Understanding the factors driving departure decisions from stopover sites is critical when predicting the dynamics of bird migration. We Investigated the Interactive effects of wind, tidal characteristics, and precipitation on the departure decisions of the Eurasian Spoonbill Platalea l. leucorodia from a major coastal stopover locality in northern Iberia. Most departing Spoonbills (>80%) crossed an adjacent mountain range to follow a direct route over Inland Iberia, while the remainder made a detour following an Indirect coastal route along the coast of the Iberian Peninsula. During four consecutive autumns, we daily monitored departing Spoonbills leaving along these two routes. The birds taking the Inland route, crossing unsuitable habitats and needing therefore higher fuel-loads, departed preferentially under favourable tailwind conditions (TWC). This represented a significant increase in distance covered and/or a decrease in energy spent per unit time. Moreover, Spoonbills taking the inland route often departed during spring tides. For the indirect coastal route, TWC did not affect the onset of migration but bird departures increased with neap tides. Precipitation and date were negatively correlated with departures towards both routes, whereas Spoonbill density at the stopover had a positive effect. Our findings provide empirical support for the role that wind assistance may play for Spoonbills to resume migration.

The Common Snipe Gallinago gallinago migrates in large numbers through central Europe towards its wintering grounds in western Europe. Over the past 20 years more than 12 000 Common Snipes were ringed at seven ringing stations in Poland during their autumn migration. Birds migrating along the Baltic coast tended to spend the winter in more northern areas than those that used southern Poland as stopover sites during migration. This pattern supports the hypothesis of a parallel autumn migration exhibited by Common Snipe. Additionally, snipes passing through Poland at the beginning of the autumn migration (originating from near breeding areas) overwintered further north than later migrants (known to originate from more northern areas), which is consistent with a leap-frog migration pattern. Our results suggest that the migration pattern of the Common Snipe is more complex than previously thought, because these birds use a combination of two different non-exclusive migratory patterns.

Seasonal bird migration involves long flights, but most time is actually spent at intermediate staging areas. The duration of stay at these sites can be evaluated with mark—recapture methods that employ day-to-day local encounters of individually marked birds. Estimates of staging duration are based on two probabilities: the immigration probability, the complement of a bird's seniority to an area, and the emigration probability, the complement of the staying probability. Estimating total staging duration from seniority and staying probabilities requires validation for resighting data and here we compare three data categories of Ruffs Philomachus pugnax passing through The Netherlands during northward migration: (1) newly colour-ringed, (2) previously colour-ringed and (3) radio-tagged Ruffs (recorded by automated receiving stations). Between 2004 and 2008, 4363 resighting histories and 95 telemetry recording histories were collected. As sample sizes for females were low, only data for males were analysed. Possible catching effects affecting estimates of staging duration were explored. Staying probability was estimated for all data. Seniority however, could not be estimated for newly marked Ruffs; the assumption of equal ‘capture’ probability for reverse-time models applied to estimate seniority is violated for seasonal resighting histories starting with a catching event. Therefore, estimates of total staging duration were based on resightings of previously colour-marked birds only. For radio-tagged birds a minimal staging duration (time between tagging and last recording) was calculated. Modelling indicated that newly colour-ringed birds had a higher staying probability than previously colour-ringed birds, but the difference translated to a prolonged staging duration in newly ringed birds of only 0.4–0.5 d, suggesting a very small catching effect. The minimal staging duration of radio-tagged birds validated estimates of staging duration for colour-ringed birds in 2007 but not in 2005. In 2005 a low resighting probability resulted in underestimates of staging duration. We conclude that (1) estimates of staying probability can be affected by catching although effects on staging duration might be small, and that (2) low resighting probabilities can lead to underestimates in staging duration. In our study previously ringed Ruffs resighted in 2006–08 yielded reliable estimates of staging duration as data had sufficiently high resighting probabilities. Average staging durations varied between 19 d in 2008 and 23 d in 2006.

Between 2005/06 and 2008/09 we studied Black-tailed Godwits Limosa I. limosa staging in the rice fields surrounding the Tejo and Sado estuaries, Portugal. Godwits were counted weekly and flocks were scanned for colour-ringed individuals. We analysed phenology, dynamics of the stopover, and estimated the size of the Portuguese staging population as well as the total western limosa population, Godwits started arriving in January. Numbers peaked in the second half of February, after which they quickly departed from the area. Comparison with previous records suggested that numbers have decreased since the early 1990s, and that godwits currently peak later than some 15 years ago. Individual staging durations averaged 22.6 days in 2007 and 25.3 days in 2009, and increased towards the end of the staging period. We estimated that a total 59 200 birds used the area in 2007 and 53 100 in 2009. Using estimates for the proportion of colour-ringed birds in the flocks, we estimated the population size of the western part of the L. l. limosa population at 133 151–140 722 birds. This is higher than previous estimates based on inventories of the breeding population, but accounts for the non-breeding segment of the population. Thus, we estimate that 38–44% of the NW European Black-tailed Godwit population stage in Portugal. It is argued that processes in Iberia are not likely to have contributed to the population decline as the area for rice cultivation has increased. Nevertheless, as godwits staging in Iberia are totally dependent on human-made habitats, changes in rice farming practices could have great impact on the total population size.

We estimated apparent survival of 33 adult Thayer's Gulls Larus thayeri and 21 adult Glaucous Gulls Larus hyperboreus nesting sympatrically at a small colony on St. Helena Island, Nunavut, in Canada's high Arctic, using five consecutive years (2003–2007) of capture-mark-resight data. Resighting probabilities were high in all years for both species (0.97). Mean survival for Thayer's (0.81 ± 0.05) was low, but for Glaucous Gulls (0.86 ± 0.05) was comparable to estimates of survival reported for large gulls elsewhere. Both species showed high annual variation in survival, with one year each of noticeably lower survival, suggesting that some factors acting on survival may have differed between species and could reflect different species' exposure to natural or anthropogenic stressors. Our findings contribute to the limited demographic information on these polar gulls, and provide a basis for future comparisons should they be affected by changes in their polar environments.

In semi-arid ecosystems, rainfall and temperature induce changes in the food chain and affect breeding conditions of raptors. We examined the influence of rainfall and temperature on the breeding success of the Eurasian Kestrel Falco tinnunculus inhabiting xerophytic scrub on Tenerife Island, Canary Archipelago. Reproductive performance was recorded during five years, and food availability (arthropods, lizards, mice and birds) was monitored monthly during a wet and a dry breeding season. We found that increased rainfall in the previous autumn was associated with an earlier laying date and a more prolonged breeding season. Mean clutch size showed a positive correlation with rainfall in the month prior to laying. Hatching and fledgling success did not vary significantly between a wet and a dry year. Temperature did not influence breeding parameters. Despite the advanced laying date and larger clutch size observed, high prey availability during egg formation in the wet year did not result in higher overall breeding success. Stable between-year number of fledglings coincided with stable prey availability during the nestling or fledgling periods. Food conditions in the dry year were more stable and attuned to harsh weather conditions regardless of rainfall during the previous autumn and pre-breeding period.

In order to examine 24-hour colony attendance patterns by mated Forster's Terns Sterna forsteri in South San Francisco Bay, California, during incubation and chick-rearing stages, we radio-marked 10 individuals consisting of five pairs and recorded colony attendance using an automated data-logging receiver system. We calculated and analyzed five variables: the total attendance time by pairs and individuals, the duration of individual attendance bouts, and the duration both members of a pair either overlapped in colony attendance or were both absent from the colony. The percentage of time spent on the colony by at least one individual of a pair was highest during incubation and declined during chick rearing. Overall, male terns spent a greater proportion of time diurnally attending the colony than females. Females spent a greater proportion of time on colony at night, and without these nocturnal records, we would have reported overall female colony attendance rates as being much lower. Despite sex-specific differences in attendance rates, the length of attendance bouts did not differ between the sexes. Simultaneous colony attendance by both members of a pair was high at night, but during the day, pairs infrequently overlapped in their colony attendance and both members were frequently absent. Our datalogging system functioned well, and our data illustrates the importance of collecting 24-hour records when considering attendance rates.

Nestboxes are a popular measure to support populations of endangered secondary-cavity breeding birds. Yet, studies of the impact of nestbox abundance and design on bird breeding ecology in intensive farmland remain scarce, We experimentally studied nestbox preferences in a Wryneck Jynx torquilla population in SW Switzerland. Initially designed for the larger Hoopoe Upupa epops, voluminous nestboxes installed at 269 locations within the study area were checked for Wryneck breeding since 2002. In 2008, we installed smaller sized, Wryneck compatible nestboxes at 135 locations (50%) randomly selected from these 269 locations. We recorded the nestbox design preferences of Wrynecks, and measured reproductive output, nestling body mass and tarsus length, while assessing patterns of intra- and interspecific competition. Wrynecks settled in territories equipped with the more suitably designed nestboxes more than expected by chance and preferentially used them for raising their broods. The number of fledged young did not depend on nestbox design, although nestlings were slightly heavier in the smaller nestboxes, probably due to reduced interspecific competition with Hoopoes. This study shows that in particular territory attractiveness can be enhanced when artificial cavities with an appropriate design are provided. Nestbox provisioning is an efficient conservation measure for endangered bird species but attention should be paid to nestbox design which has to be tailored to species-specific requirements.

Forest type and habitat structure can have profound effects on different aspects of avian life histories. These effects may, however, strongly differ across and within forests that vary in vegetation composition and structure, especially when an ancient forest has been replaced by a new forest. To test for these differences in effect, we studied Great Tit Parus major life-history traits (280 first clutches) in two Mediterranean evergreen forests during 2005–07: an ancient Holm Oak Quercus ilex and a reforested pine forest. A comparison between forests revealed that females breeding in the Holm Oak forest started laying one week later, and produced larger clutches and broods both at hatching and at fledging. Chicks raised in the Holm Oak forest also fledged in better condition. Within forests, however, the reproductive success was not higher for pairs breeding in nestboxes surrounded by oaks within the pine forest, and also reproductive success was not lower in nestboxes surrounded by pines within oak forest. Instead, vegetation maturity around nestboxes, rather than tree species composition, affected hatching success. Surprisingly, hatching success was higher in nestboxes surrounded by immature vegetation. We suggest that this may be due to a lower nest predation rate in nestboxes surrounded by immature vegetation, compared to nestboxes surrounded by mature vegetation. We suggest that different factors appear to affect variation in breeding success in Mediterranean Great Tits comparing across forests (e.g. food availability) vs. within a forest (e.g. nest predation).

Seasonal variations in the use of roosts by Black Storks Ciconia nigra in West Africa were studied by satellite tracking and field observations between 1998 and 2006. Black Storks used twelve tree species as nocturnal roost. All roosting trees were higher than the surrounding vegetation (11.4 ± 3.9 vs. 4.2 ± 0.1 m). Black storks selected dead trees in 46% of the cases and showed a preference for roosts located close to foraging areas (on average within 4 km), the distance varying significantly according to season. On average, Black Storks used roosts for four consecutive days, alternating between roosts up to 41 times per winter period. Destruction of roosting trees could impact the birds' spatial distribution.

The prevalence and intensity of Infection with isosporan Coccidia parasites in wild passerine birds varies greatly between bird species. Faeces of Infected hosts contain oocysts that are a source of new infections when ingested. As a consequence, we expect that the main route of coccidiosis transmission in the wild is related to the foraging behaviour of the hosts, and that bird species are exposed to infective oocysts, depending upon the way of foraging. We studied how prevalence and intensity of isosporan infection in wild birds are related to foraging stratum, gregariousness, and diet. Our data reveal that a bird's feeding habits play a significant role in the extent and severity of infection by isosporan Coccidia in the wild.

We investigated seasonal variation in haematological indices and immune function in the non-migratory Great Tit Parus major over a complete annual cycle. The haematocrit value showed a marked reduction in spring and summer, reaching a lowest value during moult, after which it increased to reach a maximum in winter and spring. The peak in the heterophil to lymphocyte ratio (H/L) during July indicated that Great Tits were the most stressed during the first half of the moulting period. The increase in heterophils and H/L ratio, concurrent with a reduced number of lymphocytes during the breeding season, probably reflected the cost of reproduction in terms of physiological stress and immune suppression. After breeding the number of heterophils and the H/L ratio decreased, reaching a lowest value during winter. The concentration of immunoglobulins followed the seasonal pattern in the number of heterophils, though highest values occurred somewhat later, in July–September during the second part of the moulting period, Our observations indicated large differences in activity throughout the year of different components of the immune system, This suggests differences in function among the components and possibly differences in susceptibility to stress, parasitism and hormones during the annual cycle. When juveniles became independent of their parents, the immunoglobulin concentration increased, whereas other immune measures did not show a significant change. This indicates a rapid increase of at least one component of the immune system after the young fledge.

This study provides the first description of autumn migration routes of juvenile Short-toed Eagles Circaetus gallicus tagged in southeastern Spain. Three nestlings were tagged with Argos/GPS satellite transmitters, of which two reached their wintering grounds in Mali, close to the Inner Niger Delta. Onset, duration and routes of migration differed between the two individuals, but both eventually settled in approximately the same area (c. 170 km apart). The wintering grounds were located more than 2500 km away from the breeding sites, although the birds covered some 3800–4700 km to reach the wintering area. The observed differences in migration strategies may be related to juvenile eagles migrating, or not, in mixed flocks with adults; the latter depart earlier from the breeding grounds and follow a more direct route to the wintering grounds.