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BOURNEMOUTH NATURAL SCIENCE SOCIETY | ||
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Given by: Glenn Duggan, Fellow, Zoological Society, London.
The world's first five big extinctions were due to natural phenomena of meteors and volcanic eruptions. Glenn's contention is that Man is responsible for the sixth, which is happening all around us today.
Even this week the Alaotra Grebe from Madagascar joined the extinct list, its demise due to Man's introduction of carnivorous fish into its homeland lake.
Extinctions are an inevitable part of evolution - remember the Moa and the Dodo. It is the current rate of extinctions that is so alarming. Causes were listed - agriculture (linked to population growth) - exploitation - human disturbance - long line fishing - climate change - and the introduction of invasive species.
Graphs illustrated the countries and areas holding critically endangered species. Many islands feature because their endemic bird species have nowhere to go when conditions alter.
Case Studies illustrated the problems. Lord Howe Island off Australia was one such. It was home to endemic ground feeders until the SS Makambo ran aground in 1918, releasing rats. In the 1920s Owls were introduced to predate the rats, but hunted the birds. Despite a rat cull in 1932, 8 of 15 endemic species are extinct now.
Glenn spoke about individual species that have become extinct which include the Passenger Pigeon. 3 - 5 billion birds inhabited the Americas in the 19th century. Hunted for food to extinction, the last bird died in captivity in 1914. BNSS's taxidermy specimen is one of few remaining examples in the world.
The loss of 99.9% of India's Vultures is another shocking statistic. Their demise has been caused by use of a veterinary drug diclofenac and its replacement, used to treat cattle. The loss of these prime scavengers is tipping the balance of India's ecosystem.
Glenn's top ten rare birds include the Caerulean Fly Catcher. Agriculture has cleared much of the forest of its Indonesian Island home of Sangihe. The eight remaining square kms holds the remaining 19 birds in the world. Interest in the species is generating Bird Tourism, and the hope is that this will encourage local people to maintain the forest remnant.
A list of ten priority actions that need to be taken to save critically endangered species, was discussed. Some of these actions, such as minimising the danger to sea birds from long line fishing, are being addressed with some success.
Alongside the extinctions, new species are being discovered. This statement closed a thought-provoking closely argued lecture on a hopeful note.