Wow, what a great question! I’m really going to have to think about this one.
I think the answer is probably yes – but it’s not something we could do now. In fact there’s a famous science fiction book called “Do Androids Dream of Electric Sheep?” by Philip K Dick. In the book real animals have become more or less extinct and people have robot animals instead. The main character Rick Deckard has a robot sheep that lives on the roof of his apartment. It’s a shame that in the movie made from the book, Blade Runner, there’s no mention of Rick’s electric sheep (even though it’s a brilliant movie).
There are lots of reasons that we can’t make robot animals that can live in the natural environment. I can’t go through them all here but one is that the robot animals would have to eat food. In fact, in the Bristol Robotics lab, we are building robots that can get their energy from eating food. They are called EcoBots and you can read about them here: http://www.brl.ac.uk/projects/ecobot/index.html
As you can see from the pictures these robots don’t look anything like animals. There’s a very long way to go before we could build robots that can actually live in the natural environment – and how they would eat is just one of the problems. Of course there’s also a serious ethical question here: even if we could build them would it be a good idea to have robot animals in the natural environment?