Galapagos Islands species diversity

In the second of my pieces on the Galapagos Islands, we look at the animals.

The Galapagos are the only remaining archipelago with an almost complete species composition. That’s what makes them special.

Apparently 95% of the species Darwin would have seen are still on the islands – only 5% loss in the past 150 years. That’s remarkable given the fragile nature of the environment and testament to the conservation efforts on the Galapagos.

The biggest threats to the wildlife on the islands are introduced species: rats, cats, dogs, goats, donkeys, pigs, cattle and horses. The worst are really rats, cats and goats as it is very hard to catch & kill them.

Back in Darwin’s day, the biggest threat to the wildlife was humans. Hardly surprising when you realise that Darwin was basically on a hunting trip. He spent much of his time on the islands shooting things. When he set sail, the Beagle was carrying 32 giant tortoises as food for the return journey.

The Galapagos were in fact a form of drive through. Giant tortoises were unfortunate to be the ultimate sailor’s take away – they could be kept alive on a ship for months to provide fresh meat for the sailors on long voyages.

It wasn’t until many years later that Darwin began to develop his theory of evolution, helped by his observations of the finches on the Galapagos when he was a younger man.

Basically, each island had its own version of the finch but each with a distinctly shaped beak. He realised that each had evolved a subtly different shaped beak to adapt to the available food on each island.

Darwin actually never realised that the giant tortoises were also grouped into 13 sub-species, again evolved differently on each island.

So, the animals you see on a Galapagos holiday today are, give or take a goat, cat or rat, those which have evolved there over the course of millions of years.

In my previous article on the formation of the Galapagos Islands, I mentioned that we are presumably on Galapagos version II. We know this because the evolutionary span of the animals is greater than the geological age of the land.

That is to say that the animals are older than the land they inhabit. The assumption is therefore that there was an older archipelago which gradually drifted underwater as the earth’s plates shifted. The animals basically hopped off these and onto the newer islands we see now. That’s a gross simplification but I think gives you the gist of the story.

Join us on a Galapagos cruise holiday or find out more about the Galapagos Islands.