Great lens you got there Jonathan, the 180 is a sweet lens. Just recently got the 24-120 VR Ed and the 80-400 VR ED lenses. Only done some test shots on the 400 the other night. and it is very sharp. So it should be for the price.
Keep them images coming. You might like to go and have a look at this site and become a member. There are plenty great artists there. The site is known as Deviant Art. Don't get any ideas from the name. It can be found by way of my link. Take a look around my gallery and then have a look at others by using the browes function at the top of the page.
http://rumplesriot2.deviantart.com/gallery/
Now that I have my new lens, I will have to make a visit to the zoo over the week end.
I want to see more shots taken with that lens.