EastScape Wikibuilt from the game itself
Starling egg
“Put it in a hatchery on your island with 3 Ordinary pet food: a Starling in 48 hours. From a Shooting Star, or the Star Tent. Tradable.”
Hatches
Hatches into 
Starling in your island's hatchery, in 48 hours. It comes from a Shooting Star (0.017% a swing), or the Star Tent in Cloudreach.
Sold by
Nestor the Egg Man in The Yard trades it for 400 stardust + 200 starfall ore.
The Star Tent, in Cloudreach: 6,000 Star Fragments. World events.