Overview
Sirin is a mythological creature of Rus' legends, with the head of a beautiful woman and the body of a bird (usually an owl), borrowed from the siren of the Greek mythology. According to myth, the Sirin lived in Iriy or around the Euphrates River.
History
The legend of Sirin might have been introduced to Rus' by Persian merchants in the 8th-9th century. In the cities of Chersonesos and Kyiv she is often found on pottery, golden pendants, even on the borders of Gospel books of tenth-twelfth centuries. Due to the history, the Russian culture has experienced a very strong correlation with Byzantine Empire through its steppes, the Volga river and Dniepr river. Pomors often depicted Sirin on the illustrations in the Book of Genesis as birds sitting in paradise trees.
Later (17-18th century), the image of Sirin changed and she started to symbolize world harmony (as she lives near paradise). People in those times believed only happy people could hear a Sirin, while only very few could see one because she is as fast and difficult to catch as human happiness. She symbolizes eternal joy and heavenly happiness.
Folklore
This half-woman half-bird is directly based on the later folklore about sirens. She was usually portrayed wearing a crown or with a nimbus. Sirin sang beautiful songs to the saints, foretelling future blisses. The bird was dangerous. Men who heard her would forget everything on earth, follow her, and ultimately die. People would attempt to save themselves from Sirin by shooting cannons, ringing bells and making other loud noises to scare the bird off.
From Wikipedia (CC BY-SA 4.0).