Bad reputation of crows demystified

The 326 interactions between corvids and their prey, shows that they have a much smaller effect on other bird species than was previously thought. Credit: Jorge Piñeiro

The 326 interactions between corvids and their prey, shows that they have a much smaller effect on other bird species than was previously thought. Credit: Jorge Piñeiro

In literature, crows and ravens arebad omens and are associated with witches. Most people believe they steal, eat other birds’ eggs and reduce the populations of other birds. But a new study, which has brought together over 326 interactions between corvids and their prey, demonstrates that their notoriety is not entirely merited.

Corvids—the bird group that includes crows, ravens and magpies—are the subject of several population control schemes, in both game and conservation environments. These controls are based on the belief that destroying them is good for other birds. They are also considered to be effective predators capable of reducing the populations of their prey. Continue reading

Riddle of flying bird’s weight solved by scientists

The scientists trained birds to fly towards a perch inside the device

The scientists trained birds to fly towards a perch inside the device

Scientists at Stanford University in the US have developed a super-sensitive device that can measure the weight of a bird in flight.

The invention, created by Prof David Lentink’s research team, measures the force produced by every wing flap.

The device, described in the Royal Society journal Interface, will enable researchers to carry out tests of miniature drones, to assess more precisely their flight performance.

It has also answered a physics riddle.

This question, Prof Lentink explained, is whether a container or a truck carrying birds changes in weight when the birds inside were flying. Continue reading

Escape from an evolutionary cul-de-sac

 Credit: R. Nussbaumer

Credit: R. Nussbaumer

Passion flowers with long nectar tubes depend entirely on the sword-billed hummingbird for pollination. However, as a new study by LMU researchers shows, the evolution of even such extreme specialization is by no means irreversible.

The blossoms produced by the many species of passion flowers belong to the most visually striking and attractive flowers known in the plant kingdom. Among the characteristic features of the flowers of the Tacsonia subgroup of the genus Passiflora are their extremely elongated nectar tubes. As a result, pollination in this group is wholly dependent on a single species of bird – the sword-billed hummingbird Ensifera ensifera. With its approximately 11-cm bill, which harbors a correspondingly long tongue, Ensifera is the only species of hummingbird that is capable of reaching and sampling the nectar at the bottom of the passion flowers’ 6- to 14-cm long nectar tubes. As it does so, the bird’s head inevitably comes into contact with the pollen grains, transports these to the next passion flower and pollinates it. Because passion flowers are incapable of self-pollination, this is the only means of pollination available to them. Continue reading

Birds Build Nests with Camouflage in Mind

 Scientists in the U.K. observed zebra finches making nest-building choices that took into account how well the color of materials would camouflage their homes.

Scientists in the U.K. observed zebra finches making nest-building choices that took into account how well the color of materials would camouflage their homes.

Researchers have recorded the first direct evidence that birds consider the notion of camouflage when they choose colored materials for their nests.

A team from the University of St. Andrews wallpapered male zebra finch cages in different colors. Then they filmed the birds building their nests, giving them paper strip choices for nest material in two different colors.

The scientists observed that the finches largely chose paper strips for their nest that were a match with the paper covering the walls of their cages. This told them that birds will actively seek to match a nest’s colors with those of its surroundings, and that what often looks like coincidental camouflage may indeed be a deliberate choice.

One interesting curve ball the finches threw at the researchers was to sometimes choose a small proportion of paper strips for their nests that was a mismatch with the wallpaper. The scientists think this means birds sometimes use a tactic called disruptive camouflage, wherein bits of clashing color break up the outline of the nest and make it look less like a bird lives there.

Prior evidence abounds for the idea that birds will move a nest elsewhere if predators lurk too close by, but the St. Andrews team asserts it has shown that birds may also try in more subtle ways to avoid predators.

“Like us (birds) don’t choose just any colored material to build their homes; they avoid colors that would clash with their surroundings. Knowing this gives us a better idea of how birds may actively reduce the chances of predators finding their nests,” said the report’s author, Dr. Ida Bailey.

The team’s work has just been published in the ornithological journal The AUK.

Source; Discovery News

Migrating birds sprint in spring, but take things easy in autumn

 Radar station in Falsterbo, Sweden, for tracking migrating birds. Credit: Cecilia Nilsson

Radar station in Falsterbo, Sweden, for tracking migrating birds. Credit: Cecilia Nilsson

Passerine birds, also known as perching birds, that migrate by night tend to fly faster in spring than they do in autumn to reach their destinations. This seasonal difference in flight speed is especially noticeable among birds that only make short migratory flights, says researcher Cecilia Nilsson of Lund University in Sweden, in Springer’s journal Behavioral Ecology and Sociobiology.

Nilsson, in a group led by professor Thomas Alerstam, used a tracking radar to measure over three years the speed by which birds flew over Falsterbo Peninsula, a bird migratory hot spot in south-western Sweden. The seasonal differences they found correspond with those recorded for other nocturnal passerine migrants at other sites in southern and northern Sweden. Continue reading

Burnt out birds suggest hard work could be bad for your health

 A team of scientists at the University of Exeter studied white-browed sparrow weavers, a social species in which all group members share offspring care duties, but the dominant male and female work hardest. Credit: Dominic Cram Read more at: http://phys.org/news/2014-09-burnt-birds-hard-bad-health.html#jCp

A team of scientists at the University of Exeter studied white-browed sparrow weavers, a social species in which all group members share offspring care duties, but the dominant male and female work hardest. Credit: Dominic Cram

Unequal sharing of workloads in societies could leave the most industrious individuals at higher risk of poor health and prone to accelerated ageing, according to a new study of a cooperative bird in the Kalahari Desert.

A team of scientists at the University of Exeter studied white-browed sparrow weavers, a social species in which all group members share offspring care duties, but the dominant male and female work hardest.

Dominants are the only birds that breed, with dominant males singing to attract a mate and dominant females producing all of the eggs and providing most of the care for nestlings. Continue reading