Honestly, I haven't double checked yet. When jorb said 'bonus,' I'm assuming it's added in as a bonus, not as a base stat. I may be incorrect in that and we'll need to double check how it all figures out. Still, that means we need some information as to why it's not showing up for him as it shows up for me even after only getting a few quests done.
edit: after looking back at my character sheet, I'm going to have to agree with Ukhata in that it is an implicit modifier granting you a base of 11, but costs will be treated as if you're starting at 1. I was thinking the values showed up on my character sheet since it had been so long since I had played with that character. Apologies for that, and thanks for correcting my blunder.
Forager will be a huge boon to early game as you only need to complete the first two, very easy, quests to get +10 exploration.