Kashyapa married Tamra and they had many daughters including Kaki, Shyeni, Bhasi, Gridhika, Shuchi, Griva etc. From Kaki was born crows as per Agnipurana Chapter 19.

The king of Kashi had a daughter called Kalavati. She gained knowledge of the Shaivapanchaksharamantra early in life. She was later married to the king of Mathura Dasharha. Once, when he touched her, he felt very hot. She replied that she possessed the mantra and sinners would feel hot when they touched her. The king was disappointed and she took him to the sage Garga to rid him off his sins. The sage dipped him in the Kalindi river and when he arose from it, he felt his sins take the form of many crows. Some of them died when their wings caught fire. Garga noted that crows were bad omens.

Once the king Marutta conducted a maheshwara satra. Indra and the other devas attended it. Ravana heard of this and landed there. Indra and the other devas immediately took the form of animals and birds in order to escape. Indra became a peacock, Yama became a crow, Kuber became a chameleon and Varuna became a swan. Ravana and his forces left when they couldn’t find the devas. The devas blessed all the animals whose forms they had taken. Indra gave the peacock’s feathers multiple colours, and made its eyes beautiful. He also blessed that they would be free of illnesses and when it rained, they’d be able to do a beautiful dance. Yama blessed that the crows would now receive the offerings that humans made for their forefathers, as per Uttararamayana.