Take a cotton nestlet with forceps and record its weight manually using scales. Place the nest lit randomly in a cage but on the opposite side of the water supply. Weigh each nestlet for the next four days manually using scales.
Ensure that the nestlet is dry when weighed. If not dry on a heating pad. If the nestlet is torn into several parts, weigh the largest part.
Record the weights on paper or in a pre-made spreadsheet. The UBE3A mutant animals used significantly less material to build their nests and this difference was particularly prominent between transgenic females and their control counterparts.