The Black-billed Gull (Chroicocephalus bulleri), also known as the tarāpuka or Buller's gull, is a rare, delicate seabird endemic to New Zealand. It is considered one of the most threatened gull species globally. While they can live to a staggering 40 years old, severe habitat loss and predation by introduced mammals have caused their population to plummet. Their legs and orbital eye-rings transform from dark to bright red as the breeding season progresses, a change believed to be stimulated by the presence of begging chicks. From February to June, the ring around their eyes is black, but it transitions to a bright orange-red or dark red for the rest of the year. Most birds breed on large, gravelly braided riverbeds, but a small number breed on the North Island - including around Rotorua.
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