Conservation of Amphibians and Reptiles

General Principles

• Biodiversity crisis

  • Loss and reduction in diversity at all levels (genetics → ecosystems)

  • Primarily focus on single spp. conservation due to lack of resources for anything much bigger (e.g. habitat/environment)

• Extinction

  • Rate has greatly exceeded the “normal” historical rates

  • Could lead to cascading extinction events

    • The loss of one spp. causes the loss of multiple

Current trend: Amphibians

• World-wide amphibian declines

  • 1,260 of 6,000 spp. (21%) are endangered

  • 1,856 of 6,000 spp. (32%) are threatened

  • 2,469 spp. are in decline (43%)

Current trend: Reptiles

• World-wide reptile declines

  • Reptiles not completely assessed (mostly Chelonians)

    • Best estimate 833 of 6,500 spp. (13%) endangered

  • Turtles and tortoises well reviewed

    • 108 of 257 spp. (42%) threatened

Human Impacts

• Humans have modified the environment everywhere through

  • Habitat modification, fragmentation, loss

    • Most visible human mediated environmental change

    • Agriculture

    • Urban growth and paving

    • Overall consequences:

      • Habitat alteration and fragmentation (dispersal barriers)

      • Increased mortality due to road kills

      • Loss of breeding, foraging, & over-winter areas

      • Population declines and extinction in some cases

    • Road mortality

      • Skewed sex ratios in turtle populations

        • Predicted higher sex ratio skew in high road density

        • Road mortality of females on nesting migrations

      • Historical male-biased sex ratio?

        • Proportion of males increased linearly

        • Synchronized with increase in paced roads

      • Indiana Road Mortality

        • Surveyed Lindberg Road for 1.5 years

        • Vertebrate road mortality N=8,176

          • Herps represented n=8, 016

        • Miles of paved roads in Indiana ~93,600

  • Harvest

    • Mostly for commercial exploitation

      • Consumption (food and folk medicines)

      • Luxury trade (leathers, jewelry)

      • Pet Trade

    • Focused on a relatively few spp. in any locality (developing countries)

    • Sustainable harvest by small communities can also decimate populations

    • Examples

      • Consumption: larger, long-lived spp. (Chelonians, specifically the Apalone and also Varanus lizards)

        • 1990’s Europe imported 6,000 tons of frog legs/year

        • India and Indonesia exported 50 million frogs/year

          • Banned exports in 1987 and 1992

          • Depleted natural insecticide from paddy fields

      • Luxury Trade: American Caimans → leather

      • Pet Trade: Box turtle declines in 16 states (~30,000 box turtles since 1995)

        • High prices for rare and brightly colored spp.

  • Introduction of exotic spp.

    • Exotic spp.: Introduced/non-native

      • Black and Norway Rats → great impact on islands (lizards, tuataras, tortoises)

      • Domestic cats → widespread damage in suburban and rural areas

      • Herbivores (goats, rabbits) → change vegetation

    • American Bullfrog

      • Game spp. (frog legs)

      • large

      • High mobility

      • Live 7-9 years

      • Huge reproductive potential

      • Generalized feeding habits

        • Snakes, worms, crustaceans, insects--anything that fits in its mouth

      • California: bullfrogs reduced leopard frog survivorship by 33%

      • Arizona: bullfrogs responsible for leopard frog declines (79 out of 80 sites now extirpated; 79 sites completely devoid of leopard frogs)

    • Management Tools

      • Establishment of refuges and corridors

        • Main objective: prevent extinction

        • Key issue: How much area to preserve?

        • Location, size, and shape of refuges and corridors is dependent on:

          • Whether spp., communities, and/or ecosystems are targeted for conservation

          • Natural history characteristics of the above

        • Minimum Viable Population (MVP)

          • Minimum area required for a population or spp. to survive

          • Studies of terrestrial buffer zones with freshwater turtles

            • Savannah River Ecology Laboratory (SREL)

            • Do protected acreage of wetlands protect areas critical for nesting and hibernating?

              • No, they do not

  • Management of animals in captivity

    • Animals can be managed in captivity for:

      • Short periods (temporary)

        • “Headstart” (from hatchling to 6-12 months)

        • Hatcheries (egg incubation)

      • Long periods

        • Duration of an individual’s life

        • Sometimes several generations

        • Crocodilian farming and ranching

  • Reintroductions of wild spp.

    • Intentional release of individuals to establish or enlarge the population of a target spp.

      • Target spp. usually threatened or endangered

    • Some problems

      • Generally very few of the animals that are re-introduced survive

      • Introduction of diseases into healthy populations

      • Outbreeding depression

  • Pollution

  • Diseases

The Process of Amphibian Conservation: The Eastern Hellbender model

• Phase 1

  • Health & Genetics

    • Sampled 10 states, 70 rivers, and 1200 samples

    • Blood draws for health screens and DNA samples

    • Two large clusters

      • Ohio River Drainage (Indiana, Ohio, West Virginia, Pennsylvania)

      • Tennessee River Drainage (Georgia, Tennessee, North Carolina, Virginia)

      • i.e. Hellbenders in Indiana are genetically similar to those in Ohio

  • Sampling

  • Population Assessment

    • Understand how many Hellbenders you have

      • 88 in Dr. Williams’ case

    • Density

      • 0.06/100m^2

  • Spatial Ecology

    • Health (blood work, sperm, weight class, etc.)

    • Habitat & Home Ranges (radio transmitters and radio telemetry)

    • Hellbenders are very rare; distributed randomly across the landscape with very little interaction between other Hellbenders

  • Survival

    • Annual Hellbender survival if no action is taken: 0.804

• Phase 2

  • Population Manipulation

    • Recovery Strategies

      • Population Viability Analyses

      • Captive rearing and release

      • Translocations

        • Intra-river translocation

          • 10 native adults & 10 translocated adults

        • Captive relreases

          • 10 native adults

          • 10 captive juveniles

        • Spatial Ecology

          • Home range size nearly cut in half (2212 v. 1348 m^2)

          • Extensive HR overlap among individuals

          • Two egg clutches

        • Post-translocation

          • No impact on annual survivorship of adults (80% v. 78%)

          • 50% juvenile survivrship had exceeded 30% threshold to prevent extinction :D

  • Outreach & Education

    • Mail survey

      • 1378 Distributed

      • 281 to Riparian Landowners

      • 541 Completed (41%)

    • In-person survey

      • 242 surveys conducted

      • 6 access sites

    • Focus

      • Awareness, attitudes, behaviour

    • Approach

      • “3D Model” of O & E

        • Develop the portal

        • Design the content

        • Deliver the programs

      • Evaluate impact

      • HelpTheHellbender.org

    • Impact

      • Nationally

        • 25 organizations (6 state/fed agencies, 8 zoos, 11 universities)

        • 63% monthly

        • 82% follow

        • 81% recommend to others

  • Population Modeling

    • 2011-2012, 33 Hellbenders

    • 2018, 5 male Hellbenders

    • Must focus on juveniles

      • Increase juvenile survivorship → expected local extinction in 26 years goes up to 35

        • 30-50% increase → almost completely reverse the probability of Hellbender extinction

      • Problems with heavy predation → low juvenile survivorship

• Phase 3

  • Restoration

    • Captivity can deprive animals of experiences/natural stimuli

      • Predator cues

      • Stochastic events

      • Refuge

      • Live prey

      • Habitat variability

    • Advancing Headstarting

      • Introduce captive, juvenile Hellbenders to natural conditions to better prepare them for the wild

      • Investigate the effects of:

        • Moving water

        • Predator cues

        • Microbiome

      • 90% survivorship in 200 days, then averages around 75%

• Phase 4

  • Providing farmers federal grant money to implement conservation practices in watersheds

The Many Components of Conservation Biology

• Research

• Education/Outreach

• Management

• Captive breeding

• Partnerships

  • A collaboration with many interested bodies

  • Semiannual meetings

  • Action Teams

    • Habitat

    • Outreach & Education

    • Captive Rearing/Breeding

    • Animal Health