Planning for Species Translocations and Reintroductions

Why Translocate or Reintroduce Populations? 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! 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 1991-2006 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 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 Rigorous planning, including consideration of habitat suitability, landscape context, and long-term 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

Demographic and genetic characteristics 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? 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 Captive-reared? 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 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? 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? 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

Control or eliminate the factors that extirpated the species originally! (Caughley’s declining population paradigm)

Apply Rigorous Criteria to Evaluate Translocations (Ostermann et al 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? 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 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.) 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.) 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! GT burrows provide shelter for ca. 360 other species, including amphibians, reptiles, insects, and mammals, some of which are federally and/or state-listed species and are obligate commensals Yet, the commensals are not translocated with the tortoises!

Manage Habitat and (if necessary) the Population Indefinitely Funding must be secure Performance must be monitored and enforced Net habitat loss must be reversed But 2.7 million acres of natural and semi-natural 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