While it seems helpful to offer dryer lint to nest-building birds, it is not a suitable material for the job. First, the strands of dryer lint are too short to be woven strongly. Nests built with it can develop holes, sag, or even collapse because they lack tensile strength. Furthermore, lint from fabric is more absorbent than naturally occurring materials such as twigs, dried grasses, moss, or feathers. While dryer lint seems like it would make a soft lining suitable for newly hatched birds, it readily absorbs moisture, which isn't helpful at all in trying to keep nestlings warm and dry.