How many words should a 17 month old boy say at that age? My baby can only say a few words like papa, mama, bird, etc. My daughter was talking much more at that age.

I believe that kids develop at very different paces. On average kids seem to prefer nouns at first, then gradually add verbs and adjectives. He'll experiment with one-word questions, like "milk?" for "May I have milk?" and love saying "No!" Toddlers at about 19 to 20 months have a "language explosion." After months of slow progress, they suddenly start to learn words at a ferocious rate, as many as nine a day.