Why is this owl on a scale? Because of science.
Tracking the growth of captive animals isn't just about making sure the captive animals are well taken care of. It's also an important part of understanding animal life cycles and how life in captivity differs from life in the wild. Data on millions of animals is stored in the Zoological Information Management System—a database used by zookeepers, aquarium officials, and researchers. In order to have that database, though, zoos and aquariums must do annual inventories of their charges—measuring height and weight, and recording data on details like egg-laying patterns. And this is where the cute comes in.
The Guardian has a slideshow of images taken last week during the London Zoo's animal inventory. If you've ever wanted to see somebody stretch a tape measure around a penguin's chubby belly, or coo over meerkats climbing around a scale, this is your chance.