A vulatrice egg is an ingredient for a spirit vulatrice, a level 43 Summoning familiar. You need a Green charm, the Vulatrice egg, and 88 Spirit shards to create the creature. In order to obtain a vulatrice egg, you must use the spirit cobra's special ability on a vulture egg (requires level 63 Summoning). There is also the chance to receive it from catching the Magpie impling or Spirit impling with a Butterfly net or Magic butterfly net and Impling jar as rare drop.