Mammal Species: 1076 (5 of which I saw but wasn't able to photograph)
This number doesn't include subspecies, which I'm keen on adding soon. It's also constantly in flux as I discover I actually hadn't seen species I thought I had (usually due to a zoo's mislabeling) or subspecies are elevated to full species. I'm also not totally sure which taxonomic scheme to follow. For the most part I'll follow how wikipedia or zootierliste separate species. If I followed Lynx, especially for Bovids my number would be even higher.
I've been thinking of starting a # of mammal species seen poll soon- consider the above a preview haha.