In 1964, an Australian couple camped on a North Queensland island; their decades-long campaign helped a pigeon colony recover from under 2,000 birds to more than 40,000

Margaret and Arthur Thorsborne were not scientists. They were a nurse and a teacher from the Gold Coast who liked camping. In 1964 they pitched a tent on Hinchinbrook Island, a wild, mountainous stretch of North Queensland coastline, and fell in love with the place. Wildlife Queensland notes that it was this first trip that lured the couple to settle in the region permanently. According to a 2016 study published in Emu-Austral Ornithology, a holiday they took the following year would become one of the longest-running wildlife population surveys in the world. At the time, neither of them could have guessed that.

A holiday that turned into a calling

The Thorsbornes settled in the area not long after their first camping trip there. They built a house on the banks of a creek near the town of Cardwell, situated between Townsville and Cairns. It was supposed to be a peaceful life among the rainforest. Instead, it became the basis for a conservation career that lasted the rest of their lives.


The birds that no one outside was tracking

When the couple first visited the Brook Islands in January 1965, thousands of huge white-and-black birds came in from the mainland to roost that evening as the light faded. The people living there told them that the birds were called pied imperial pigeons or nutmeg pigeons, and that they had been almost entirely hunted down, leaving very few to hunt. In her memoirs, Margaret mentioned how surprised she had been because to her, it seemed like there were thousands of them. Australian Geographic later featured the couple and described that evening as a turning point in their lives.

The pied imperial pigeon is a distinctive bird in Australia. It migrates from New Guinea and Indonesia in spring and nests in large colonies on offshore islands, such as North Brook, going daily back to the mainland to feed on rainforest fruits. These daily trips made the birds easy to catch and hunt. Hunting parties would ambush them mid-flight, sometimes killing over a thousand birds in a single outing.

A ten-year favour that lasted half a century

Concerned about what they had seen, the Thorsbornes contacted Charlie Roth, Queensland's chief fauna officer with the Department of Primary Industries, who suggested they count the birds for ten years to get a clearer picture of the population. They agreed. In 1965 they began going to North Brook Island each breeding season to count the evening flight of pigeons returning from the mainland. A ten-year commitment to fieldwork turned into a lifelong commitment. Margaret continued the count for fifty years right up until her health failed, not long before her death in 2018.

From a low of under 2,000 birds to over 40,000

The numbers paint their own picture. According to the Emu study, the first proper count, in the 1965–66 season, recorded 4,692 birds. For the next few years, illegal shooting took its toll on the colony, bringing the numbers down to as low as 1,451 birds by 1968–69. As per the Emu study, large-scale shooting of the birds ceased to occur in that particular year owing in part to the media publicity that came along with the Thorsborne family’s effort. After this point, the numbers began increasing steadily, crossing the range of 25,000 to 35,000 in the 1992–93 season.

According to the tribute written by the Australian Rainforest Conservation Society shortly after Margaret’s death, the annual census results had started exceeding 40,000 from then on. Occasional cyclones temporarily reduced the bird population. Cyclone Yasi in 2011 destroyed most of the birds’ feeding area, reducing their numbers to just over 5,000 the following year; the population later recovered to more than 21,000 and continues to increase.

Why this story matters beyond Australia

It is worth remembering that none of this happened because of a government agency or a large conservation charity. It began with two people who liked camping and kept returning year after year to count birds by hand on a small, humid island for five decades. The observations made by them are still used by ecologists in understanding how bird colonies respond to hunting pressure, habitat loss and increasingly severe cyclones.

The story of the Thorsbornes is a useful reminder for those who think conservation can only be undertaken by big institutions. Long-term, unglamorous, unpaid observation, done consistently, year after year, can create a scientific record that outlives the people who started it. The Thorsbornes set up a system back in 1965, and the pigeons on North Brook Island are still counted annually using that system. Margaret and Arthur never set out to become conservationists. They just kept coming back.