic and genetic characteristics of
translocated individuals (and recipient
population, if extant)
Use of wild-born vs. captive-reared individuals
Number of individuals released
Release into core or periphery of range
Controlling or eliminating factors that
extirpated the species originally
Commitment to manage habitat and (if
necessary) the population indefinitely
Rigorous Planning: Include
Empirical Assessments and
Modeling
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Field habitat evaluations in donor and recipient
sites
Habitat suitability modeling – ideally, based on
empirical data from extant populations in the
same region
Spatially-explicit population modeling
Consideration of alternative future scenarios
Validation and revision of models based on
new information
Or other surrogate of prey productivity
Demographic potential of wolves under current landscape conditions and
moderate mortality risk scenario, as predicted by PATCH. Areas in yellow
have <50% probability of occupancy.
From:
Carroll (in prep).
Demographic potential of wolves under future (2025) landscape conditions
and moderate mortality risk scenario.
From:
Carroll (in prep).
Predicted recolonization potential for wolves under current landscape
conditions and moderate Canadian mortality risk scenario, assuming a 250
km/yr maximum dispersal distance over 200 years.
From:
Carroll (in prep).
Predicted recolonization potential for wolves under current landscape
conditions and moderate Canadian mortality risk scenario, assuming a 1500
km/yr maximum dispersal distance over 200 years.
From:
Carroll (in prep).
Predicted potential for wolf dispersal from a reintroduction site in northern
Maine to other areas of the northeastern U.S. and southeastern Canada under
current landscape conditions and moderate mortality risk scenario
over 200 years.
From:
Carroll (in prep).
Demographic and genetic
characteristics
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Release juveniles or adults?
Select individuals from a donor population
close to recipient site, if possible
Release a large number of individuals
Release a genetically diverse mix of individuals,
if possible
If augmentation, analyze genetics of donor and
recipient populations to guard against
inbreeding and outbreeding depression
Release Adults or
Juveniles?
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Seemingly more efficient to release adults,
as they can breed immediately
However, integrating genetic with
demographic considerations, one recent
modeling study of griffin vultures found that
release of juveniles reduced long-term
extinction risk from the accumulation of
mutations (Robert et al. 2004)
Wild-born or Captivereared?
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Griffith et al. (1989) review of mammal and
bird translocations showed greater success
with wild-born animals, as expected from
selection theory
A few generations of domestication can
have negative effects – e.g., for steelhead
trout, genetic effects of domestication
reduce subsequent reproductive capabilities
by ca. 40% per generation when fish are
moved to natural environments (Araki et al.
2007)
However, in some cases (e.g., black-footed
ferret) captive breeding is the only choice
Rapid population growth of black-footed ferrets in
Shirley Basin, WY. Releases of captive-born animals
ended in 1994. Lambda since 2000 estimated as 1.35
(from Grenier et al. 2007)
Release into Core of
Original Range?
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Reviews (Griffith et al. 1989, Wolf et al.
1996) suggest release into core of historical
range is preferable
For many mammals and birds, however,
ranges have collapsed from the center
outward, with peripheral populations
persisting (e.g., Lomolino and Channell
1995, 1998)
Perhaps peripheral populations are, in sum,
adapted to a greater range of conditions
and are pre-adapted to anthropogenic
disturbance
Hard or Soft Release?
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Hard release – individuals are released
immediately into recipient site without
any assistance
Soft release – individuals are released
with supplemental food, shelter, etc.
or kept penned, then often gradually
weaned away from human assistance
Site fidelity by penning treatment in gopher tortoises. Dispersers (unshaded)
are individuals that travelled > 1 km from core release area without
establishing a burrow. (From Tuberville et al. 2005)
Control or eliminate the factors that
extirpated the species originally!
(Caughley’s declining population
paradigm)
Apply Rigorous Criteria to
Evaluate Translocations
(Ostermann et al. 2001)
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Survival and recruitment rates in donor population
Survival rate of released animals
Recruitment rate of released animals
Growth rate of reintroduced or augmented
population (at recipient site)
Establishment of a viable (self-sustaining)
population
However, as of 1994, less than half of
reintroduction projects had been assessed
Key Research Questions
(Armstrong and Seddon 2007)
Population Level
 How is the establishment probability
affected by size and composition of the
release group?
 How are post-release survival and dispersal
affected by post-release management?
 What conditions are necessary for
persistence of the reintroduced population?
 How will genetic makeup affect persistence
of the reintroduced population?
Key Research Questions (cont.)
Metapopulation Level
 How heavily should source populations
be harvested?
 What is the optimal allocation of
translocated individuals among sites?
 Should translocation be used to
compensate for isolation?
Key Research Questions (cont.)
Ecosystem Level
 Are the target species/taxon and its
parasites native to the ecosystem?
 How will the ecosystem be affected by
the target species and its parasites?
 How does the order of reintroductions
affect the ultimate species
composition?
Gopher Tortoise “Relocations”
– the biggest translocation
issue in Florida
Need for GT Relocations?
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In Florida, the stronghold of the species,
populations have declined 50-60% over the
past 60-93 years
FWC reclassified the GT from SSC to
Threatened in 2007, and it is in review for
listing as Threatened under the federal ESA
(the western population already is listed)
Incidental take (burying alive) is no longer
permitted, and relocations are now the
major conservation measure
History and Future of GT
Relocations
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Relocations began in the 1970s and
were permitted by GFC (FWC) since
the mid-1980s
Virtually no monitoring of relocated
populations has occurred
No review of relocation success has
been conducted, except a couple local
case studies
History and Future of GT
Relocations (cont.)
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Since GTs are long-lived, at least 20 years of
monitoring post-relocation are needed (Dodd
and Siegel 1991)
Problems identified with past relocations:
- difficulty identifying suitable recipient sites
- movement of tortoises to sites with little or no
consideration of population demographics, habitat quality
and long-term management
- translocation of tortoises to sites later slated for
development themselves
Problems (cont.)
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lack of consideration of conservation
genetics and potential outbreeding
depression
disruption of resident population social
structure and behaviors
the tendency for GTs to exhibit homing
behavior and low site-fidelity once being
moved
transmission of disease and parasites
human predation at recipient sites
The missing component of GT
translocations: commensals!
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GT burrows provide shelter for ca. 360
other species, including amphibians,
reptiles, insects, and mammals, some
of which are federally and/or statelisted species and are obligate
commensals
Yet, the commensals are not
translocated with the tortoises!
Manage Habitat and (if necessary)
the Population Indefinitely
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Funding must be secure
Performance must be monitored and
enforced
Net habitat loss must be reversed
But 2.7 million acres of natural and seminatural habitat in Florida is predicted to be
lost by 2060 (Zwick and Carr 2006),
including at least 700,000 acres of GT
habitat (FFWCC 2006) – this will not work!
There is a better future possible - a net
gain in natural and semi-natural habitat