Bat biodiversity is in danger on islands worldwide

Date: June 21, 2017

Source: University of Helsinki

A new study from the University of Helsinki investigates knowledge gaps among the largely unknown, but greatly threatened, group of island-restricted bats, and leads future research efforts to actual priorities. Island ecosystems, as a consequence of isolation from mainland, have evolved peculiar faunas with a great number of species found nowhere else. They are also some of the most vulnerable habitats in the world due to limited resilience to anthropogenic threats.

"Island bats play a fundamental role in the maintenance of insular ecosystems through seed dispersal, pollination, and suppression of arthropod pests," highlights Irene Conenna from the Metapopulation Research Center at the University of Helsinki.

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Most island vertebrate extinctions could be averted, concludes new study

Control and eradication of invasive species could prevent as much as 75 percent of all island-level extinctions predicted for globally threatened vertebrates

Date: August 18, 2016

Source: University of California - Santa Cruz

Eight of every ten species extinctions has occurred on islands, and invasive mammals are the leading reason for those losses. Currently, 40 percent of species at risk of global extinction are island inhabitants.

In the most thorough study of its kind, scientists have now analyzed global patterns of island vertebrate extinctions and developed predictive models to help identify places where conservation interventions will provide the greatest benefits to threatened island biodiversity.

Control and eradication of invasive species are effective conservation tools, but conservation scientists have lacked tools for identifying where these efforts will have the greatest impact. The new study, published August 18 inNature Communications and led by UC Santa Cruz researcher Erin McCreless, closes that gap.

Humans have introduced non-native rodents, destructive herbivores such as goats, and predators like feral cats and foxes to islands around the world. These novel disturbances decimate native island wildlife and change entire island ecosystems. At the same time, islands are hotspots of biodiversity and often support rare and unique species occurring nowhere else in the world.

Controlling invasive mammal populations, or removing them entirely from islands, is a highly effective tool for conserving island species and ecosystems, and such actions have contributed greatly to the recovery of many threatened island species. Conservation dollars are limited, however, and it is important that invasive mammal management efforts be focused on the islands where they will go the furthest toward conserving native island biodiversity.

 Continued 

Why do islands give rise to such unusual creatures?

Land of opportunity

Presented byProf Richard Fortey Biologist & writer

Islands make up a sixth of all land on Earth. Some are formed from lava expelled by volcanoes under the sea, such as the Hawaiian Islands. Others, like Madagascar, are created when landmasses break apart over hundreds of millions of years. 

Isolated from the mainland, a new island often provides a unique habitat. With its own set of conditions, life can evolve differently. Some creatures develop the most unusual traits to survive – and thrive – in their new home. In many cases, separated from their mainland ancestors, they eventually transform into new species altogether.

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Island rodents take on nightmarish proportions

Rodents of unusual size are 17 times more likely on islands than elsewhere

Date:June 22, 2015

Source:Duke University

Summary:Researchers have analyzed size data for rodents worldwide to distinguish the truly massive mice and giant gerbils from the regular-sized rodents. They found that the furry animals with chisel-like teeth are 17 times more likely to evolve to nightmarish proportions on islands than elsewhere. 

The results are in keeping with an idea called the 'island rule,' which previous studies claimed didn't apply to rodents. 

The study appears online in the journal Proceedings of the Royal Society B.

Duke University biologists Paul Durst and Louise Roth analyzed data from more than 1,000 rodent populations representing more than 60 species across the globe. The dataset included mice, rats, squirrels, hamsters and porcupines, ranging in size from the tiny 0.2-ounce harvest mouse to the nearly 50-pound North American beaver.

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Sixty tuatara released onto Auckland island

Tuatara to be released on Motuihe Island
March 2012. Sixty tuatara are now living in the wild on Motuihe Island easily accessible by ferry from downtown Auckland. The tuatara were released on Motuihe in a translocation project led by the Motuihe Trust and supported by the Department of Conservation (DOC).

Motuihe Trust chairman John Laurence says the trust is aiming to establish a population of tuatara in the heart of Auckland that's easy to reach and can be enjoyed for generations to come.

"Tuatara were once found all over New Zealand but were wiped out on the mainland by rats. They now survive only on islands, like Motuihe, that have been cleared of rats," says John Laurence.

"Trust volunteers have worked hard creating a home for tuatara and other native wildlife on Motuihe by planting more than 350,000 native trees on the pest-free island."

Tuatara released on Motuihe Island
The tuatara were released into burrows prepared by the Motuihe Trust. Department of Conservation Auckland Area Manager Brett Butland says DOC and the Motuihe Trust are working together to restore the natural heritage of Motuihe.

"DOC eradicated Norway rats and mice from Motuihe in 1997. We made the island completely pest-free by removing feral cats and rabbits in 2005," says Brett Butland.

"Removing the pests, particularly rabbits enabled the Motuihe Trust to establish a nursery on the island that produces up to 55,000 native plants a year. The trust is doing a fantastic job restoring the native forest on Motuihe to provide a habitat for rare and threatened wildlife. The tuatara join little spotted kiwi, kakariki, tieke (saddleback), bellbird and shore skinks that the trust and DOC have released on Motuihe."

Pest traps and tunnels
The survival of the native wildlife on Motuihe depends on keeping the island pest-free. DOC maintains a network of traps and pest detecting tunnels on the island.

"We need everyone travelling to Motuihe, and other pest-free islands in the Hauraki Gulf Marine Park, to check their boat, kayak and gear to ensure they're not carrying stowaway pests," says Brett Butland.

Background information
Rats drove tuatara off mainland New Zealand. To secure their survival DOC has created sanctuaries for these unique reptiles by eradicating rats on a number of islands with tuatara populations.

The 60 tuatara released on Motuihe came from Lady Alice Island off the east coast of Northland. Lady Alice, Whatupuke and Coppermine islands are in the Hen and Chickens group of islands managed by DOC. They were cleared of Pacific rats in the 1990s.

Each island now has a self-sustaining population of tuatara. Tuatara are doing well on Lady Alice Island. The 60 tuatara moved to Motuihe represent less than 1% of the island's tuatara population.

Tuatara were released on pest-free Tiritiri Matangi Island in 2003. The release of tuatara on Motuihe means there are now two islands in the Hauraki Gulf Marine Park the public can visit to see tuatara in the wild.

http://www.wildlifeextra.com/go/news/tuatara-auckland.html