Friday the thirteenth – a lucky day for the silver gibbons at Prague Zoo. Last December, the experienced female Alang Alang gave birth to her fourth offspring. The energetic nature of the male, now named Bayu by the keepers, is reflected in his name, which means "wind" in Indonesian. The curious and playful young male stands out for his fearlessness and is training in the typical brachiation for gibbons. The first offspring of this endangered species was born at the Prague Zoo ten years ago, marking the first addition of its kind in the Czech Republic.