Some birds better than others at adjusting to habitat degradation

August 30, 2017

Before habitat degradation from impacts like grazing begins to cause population declines, the first response by wildlife usually comes in the form of behavioral changes—for example, switching their diets in response to changes in food availability. A new study from The Condor: Ornithological Applications looks at the diets of seed-eating birds in a South American desert and finds that while some can switch between seed types when grazing alters local plant communities, others continue to stick to old favorites, limiting their options.

Luis Marone of the Argentine Arid Zones Research Institute (IADIZA-CONICET) and his colleagues collected soil samples at grazed and ungrazed sites in Argentina's Monte Desert to assess the composition of the seed bank in each area, finding fewer of the large grass seeds that birds prefer in the grazed areas. Flushing the digestive tracts of captured birds revealed that two seed generalists, Common Diuca-Finch and Rufous-collared Sparrow, adjusted their diet accordingly and ate more forb seeds at grazed sites, while grass seed specialists Many-colored Chaco Finch and Ringed Warbling-Finch did not.

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Bahamian songbirds disappeared during last glacial-interglacial transition

August 29, 2017 by Sarah Nightingale

Two species of songbirds that once made a home in the Bahamas likely became extinct on the islands because of rising sea levels and a warmer, wetter climate, according to a new study by researchers at the University of California, Riverside and the University of Florida, Gainesville. The study, which was published today in the Proceedings of the National Academy of Sciences, presents a historical view of how climate change and the resulting habitat loss can affect Earth's biodiversity.

Titled "Origin, Paleoecology and Extirpation of Bluebirds and Crossbills in the Bahamas Across the Last Glacial-Interglacial Transition," the authors are Janet Franklin, distinguished professor of biogeography in UCR's College of Natural and Agricultural Sciences, and David Steadman, curator of ornithology at the Florida Museum of Natural History at the University of Florida.

The Eastern Bluebird (Sialia sialis) and Hispaniolan Crossbill (Loxia megaplaga) were among 17 species of birds that were found on the Bahamian Island of Abaco during the last Ice Age, but that no longer live there today. Both species are still alive elsewhere, with the former found in continental North America and the latter in Hispaniola. Fossil records from Abaco suggest that these birds resided on the island year-round, as opposed to migrating there in winter.

"The abundance of fossils, the presence of young birds among the fossils, and the evolution of a shorter wingspan in the Eastern Bluebird all suggest that these birds did not migrate to the island but were a resident population. But then they disappeared," Franklin said.

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Truck- and Plane-Size Pterosaurs Once Flew Over Dinosaurs

By Laura Geggel, Senior Writer | August 29, 2017 12:47pm ET

CALGARY, Alberta —  The fossilized remains of two pterosaurs — winged reptiles that flew sky high during the dinosaur age — suggest that the soaring truck- and plane-size beasts were closely related to the gigantic Quetzalcoatlus northropi, the largest pterosaur on record, new research finds.

Both pterosaurs date back to the Maastrichtian, a period that occurred between 72 million and 66 million years ago. It ended when a 6-mile-wide (10 kilometers) asteroid slammed into Earth, ending the reign of the nonavian dinosaurs and countless reptiles, including the pterosaurs.

The newly unearthed pterosaurs were found in Jordan in 2005 and 2008, and both belong to a family of pterosaurs called Azhdarchids, which includes the famous Q. northropi — a pterosaur the size of an airplane, with an almost-40-foot (12 meters) wingspan. [Photos of Pterosaurs: Flight in the Age of Dinosaurs]

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Epigenetics may explain how Darwin's finches respond to rapid environmental change

Date: August 24, 2017

Source: University of Utah

Summary:

Epigenetics may explain how Darwin’s finches respond to rapid environmental changes, outlines a new report.

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Mimicking birdsongs

Researchers develop simple device to recreate complex birdsongs

Date: August 28, 2017

Source: Harvard John A. Paulson School of Engineering and Applied Sciences

Summary:

A simple device has been developed that mimics complex birdsongs. The device uses air blown through a stretched rubber tube to recreate birdsongs found in nature, including the songs of zebra and Bengalese finches.

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Sense of smell is key factor in bird navigation, new study shows

Date: August 29, 2017

Source: University of Oxford

Summary:

How do birds navigate over long distances? This complex question has been the subject of debate and controversy among scientists for decades, with Earth's magnetic field and the bird's own sense of smell among the factors said to play a part. Now, researchers from the universities of Oxford, Barcelona and Pisa have shown in a new experiment that olfaction -- or sense of smell -- is almost certainly a key factor in long-distance oceanic navigation, eliminating previous misgivings about this hypothesis.

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Reed warblers have a sense for magnetic declination

Date: August 17, 2017

Source: Cell Press

Summary:

Researchers recently showed that migratory reed warblers depend on an internal geomagnetic map to guide them on their long-distance journeys. But it wasn't clear how the birds were solving the difficult 'longitude problem,' determining where they were along the east-west axis and which way to go. The team's latest report shows birds rely on changes from east to west in magnetic declination, the angular difference between geographic north and magnetic north.

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