Animals understand numbers

[Catherine]

Quote:I will have a close look at this later. I might link to it from my website as further evidence of animal intelligence.

It is a well done article and it took me a while to read it and think about it.
As Catslave says, we underestimate animals. 
When they are actually observing animals to see how they work with numbers they learned a lot.
For a bird to be aware of how many eggs are in a nest and know when to add another egg is  pretty clever. The bird has to be aware of so many things.
I think the more we study animal intelligence the more surprised we will be.