Barry Webster said this quote

In the evenings, Sam performs exercises to prepare his body for love-making with Franz. He practices kissing (something he’d once hated) by smooching deer lips, antelope ears, frog anuses, and the great, whiskered muzzles of sleeping bison. He improves his petting skills by necking with juniper bushes and pine tree trunks with such passion that the bark snaps and sap runs, or with such tenderness that the whole forest goes silent and swallows nest in his hair.