Annual Weigh-in At London Zoo

England Europe Great Britain Humboldt penguins London London Zoo Regent's Park UK United Kingdom ZSL Zoo Zoological Society of London animal animal welfare animals annual captivity measurement measuring weigh in weigh-in weighing Humboldt penguins ZSL London Zoo annual weigh-in London United Kingdom August 19 2025 animal health vital statistics well-being keepers enclosure monitoring animal care zoo management wildlife conservation animal welfare zoo animals penguin species weigh-in event zoo keepers animal monitoring photo call animal statistics zoo event animal tracking London Zoo event animal health check animal records zoo photography animal enclosure wildlife health animal well-being.