the nest should be knitted very tightly

when choosing the yarn weight & needles, I suggest using (at least) 2 strands of your chose yarn, and the needle suggested by the yarn’s wrapper
~ nest size & yardage will be affected by the weight of yarn & size of needle

All of the wildlife rescues wash their nests in hot water, so use of acrylic yarn is recommended, as it holds up well to all the washings and doesn’t shrink. Dishcloth cotton is also a good option.