At the important wintering site, East Dongting Lake in the Yangtze River floodplain, Lesser White-fronted Geese Anser erythropus showed within-season shifts in distribution and abundance between local areas. On arrival in November, over 4,000 geese grazed high-biomass stands of new growth spikerush Eleocharis migoana on exposed mud flats at Caisang Lake. High feeding densities depleted Eleocharis by early December, when the geese departed to feed on old-growth above-ground Carex heterolepis at nearby lakes. Cool, arid conditions inhibited plant growth until January, when the grass Alopecurus aequalis and C. heterolepis restarted growing, attracting geese back to Caisang Lake. Greater numbers returned in late February when E. migoana began to grow, rapidly building to peak at 4,500 in late March when geese began spring migration. Habitat management that maintains these patterns of plant growth and availability may be critical to keeping present Lesser White-fronted Goose numbers at this site.

Iceland has a large resident population of Purple Sandpipers Calidris maritima, but is also believed to be a wintering area for other populations and is a stopover site for migrants. To determine the wintering areas of those that prepare for westward migration to the Nearctic in spring, Purple Sandpipers were colour-ringed on the coast of southwest Iceland in May 2003 and 2005. We searched for colour-ringed birds along the coasts of Iceland, the European mainland and Britain, particularly in winter 2005/06. Out of 326 marked birds, 82 were re-sighted during 2003 to 2009, of which 69 were seen during winter (October to March) 2005/06. Most sightings (55) in winter 2005/06 were from southwest Iceland, extending the known winter range of this population to Iceland. Resightings from northern Scotland confirmed the evidence from biometrics that this wintering population originates from the Nearctic. The maximum number of colour-marked Purple Sandpipers in Britain and Ireland in winter 2005/06 was estimated at about 65, which was approximately a quarter of the marked sample estimated to be alive. Therefore, the majority of the colour-ringed birds must have wintered elsewhere, most likely in Iceland. There was no evidence of sexual segregation according to whether they wintered in Iceland or Britain. However, those that were colour-ringed before 15 May were more likely to be seen in Iceland than in Britain, whereas those colour-ringed after 15 May were more likely to be seen in Britain, indicating that the migration from Britain takes place mainly after mid-May. Although there have been no ringing recoveries, biometry data suggest that Purple Sandpipers that prepare for westward migration in Iceland in spring, breed in Canada. This population shows a unique winter range for a wader that includes Greenland, Iceland and northwest Europe along the East Atlantic flyway.

For a long time, agricultural areas had considerable ornithological value, an ecological richness which in The Netherlands was epitomised by the term ‘meadow birds’. However, over the last half century, agricultural intensification has negatively affected the quality of meadow bird habitats. Here we provide a quantitative characterization of agricultural habitats and their use by Blacktailed Godwits Limosa I. limosa in the south-western part of the province of Friesland, The Netherlands, in 2009, to provide a yardstick to evaluate further change. We used groundwater level, vegetation typology, relief in the landscape, the occurrence of foot drains, land use and soil characteristics such as textures and peat to describe the landscape that comprised 43 polders covering 8480 ha. We used a Principal Component Analysis to summarize landscape characteristics and find that much of the habitat variation is explained by a combination of herb richness of the vegetation, the presence or absence of foot drains and groundwater level. The modern agricultural landscape of southwest Friesland consists of 80% of uniform, intensively managed landscape with herb-poor meadows and low groundwater levels, the remaining 20% being taken by remnants of the former herb-rich meadows. The whole study area was searched weekly and Black-tailed Godwits were mapped between arrival and egg-laying. The positive relationship between godwit density and the first PC axis indicates that Black-tailed Godwits preferred herb-rich polders with high groundwater levels and the presence of foot drains. Soil texture was poorly correlated with godwit breeding densities for intensively managed (herb-poor) parcels, but for herb-rich meadows, soils of sandy clay loam and sandy clay harboured the highest densities of godwits. To protect Black-tailed Godwits, areas should have a herb-rich vegetation, contain foot drains and high groundwater tables should be re-established.

We monitored nests of Kentish Plover Charadrius alexandrinus and Black-winged Stilt Himantopus himantopus breeding in rice fields near the Doñana National Park (southwest Spain) during the breeding seasons 2005–2007. We used a logistic-exposure method to calculate nest success and examined daily nest survival as a function of year, locality, nest age, and date. Nest success was also calculated using a model assuming constant nest survival through time (equivalent to the Mayfield method). Daily nest survival increased during incubation in Black-winged Stilt, probably due to a higher predation risk during the first days of incubation. Daily nest survival in Kentish Plover showed little variation in relation to nest age, suggesting a constant but lower predation rate. Nest survival also varied with date in Kentish Plover and showed higher values in the middle of the nesting season. The nest success of Black-winged Stilt and Kentish Plover breeding in rice fields (50% and 45%, respectively, based on the Mayfield method) was within the range of nest success reported in stable populations breeding in natural habitats. The observations suggest that rice fields adjacent to the marshes of the Doñana National Park are an important additional breeding habitat for the two wader species studied.

Two populations of Bar-tailed Godwits Limosa lapponica occur along the East-Atlantic Flyway. The European population (L. l. lapponica) is supposed to breed in northern Scandinavia and has been suggested to only winter in Europe. The Afro—Siberian population (taymyrensis) is supposed to breed in Northern Siberia and is thought to winter exclusively in West Africa. An analysis of 946 metal ring recoveries accumulated by EURING (with data going back to 1935), in combination with an analysis of over 13,000 resightings of almost 4000 individuals marked with colour-rings in 2001–2010, enabled us to examine whether there is evidence for overlap of the populations in summer and winter. Nearly all marked individuals behaved according to the previously suggested leap-frog migration pattern. On the basis of the present sample, only 0.8% of (colour) ringed birds that were recovered and/or resighted on the wintering grounds in Europe or West-Africa made a change between the two supposed wintering areas. This is far less than was previously estimated on the basis of biometric data. The distinct migratory behaviour of the two populations makes them near-completely separated in summer and winter. The Bar-tailed Godwit along the East-Atlantic Flyway thus exhibits a clear leap-frog migration, in which the Siberian breeders winter south of the European breeders.

Flight directions and routes of migrating birds are determined by the birds' compass orientation, but also by effects of wind, social influence, responses to topography and landmarks, and to navigation cues. We investigated the orientation and routes taken by arctic shorebirds during autumn migration in southern Sweden at three different sites situated within a distance of 200 km from each other, in relation to the birds' destinations. We used three different methods, visual telescope observations, tracking radar registration and ring recoveries. Mean track directions differed significantly between the different sites in a way that demonstrated fine-scaled orientation changes when the shorebirds passed the southern Baltic region. The gradual change cannot be explained by different wind conditions at the different sites or by distinct responses to specific topographical features, i.e. the birds were not following coastlines or prominent landmarks in any detailed way. Neither could it be reconciled with orientation according to any of the main compass mechanisms known to be used by migrating birds which indicates that the control of flight courses and paths may be more complex than expected. The shorebirds might travel within a slightly winding flight corridor in broad agreement with the large-scale topography to maximize general association with coastal habitats during migration. Juvenile birds had a significantly different orientation than adults, particularly when the juveniles travelled in flocks without any adults. Juvenile birds may learn the general flight paths and course changes in relation to the large-scale topography from older and experienced individuals in the flocks, but most of this learning process between generations probably does not take place until after the birds' first autumn migration.

Aquatically foraging Bewick's Swans Cygnus bewickii have been repeatedly reported to be accompanied by diving ducks, but the exact nature of this relationship is unclear. Based on field observations, we found a strong correlation between the number of foraging swans and the number of foraging Common Pochards Aythya ferina and Tufted Ducks Aythya fuligula at our study site (Lauwersmeer, the Netherlands), with the median ratio being close to one diving duck per swan. To determine whether the association was kleptoparasitic or commensal, we measured in a series of experimental trials the instantaneous intake rates of Bewick's Swans and Common Pochards when foraging alone and when foraging together. On average, pochards in company with a swan attained twice the instantaneous intake rate as compared with foraging alone. This was mainly due to gleaning food items that floated away as a result of the swan's trampling activity, and was not due to stealing: in fact, food intake rates of swans were not affected by the presence of a pochard.

Given the many detailed studies on the breeding biology of gulls, surprisingly little is known about conspecific brood parasitism (CBP) in these birds. CBP has been recorded in only a few of the roughly 60 species of Laridae. We studied CBP in two colonies of Common Black-headed Gull Croicocephalus ridibundus in northeastern Poland, during two consecutive years. We found parasitism in 22% and 10% of the monitored nests in the colonies, as determined with protein fingerprinting. Among the parasitic females we found only one that acted as both parasite and host. In both colonies, most cases of parasitism involved nests of females more related than average to the parasitic female. The rare cases of egg expulsion involved hosts with low relatedness to the parasite. We suggest that kin selection is implicated in CBP in the Blackheaded Gull.

Gut bacterial loads in avian nestlings may be affected by factors such as climate, seasonality and brood size. There is no published information on this subject for wild birds, despite its potential importance for nestling welfare and growth. We studied the associations of these factors with abundances of two common gut bacterial types, enterococci and Enterobacteriaceae, in nestling Pied Flycatchers Ficedula hypoleuca in central Spain. To that end, we obtained faecal samples from 54 broods (102 nestlings) on day 7 and 13 after hatching, for detection and estimation of bacterial abundance. Enterobacteriaceae loads on day 7 were positively correlated with mean temperature during the preceding seven days and negatively correlated with rainfall and hatching date. The negative associations of Enterobacteriaceae loads with rainfall were only found for early broods, at low temperatures. Enterococci loads on day 7 were positively associated with mean temperature. On day 13, Enterobacteriaceae loads were negatively correlated with hatching date, while enterococci loads were positively correlated with mean temperature. Enterobacteriaceae are apparently more sensitive to seasonal changes and climatic variation than enterococci, possibly in relation to variation in diet and nutrition. By contrast, enterococci are only sensitive to thermal variation. The attainment of full thermoregulatory capacity by nestlings reduces climatic effects on Enterobacteriaceae loads.

Over a five-year period we monitored breeding parameters in a colony of Tree Sparrows Passer montanus in central Spain. This multi-brooded species can raise one to three broods per season. In this study, we analyzed inter-brood variation in reproductive success to infer the existence of seasonal patterns. We also explored inter-annual variation of life-history traits, which is of particular interest in a declining species like the Tree Sparrow. In agreement with our expectation of a multi-brooded species, clutch size showed a quadratic relationship with laying date. We found that the inter-brood interval varied significantly depending on the number of breeding attempts, which suggests that the species may engage in time-saving behaviours as reported for other multi-brooded passerines. Nestlings from second broods fledged in better condition than nestlings from first and third broods. Fewer fledglings were produced in third broods than in preceding breeding attempts. The reproductive output of third broods varied to a large extent among years, whereas inter-annual variation was much less marked in first and second broods. Over the years, we also detected a decrease in nestling size (tarsus and wing length), which was consistent among breeding attempts. Finally, the productivity of the colony remained fairly stable over the study period. This pattern contrasts with negative population trends detected by national monitoring programmes. The proximity of wetland habitats in the surroundings of our colony — essential for adequate invertebrates for the chicks — is suggested as a main reason for this difference.

We report co-operative group foraging in the African Penguin Spheniscus demersus. Groups of approximately 25–165 African Penguins were observed circling schools of pelagic fish, sometimes forcing them to the surface. During this behaviour 66–75% of penguins were underwater at any given time. Smaller numbers of African Penguins also joined foraging groups of Cape Gannets Morus capensis and Cape Cormorants Phalacrocorax capensis, but did not appear to corral fish schools when outnumbered by these species. African Penguins are listed as Endangered due to ongoing rapid population decreases. If group foraging confers an advantage to African Penguins, their dwindling populations may suffer from an Allee effect as colonies become too small to support sufficient densities of birds for foraging groups to form.

Nominate Barn Owls Tyto a. alba can be sexed based on flecking patterns of the underwing and underbody, but in the Dutch population consisting of the nominate subspecies and T. a. guttata, overlap in flecking exists between the sexes. In this paper we describe a new method to sex Barn Owls based on apical bar widths of the primaries. Data were obtained from 240 dead Barn Owls that were sexed by autopsy. The apical bars of the primaries 10 and 8 were narrower than 7.5 mm in males and wider than 7.5 mm in females. The widths of more basal bars of the primaries and secondaries overlapped between the sexes. The method was validated by providing 20 carcasses to 10 instructed volunteers, who measured the apical bar widths to sex the birds. The measuring error per owl specimen averaged at 2.2% (range 0.8–3.9%), and the proper sex was assigned in all cases.

Reusing old nests for breeding might provide birds with benefits such as saving the time and energy needed to build a new nest, or by decreasing the risk of predation while building a nest. Despite these benefits, many species use their nests only once. This study aimed to determine how frequently Eurasian Blackcaps Sylvia atricapilla, which build delicate open cup nests that are particularly susceptible to damage, might reuse their nest within a season and if extensive damage to a nest limited its reuse. I conducted the study in 2002–2008 in forests next to the city of Bydgoszcz in central Poland. I examined 479 Blackcap nests after the failure or success of the nest was known. Nests were classified as damaged or undamaged (73.7% of the sample). Only four nests were reused, representing 0.8% of all nests and 1.1% of the undamaged nests. The large number of undamaged but inactive nests indicated that the extent of damage was unlikely to be the reason that nests were rarely reused. The study also showed that Blackcaps rarely used material from an old nest to build a new nest.