High-Speed Evolution: Cars Driving Change In Cliff Swallows

I imagine that adjusting to life around humans, with all our buildings and fast-moving transport mechanisms, is tough for a bird. It’s estimated that some 80 million birds are killed in motor vehicle collisions every year, and with an ever-growing population of people driving around and paving roads in more remote areas, things must be getting harder and harder for the animals we share our world with. But, the American Cliff Swallow (Petrochelidon pyrrhonota) isn’t one to let people ruin the neighborhood. More and more, their huge nesting populations can be found in man-made structures like bridges and overpasses, and have even become cultural fixtures in areas like California. Their new nesting sites allow them to survive even as their former habitat disappears, but it comes at a cost: by living near roadways, the birds are more at risk than ever of being on the wrong end of an oncoming vehicle.
Charles and Mary Brown have been studying the cliff swallows in Keith County, Nebraska for the past 30 years. The ultimate goal of their research is to understand why colony sizes vary, and together, the two have studied everything from parasites and diseases to social interactions between birds, with over a hundred publications between them. The American Ornithologists Union describes their three-decade long research on cliff swallows as “one of the most outstanding and most complete studies of any avian species .” Every year, the team monitors the birds and collects any dead ones they can find for further analysis. Slowly, they noticed something strange: even though nests under overpasses and on bridges should have put more swallows in harms’ way, over time, fewer and fewer swallows are winding up as roadkill.

Lees meer: Discover blogs: Science Sushi

Why bird fathers are left holding the baby

Scientists have cracked a 140 year-old mystery as to why it’s the father rather than the mother that takes care of the young in some bird species.

Darwin noted in 1871 that in most animals it is the females that spend the most time looking after the young, while males focus on competing with each other for females. Evolutionary biologists argued that this was due to female birds investing significant amounts of energy in producing eggs, making it in their interest to ensure their offspring’s survival by fully caring for them. However, in some species sex roles are reversed, and females produce the eggs but then leave it to their male mates to care for the offspring.

Lees meer: Birdwatch Magazine

Homing pigeons navigate by sound

Pigeons are known to use several methods to navigate, but perhaps the least known is sound – new research has found it to be more important than was thought.

Homing pigeons are well-known to be great navigators, returning to their home lofts using landmarks, orientation by the sun, the earth's magnetic field and also the spatial distribution of atmospheric odours . However, it seems that sound waves may play a hitherto unsuspected role in this mysterious ability.

Using an 'acoustic ray tracing program', scientists from Cornell University, New York (NY), USA, were able to trace sound waves generated by movements deep in the oceans and affected by different densities in the earth's crust, and found that they are key to pigeons' abilities to find their home loft.

Lees meer: Birdwatch Magazine

Environmental Change Impacts On Migratory Shorebirds Differ for Males and Females

Extensive shell fishing and sewerage discharge in river estuaries could have serious consequences for the rare Icelandic black-tailed godwits that feed there. But it is the males that are more likely to suffer, according to new research from the University of East Anglia.

Research published today in the journal Ecology and Evolution reveals very different winter feeding habits between the sexes.

Both males and females mainly consume bivalve molluscs, sea snails and marine worms, probing vigorously into soft estuary mud with their long beaks. But the study shows that females, which are larger and have longer bills, are able to peck further into the silt to secure larger, deeper buried prey in areas that the shorter-billed males cannot reach. This means that human impacts on estuaries may have different impacts on males and females, depending on which prey sizes are most affected.

Lees meer: ScienceDaily