The buffer size as quoted in the manual is dependent on a specific card, namely the Sony QD-H32 XQD. You'll see it at the top of that page.
The real buffer size is much smaller (I think in the high 40's for 14 bit lossless compressed); these figures depend on how quickly the card can drain the buffer while shooting. So in theory if you had an adequately fast card (i.e. as fast as you were shooting) by this measure the "buffer" would be the same size as the card.
Because the D4 and XQD came out together most documents are quoting buffer using that card. Take a very slow CF card instead, and you get dramatically smaller numbers. For example in the quoted page Rob sees 74 14 bit lossless with the XQD but only 55 with the 133x CF.
So the difference in 12 and 14 bit lossless in the manual (92 vs. 75) is with that specific card. To the OP, if you want a higher number wait a bit for the new XQD cards and it will go up.
Personally for wildlife I'd shoot 14 bit, as (at least for me) lighting is always a challenge and getting that additional shadow detail is often very useful (e.g. under-wing in flight, or dark bird in bright sun getting more detail on the shady parts).