Birds' share of dinosaur extinction, the 'battle' between cattle and wildlife and more in this week's news

An extinction to crow about
Ancient birds took a heavy hit in the global catastrophe that wiped out the dinosaurs, a new study finds. Shoulder fossils from a menagerie of species that once lived in the United States and Canada suggest that four branches of the avian family tree disappeared suddenly about 65 million years ago. This mass extinction, blamed on a meteorite impact, likely opened up new ecological niches for surviving species — giving wing to an evolutionary explosion among the relatives of modern birds, paleontologists at Yale University and the Royal Saskatchewan Museum Fossil Research Station in Canada report September 13 in the Proceedings of the National Academy of Sciences. —Devin Powell

DEATH ON WINGS Shoulder fossils unearthed in North America have revealed a diverse range of ancient birds that suddenly died off in the same extinction that wiped out the dinosaurs 65 million years ago. Nicholas Longrich

Cattle vs. wildlife
The first direct measurements of how Kenya’s storied wildlife affects the growth of cattle that share with them savanna grazing land finds both the expected downside and an unexpected upside. Livestock managers widely assume that wildlife competes with livestock for resources, say Wilfred Odadi of Kenya’s Mpala Research Centre and his colleagues. To test that assumption, the researchers monitored weight gain and other measures of cattle health on the savanna. A wildlife-linked dip did appear in the dry season, but a wildlife assist boosted cattle growth during the wet season. Actual data should inform tense conservation debates, the international research team says in the Sept. 23 Science. —Susan Milius

Where whales meet
As the Arctic ice cover shrinks, the Northwest Passage opens not just for ships but for whales. Satellite tracking shows that bowhead whales previously blocked into their own oceans end up in the same Arctic waters when ice recedes during the summer.  Previous tracking found whales exploring the entrances to Arctic passageways, but in August 2010 a bowhead whale from West Greenland and one from Alaska swam far enough to occupy the same waters, report Mads Peter Heide-Jørgensen of the Greenland Institute of Natural Resources and his colleagues.  In an upcoming Biology Letters, they note that populations long considered separate by wildlife biologists and managers may now be mixing. —Susan Milius

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