I've camped at the site right next to the cafe several times. Its also right next to Loch Morlich on the Cairngorm ski road.
As a lazy camper I have often breakfasted at the cafe and I can assure you it is red hot for Red Squirrels, five bouncing around outside while you tuck into the full Scottish is not unusual. Bird-wise its always been mostly Chaffinches and Siskins with a leavening of other common woodland birds. I've never seen Crested Tit at the feeders but they are around in the forest so its perfectly possible.
Pine Marten would mean an overnight stakeout. Not unthinkable but hard work I expect. You are quite a bit higher than the Spey valley floor there so it can be ruddy cold: we have had ice on the inside of the tent in May!
If martens are regularly coming to the nuts you have a head start but I would be tempted to lob a few jam/peanut butter sarnies up there as well. Of course you could start a nearby bait site to attract the martens BUT the cafe is right next to a road. to avoid making them cross the road more than they are doing anyway I would suggest the responsible course would be to keep any additional bait on the same side as the cafe.
Alternatively book a night or two at the comfortable centrally heated midge-proof hide run by Speyside Wildlife, Badgers guaranteed, Pine Martens usual but not inevitable, Bank Voles and Wood Mice also present.
John
