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Half a century ago, Belgian Zoologist Bernard Heuvelmans first codified cryptozoology in his book On the Track of Unknown Animals.

The Centre for Fortean Zoology (CFZ) are still on the track, and have been since 1992. But as if chasing unknown animals wasn't enough, we are involved in education, conservation, and good old-fashioned natural history! We already have three journals, the largest cryptozoological publishing house in the world, CFZtv, and the largest cryptozoological conference in the English-speaking world, but in January 2009 someone suggested that we started a daily online magazine! The CFZ bloggo is a collaborative effort by a coalition of members, friends, and supporters of the CFZ, and covers all the subjects with which we deal, with a smattering of music, high strangeness and surreal humour to make up the mix.

It is edited by CFZ Director Jon Downes, and subbed by the lovely Lizzy Bitakara'mire (formerly Clancy), scourge of improper syntax. The daily newsblog is edited by Corinna Downes, head administratrix of the CFZ, and the indexing is done by Lee Canty and Kathy Imbriani. There is regular news from the CFZ Mystery Cat study group, and regular fortean bird news from 'The Watcher of the Skies'. Regular bloggers include Dr Karl Shuker, Dale Drinnon, Richard Muirhead and Richard Freeman.The CFZ bloggo is updated daily, and there's nothing quite like it anywhere else. Come and join us...

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Wednesday, January 28, 2009

GUEST BLOGGER OLL LEWIS: A Species To Grebe For

Oll Lewis, the Welsh dude who lives in my spare bedroom, who also happens to be the CFZ ecologist, and Richard's assistant as far as looking after the CFZ menagerie is concerned, is rapidly becoming one of the most popular bloggers on the network. Today he takes a look at extinction - a much overused word, especially in cryptozoology - and discusses the tragic extinction of one, fairly obscure, species - a flightless waterbird from Central America.

There are lessons for us all here, but after reading this little homily I bet that, like me, you will want to go to Guatamala just to see for yourself if there are any left...


There are countless sad tales one could tell about how species become have extinct. Dodos, if you want the most famous example, died out as a result of man accidentally bringing rats to their island and those rats eating the dodo eggs. The great auk was hunted to extinction by humans and one of the last auks ever seen was executed for witchcraft. In my opinion though the most tragic tale of extinction is that of the poc (Podilymbus gigas), also known as the Atitlán grebe or the giant grebe.

The poc was a large flightless grebe found only on or around lake Atitlan in the mountains of South West Guatemala. In the early 1950s this localised species was thriving with more than 200 pocs on the lake, but this was soon to change. In 1958 small mouth bass (Micropterus dolomieu) were introduced into the lake to encourage tourism to the area and this was followed by large mouth bass (Micropterus salmoides) in 1960. This plan to increase tourism in the area worked and soon enough there were throngs of fishermen with more money than sense eager to catch fish in the lake.

All this was very bad news for the poc. Both species of bass were eating the same food as the poc, crabs, and were much more efficient at catching it, which led to a sharp decline in available food. As every biologist knows, when the numbers and availability of a prey species is in decline numbers of the predator species will start to decline as individuals start to starve to death and the poc was no exception. The larger fish also went after chicks, hastening the decline. Things went from bad to worse for the poc when an an industry sprouted up on the lake to sell reed mats to tourists. These mats proved very popular and lead to the destruction of a large amount of the reed beds where the poc nested.

In 1966 in a last ditch attempt to save the species, which was now thought to number only 80, Dr Anne LaBastille, an expert on the species, decided to move the birds to a safer location, while there were still enough breeding pairs for there to be a possibility of recovery. However, when the scientists attempted to catch the pocs over a third of the birds flew away, which is unusual behaviour for a flightless bird to say the least.



It turned out that a large number of the grebes were not even pocs at all but a much more common species, the pied-billed grebe (Podilymbus podiceps), which made the rescue plan all the more difficult. Eventually though LaBastille’s plan was successful and by 1973 there were 210 pocs, the species had recovered!

Then in 1973 an earthquake came resulting in the deaths of all but 30 of the birds. The species was functionally extinct, just when it looked like they may have been saved. The species went into a slow decline and the past poc was seen on the lake in 1989.

1 comment:

Christopher Johnstone said...

What an odd story... I checked this. According to that fount of accuracy, wikipedia, the earthquake shattered the lakebed and caused a drop in the lake level, contributing to environmental disturbance. The grebes weren't killed in the earthquake, but dwindled as a result of post-earthquake environmental change. Also, 30 individuals is usually enough to sustain ok genetic diversity. There's no reason to think that 30 is definitely too low. A lot of species have been brought back from fewer... however, it turns out that the remaining individuals were largely hybrids with the pied grebe.

Also, also, although the bass may have contributed to decline, it seems unlikely that they were part of a second order mechanisms of decline, because the closely related pied grebe did persist on the lake. Possibly, the bass somehow altered the environmental conditions so that they were more favorable for the pied grebe and then decline occurred due to hybridization and/or competition. Understanding why pied grebes invaded a lake that they had previously been absent from seems the key here. There's no clear evidence why it happened though.

http://md1.csa.com/partners/viewrecord.php?requester=gs&collection=ENV&recid=1889117&q=Atitl%C3%A1n+grebe&uid=&setcookie=yes

Extinction via hybridization isn't typically thought of as a normal form of extinction, but it has been occurring quite a bit in the last fifty years or so (especially with plants and fish).

Chris