Where are all the Tauros gone? Been in Canada for 4 days now but have not seen a single one

They went "rare" about when Gen 2 launched. There were so many at the start they were like Pidgeys – glad I kept a couple.

In Texas, my pokedex says I have seen 106 of them...it has been quite a while though, most of those were before gen 2. I'm going to Heracross territory on Saturday and Sunday, I hope I have some luck--I have 45 rare candies ready.

Now that you mention it, I haven't seen one in ages.

The white man shot them all.

I too don't see them often on the east coast

If you really are just visiting North America from Europe or New Zealand or something. I would look closer into current nests in the area (or maybe even a little more detailed map). If not, there is a very high likelihood you'll miss it. On my trip, if I miss Heracross this time (South Padre Island), I can go a bit closer to Corpus Christi some other time.

Seems to be a general theme. I remember that Mr. Mime used to be everywhere once. Now you can walk for days without encountering one. I blame global warming.

I used to see a dozen a week, and only tried catching the very low CP or very high CP ones.

I have not seen one in over a month. I am glad I saved 3 or 4 of them.

My Dex says I have seen 111 of them. I know that I haven't seen a single one since Gen 2 release.

I never even noticed. But now that you mention it, yeah, I haven't seen a Tauros in a very long time.

They're quite rare since gen 2 here in North Florida; Corsola - who overlap in this area - are a little more common.

Before gen 2, I caught 74 Tauros, but foolishly kept only 3. Since then, I kept all 4 that I caught, even the level 1 and 8!

After reading some stuff about the upcoming event I am hopeful that regionals will soon be available worldwide, if only for a short time.

They were hunted to extinction by cowboys looking for bison to put in their burgers, ....

Seriously, just watered down like everything else when G2 came out.

Just caught one last night. But yeah, they're a rare catch here now.

I really think they should allow the regionals to nest. It would enable a dedicated traveler to seek out a nest without overly annoying the locals.
The way it is now, if you travel looking for a regional exclusive you better be prepared to put your vacation at second priority because it may take full Pogo dedication to find that Pokémon. And if you want one with good IV's? You need a couple weeks or get lucky.