Birdsong Bluster May Dupe Strange Females, but It Won't Fool Partners

Male birds use their song to dupe females they have just met by pretending they are in excellent physical condition.

Just as some men try to cast themselves in a better light when they approach would-be dates, so male birds in poor condition seek to portray that they are fitter than they really are. But males do not even try to deceive their long-term partners, who are able to establish the true condition of the male by their song.

Lees meer: ScienceDaily

Drought in the Horn of Africa Delays Migrating Birds

The catastrophic drought last year in the Horn of Africa affected millions of people but also caused the extremely late arrival into northern Europe of several migratory songbird species, a study published December 6 in Science shows. Details of the migration route was revealed by data collected from small backpacks fitted on birds showing that the delay resulted from an extended stay in the Horn of Africa.

The extensive 2011 drought in the Horn of Africa had significant consequences for European songbirds such as thrush nightingale and red-backed shrike. These birds visit northern Europe every spring to mate and take advantage of ample summer food resources.

Lees meer: ScienceDaily

City birds use cigarette butts to smoke out parasites

Stuffing cigarette butts into the lining of nests may seem unwholesome. But a team of ecologists says that far from being unnatural, the use of smoked cigarettes by city birds may be an urban variation of an ancient adaptation.

Birds have long been known to line their nests with vegetation rich in compounds that drive away parasites. Chemicals in tobacco leaves are known to repel arthropods such as parasitic mites, so Monserrat Suárez-Rodríguez, an ecologist at the National Autonomous University of Mexico in Mexico City, and her colleagues wondered whether city birds were using cigarette butts in the same way.

Lees meer: Nature News

Fairy-Wren Babies Need Password for Food

It's always a good idea to listen to your mother, but that goes double for baby fairy-wrens even before they are hatched.

If those fairy-wren babies want to be fed, they need to have a password -- a single unique note -- taught to them by their mothers from outside the egg. The nestlings incorporate that password right into their begging calls, according to researchers who report their discovery online on Nov. 8 in Current Biology, a Cell Press publication.

Lees meer: ScienceDaily

City Birds Adapt to Their New Predators

Urban growth alters the behaviour of birds. Faced with the same threat, city and country birds do not react in the same way despite being from the same species. According to a new study, urban birds have changed their anti-predator behaviour in new environments.

When a bird is faced with a predator, its only objective is to escape. However, city birds do not react in the same way as their countryside counterparts, despite being from the same species. Urbanisation plays an influential role in their survival strategies.

Lees meer: ScienceDaily

Clever jays switch food-finding tactics

Jays demonstrate "flexible tactics" by switching between storing food and stealing from others' stashes, scientists have found.

The woodland birds are known as the shy members of the notoriously intelligent corvid family.

But birds were observed boldly stealing food from subordinates' hiding places in the University of Cambridge study.

Researchers found that the jays' strategy was dependent on the relative social rank of their opponent.

The results are published in the journal Animal Behaviour.

Lees meer: BBC Nature

Migration Routes and Strategies in a Highly Aerial Migrant, the Common Swift Apus apus, Revealed by Light-Level Geolocators

Auteurs: Suanne Akesson, Raymond Klaassen, Jan Holmgren, James W. Fox, Anders Hedenstrom
Bron: PLoS ONE 7(7):e41195. doi:10.1371/journal.pone.0041195
Abstract: The tracking of small avian migrants has only recently become possible by the use of small light-level geolocators, allowing the reconstruction of whole migration routes, as well as timing and speed of migration and identification of wintering areas. Such information is crucial for evaluating theories about migration strategies and pinpointing critical areas for migrants of potential conservation value. Here we report data about migration in the common swift, a highly aerial and long-distance migrating species for which only limited information based on ringing recoveries about migration routes and wintering areas is available. Six individuals were successfully tracked throughout a complete migration cycle from Sweden to Africa and back. The autumn migration followed a similar route in all individuals, with an initial southward movement through Europe followed by a more southwest-bound course through Western Sahara to Sub-Saharan stopovers, before a south-eastward approach to the final wintering areas in the Congo basin. After approximately six months at wintering sites, which shifted in three of the individuals, spring migration commenced in late April towards a restricted stopover area in West Africa in all but one individual that migrated directly towards north from the wintering area. The first part of spring migration involved a crossing of the Gulf of Guinea in those individuals that visited West Africa. Spring migration was generally wind assisted within Africa, while through Europe variable or head winds were encountered. The average detour at about 50% could be explained by the existence of key feeding sites and wind patterns. The common swift adopts a mixed fly-and-forage strategy, facilitated by its favourable aerodynamic design allowing for efficient use of fuel. This strategy allowed swifts to reach average migration speeds well above 300 km/day in spring, which is higher than possible for similar sized passerines. This study demonstrates that new technology may drastically change our views about migration routes and strategies in small birds, as well as showing the unexpected use of very limited geographical areas during migration that may have important consequences for conservation strategies for migrants.

Lees meer: PLoS ONE

Robins start with a magnetic compass in both eyes, and end up with just one

Here’s an amazing fact: Adult robins have a magnetic compass in their right eye that allows them to sense the direction of the Earth’s magnetic field, and navigate when all other landmarks are obscured. Here’s an even more amazing fact: Baby robins have two such compasses, one in each eye. They lose the left one as they grow up.

Robins kick-started the study of magnetic senses in the first place. In the 1950s, a German biologist called Hans Fromme showed that robins would always try to escape from a cage in the same direction when it came time to migrate. Even though they had no visual bearings, they headed south-west, as if sunny Spain lay just beyond their cages. In 1966, the husband and wife team of Wolfgang and Roswitha Wiltschko showed that a powerful magnet could disrupt this constant vector, sending them skittering in all sorts of directions.

Lees meer: Not Exactly Rocket Science

Cuckoo Tricks to Beat the Neighborhood Watch

To minimise the chance of being recognised and thus attacked by the birds they are trying to parasitize, female cuckoos have evolved different guises. The new research, funded by the Natural Environment Research Council, was published August 3, in the journal Science.

The common cuckoo (Cuculus canorus) lays its eggs in the nests of other birds. On hatching, the young cuckoo ejects the host's eggs and chicks from the nest, so the hosts end up raising a cuckoo chick rather than a brood of their own. To fight back, reed warblers (a common host across Europe) have a first line of defence: they attack, or 'mob', the female cuckoo, which reduces the chance that their nest is parasitized.

Lees meer: ScienceDaily

Starling population crashes across Europe

New figures show that 40 million Starlings have disappeared from the European Union, including Britain, since 1980.

The news comes on top of the figures suggesting that 300 million famland birds have been lost from Europe over the same period. The crash is triggering concern about the bird’s future status as a widespread and familiar species, and in Britain, the RSPB has launched a research project to see why this bird’s population is in freefall here, too. In 2002 Starling was added to Britain's ‘red list’ of Birds of Conservation Concern, because its population had halved during the previous three decades.

Lees meer: Birdwatch Magazine

Songbirds Migrate On Strict Schedule

A new study by York University researchers finds that songbirds follow a strict annual schedule when migrating to their breeding grounds -- with some birds departing on precisely the same date each year.

The study, published in the journal PLoS ONE, is the first to track the migration routes and timing of individual songbirds over multiple years. Researchers outfitted wood thrushes with tiny geolocator "backpacks," recording data on their movements.

Spring departure dates of birds heading from the tropics to North American breeding grounds were surprisingly consistent, with a mean difference of only three days from year to year, the study reports. Fall migration, however, was far less predictable. Males on average flew faster than females, and first-timers lagged behind those with more than one journey under their wings.

Lees meer: ScienceDaily

Arctic birds: Rock ptarmigans stay fit when fat

Experiments using miniature treadmills have revealed how an Arctic-dwelling bird is superbly adapted for life in extreme conditions.

The rock ptarmigan - a chicken-like bird that lives year-round on the Arctic ice and tundra - is just as fit when it has fattened up for the winter.

The birds, also known as snow chickens, can double in weight.

Scientists presented the results at the Society for Experimental Biology's annual conference in Salzburg, Austria.

Lees meer: BBC Nature

Prettier tits (the bird!) get more help from their partners

After a long, cold winter, nothing says spring like the hopeful songs and dances of horny male birds looking for mates. Throughout Europe and western Asia, the blue tit is one of the most colorful birds to engage in this annual hormone-driven spectacle. The males bring their A game, flitting about, singing beautiful songs, and offering gifts, trying everything in their power to convince their potential mates they are the best man around. One thing is for certain when it comes to blue tit love: it’s ladies’ choice. But, as a new study published today in Frontiers in Zoology found, the guys do have minds of their own: they’re better dads when they’ve landed an attractive mate.

Lees meer: Scientific American Blog Network

Wing marker woes: a case study and meta-analysis of the impacts of wing and patagial tags

Auteurs: Sarah A. Trefry, Antony W. Diamond, Linley K. Jesson
Bron: JOURNAL OF ORNITHOLOGY, 2012, DOI: 10.1007/s10336-012-0862-y
Abstract: The marking of individual birds has a long history in ornithology. This inexpensive and simple practice has been used to shed light on migration, behavior, and age-specific survival and recruitment. However, problems associated with markers and tags have often been overlooked. Wing tags have been used for over 40 years on frigatebirds, but their effects on this family of highly aerial seabirds have not been examined. Following higher than expected nest failure of treatment birds in the previous breeding season, we designed a study to test the impact of wing tagging and other standard capture and sampling methods on the nest success of Magnificent Frigatebirds (Fregata magnificens). Twelve nests were assigned to each of various band, measure, bleed, wing tag, and control treatments in the 2010/2011 breeding season on Barbuda, West Indies. We modeled nest fates using generalized linear models. Wing tags had a substantial negative effect on pre-fledging nest success, which was 42 % (10/24) for control nests, 39 % (14/36) for all non wing-tagged treatments, and 15 % (7/48) for wing-tagged treatments. We also conducted two meta-analyses, with different effect size calculations, to explore the general impact of wing and patagial tags on all birds. Our log odds ratio model showed a significant effect on survival and hatch and nest success, while our standardized mean difference model dealing largely with outcomes of behavioral, condition, and reproductive parameters (e.g., number of chicks and hatch date) showed no difference between marked and control birds. We consider possible mechanisms by which wing tags might contribute to lower nest success in frigatebirds, and propose that alternative markers be considered carefully before being applied to any species.

Parents adjust feeding effort in relation to nestling age in the Eurasian Kestrel (Falco tinnunculus)

Auteurs: Ronny Steen, Geir A. Sonerud, Tore Slagsvold
Bron: JOURNAL OF ORNITHOLOGY, 2012, DOI: 10.1007/s10336-012-0838-y
Abstract: In altricial birds, parents are assumed to optimize the total food delivery to the brood given the time constraints set by self-feeding and food collecting. Older nestlings may require more food than younger ones, and nestlings may need more energy when their growth rate is higher. By video monitoring prey deliveries in ten nests of the Eurasian Kestrel (Falco tinnunculus), we examined whether parents adjusted feeding effort in relation to nestling age. Based on published data on the growth and energy intake of Kestrel nestlings, we predicted parental prey mass delivery to peak at a nestling age of 15–17 days. The prediction was supported. The decrease in provisioning rate during the later nestling stages was best explained by nestling age. However, we cannot be conclusive as to whether this was caused by a decrease in nestling food demand, or by a seasonal decrease in the availability of voles, the dominant prey. The change in provisioning was mostly an effect of a change in the number of prey items delivered. However, prey size also tended to decrease with increasing nestling age. This is opposite to what has been found in most non-raptorial altricial birds, and may have been caused by the ability of Kestrel parents to dismember large prey and thus overcome the gape size-restricted swallowing capacity of small nestlings, together with a need to provide smaller prey to older nestlings when they start to feed unassisted.

Mobs Rule for Great Tit Neighbors

Great tits are more likely to join defensive mobs with birds in nearby nests that are 'familiar neighbours' rather than new arrivals, Oxford University research has found.

Many small birds will defend their nests by joint mobbing, where individuals gang up to harass a potential predator. Scientists studying great tit populations in Wytham Woods, Oxfordshire, wondered whether this sort of defensive behaviour might be behind observations showing that birds successfully raised more chicks when they were alongside familiar neighbours -- those that had occupied the nest box next door for several breeding seasons.

Lees meer: ScienceDaily

Foraging success in a wild species of bird varies depending on which eye is used for anti-predator vigilance

Auteur: Guy Beauchamp
Bron: LATERALITY, DOI: 10.1080/1357650X.2011.648194
Abstract: Brain lateralisation in animals with laterally placed eyes often leads to preferential eye use for ecologically relevant tasks such as monitoring predators and companions. Few studies of preferential eye use have been conducted in the wild and it is not clear if such preferences in the wild are widespread, how individuals can benefit from them, and which ecological factors influence their evolution. In a wild species of bird the extent to which foraging success varied depending on which eye is used during concomitant anti-predator vigilance was examined. When foraging in open mudflats, semipalmated sandpipers (Calidris pusilla) are frequently exposed to predation attempts by falcons (Falco spp) that originate from the tree cover bordering mudflats. Sandpipers spread along the receding tideline and can face the riskier side of their habitat primarily with the left or the right eye as they forage. If foraging is mostly incompatible with vigilance, the rate at which prey items are collected should decrease when birds use their less-preferred eye to scan cover. If foraging and vigilance can be carried out simultaneously, time spent foraging should not be affected but the efficiency with which their burrowing amphipod prey are located may be reduced, thus leading to decreased capture rate. Birds facing the riskier side of the habitat with their right eye captured significantly more prey than those scanning the same side with their left eye. Specialised eye use in sandpipers may allow individuals to perform simultaneous tasks, such as foraging and vigilance, more efficiently.

Hypes on the Mudflats

Waders Imitate Each Other

Current distribution models for social animals are inadequate because they do not take into account that species do not just compete with each other but may also attract one another. This is one of the results Eelke Folmer presents in his PhD thesis. Folmer studied 'self-organization' by various species including foraging waders on the Wadden mudflats. Folmer will defend his PhD thesis 'Self-Organization on Mudflats' at the University of Groningen on 20 April 2012.

An ecologist, watching foraging birds on the mudflats through binoculars, cannot help wondering why, for example, a large group of knots is at one specific spot rather than another; and why the curlews are so far apart? Soil samples, observations, and surveys all provide a wealth of data. But finding ecological patterns and regularities in all these data is quite a task. Computer simulations, spatial statistical models and structural equation models may help in sorting out the information and revealing processes of self-organization.

Lees meer: NIOZ

Ravens Remember Relationships They Had With Others

In daily life we remember faces and voices of several known individuals. Similarly, mammals have been shown to remember calls and faces of known individuals after a number of years. Markus Boeckle and Thomas Bugnyar from the Department of Cognitive Biology of the University of Vienna show in their recent article, published in Current Biology, that ravens differentiate individuals based on familiarity.

Additionally, they discovered that ravens memorize the closeness of a relationship and affiliation.

Lees meer: ScienceDaily

Pigeons' Homing Skill Not Due to Iron-Rich Beak: Cells Cannot Sense Magnetic Fields

The theory that pigeons' famous skill at navigation is down to iron-rich nerve cells in their beaks has been disproven by a new study published in Nature.

The study shows that iron-rich cells in the pigeon beak are in fact specialized white blood cells, called macrophages. This finding, which shatters the established dogma, puts the field back on course as the search for magnetic cells continues.

"The mystery of how animals detect magnetic fields has just got more mysterious," said Dr David Keays who led the study.

Lees meer: ScienceDaily

Birds: Divorce and Breeding Dispersal May Support the Better Option Hypothesis

Divorce and breeding dispersal in the dunlin Calidris alpina may provide support for the better option hypothesis.

Dunlins are long-lived shorebirds that often mate with the same partner over several seasons. In 126 recorded breeding attempts by dunlins, biologists Lars-Åke Flodin and Donald Blomqvist found that 23% of the pairs divorced.

They compared the breeding success of males and females before and after divorce to explore some causes and consequences of divorce.

Divorcing couples did not differ from non-divorcing couples in nest success in the season preceding divorce, both in terms of total nest failure or the number of eggs in the nest.

Non-divorcing pairs and male divorcees that paired with new partners had similar nest success in consecutive years.

However, female divorcees that found new partners doubled their nest success.

The authors concluded that female dunlins divorce to upgrade to a better mate or territory.

Bron: ScienceDaily

Fidelity to Roost Sites and Diet Composition of Wintering Male Urban Common Kestrels Falco tinnunculus

Auteurs: Jan Riegert, Roman Fuchs
Bron: ACTA ORNITHOLOGICA 46(2):183-189. 2011 doi: http://dx.doi.org/10.3161/000164511X625955
Abstract: During harsh winters, partially migratory raptors face to making a decision whether leave their breeding sites or not. However, decision to leave brings advantages for maintaining own body condition, but also disadvantages for further reproduction. We studied individual variability in fidelity to roost sites during two winters. The kestrel males in České Budějovice (Southern Bohemia) roost near their breeding sites for most of the winter. Individuals occupy the same roost site continuously, unless they temporarily leave the city. We collected pellets at the males' roost sites from November to April in 1996/1997 and 1997/1998. We analysed the factors that affect males' presence (proportion of days with snow cover — PSC, snow depth and mean temperature). There were fewer absences, overall, in 1997/1998 than in 1996/1997, probably due to milder weather conditions, and better prey availability. Individuals responded differently to periods of snow cover; some males left the city but others remained. Males that remained had a higher proportion of non-vole prey (birds, insectivors and insects) in their diet compared to those that left. Moreover, the proportion of birds in diet was positively correlated with PSC in males that stayed at roost sites during the period with snow cover. We suggest that males able to feed on birds during snow cover could remain in the city in harsh winters, and this would give them an advantage during competition for breeding sites in the following spring.

Plumage yellowness predicts foraging ability in the blue tit Cyanistes caeruleus

Auteurs: Vicente Garcia-Navas, Esperanza S. Ferrer, Juan Jose Sanz
Bron: BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, DOI: 10.1111/j.1095-8312.2012.01865.x
Abstract: Carotenoid-based coloration in adult birds has been often regarded as an honest signal of individual quality. However, few studies have demonstrated a link between carotenoid display and the quantity or quality of resources provided to the offspring. The present study investigated the expression of a carotenoid-based ornament, the breast plumage yellowness of the blue tit Cyanistes caeruleus, in relation to the level of parental provisioning effort and the amount of carotenoid-rich prey provided to the young. The study was conducted in two forest types (evergreen and deciduous), which also allowed an exploration of the possible existence of habitat effects on the coloration of breeding birds. It was found that plumage colour intensity (carotenoid chroma) correlated positively with nestling provisioning rates of both males and females, supporting the good parent hypothesis. In addition, carotenoid chroma was positively related with the proportion of Lepidoptera larvae brought to the nest in both sexes. Female but not male coloration was positively linked to breeding success (proportion of fledged young). Nestling coloration did not correlate with that of their parents, nor the frequency with which they were fed. Hue and lightness of nestling's plumage correlated positively with body mass and tarsus length, respectively. The results obtained in the present study indicate that ventral plumage coloration in blue tits may advertise the ingested carotenoids (carotenoid foraging ability) and also their overall parental quality in terms of nestling provisioning rates. This suggests that plumage yellowness can be used as an indicator of foraging ability in this species.

Birds evolved compass 'head up display'

Certain birds may have compass information mapped directly onto their vision, much as fighter pilots have ‘head up displays’ overlaying flight information on their view of the skies.

It’s well known that birds, such as the European Robin, can detect the Earth's magnetic field in order to help them navigate on long migratory flights.

This ‘compass’ sense must be associated with the eyeball, because the birds cannot detect magnetic fields in darkness.

But now scientists from the UK and Singapore have shown that birds may really ‘see’ the invisible force of magnetism, giving them a compass on top of their normal vision: rather like aircraft ‘head up displays’ which overlay crucial navigation information on a transparent screen in front of the pilot.

Lees meer: University of Oxford

Individually tracked geese follow peaks of temperature acceleration during spring migration

Auteur(s): Rien E. van Wijk, Andrea Kölzsch, Helmut Kruckenberg, Barwolt S. Ebbinge, Gerhard J. D. M. Müskens, Bart A. Nolet
Bron: Article first published online: 8 NOV 2011 DOI: 10.1111/j.1600-0706.2011.20083.x
Abstract: Many migratory herbivores seem to follow the flush of plant growth during migration in order to acquire the most nutrient-rich plants. This has also been hypothesized for arctic-breeding geese, but so far no test of this so-called green wave hypothesis has been performed at the individual level. During four years, a total of 30 greater white-fronted geese Anser albifrons albifrons was tracked using GPS transmitters, of which 13 yielded complete spring migration tracks. From those birds we defined stopover sites and related the date of arrival at each of these stopovers to temperature sum (growing degree days, GDD), snow cover, accumulated photoperiod and latitude. We found that geese arrived at spring stopovers close to the peak in GDD jerk; the ‘jerk’ is the third derivative, or the rate of change in acceleration, and GDD jerk maxima therefore represent the highest acceleration of daily temperature per site. Day of snow melt also correlated well with the observed arrival of the geese. Factors not closely related to onset of spring, i.e. accumulated photoperiod and latitude, yielded poorer fits. A comparison with published data revealed that the GDD jerk occurs 1–2 weeks earlier than the onset of spring derived from NDVI, and probably represents the very start of spring growth. Our data therefore suggest that white-fronted geese track the front of the green wave in spring.

'Magic mud' on tidal flats key to shorebird populations

The "magic" in the mud was first uncovered just south of Vancouver where up to half the world's western sandpipers touch down to refuel as they migrate north.

Now the gooey, paper-thin biofilm has also been found to be a key bird food on the other side of the Pacific, revealing what researchers say is a "missing link" in the avian world.

Biofilm can make up to 70 per cent of the diet of small shorebirds, which slurp up the stuff like energy drinks, says Environment Canada researcher Robert Elner, who led the international team that reports its study findings this week.

Lees meer: Canada.com

Cross-hemisphere migration of a 25 g songbird

Auteurs: Franz Bairlein, D. Ryan Norris, Rolf Nagel, Marc Bulte, Christian C. Voigt, James W. Fox, David J. T. Hussel, Heiko Schmaljohann
Bron: BIOLOGY LETTERS, doi 10.1098/rsbl.2011.1223
Abstract: The northern wheatear (Oenanthe oenanthe) is a small (approx. 25 g), insectivorous migrant with one of the largest ranges of any songbird in the world, breeding from the eastern Canadian Arctic across Greenland, Eurasia and into Alaska (AK). However, there is no evidence that breeding populations in the New World have established overwintering sites in the Western Hemisphere. Using light-level geolocators, we demonstrate that individuals from these New World regions overwinter in northern sub-Sahara Africa, with Alaskan birds travelling approximately 14 500 km each way and an eastern Canadian Arctic bird crossing a wide stretch of the North Atlantic (approx. 3500 km). These remarkable journeys, particularly for a bird of this size, last between one to three months depending on breeding location and season (autumn/spring) and result in mean overall migration speeds of up to 290 km d−1. Stable-hydrogen isotope analysis of winter-grown feathers sampled from breeding birds generally support the notion that Alaskan birds overwinter primarily in eastern Africa and eastern Canadian Arctic birds overwinter mainly in western Africa. Our results provide the first evidence of a migratory songbird capable of linking African ecosystems of the Old World with Arctic regions of the New World.

Lees ook: LiveScience

The fascinating love life of the Dunnock

I watched a Dunnock today, feeding under the garden table, with that characteristic half hopping half walking way Dunnocks have, pecking here and there things too small to be seen at a distance, maybe seeds or small invertebrates. Dunnocks, or Hedge Sparrows (Prunella modularis) are little birds, which live their lives mostly unnoticed amongst the undergrowth and are easily overlooked or taken for House Sparrows. They have a grey chest and head and chestnut backs with dark stripes, a thin beak and orange legs. Both males and females look similar, females just a bit smaller than males. In gardens they often feed on the ground, under bird tables when there is some cover, and they prefer to skulk than to sit out in the open. Only in the spring, where males sing their weak, warbling song from a prominent perch they are somewhat more likely to be noticed (above). Contrasting with their modest attire and retiring habits the Dunnock shows a variable mating system - including a common arrangement of two males and a female, a system called polyandry- , and a courtship behaviour that can only be described as peculiar. I was lucky enough to witness courting Dunnocks a few years back.

Lees meer: The Rattling Crow

Migration and wintering areas of adult Montagu's Harriers (Circus pygargus) breeding in Spain

Auteurs: Liminana Ruben, Soutullo ALvaro, Urios Vicente, Reig-Ferrer Abilio
Bron: JOURNAL OF ORNITHOLOGY Volume: 153 Issue: 1 Pages: 85-93 DOI: 10.1007/s10336-011-0698-x
Abstract: Between 2006 and 2008, 14 Montagu's Harriers (Circus pygargus) were tagged with satellite transmitters at their breeding grounds in NE Spain, recording a total of 18 autumn and 10 spring journeys. In both autumn and spring migrations, harriers migrated between Europe and West Africa along a relatively narrow corridor between the coast of Morocco and Western Sahara and the western border of Algeria. Birds tended to follow a slightly more westerly track during spring migration compared to autumn migration. Harriers started autumn migration in late August-early September, arriving at their wintering grounds in early-mid-September, after travelling between 8 and 25 days, and covering a mean of 187 km a day. Spring migration started in mid-March, with birds arriving at the breeding grounds in mid-April after covering a mean of 114 km a day. On average, spring migration lasted longer, with birds covering longer distances than during autumn migration, and distances travelled in a day tended to be shorter. Significant differences in the routes followed by harriers were observed among seasons and individuals, with the same individuals following different routes in different years. Wintering areas were located in northern Senegal and the southern border of Mauritania with Mali, with some birds breeding in the same colony in Europe separated more than 1,200 km during the wintering season. Birds showed a relatively high fidelity to their wintering areas. Several birds moved from one area to another during the wintering period, which resulted in larger wintering areas, whereas others remained in the same area during the whole wintering season.

Adoptions de jeunes buses par des pygargues.

L'adoption chez les oiseaux est la fourniture de soins à des poussins ou à des œufs par des adultes qui n'ont pas lien de parenté avec eux.
Les cas d'adoption interspécifique ont été rarement rapportés : on a toutefois noté en Amérique du Nord, des cas de Pygargues à tête blanche (Haliaeetus leucocephalus) ayant adopté de jeunes Buses à queue rousse (Buteo jamaicensis).

Ivan Literak et Jakub Mraz ont décrit en 2011 dans le Wilson Journal of Ornithology l'observation en mai 2007 d'une Buse variable (Buteo buteo), âgée d'environ deux semaines, dans un nid de Pygargues à queue blanche (Haliaeetus albicilla) à Hrachoviste, en Tchéquie.

Lees meer: Ornithomedia.com

Climate Adaptation Difficult for Europe's Birds

For the past 20 years, the climate in Europe has been getting warmer. Species of bird and butterfly which thrive in cool temperatures therefore need to move further north. However, they have difficulty adapting to the warmer climate quickly enough, as shown by new research published in the journal Nature Climate Change.

Åke Lindström is Professor of Animal Ecology at Lund University, Sweden. Together with other European researchers he has looked at 20 years' worth of data on birds, butterflies and summer temperatures. During this period, Europe has become warmer and set temperatures have shifted northwards by 250 km. Bird and butterfly communities have not moved at the same rate.

Lees meer: ScienceDaily

Mere fear shrinks bird families

Nothing but fear itself can actually be dangerous for nesting birds.

Song sparrows protected from attack but subjected to recordings of predator yowls and leaf-crunching approach noises raised 40 percent fewer offspring in a year compared with neighbors living amid innocuous noises, says population ecologist Liana Zanette of the University of Western Ontario in Canada. Predators do not need to kill a single prey to have a big effect, she says.

Lees meer: Science News