Does anyone know when you can tell the sex of a buttercup chick?

[roysnider]

I have 3 buttercups and they are about 4 weeks old. When can you tell the sex of them and how?

 

[Cowgirl71]

I've never had them, but I would think you can sex them pretty young because the roosters and hens are colored very differently... https://secuservices.com/ideal/newideal/selectproduct.aspx?qty=1&ID=SBS&Product=241