What do I need to know about the cloud forest?

For 10 days, you should be good with two pairs of quick dry socks - wash them as soon as you get back to camp, then they'll have a full day and a half to dry, and you'll have clean and dry socks to wear each morning! Do you know if you'll need hiking boots or waterproof boots? If it's the latter, I did very well in knee-high rubber boots from KMart (but I wasn't in montane forest). I read - and loved - http://www.amazon.com/exec/obidos/ASIN/0684187108/metafilter-20/ref=nosim/ while I was doing fieldwork in the southeastern Peruvian Amazon. How long has your friend been there? Would she or he appreciate something like a box of girl scout cookies, or nutella, or peanut butter, or clif bars? You may want to bring clif bars or something similar, actually - they're great mid-afternoon energy pickups.

I've never been to a cloud forest, but if it's anything like the other misty, foggy places I've visited, take quick-dry everything. You will never get a conventional towel or cotton underwear properly dry if you hang them up in the mist.

I really wished I'd had a backpack cover when I was there - the cheap kind that's just a plastic shell with an elastic rim that hooks over the backpack. I brought a fitted sheet, to my husband's irritation, until we used it almost every place we stayed for something. Lots of ziploc bags, for separating wet and dry. Flip flops. A steroid cream for rashes and other irritations, should they occur (I never got any, husband did). Have a blast. Cloud forests are beautiful. I went to the cloud forest in Costa Rica where my husband studied tree frogs as a grad student at UCLA, so I'm having lots of happy memories raised by this question.

Peruvian cloud forest can encompass many different things. The biggest variable is elevation - the cloud forest can be up to 12,000 feet and down to maybe 3,000. You can also find places within "cloud forest" zones that have been de-forested long ago and really resemble other parts of the Andes except for that they are often draped in frigid fog most of the time. Since you're going on a frog study I'm guessing you'll be in some intact forest and probably on the lower end of that elevation spectrum. At the lower elevations it can get hot and there can be biting flies (also mosquitos but the flies hurt more). At the high elevations it can be very damp and cold (imagine a winter day in the pacific NW without the comfort of insulation or heating), so be prepared for all of that. Long sleeves are your friend. It's April so the rainy season is ending, which means it can still be wet but it's one of the nicest months of the year in my opinion. About society, well again there's a lot of variability, but the local people are most likely to be Quechua-speaking farmers. Women especially often don't speak Spanish, but men usually do due to contact with tourism, wage labor, etc. Quechua communities aren't always very friendly to outsiders, but sometimes can be very hospitable. Hospitality usually takes the form of potatoes. Again this depends on the particulars of where you will be - at an isolated field station, in/near a village or what? If you're going to have a lot of contact with a community it's nice to bring something you can share - soccer ball is a hit 100% of the time. Bring a book or two to read while you're there that you don't mind getting totally trashed. If you have any more specifics about where you're going I might be able to offer some more tips. Overall, don't worry it's going to be fantastic!