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 London United Kingdom August 19 2025 zookeeper Humboldt penguins photocall annual weigh-in ZSL London Zoo vital statistics animal monitoring health well-being WIktor Szymanowicz NurPhoto animal care zookeepers penguin weighing London Zoo animal health wildlife conservation animal welfare zoo management animal records species monitoring zoo event animal statistics conservation efforts wildlife management animal tracking zoological society animal health monitoring penguin care animal well-being.