Pattern is flexible. You can use any left-over yarns you might have around. Ribbing & garter stitch are meant to allow for the most stretch for fitting on the birds. Using yarn that has elastic in it is an alternative.

Alter gauge to fit the weights of the yarns and needle size you use.

This was originally designed for donation to the Best Friends Animal Society in Utah, USA, for the parrots in rescue there. It is an adapted and altered version of the one listed on their website (link to their site provided in Google Doc). I am not a professional designer by any means so please keep this in mind with the design’s tech skills and the level of support I can/can’t provide. Thank you!