Giant, fruit-gulping pigeon eaten into extinction on Pacific islands

Fossils present that Tongoenas burleyi, a newly described genus and species, inhabited the Pacific islands for no less than 60,000 years, however vanished inside a century or two of human arrival round 2,850 years in the past.

In contrast to the dodo and the extinct Viti Levu big pigeon of Fiji, nevertheless, T. burleyi may fly. This canopy-dwelling species co-evolved with fruit-bearing bushes within the mango, guava and chinaberry households, performing as a vital forest cultivator by spreading seeds to new areas. The dimensions of a giant duck, Tongoenas burleyi was doubtless able to swallowing fruit as large as a tennis ball, stated examine lead creator David Steadman, curator of ornithology on the Florida Museum of Pure Historical past.

“A few of these bushes have large, fleshy fruit, clearly tailored for an enormous pigeon to gulp complete and move the seeds,” Steadman stated. “Of the fruit-eating pigeons, this fowl is the biggest and will have gulped larger cover fruit than any others. It takes co-evolution to the intense.”

The absence of T. burleyi from the Tongan islands may threaten the long-term survival of native bushes that trusted the pigeon as a seed transporter, stated examine co-author Oona Takano, a doctoral scholar on the College of New Mexico.

“T. burleyi supplied an vital service by transferring seeds to different islands,” stated Takano, who was beforehand a analysis assistant on the Florida Museum. “The pigeon species on Tonga as we speak are too small to eat giant fruits, which imperils sure fruit bushes.”

When Steadman first discovered T. burleyi fossils in a cave on the Tongan island of ‘Eua, he was instantly impressed by their measurement: The fowl was about 20 inches lengthy, not together with the tail, and weighed no less than 5 instances as a lot as the common metropolis pigeon.

“I stated, ‘Oh my God, I’ve by no means seen a pigeon that large,'” Steadman stated. “It was clearly one thing completely different.”

As soon as he and archaeologist David Burley of Simon Fraser College — who can also be the species’s namesake — started excavating charred and damaged stays of T. burleyi at archaeological websites, “we knew it was one other human-caused extinction,” Steadman stated. “Pigeons and doves simply plain style good.”

Columbids, the household that features pigeons and doves, had few predators or opponents earlier than individuals reached the Pacific islands, he stated. The area was devoid of primates and carnivores similar to cats, canines and weasels, and hawks and owls have been absent from many islands. The birds flourished on this nurturing surroundings, diversifying over the previous 30-40 million years.

At the moment, the Pacific islands are the worldwide epicenter of pigeon and dove variety, with greater than 90 species, starting from fruit doves as mild as a handful of raisins to the turkey-sized, ground-dwelling topped pigeon of New Guinea. However the quantity and distribution of birds within the area is a shadow of what it as soon as was, Steadman stated. Tonga’s 4 remaining species of pigeons and doves symbolize lower than half of the islands’ historic variety.

“That is one other instance of how trying on the fashionable fauna does not yield a whole image of a area’s variety,” he stated.

Steadman and Takano analyzed the options of columbid hindlimbs, dividing them into three teams: tree-dwelling species, ground-dwellers and people who stay each on the bottom and in bushes. Pigeons and doves that spend most of their time within the cover are likely to have shorter legs, extra appropriate for perching and gripping in excessive winds. People who forage for seeds on the bottom have longer legs tailored for strolling and working. Birds that flit between the understory and the forest flooring have legs which are a mix of the traits of the opposite two teams.

The researchers discovered stunning settlement between the groupings primarily based on leg traits and molecular information: In different phrases, canopy-dwelling pigeons are typically extra intently associated to at least one one other than to birds within the different two teams.

“Provided that there are 350 species of pigeons and doves, individuals would possibly suspect these large modifications in life-style developed independently many instances,” Steadman stated. “However proper now, we do not have proof that it occurred greater than as soon as — no less than within the tropical Pacific.”

The comparatively brief hindlimbs of T. burleyi mark it as a canopy-dwelling species. Steadman hypothesized the species featured the intense, even gaudy, plumage of different pigeons that stay in treetops, the place intense colours present higher camouflage than the muted browns and grays of pigeons that stay on the bottom.

The researchers devoted the examine to the reminiscence of W. Arthur “Artwork” Whistler, whose experience in West Polynesian botany was unsurpassed, Steadman stated. Whistler died from COVID-19 in April.

“There wasn’t a plant on Fiji or Tonga that Artwork did not know, together with the entire pigeon-dispersed fruits,” Steadman stated. “He was a real plant nerd and full salt of the earth. He all the time made time for individuals.”