Exotics and Invasives + rewilding

exotic/alien

non native

invasive species

• species that are introduced to a new area and which out-compete the native species

• impacting the normal ecological processes and reducing species diversity

Not all alien species are invasive, but some native species can be

Introductions globally #2 threat to ecosystems (after habitat destruction)

May be #1 threat in US--$137 billion/year in damages and control costs

Introductions have occurred intentionally and by accident

Intentional

• To meet food, social or other needs of humans

• Animals transported for food, sport, or aesthetics

• Plants for food or ornamental purposes

• Control of previously introduced species

Accidental

• Ships have provided a prime route for introductions

• Pet and exotic plant trade releases

• Releases of livestock

Hawaiian Mammals

• Norway and black rats

  • introduced accidentally from ship cargo

• Mongoose 

  • introduced on many islands, including HI, to control rats

• Only one native mammal species remains on the HI islands

  • the Hawaiian hoary bat

channel islands case study

• Endemic fox and spotted skunk top predators, with occasional visits by golden eagle

  • Competition driving ecological force

• Intro of pigs provided stable prey for eagle

  • Eagles also preyed on foxes

    • Foxes decline

    • Skunks increased

    • Competition no longer the dominant ecological force controlling small predators--predation is now

    • Foxes were on verge of extinction

• Pig eradications correcting problem

guam case study

• Brown tree snake introduced in early 1950s via military transports

• Spread over island and by mid-1970s was at a density of 100/ha

• Numerous endemics became extinct

• Guam rail and Micronesian kingfisher saved by captive breeding

• Power outages

• 1991—Brown Tree Snake Control Act

• Methods of control

  • Collection

  • Poison bait

  • Snake dogs

  • Aerial poisoned (acetominophen) mice

imported red fire ants

• Accidental intro from South America

• First discovered in AL by E.O. Wilson while still in high school

aquatic aliens

• 112 species

• zebra mussels

  • economy, native molluscs

san francisco bay

• 250 species of plant and animal alien species

• Examples of invasives:

  • Green crab

  • Asian clam

  • Mitten crab

florida

• 25% of plant and animal groups non-native

• 20 endangered species primarily threatened by introduced species

• All habitats

other invasives

• Water hyacinth

  • ornamental, now found in 50 countries

• Nile perch

  • extinction of 200 endemics in Lake Victoria

• Red-eared slider

  • natural distr. Mississippi River drainage, global now due to pet trade

• Cane toad

  • introduced as a control for ag. pests, kill many native predators

• Mute swan

  • from Europe

Spotted lanternfly

• Asian origin

• 2014 found in PA

controlling invasives

• Invasive Species Specialist Group of Species Survival Commission (SSC) of World Conservation Union (IUCN)

  • 146 scientists from 41 countries

  • Empower countries to fight invasive species

  • Invasive Alien Species Specialist Group

• New Zealand world leaders

  • have a lot of rare animals and have done a lot of work to preserve them

• Other invasive mammals:

  • Pigs

  • Goats

  • Cats

  • Burros & horses

Re-Wilding North America: goals and why

• Goals: 

  • 1) Restore NA’s Pleistocene ecology & natural processes 

  • 2) Save megafauna of world

• why

  • north america has lost a majority of its large vertebrate species

Re-Wilding North America: how and issues

• how

  • introduce closely related modern species as proxies for extinct ones

  • phase 1

    • feasible species, won’t take a lot of time to acclimate

  • phase 2

    • african and asian species onto reserves

  • phase 3

    • make large historical parks

• issues

  • the great plains are used for agriculture

  • these habitats have greatly changed

  • disease transmission