A magnetometer in the upper beak of birds?

Iron containing short nerve branches in the upper beak of birds may serve as a magnetometer to measure the vector of the Earth magnetic field (intensity and inclination) and not only as a magnetic compass, which shows the direction of the magnetic field lines. Already several years ago, the Frankfurt neurobiologists Dr.Gerta Fleissner and her husband Prof. Dr. Günther Fleissner have discovered these structures in homing pigeons and have, in close cooperation with the experimental physicist Dr. Gerald Falkenberg (DESY Hamburg), characterized the essential iron oxides."After we had shown the system of dendrites with distinct subcellular iron-containing compartments in homing pigeons, immediately the question was posed whether similar dendritic systems may be found in other bird species, too", as Gerta Fleissner, the principal investigator, comments. Meanwhile they could describe similar candidate structures in the beaks of various avian species. X-Ray-fluorescence measurements at DESY demonstrated that the iron oxides within these nervous dendrites are identical. These findings were published few days ago in the high-ranking interdisciplinary online journal PlosOne.

Lees meer: Biology News Net

Migrants travel flexibly

A new study shows that migrating birds are able to keep their travel dates flexible, and can respond to the effects of climate change by leaving earlier. However this doesn’t mean that birds will always arrive earlier.

The research, published online in Current Biology, reveals that Pied flycatchers which migrate don’t necessarily reach their destination earlier as they may experience travel delays due to harsh weather conditions on the final leg of their journey through Europe.

Lees meer: Birdwatch

Life-history and ecological correlates of population change in Dutch breeding birds

Auteurs: Chris A.M. Van Turnhout, Ruud P.B. Foppen, Rob S.E.W. Leuven, Arco Van Strien, Henk Siepel
Bron: BIOLOGICAL CONSERVATION Volume 143, Issue 1, Pages 1-266 (January 2010)
Abstract: Predicting relative extinction risks of animals has become a major challenge in conservation biology. Identifying life-history and ecological traits related to the decline of species helps understand what causes population decreases and sets priorities for conservation action. Here, we use Dutch breeding bird data to correlate species characteristics with national population changes. We modelled population changes between 1990 and 2005 of all 170 breeding bird species using 25 life-history, ecological and behavioural traits as explanatory variables. We used multiple regression and multi-model inference to account for intercorrelated variables, to assess the relative importance of traits that best explain interspecific differences in population trend, and to identify the environmental changes most likely responsible. We found that more breeding birds have increased than decreased in number. The most parsimonious models suggest that ground-nesting and late arrival at the breeding grounds in migratory birds are most strongly correlated with decline. Increasing populations are mainly found among herbivores, sedentary and short-distance migrants, herb- and shrub-nesting birds and large species with a small European range. Declines in ground-nesting and late arriving migrant birds suggest that agricultural intensification, eutrophication and climate change are most likely responsible for changes in Dutch breeding bird diversity. We illustrate that management strategies should primarily focus on the traits and causes responsible for the population changes, in order to be effective and sustainable.

Lees ook: Wetenschapsagenda

Birds Follow Their Noses During Migration

Birds largely rely on their sense of smell to navigate on their long migration routes. Indeed, the “third sense” has been shown to be a more important for them than orientation based on the sun and the earth’s magnetic field. Exactly how birds navigate on their migration routes has not yet been fully clarified. How does a bird develop an “internal map”? How does it find its way back to last year’s nest?

Adult migratory birds are clearly able to remember migration routes. Even if they end up flying over unknown terrain, they still manage to find their way to the right place. Researchers at the Max Planck Institute for Ornithology in Radolfzell and their colleagues at the universities of Princeton, Pisa and Copenhagen have established in a field study that odours considerably facilitate bird migration and act as a more important navigational cue than the sun and the earth’s magnetic field.

Lees meer: ScienceDaily

Where Do Puffins Go in the Winter?

A recent increase in winter mortality in Atlantic puffins could be due to worsening conditions within the North Sea, according to new findings published in the scientific journal Marine Biology. The study used geolocation technology to track puffins from the Isle of May National Nature Reserve, home to the largest colony of puffins in the North Sea. The puffin population on the Isle of May has declined by 30% in recent years.

The research team included scientists from the Centre for Ecology & Hydrology and the British Antarctic Survey and was led by Professor Mike Harris, Emeritus Research Fellow at the Centre for Ecology & Hydrology, who has studied puffins for 37 years.

Professor Harris said, "Modern technology has come to the aid of the puffin just when it was needed. The quarter of a million puffins that breed in northeast Britain head out to sea during the winter and we previously thought that they stayed in the North Sea. We now know that some make long trips into the Atlantic during winter. This is vital new knowledge which should help us explain recent declines in puffin numbers."

Lees meer: ScienceDaily

Some Birds Listen, Instead of Look, for Mates

Looks can be deceiving, but certain bird species have figured out that a voice can tell them most of what they need to know to find the right mate.

Andrew DeWoody, a Purdue University associate professor of forestry and natural resources, found that the higher the pitch of a male bird's song, the more genetic diversity that bird has, making him a better mate for breeding. His study was published Dec. 2 in the early online edition of PLoS Biology.

"If you have a diverse set of genes, that can translate into physiology and morphology diversity as well," DeWoody said. "Animals that are heterozygous, or have genetic diversity, are often bigger, stronger or can run faster."

Lees meer: ScienceDaily