About 122 species of birds have been recorded there. Most of the birds are seen at the far-end of the marsh, which is inaccessible by foot, so a canoe is a must. Go in early to late spring, when the birds are all around. From July to the first of September, the birds are a 'drag' there. September thru late October is good for fall migrants.
Winter is boring.
Hardscrabble Road, near the Little Ossipee and Saco Rivers. I suggest making a trip out in early spring and late summer, early fall. This site is famous for Bicknell's Thrush, which usually migrates through during the month of July. Good warblers can be seen, go in early spring, and early fall. Some years are good for hawk migration in fall.