In this study, we describe food availability and diet selection of the Red Knot Calidris canutus islandica wintering in three estuarine bays on the French Channel coast. We examined whether the distribution of birds is related to the density and availability of high quality prey. Results indicate strong seasonal and inter-annual variation in the abundance of birds and considerable variation in prey-item abundance and diet selection depending upon site. At Mont Saint-Michel Bay, the prey community was dominated by Baltic Tellins, Macoma balthica. As expected from their high meat-to-shell ratio, Macoma contributed more than 90% of the diet. Most of the cockles, Cerastoderma edule were too large and their quality too low to be preyed upon. Less than 100 km away, in Saint-Brieuc Bay, Red Knots mainly selected the Thin Tellin Tellina tenuis. Although Tellina are a lower quality prey than Macoma, they occurred at a high density and in some winters might explain why the number of Red Knots exceeds those at Mont Saint-Michel Bay. At Bay des Veys, Normandy, Red Knots were restricted to a small intertidal area and fed on Abra tenuis, Macoma balthica and Hydrobia ulvae.

Various factors such as food, climate, nest predation, and phylogenetic relationships influence parental behaviour in birds. However, few studies have addressed how the tidal cycle shapes incubation behaviour in seabirds. In the intertidal zone, spatiotemporal limitations in foraging opportunities for the parents are expected to affect breeding behaviour. We studied tide-associated incubation behaviour in Saunders's Gulls Larus saundersi, nesting in a colony on recently reclaimed land and foraging on tidal mudflats, near Incheon in the Republic of Korea. This colony is the last remaining colony in the Republic of Korea. In May 2012, the number of non-foraging adults present in the 200 ha nesting area was monitored; also parental activity at ten nests was videotaped during the daytime, using a car black box recording system. Presence in the colony and parental activity were analysed in relation to the tidal cycle, ambient temperature, time of day, and nesting success. Our results indicated that the number of non-foraging adults staying in the nesting area was higher at high tide than at low tide, and the time that parents incubated eggs increased with higher sea level. The observed pattern was more apparent during ebb tide than during flood tide. No association of time of day, ambient temperature, and nesting success was found. We conclude that the parents regulate incubation in response to the exposure time of their foraging areas and possibly the dietary activity of benthic organisms in the mudflats.

In this study we examined the effect of different livestock grazing treatments on breeding bird densities in a salt marsh habitat. To avoid an experiment on the large scale needed to directly measure grazing effects on bird densities, we followed a two-step approach. First, we measured vegetation micro-patterns (mosaic of lower vegetation and taller patches at 4×4 m) around Common Redshank Tringa totanus and Eurasian Oystercatcher Haematopus ostralegus nests and at random sites paired with these nests sites to judge suitability of micro-patterns for nest building. Secondly, we measured micro-patterns at 120 permanent plots in five different experimental grazing treatments to determine how grazing affects micro-patterns. We compared low stocking density of both cattle and of horses, high stocking density of cattle and of horses, and intermittent grazing with a high stocking density of cattle (i.e. yearly intervals of grazing and no grazing). Redshank and Oystercatcher nests occurred in sites with taller vegetation and more pronounced micro-patterns than found at random sites. Paddocks grazed with low densities of livestock or with a high density intermittent grazing treatment had micro-patterns preferred by the birds. We conclude that Redshanks and Oystercatchers may benefit in terms of potential nest sites from grazing at low livestock densities or at intermittent stocking densities through effects of grazing on micro-patterns in the vegetation.

Migratory birds have evolved physiological and behavioural adaptations for crossing large ecological barriers through the accumulation of large amounts of fat and protein during the pre-migratory phase. Nevertheless, most migrant passerines usually need several stopovers en route to replenish their energy reserves and to rest. Migratory decisions at a stopover site strongly depend on body condition at arrival. Previous studies showed that lean birds prolong their stopover compared with fat birds that leave after a very short time. During the stopover, lean birds may reduce their metabolic costs by lowering body temperature (adaptive hypothermia hypothesis). However, it is not clear whether hypothermia can be an active economising strategy or just an unavoidable consequence of bad condition to avoid starvation. We used temperature loggers to measure skin temperature of 19 Garden Warblers Sylvia borin caught at a spring stopover site (Ponza Island, Tyrrhenian Sea) and kept overnight in cotton bags. We found that both body condition and activity were positively correlated with skin temperature during the night. The data showed a gradual nocturnal temperature drop of more than 3°C in lean birds, particularly in the central part of the night, followed by a recovery to normothermic levels. Overall, birds in worse physical condition lost more body mass during the night than birds in better condition, but this was especially true for birds that lowered their body temperature the least. These results indicate that hypothermia is associated with low body condition and that it may be functional by reducing body mass loss during migration.

The repair jobs that birds have to do to maintain high quality plumage take energy and time, so should be under intense selection. Recently, we have shown that secondary moult in the Eurasian Golden Plover Pluvialis apricaria is incomplete, irregular and asymmetric between wings, and argued that this reflected their ‘relaxed’ migratory habits. On the basis of this hypothesis, we predict that relatives of this species that have to make long flights between breeding areas and winter quarters would invest more in the moult of secondaries. To test this we collected data on moult patterns in two populations of Pacific Golden Plovers Pluvialis fulva (Siberia and Alaska), on American Golden Plovers Pluvialis dominica (Alaska) and Grey Plovers Pluvialis squatarola. Data were from the breeding, staging (Mongolia and Indiana) and wintering (Uruguay) areas. We found patterns consistent with our prediction: Pacific Golden Plovers from Siberia, and Grey Plovers have a similar moulting pattern to Eurasian Golden Plovers. Although both go to remote winter quarters, they migrate mainly over land, probably making short or moderate flights, as they are able to stage frequently. In contrast, the Alaskan populations of Pacific Golden Plovers and American Golden Plovers tend to renew all their secondaries from their second wing moult onwards. In line with their moult patterns, these two populations are known to make very long non-stop flights between breeding and winter areas. We argue that irregular moult and the partial renewal of secondaries is a primitive character in all four species. The full replacement of secondaries in the Pacific Golden Plovers and American Golden Plovers from Alaska may be considered as an adaptation for very long demanding flights. Regular moult patterns of secondaries, as found in many other shorebirds, could be a further refinement of this adaptation.

We determined the degree of connectivity in the Eurasian Reed Warbler Acrocephalus scirpaceus between breeding regions in central and northern Europe and stopover sites in Iberia, during the autumn migration. We used both recovery data and wing length analyses to achieve this. Biometric data were obtained during 2009 at 11 sampling localities in Iberia, which we amalgamated into four major migratory areas within the region (Central, Western, Eastern and Southwestern Iberia, hereafter CI, WI, EI, SW). From the EURING database, we selected birds captured at their breeding sites in Europe and recaptured in Iberia during the autumn migration. Reed Warblers passing through WI had shorter wings than those in CI, EI and SW, suggesting that birds in WI migrated shorter distances, a fact also supported by recovery data. Although Reed Warblers showed some population overlap when passing through Iberia, we found that birds passing through EI and CI came from areas further to the east (continental Europe) than those passing through WI (mainly British Isles), thus supporting parallel migration. Reed Warblers tended to converge in southwestern Iberia, suggesting an effect of nearby geographical barriers.

Conservation of long-distance migratory shorebirds is complex because these species use habitats spread across continents and hemispheres, making identification of critical habitats and potential bottlenecks in the annual cycle especially difficult. The population of Black-tailed Godwits that breeds in Western Europe, Limosa limosa limosa, has declined precipitously over the past few decades. Despite significant efforts to identify the root causes of this decline, much remains unclear. To better understand the migratory timing, use of stopover and nonbreeding sites, and the potential impact of breeding success on these parameters, we attached 15 Argos satellite transmitters and 10 geolocation tracking devices to adult godwits nearing completion of incubation at breeding sites in southwest Friesland, The Netherlands during the spring of 2009. We successfully tracked 16 adult godwits for their entire southward migration and two others for part of it. Three migration patterns and four regions of use were apparent. Most godwits left their breeding sites and proceeded south directly to stopover sites in the Mediterranean — e.g. Spain, Portugal, and Morocco — before flying on to non-breeding sites in West Africa. Other individuals spent the entire nonbreeding season in the Mediterranean. A third pattern included a few individuals that flew nonstop from their Dutch breeding sites to nonbreeding sites in West Africa. Tracking data from this study will be immediately useful for conservation efforts focused on preserving the dispersed network of sites used by godwits during their southward migration.

Many ecologists mark their free living study animals with the aim to collect knowledge on individual life histories. Yet, marking animals may affect life histories and it is important to quantify such effects. Literature on this subject is relatively rare, especially when it concerns the effect of bird rings. This is partly because control groups are often missing, since the rings were not applied with the goal to measure their effect on life histories. From studies in captivity there is evidence that the colour of rings may affect partner choice and in the field certain outstanding colours of rings may affect predation risk. Here we use data of an ongoing study of Great Tits Parus major to analyse whether the colour of rings fitted in different combinations to nestling Great Tits (day 14, n = 9818) affected their life histories in terms of natal dispersal, first year local recapture rate, breeding performance and second year local recapture rate. We measured reflectance spectra to quantify the brightness of the colour rings, and we used a human panel to judge the conspicuousness of the rings against a grey background. We found support for a positive effect of the conspicuousness, as judged by human observers, of the colour ring combination on local recapture rate, but not on natal dispersal suggesting that survival was affected. No effect was detected on breeding performance. The brightness of the rings did not explain variation in life history components. Although the effect of conspicuousness was statistically weak, the effect size is of potential biological importance. Life expectancy of individuals without conspicuous rings is estimated to be 28% shorter than for individuals with three conspicuous rings. Our result could have a considerable impact on life history studies where fitness measures are based on colour-marked bird populations. Colour of the colour rings will affect the variance of fitness estimates and may even bias the mean of fitness estimates when specific colours are used in specific periods, in specific environments or to mark particular categories of birds like year classes.

The western subspecies of Yellow-billed Cuckoo Coccyzus americanus occidentalis has undergone severe population declines over the last two decades. Numerous petitions have warranted its listing under the Endangered Species Act; however, the question of whether the western subspecies is genetically separated from the eastern C. a. americanus form is controversial. Previous research found small, but significant divergence in a single mitochondrial gene based on a limited number of samples. In this study, I analyze 949 base pairs of the same mitochondrial cytochrome b gene from additional samples in both the western and eastern subspecies to reassess the evolutionary distinctiveness of the western taxa. Unlike the previous study, I did not find any fixed genetic differences, but only found slight, insignificant genetic differentiation between the subspecies. The separation into distinct subspecies of the eastern and western Yellow-billed Cuckoo might be more recent than can be captured by a single mitochondrial gene; alternatively high levels of gene flow might prevent complete segregation. Interestingly, I found a substantial amount of haplotype variation within the western samples, which may indicate genetic differences between western sampling locations. Future studies incorporating next generation sequencing are recommended to resolve the taxonomic status of Yellow-billed Cuckoo.

We investigated the factors influencing the dynamics of Long-eared Owls Asio otus wintering in Moscow. The study was carried out in 2001–2011. Twelve communal roosts and 14 solitary wintering owls were found. Number of active roosts was positively correlated with the total number of wintering owls per year. The four largest roosts were active for many years, with up to 16 individuals in a single winter (9.9 ± 1.3 on average). Generalized linear models indicated that the number of wintering owls was influenced simultaneously by the abundance of Common Vole Microtus arvalis in the previous autumn and in spring, and the owls' breeding numbers in the study plot. The most important factor was vole abundance in early spring indirectly indicating food supply in late winter. The influence of weather was investigated on the regularly surveyed local site in Moscow. The maximum number of owls at the roosting site varied from 0 to 9 individuals (2.1 ± 0.4 on average). Among weather factors, the most important influence on the dynamics of owls was by snow cover and wind jointly, though the snow was undoubtedly of greatest significance. Air temperature and precipitation turned out to be almost of no importance for owl dynamics at the roosting site.

There is little information on flight feather moult in darters (Anhingidae). I used a combination of direct observations and photographs to confirm that the normal pattern of moult is to replace all remiges synchronously, but not all rectrices. I surmise that at least some rectrices are retained year-round because they are important for controlling body angle and depth while diving in shallow water. However, a few birds do not replace all their remiges at once, retaining some inner primaries and secondaries. The retained feathers are insufficient to allow flight, and the reason why these feathers are retained is unknown.