I understand the principle: I spent two-three hours shooting a pair of marmots in Yoho NP (Canada), not because I particularly wanted to shoot them for that long, but because the rock the marmots were sunning themselves on was very near the road, and I, with the tripod and large lens, was too tempting a target for anyone who drove by to resist. While I had parked down the road and approached quietly, most pulled off right there, including a whole busload of Japanese tourists. One couple insisted on walking up to try to get a shot of them with their P&S, and couldn't be argued out of it (it had to be a 20mme lens...).
I took up deliberately misleading people by pointing my camera at the nearby mountain vista whenever I heard a car coming. This worked for the most part (but not on that last couple). The result was that I could never coax both the marmots into a good position on the rock before they would be scared off. The failings of the one-marmot photo are my own.
In Algonquin, after I waited long enough with tripod that the moose were grazing right in front of me, a European couple spotted me and came over to pet (sic) the moose, right in front of my camera.
[Neither of these were quite as good as the foreign tourists in Jasper (Banff?), who, overhearing a conversation I was having with another photographer, pestered me for the best way to find a bear off-trail at daybreak during cub season. I explained to him that he really did not want to suprise a bear off trail at daybreak in cub season, especially not with is small children, but he didn't seem to believe me.]