Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Fragmented habitats no ultimate refuges for forest-dwelling tropical birds

01.12.2004


Deep-woods bird species that manage to hang on in remaining patches of a deforested area of Brazil gain no real advantage in avoiding extinction, Duke University ecologists have found. The researchers studied the coastal region harboring the greatest number of threatened birds in the Americas.



"We found that species that also tolerate secondary habitats are not deforestation’s survivors," said Grant Harris, the first author of a paper on the subject published in the December issue of the research journal "Conservation Biology." "If you lose your habitat, everybody is equally threatened," added Harris’ co-author, Stuart Pimm. "There’s no special class of species that seems to adapt well to the habitats we create for them."

Harris recently completed his doctorate under Pimm at Duke’s Nicholas School of the Environment and Earth Sciences and is now employed by the U.S. Forest Service in Alaska. Pimm is the Nicholas School’s Doris Duke Professor of Conservation Ecology who does extensive work in tropical areas.


Their research was funded by the American Philosophical Society.

"Deforestation is rarely total or completely permanent," the two authors wrote in their "Conservation Biology" paper. "Small patches of original habitat remain and, in time, secondary forests, gardens or plantations replace some cleared areas." Given that reality, the two authors designed a study to explore how well some species survive in deforested habitat and whether some surviving species can persist in such landscapes.

Their study focused on Brazil’s Atlantic Forest, which the authors estimate now has been reduced to 119,540 square kilometers, or about 10 percent of its original extent. "There are more species threatened with extinction in this coastal strip of rain forest than anywhere else in the Americas," Pimm said in an interview. "Starting maybe 75 years ago people began moving inland from the coastal cities that have been settled for 500 years. As a consequence, very little of the coastal forest in the lowlands now remains. Much of what remains is in impenetrable mountains."

Deforestation along the approximately 800-mile-long coastal strip is also drying out the highlands further west, Pimm added. "As the lowlands area cleared, they become hot," he said. "And the uplands then begin to suffer because they’re not getting the flow of moist air off the land."

While deforestation affects other kinds of animals -- ranging from mammals to insects -- the scientists focused on birds because "we know birds very well," Pimm said. "The Atlantic Coast Forest has 200 species of birds found only there, which is more than are found in all the forests of eastern North America." Harris labeled the Atlantic Forest "the region with the most threatened birds in the Americas."

The Duke researchers estimated the forest’s original extent by consulting data from remote sensing technologies. They also followed what Pimm called "some very simple rules of thumb: If there are four feet of rain a year and it’s warm and the rain falls in every month you’re going to have lush tropical foliage."

They estimated how many varieties of birds lived in the region before deforestation by consulting available records and superimposing maps of the known ranges of tropical species. Dissatisfied with available data on the extent of the current forest, they created their own map using dry season satellite imagery that accounted for cloud interference. They then digitally superimposed available bird range maps on their own current forest map using the Nicholas School’s advanced Geographical Informational System (GIS) facilities.

What emerged was their own estimate of remaining distributions of two categories of bird species. Those categories were "forest obligate" birds that cannot exist outside the deep woods and purported "survivor" birds that could make do in more marginal "secondary habitats." "There is a subset of forest endemic birds that are also seen in other secondary habitats like gardens, plantations and golf courses," Harris said. "This has led some researchers to claim that if entire regions were completely deforested, this subset of forest endemic birds will not go extinct because they also tolerate secondary habitats."

But their Conservation Biology paper found otherwise. "We found no survivors," they wrote. "Habitat loss threatens forest-obligate birds and those using secondary habitats equally." Harris called the paper "the first analysis incorporating the amount and spatial arrangement of species’ remaining ranges in a regional, scientific context."

Members of Pimm’s research group, Harris included, have worked extensively for years in Brazil’s Atlantic Forest because of the extinction threats.

That group’s research website includes Pimm’s own personal account http://www.nicholas.duke.edu/people/faculty/pimm/explore/index.html of some of the difficulties scientists face locating forest obligate bird species in the rugged mountain refuges west of the original lowland forest -- in this case now occupied by bustling Rio.

"Wherever you are in Rio de Janeiro you’ll find a parrot, because it is just a common bird there," Pimm said. It hasn’t lost as much of its habitat as most species have simply because it has a big range. "On the other hand, if a species has lost 95 percent of its range, irrespective of whether is uses human habitats or not, it is still considered to be on the brink of extinction."

Monte Basgall | EurekAlert!
Further information:
http://www.duke.edu

More articles from Ecology, The Environment and Conservation:

nachricht Value from wastewater
16.08.2017 | Hochschule Landshut

nachricht Species Richness – a false friend? Scientists want to improve biodiversity assessments
01.08.2017 | Carl von Ossietzky-Universität Oldenburg

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Fizzy soda water could be key to clean manufacture of flat wonder material: Graphene

Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.

As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...

Im Focus: Exotic quantum states made from light: Physicists create optical “wells” for a super-photon

Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.

Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...

Im Focus: Circular RNA linked to brain function

For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.

While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...

Im Focus: RAVAN CubeSat measures Earth's outgoing energy

An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.

The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...

Im Focus: Scientists shine new light on the “other high temperature superconductor”

A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.

Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Papers – ICNFT 2018, 5th International Conference on New Forming Technology

16.08.2017 | Event News

Sustainability is the business model of tomorrow

04.08.2017 | Event News

Clash of Realities 2017: Registration now open. International Conference at TH Köln

26.07.2017 | Event News

 
Latest News

Gold shines through properties of nano biosensors

17.08.2017 | Physics and Astronomy

Greenland ice flow likely to speed up: New data assert glaciers move over sediment, which gets more slippery as it gets wetter

17.08.2017 | Earth Sciences

Mars 2020 mission to use smart methods to seek signs of past life

17.08.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>