Transcript Ext3
Biology 1229 Extinction 3: Good News Stories The four horsemen of the extinction crisis I: Habitat destruction Formation SLOSS? of parks and reserves Blue and John Crow Mountains National Park 800 km2 of habitat protected Ongoing surveys to establish basic population biology of species Moapa Dace Moapa coriacea Upper headwaters of the Muddy River, Clark County, Nevada 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 Moapa Valley national Wildlife Refuge 106 acres (= 43 ha) Restoration of stream Breeding habitat produces 95% of Moapa Dace recruited into population SLoSS Single Large or several small? The great debate in reserve design! Risk vs habitat Amount of habitat required Many or one population? The four horsemen of the extinction crisis II: Overkill Antarctic fur seal Antarctic Fur Seal Arctocephalus gazella Breeds on islands around the Antarctic Sexually dimorphic Males: 200 kg Females: 40 kg Eat Krill 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 <1000 animals total Hunting ceases Firstly for commercial reasons Followed by legal protection CCAMLR CITES IUCN 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 The four horsemen of the extinction crisis III: Invasive species Mainland islands and eradications in New Zealand No (or fewer) rats, etc Many species hanging on Rats (etc) Finite space and habitat Many species extinct Lots of space and habitat Two strategies Make more of the islands useful for conservation Eradication of predators Make the mainland more like an island The ‘Mainland Island’ concept Predator eradication Pigs (Adams Island) Cats (Macquarie; Marion) Rats The biggest baddie for birds! 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 Aerial poison drops Use mammal-specific poison Useful mainly in places where there shouldn’t be any mammals… Need to know about biology of target Get correct rates & densities of poison spread etc. Problems Putting an awful lot of poison into the environment 12 tonnes on Campbell Island! ‘collateral damage’ Dangerous Results Significant species recovery of many Seabirds, landbirds, endangered insects, even plants! New habitat for reintroductions Few reinvasions Exporting the revolution “There’s no island in the world from which we can’t eradicate rats” Pete McClelland, Rat eradication guru But… There are only so many islands Only so much habitat Some important habitat simply won’t grow on islands Mainland Islands All the rage in New Zealand conservation Build a fence, eradicate the predators and re-introduce the species you want 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 Reintroduced 12 species of birds 6 IUCN red-listed Tuatara Giant Weta The four horsemen of the extinction crisis IV: Climate change Problems with climate change Extreme weather events (see natural disasters) Changes in habitat zone Northward shifts in climatic zones Plants and animals can’t keep up… 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…