Domestic cats are known killers, and when let loose they can
do real predatory damage. Cats (Felis catus) can wipe out entire populations of native birds and small mammals such as mice, squirrels and rabbits when introduced to island environments. Eradication efforts have historically been implemented to remove these non-native predators from islands. A new study shows that domestic cats can wreak havoc on the mainland as well. Researchers say un-owned cats kill far more birds and mammals than previously thought, making them the greatest human-related cause of these wildlife deaths in the United States. Sue is something of a celebrity among dinosaurs, being the best-preserved T. rex fossil ever found. But in truth, the gender of dinosaurs is rarely, if ever, known. A study in 2005 first laid claim to a new way to sex dinosaurs using a distinctive bone formation. Now paleontologists in China have found that ancient birds also had this structure, confirming that birds and dinos shared similar gender divisions and reproductive habits.
Researchers excavated the 125-million-year old birds’ feathers, organs and bones from petrified lake-bottom mud in northeastern China. These birds, called Confuciusornis sanctus, were buried by the hundreds following catastrophic volcanic eruptions in the Mesozoic era.
For the New Caledonian crow, birdbrain is a misnomer: These members of the corvid family have proved their problem-solving and tool-wielding abilities again and again. The birds may have yet another impressive cognitive capacity, a new study suggests: causal reasoning. The ability to link an event with the mechanism that caused it, even if that mechanism is hidden, is the basis of modern science—and our most basic knowledge of the world around us. If New Caledonian crows are capable of causal reasoning as well, we can better trace and understand the evolution of this ability.
Birds are the modern descendants of dinosaurs, but the exact details of the family tree are controversial. Archaeopteryx, the winged creature found in German fossil beds whose name means “first from a feather,” was long thought to be the first bird. Last summer, a Nature paper by Xu Xing, of China’s Institute of Vertebrate Paleontology and Paleoanthropology, claimed that Archaeopteryx was related to birds but actually belonged on a separate branch of the tree, with other bird-like dinosaurs.
Scientists still debate the rightful place of Archaeopteryx in the dinosaur-bird lineage, but what’s undisputed are Xu’s contributions to paleontology. He has named 60 dinosaur species, more than any other living paleontologist, and his stamping grounds are the fossil beds of Liaoning Province, northeast of Beijing, where many of the feathered dinosaurs and early birds were discovered. Kerri Smith enumerates Xu Xing’s contributions to the study of birds and their dinosaur relatives in a profile at Nature News: Read More
An adult reed warbler feeds a common cuckoo chick,
not recognizing the baby bird as a parasite
In the world of birds, cuckoos are pretty unpopular. Maybe it’s something about how they lay their eggs in others’ nests so that their chicks will steal food and attention from the natural-born chicks. This can kick off an evolutionary arms race that researchers are already familiar with: the cuckoo eggs evolve to look more and more like the host eggs, and the hosts evolve to get better and better at recognizing the foreign eggs.
Now researchers have discovered another cuckoo-versus-host evolutionary race running in parallel—and it has led to the evolution of two different forms of the same species of female cuckoo.
What’s the News: One of the leading theories explaining why birds can travel thousands of miles each year without getting lost is that they are equipped with an internal compass on their beaks: iron crystals in cells there could be orienting to the Earth’s magnetic field, sending a message to their brains that helps them steer.
It turns out, though, that those beak cells, which had been previously identified as neurons capable of sending such a message, aren’t neurons at all. A new study shows convincingly that those iron-bearing cells are macrophages, immune cells that could never play that role. Birds’ magnetic navigation skills must be coming from somewhere else.
Before they can talk, babies use gestures to communicate: sentiments such as “take this away,” “look over there,” and “put me down” can be made abundantly clear without words. Chimps gesture to each other, as well, pointing out particular spots where they’d like to be scratched or groomed. These symbolic gestures are believed to be an important precursor to language. Now, researchers have observed ravens using gestures in the wild—the only non-primates seen doing so.
California birds are getting slightly bigger, according to a study published in Global Change Biology in which researchers measured and weighed 33,000 birds over the past 40 years. The increases were small, but significant: in the last 25 years robins have grown 0.2 ounces in mass and 1/8th of an inch in wing length, for example. But the finding runs counter to the only other long-term study measuring avian size in North America, which found that birds in Pennsylvania have shrunk slightly over recent decades. And it seems to disagree with other recent suggestions that animals may shrink in a warming world: Bergmann’s rule holds that animals generally get bigger as they get farther away from the equator, because larger animals are better able to retain heat.
Researchers at Wake Forest University in North Carolina have now learned that Nazca boobies perpetuate a “cycle of violence”: bullied chicks tend to become bullies and pass on the pain. When parent birds leave their nests to eat, baby boobies are often visited by sexually and physically abusive non-breeding adults; the chicks, when grown, are more likely to abuse unrelated chicks. “The link we found indicates that nestling experience, and not genetics, influences adult behaviour,” lead researcher David Anderson told BBC.