Well in Sydney there's a lot of dust in the mats but that's just about it. This is the official state track so they keep it clear of "wildlife", the mats are just old since they've been around since the 2000 Olympics. We do see some rabbits run across the field from time to time where there aren't too many people around.
I used to train at some other tracks in Sydney but this was before I got involved in the pole vault. Found all sorts of bugs around the tracks.
I found one brown spider with MASSIVE fangs. Having migrated to Australia from the US I really didn't have any idea what it was exactly. As I was about to go in for a closer look somebody pulled me back and told me it was a 'Funnel Web Spider' and I should back off! I didn't know what that was so I looked it up...
"The Sydney funnel-web spider is one of the most dangerous spiders in the world and will defend itself aggressively if threatened or frightened. For this reason, humans are strongly advised not to approach them. Chances of being bitten are high if encountered, and bites can be lethal within 15 minutes if not treated."

http://en.wikipedia.org/wiki/Sydney_funnel-web_spider
Luckily this was at a smaller track - funnel webs usually steer clear of crowded areas.