Dead deer that vultures peck at, leftovers from other animals — I wrote about that kind of rotting meat as 'carrion.'
Literal
Vulture [subject-が] pecks dead deer [and-とか], other animals [possessive-の] leftovers [and-とか], that-kind-of rotted meat [object-を] carrion [quotative-と] wrote.
~とか~とか lists examples casually: 'things like dead deer... and leftovers...' ハゲタカ (vulture) is in katakana as is standard for animals. 食べ残し (leftovers) is a compound: 食べる + 残す (leave behind). 死肉 (carrion/dead meat) is being defined by the writer — they're explaining their word choice.