It sings at dusk. A high-pitched whistling call that echoes through suburban gardens and urban parks. The whistling tree frog also known as the brown tree frog is smaller than its relatives reaching only five centimetres in length. Brown colouration with dark markings provides camouflage amongst leaf litter and bark. Whariki. The Māori name applies to this introduced species. European settlers brought the whistling tree frog to New Zealand in the late nineteenth century likely from Australia. It established populations throughout the North Island and northern South Island where climate conditions suited its requirements. Unlike native frogs which are restricted to specific habitats this species thrives in urban environments. The frog inhabits gardens parks and urban wetlands with permanent water. It adapts well to modified environments and artificial ponds. Breeding occurs in spring and summer when males produce distinctive whistling calls from vegetation near water. Eggs are laid in small clusters attached to submerged plants. Tadpoles develop rapidly metamorphosing into froglets within weeks. Diet consists of small insects spiders and other invertebrates. The whistling tree frog is an opportunistic feeder that consumes available prey in urban habitats. This generalist diet allows it to thrive in gardens where native specialists cannot survive. It competes with native invertebrates and potentially with native frogs for food resources. Classified as Introduced the whistling tree frog is widespread and common. While less aggressive than larger introduced frogs it still represents a threat to native ecosystems through competition and potential disease transmission. Conservation efforts focus on monitoring populations and preventing spread into regions where native frogs still persist. Urban residents often welcome the frog for its pleasant call unaware of its ecological impact.