Wind farms cause bird declines

A new study of UK wind farms suggests that numbers of several breeding birds of decline close to the wind turbines which would make their appropriate siting even more important.

The study took place on uplands where several species of high conservation concern breed. Twelve major upland wind farms were surveyed six times during the breeding season for a dozen common species including Golden Plover, Lapwing, Curlew, Snipe, Red Grouse, Common Buzzard, Hen Harrier, Kestrel, and Skylark, Meadow Pipit, Stonechat and Wheatear.

The results, published in the Journal of Applied Ecology, should help developers planning renewable energy projects by offering greater certainty as to likely impacts so that they can quickly progress acceptable proposals in appropriate locations by avoiding important areas for birds. If wind farms are sited inappropriately in areas where these vulnerable birds breed at high densities, then those populations may subsequently decline.

Lees meer: Birdwatch

Birds unveil 'silver wings'

Some birds have silver wings, created by a previously unknown structure in their feathers, scientists have discovered.
A delicate arrangement of barbules creates a silver sheen upon otherwise dark feathers.
The effect is different to the usual iridescence that adds colour to the plumage of many birds.

Pelicans, ducks, vultures and cranes all possess these silver wings, which might indicate a bird's fitness.

Lees meer: BBC - Earth News

Migrating Birds Chill To Fatten Up

Marathon runners are famed for pasta packing in the days before a big run but when tiny passerine birds set out on their epic migrations, the distances are too great to cover on the energy reserves with which they embark.

Michał Wojciechowski and Berry Pinshow explain that most birds stop off en route to their destination to refuel. One of the Eurasian blackcaps' preferred refuelling stops is Midreshet Ben-Gurion, Israel, where the birds fill up on fruit and insects before setting off again. Knowing that birds expend twice as much energy during stopovers than they use in transit, the duo wondered whether the tiny aviators drop their body temperature at night during stopovers to save energy and build up their reserves faster.

Lees meer: ScienceDaily

Arctic geese winter further north

The winter distribution of an Arctic goose has shifted northwards as climate has warmed over the last 40 years, with birds once wintering in Mexico now staying in Alaska.

Studies have shown that, until recently, nearly the entire population (90 per cent) of Pacific Black Brant spent the winter in Mexico. Now as many as to 30 per cent are choosing to spend their winters in Alaska instead. Fewer than 3,000 geese were detected wintering in Alaska before 1977, and this has now jumped to as many as 40,000 birds.

Lees meer: Birdwatch

Why do birds participate in mixed-species foraging flocks? A large-scale synthesis

Auteurs: Hari Sridhar, Guy Beauchamp, Kartik Shanker
Bron: ANIMAL BEHAVIOUR, Volume 78, Issue 2, August 2009, Pages 337-347
Abstract: Mixed-species flocks of foraging birds have been documented from terrestrial habitats all over the world and are thought to form for either improved feeding efficiency or better protection from predators. Two kinds of flock participants are recognized: those that join other species ('followers') and are therefore likely to be the recipients of the benefits of flock participation and those that are joined ('leaders'). Through comparative analyses, using a large sample of flocks from around the world, we show that (1) 'followers' tend to be smaller, more insectivorous, and feed in higher strata than matched species that participate in flocks to a lesser extent and (2) 'leaders' tend to be cooperative breeders more often than matched species that are not known to lead flocks. Furthermore, meta-analyses of published results from across the world showed that bird species in terrestrial mixed-species flocks increase foraging rates and reduce vigilance compared to when they are solitary or in conspecific groups. Moreover, the increase in foraging rates is seen only with flock followers and not flock leaders. These findings suggest a role for predation in the evolution of mixed-species flocking. Species that are vulnerable to predation follow species whose vigilance they can exploit. By doing so, they are able to reduce their own vigilance and forage at higher rates.

Trans-Sahara migrants select flight altitudes to minimize energy costs rather than water loss

Auteurs: Heiko Schmaljohann, Felix Liechti, Bruno Bruderer
Bron: BEHAVIORAL ECOLOGY AND SOCIOBIOLOGY, Volume 63, Number 11 / September, 2009
Abstract: Meteorological conditions influence strongly the energy and water budget of birds. By adjusting their flights spatially and temporally with respect to these conditions, birds can reduce their energy expenditure and water loss considerably. By radar, we quantified songbird migration across the western Sahara in spring and autumn. There autumn migrants face the trade-off between (a) favorable winds combined with hot and dry air at low altitudes and (b) unfavorable winds combined with humid and cold air higher up. Thus, it can be tested whether birds may chose altitudes to minimize water loss instead of energy expenditure.
We predicted optimal flight altitudes with respect to water loss and energy expenditure based on a physiological flight model when crossing the western Sahara and compared these model predictions spatially and temporally with measured songbird densities. The model aiming for minimal water consumption predicted a mean flight altitude of 3,400 m under autumn conditions.
However, 64% of the nocturnal songbird migration flew at altitudes below 1,000 m above ground level profiting from tailwind. This preference for tailwind in autumn, despite the hot and dry air, emphasizes the importance of energy savings and diminishes the significance of possible water stress for the selection of flight altitude. Nevertheless, during daytime, high energy expenditure due to air turbulences and water loss due to warmer air and direct solar radiation prevent songbirds from prolonging their nocturnal flights regularly into the day. Birds crossing the Sahara save water by nocturnal flights and diurnal rests.

Great tits acquire taste for bats

A Hungarian cave has turned out to be a larder of highly unusual food for great tits: hibernating pipistrelle bats.

Over two winters, researchers found the birds were systematically hunting bats by sight and sound as they hibernated through the cold months.

Writing in the journal Biology Letters, the scientists say this is the first proof of bat-hunting in songbirds.

Great tits usually dine on smaller prey such as insects and seeds, with bat-eating probably very rare.

The researchers found the birds preferred other food when they could get it.

Lees meer: BBC News

Skylarks recognise neighbours

New research shows that Skylarks are able to distinguish between the songs of their neighbours and those of strangers, who may pose a threat, enabling them to readily see off any intruders.

Scientists from Queen Mary, University of London studied the songs of Skylarks and compared their structure. They found that the songs of neighbouring Skylarks share more syllables with one other than they do with those of strangers, rather like a dialect.

Lees meer: Birdwatch

Birds use fatal fragrances

Highly aromatic plants are often used in birds' nests and new research has demonstrated that these fatal fragrances are particularly chosen to kill off bacteria that would otherwise infect the nestlings.

Biologists studied the nests of Blue Tits on Corsica which
are known to incorporate fresh fragments of aromatic plants when building them.
Previous research has shown that this does not reduce infestation by nest
ectoparasites, but does improve growth and condition of chicks at fledging.


Lees meer: Birdwatch

Bird's Tool Use Called 'Amazing'

Just like in Aesop's fable, scientists now find that crows might indeed learn to drop stones in pitchers to raise the height of water inside, in this case to bring a tasty, floating worm within reach.

This suggests the fanciful millennia-old tale might actually have been based on fact.

In Aesop's fable, "the crow and the pitcher," a thirsty crow dropped stones in a pitcher to raise the water level and quench its thirst. Past experiments have shown that crows and their relatives — altogether known as corvids — are indeed "remarkably intelligent, and in many ways rival the great apes in their physical intelligence and ability to solve problems," said researcher Christopher Bird at the University of Cambridge in England.

Lees meer: Live Science

'Feather-eating bugs' dull birds

Brightly coloured birds can become infected with bacteria that eat their feathers.

That in turn can affect the health of the birds and dull their plumage.

The discovery comes from a study that found that 99% of all Eastern bluebirds surveyed in Virginia, US were infected with feather-degrading bacteria.

Such bacteria were first discovered a decade ago, but the latest research is the best evidence yet that the bugs affect the colour and health of birds.

Lees meer: BBC Earth News