Why is Sparkles built on Songbird?

Sparkles will ultimately be built on the Flare network but is initially launching on Songbird. Songbird is the Canary network for Flare, where “innovations and new dApp launches happen first on Songbird and then may be rolled out on Flare after testing”.

This gives the network, and the dApps, the opportunity to ensure that everything is working smoothly prior to the launch of Flare network.

You can read more about why Songbird is being used here.