Pages

Sunday 25 January 2009

Jaguars - the British connection

Many of us will have watched TV wildlife series on South America and seen the brief glimpse that fortunate scientists manage to get of a Jaguar. These cats are extremely hard to see, confined as they are to dense rainforest, although a few Mexican Jaguars stray across the Rio Grande into southern Texas. However, they are the quintessential South American big cat.

So it is a bit surprising that the oldest known fossil Jaguars actually come from Europe – indeed some of the best preserved of them come from Westbury-sub-Mendip near Bristol at a cavern that filled in about 2 million years ago.

These fossil Jaguars, whose scientific name is Panthera gombaszoegensis, were slightly larger and more long-legged than the modern form, which suggests that they were more adept in open country than the forest adapted modern P.onca.

The range was not of course confined to Britain – in fact fossils have been found all over Europe and they probably also reached India. They must have reached into North East Asia because they crossed the Bering land bridge into North America about 1.5 million years ago.

About the same time, or slightly later, early Lions also crossed in to North America, and both species had a vast range – Jaguars of the modern form reached as far north as Nebraska during the Ice Ages and as far south as the tip of South America. Lions likewise reached South America, but it seems that the two species competed – fossil sites usually have one or the other but not both. Jaguars died out in the Old World during the Ice Ages but lions survived in North America until about 10,000 years ago.

The traffic across the Bering land bridge was not all one way – both Cheetahs and Pumas crossed from their ancestral home in North America into the Old World, and Pumas eventually reached Britain. However, Pumas died out in Eurasia and Cheetahs died out in North America at the end of the last Ice Age, at the same time as most other large mammals in North America – including Pumas (modern North American pumas descend from South American survivors).

What does this mean for conservation? Well, first of all, we need to be careful when we talk about an animals “natural” range. An animals’ range may be its current range (where it lives now), its historic range (where it lived when people started taking notes about it), or its prehistoric range (where it used to live) – and this last may not even be on the same continent as the current range.

We should also consider its future range – as the environment changes for reasons both human and natural the place where an animal lives now may progressively cease to be suitable, while other parts of the world may become ideal if it could expand its range to the area. Because of barriers to migration, whether these are oceans, rivers, or just farmland or other man-made habitats a creature cannot cross, nature reserves run the risk of becoming (as one article I read put it) “condemned cells” where species slowly fade away. The only solution is to seriously consider introductions of species outside their current range, although this too is obviously a potential risk to existing faunas. Mostly this applies to mammals – most birds will simply fly to suitable habitat as soon as it becomes available ( for example, Little Egrets have colonised the UK in recent years as a result of a warming climate). However in the case of large predators human resistance will be understandably intense – would people in this country support reintroduction of Brown Bear or Wolf? – or people in Bulgaria support reintroduction of lions – which survived in the Balkans until at least 400 BC? This is not as out of the box as its sounds – some activists have seriously suggested the introduction of the modern relatives of extinct North American large mammals such as Elephants, Cheetahs, even Lions, as a way of “repairing” the lost ecosystem of pre-human North America.

2 comments:

  1. Boy - there are a lot of books I could reccommend on these subjects!

    My favorite author of all time (today, at least) is Colin Tudge, from over in your neck of the woods. He has written several good ones, but in particular you might be interested in "The Variety of Life: a Survey and a Celebration of All the Creatures that have Ever Lived".

    Also try "The Time Before History" by Colin, as well.

    Another book you might find interesting is "The Last Giant of Beringia: the Mystery of the Bering Land Bridge" by Dan O'Neill

    All of these are very informative, extremely well written, and quite exciting!

    ReplyDelete
  2. Thanks for the book advice Ruth - I will look out for them. At the moment I am reading "Lost Land of the Dodo" - which is an ecological history of Mauritius. I plan to do a series of posts on what I learn - it is a fascinating (and tragic) read

    ReplyDelete