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 Humboldt penguins enclosure photocall annual weigh-in ZSL London Zoo animals vital statistics health monitoring well-being keepers record zoo wildlife conservation zoological animal care penguin species animal welfare zoology data collection animal health monitoring weigh-in event ZSL animal measurement zoo staff wildlife documentation animal management London event.