Biology 1229

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Biology 1229

• Extinction 3 Good News Stories

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The four horsemen of the extinction crisis I
Habitat destruction

• Formation of parks and reserves
• SLOSS?

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Blue and John Crow Mountains National Park

• 800 km2 of habitat protected
• Ongoing surveys to establish basic population
  biology of species

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Moapa Dace

• Moapa coriacea
• Upper headwaters of the Muddy River, Clark
  County, Nevada

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Moapa Dace

• Once widespread throughout Muddy River
  tributaries
• Requires thermal springs (30 C) for breeding
• Habitat destruction
• Hot springs resorts!
• Swimming pools in hot springs
• (treated with Chlorine!)
• Dams
• Planting of exotic species
• Water sucked out of aquifer for developments
• Also invasive species (aquarium species)
  Tilapia
• 3800 in 1994 850 in 2003

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Moapa Valley national Wildlife Refuge

• 106 acres ( 43 ha)
• Restoration of stream
• Breeding habitat produces 95 of Moapa Dace
  recruited into population

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SLoSS

• Single Large or several small?
• The great debate in reserve design!
• Risk vs habitat
• Amount of habitat required
• Many or one population?

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The four horsemen of the extinction crisis II
Overkill

• Antarctic fur seal

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Antarctic Fur Seal

• Arctocephalus gazella
• Breeds on islands around the Antarctic
• Sexually dimorphic
• Males 200 kg
• Females 40 kg
• Eat Krill

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Hunted for fur

• Intensively in late 18th/early 19th Centuries
• Partial recovery in 19th Century
• Followed by more hunting
• Commercially extinct in early 20th century
• Between 1 3 remaining colonies remaining
• lt1000 animals total

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Hunting ceases

• Firstly for commercial reasons
• Followed by legal protection
• CCAMLR
• CITES
• IUCN

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Current populations (as of 2004)

• All around sub-Antarctic
• 11/14 populations increasing
• 2.7-6.2 MILLION seals on South Georgia alone
• Doing well out of whale decline?
• IUCN Least Concern

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The four horsemen of the extinction crisis III
Invasive species

• Mainland islands and eradications in New Zealand

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No (or fewer) rats, etc
Many species hanging on
Rats (etc)
Finite space and habitat
Many species extinct
Lots of space and habitat
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Two strategies

• Make more of the islands useful for conservation
• Eradication of predators
• Make the mainland more like an island
• The Mainland Island concept

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Predator eradication

• Pigs (Adams Island)
• Cats (Macquarie Marion)
• Rats
• The biggest baddie for birds!

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How to eradicate rats?

• By hand
• Breaksea Island (26 ha) 1986
• By Air
• Codfish Island (1800 ha) 1998
• Kapiti Island (2200 ha) 1996
• Several others in this size range
• Scaling it up
• Campbell Island (11300 ha) - 2001

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Aerial poison drops

• Use mammal-specific poison
• Useful mainly in places where there shouldnt be
  any mammals
• Need to know about biology of target
• Get correct rates densities of poison spread
  etc.

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Problems

• Putting an awful lot of poison into the
  environment
• 12 tonnes on Campbell Island!
• collateral damage
• Dangerous

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Results

• Significant recovery of many species
• Seabirds, landbirds, endangered insects, even
  plants!
• New habitat for reintroductions
• Few reinvasions

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Exporting the revolution

• Theres no island in the world from which we
  cant eradicate rats
• Pete McClelland, Rat eradication guru

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But

• There are only so many islands
• Only so much habitat
• Some important habitat simply wont grow on
  islands

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Mainland Islands

• All the rage in New Zealand conservation
• Build a fence, eradicate the predators and
  re-introduce the species you want

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Karori Wildlife Sanctuary

• (Almost) downtown Wellington, New Zealand
• Former reservoir for drinking water
• 252 ha
• 8.6 km of predator-proof fence erected in 1999

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Reintroduced

• 12 species of birds
• 6 IUCN red-listed
• Tuatara
• Giant Weta

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The four horsemen of the extinction crisis IV
Climate change
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Problems with climate change

• Extreme weather events (see natural disasters)
• Changes in habitat zone
• Northward shifts in climatic zones
• Plants and animals cant keep up

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Assisted migration to help deal with climate
change?

• Give the species a helping hand?!
• Serious ethical issues with introducing new
  species
• Serious ethical issues with standing by and
  watching species go extinct