WELLINGTON, New Zealand, Feb. 4 (UPI) -- New Zealand researchers say the local extinction of two bird species a century ago is linked to the present decline of a common forest shrub.
Scientist at the University of Canterbury say the disappearance of two pollinating birds -- the bellbird and stitchbird -- from the upper North Island of the country has led to a slow decline in common plants including the New Zealand gloxinia in what they say is rare experimental proof of a breakdown in a local ecosystem, the BBC reported Friday.
Gloxinia, a shade-growing forest shrub about 6 feet tall and producing an orange tubular flower, depends on three birds for pollination: the bellbird, stitchbird and the tui.
Bellbirds and stitchbirds vanished from the upper North Island in the late 19th century, killed off by rats brought in by ships or by stoats introduced to control the local rabbit population, researchers say.
The researchers compared the situation on the mainland with that of three nearby island bird sanctuaries where the birds remain abundant, finding pollination rates were vastly reduced on the mainland with seed production 84 percent lower compared with the islands.
"This plant is in trouble but it's a slow-motion disaster," researcher Dave Kelly says. "It hasn't been well pollinated for about the last 140 years -- that's about when these birds disappeared off the North Island."
"In that time there haven't been enough seedlings coming through and so the plant is quietly crumbling away, fading away," he says.
Stephen Hopper, director of the Kew Royal Botanic Gardens in London, described the study as an "elegant" piece of research that "highlights the cascading effects of extinction."
