Apparently, she was the only god to somehow get on with Anansi, and she was the only one who was willing to do him a favour. When Charlie, Anansi's son, goes to the beginning of the world, he meets the gods, who tell him they refuse to help him due to Anansi's humiliation of them; but Tiger directs him to the Bird Woman, who dwells in a cave. The Bird Woman appears as a little old woman with an old coat, and she wants blood payment. She asks for some offering, and Charlie asks for his brother to be banished - he means to be banished from his house, but she takes this offer literally and assumes Charlie means he wants his brother dead.
In the novel
The Bird Woman ruthlessly hunts down Spider, Charlie's brother, all over the world, she can control the birds in the vicinity and make harmless birds like pidgeons extremely aggressive. She watches Charlie from a distant field when he is on a train to London. Both brothers are stalked by the Bird Woman over the few weeks; and eventually Charlie has had enough and says to call off the deal. But the Bird Woman doesn't listen, she finally goes too far. She abducts Spider in the middle of an Italian square, after he has pulled Charlie all over the world to escape from her, and she encloses him in a swarm of birds, and when the swarm disappears, Spider is gone. The Bird Woman comes up to Charlie and says that he must call off the deal if he wants Spider back.
The Bird Woman takes Spider to her dimension, and rips out his tongue. She then ties him to stakes and leaves him for Tiger. But he escapes, and calls up an army of spiders. They banish Tiger and the Bird Woman's deal is over.
Spider orders Charlie to call off the deal, and when Charlie returns Spider's tongue, Charlie goes to the Bird Woman and gives the feather - the contract - over to her and she accepts the deal is over. She ceases her pursuits of the brothers and eventually joins in their celebrations with the other gods. She witnesses the banishment of Tiger and she goes back to living in her dimension.
She was a great deal maker; she could never give up or be distracted. She could also track her clients across entire universes. Also she was a shape shifter, able to turn into three distinct forms.