Biggest differences are the chip size and the lens size. These compare to 1/4 inch ccds on the Canon and 1/6th inch on the Panasonic. So you would expect a better quality image on the Canon.
As far as the lenses go the Canon has a 58mm compared to the 37mm of the Panasonic. That should give the Canon the edge in poorer light conditions.
I am not so sure about the Panasonic's manual settings (Reviews suggest Programmed settings only?) but the Canon has full manual control, this may well be important to you in your wildlife shoots. (incidentally I have some wildlife myself - 2 girls and a boy!).
Like Lloyd, I have an XM2 and I have to say I am delighted with it. So if you have a spare £1,200 to £1,400 then why not. Having said that, if you are only an occasional videographer, its a lot of dosh for a second cam and the Panasonic does get good reviews.
Incidentally I am also with Lloyd on the external mic. There is a little bit of motor noise from the XM2. Unlike Lloyd though, I can't afford the Sennheiser so I bought a Rode (and I am very pleased with it too).
COMPAQ something or other with 500Gb Boot Disk, 1Tb external Firewire Disk, 4Gb Memory and a super duper sound card, 19" TFT Monitor etc etc etc
Sony TRV33e : Sony TRV310e : Canon XM2
Sony Vegas Studio editions to v11
Remember, there is always more to learn than there is to teach.