First I saw the hooves. After that, the trophy head made sense. These fence adornments are remnants of the ailanthus tree (tree of heaven). Property owners generally disregard the ailanthus’ metaphoric qualities, written about in Betty Smith’s 1943 novel, A Tree Grows in Brooklyn, and chop it down. The MTA, on whose property these tree parts once grew, used a chainsaw.
Pix and other images 