Radosław Włodarczyk

Adjustments and Exploitation of Body Stores During Post-Juvenile Molt in Common Snipe Gallinago gallinago

Abstract. Post-juvenile molt of Common Snipe was investigated during 2004-05 at the Jeziorsko reservoir, central Poland. Body mass and mass of fat stores were dependent on the stage of post-juvenile molt. The body mass increased prior to the commencement of molt, but during the intensive stage of the process it decreased and returned to the previous level. Fat-free body mass increased during molt, which may be attributed to increased protein synthesis or the higher water content of growing feathers. Fat stores were similar in snipe before and in the initial stage of molt; however, they decreased significantly during the transition to the intensive stage of the process. In total, snipe lost approximately 57% of the mass of fat loads over the course of molt (4.9% of lean body mass). Being a highly energetic constraint, post-juvenile molt is suggested to affect certain life history traits of Common Snipe such as the length of the staging periods during the autumn migratory period.

Natal and breeding dispersal in Mute Swans Cygnus olor: influence of sex, mate switching and reproductive success

Abstract Dispersive behaviour in birds is shaped by a set of different external factors (climate, human pressure, territory quality), as well as by internal constraints (reproductive strategy, sex, age, competitive abilities). Natal and breeding dispersal was studied in the migratory population of the Mute Swan Cygnus olor in Poland. The species showed male-biased natal dispersal with mean dispersal distance of 99.7 ± 20.0 km for males and 17.7 ± 5.4 km for females. Consistently, larger proportion of female swans showed natal philopatry, when compared with males (36.4% vs. 9.1%). The dispersal distance has shortened over the last three decades. This tendency prevailed in males and was associated with reduction in annual migration distance due to milder winters and adaptation for wintering in urban areas. Analysis of breeding dispersal showed that only 12.3% of breeding attempts were associated with changing territories (N = 945). Breeding dispersal distance was female-biased (0.66 ± 0.19 km for females vs. 0.35 ± 0.14 for males; N = 316 individuals). Occurrence of mate-switching and poor reproductive success were positively associated with probability of dispersal, but moving to a new territory did not increase breeding output in a season following dispersal event. Dispersive behaviour in the Mute Swan may be perceived as a part of species-specific ecological flexibility, allowing individuals to adjust to the changing conditions at the breeding grounds.

The Migration System of Common Snipe Gallinago gallinago on Autumn Passage Through Central Europe

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.

A new insight into the ageing of Common Snipe Gallinago gallinago ‐ the value of contrast within the wing coverts of adults

The ageing criteria for Common Snipe Gallinago gallinago are complex, and a significant proportion of birds in autumn which have completed moult cannot be aged. Jeziorsko Reservoir is an important stopover site for Common Snipe during autumn migration through central Poland. Detailed studies of wing coverts show that in a proportion of adult birds a contrast or moult limit between old, faded feathers and new ones grown during the moult can be used as an additional criterion to distinguish adults from first‐year birds that have completed their post‐juvenile moult. In particular, the presence of one or more old humeral coverts allowed a high proportion of birds, otherwise of indeterminate age, to be identified as adults. Since these feathers are normally hidden under the scapulars, careful plumage examination is needed to age birds correctly.

Ecological, physiological, and morphological correlates of blood hemoglobin concentration in a migratory shorebird.

The information on the phenotypic and ecological factors that influence hemoglobin concentration in free-living birds is scarce. In order to recognize sources of variation in hemoglobin levels of migratory shorebirds, we measured whole-blood hemoglobin concentration in 553 juvenile and 166 adult common snipe Gallinago gallinago during autumn migration through central Poland. Among the intrinsic determinants of hemoglobin concentration in common snipe, we identified traits such as age, wing morphology, developmental stability, nutritional condition, and molt. We found that adult birds had higher hemoglobin concentrations than juveniles. Hemoglobin concentration was not related to body size, but it correlated with wing morphology. In adult males there was also a positive relationship between hemoglobin concentration and developmental stability, measured by fluctuating asymmetry in wing shape. The process of molt was found to affect blood hemoglobin concentration in both juvenile and adult common snipe, as the lowest concentrations were recorded in the initial stages of molt. Finally, we recorded a gradual increase in hemoglobin concentration of juvenile and adult snipe over the course of the autumn migratory season, and this trend was attributed to higher fat loads carried by late migrants. Hemoglobin concentration also correlated with other indices of nutritional state, such as plasma concentrations of proteins. All this clearly indicates that hemoglobin concentration may reflect a wide range of physiological processes, but in spite of this immense variation, it is likely to reliably indicate phenotypic quality of birds.

Hemoglobin concentrations in waders vary with their strategies of migration: A comparative analysis

The aim of this study was to determine whether blood oxygen capacity of waders varies with respect to migration at both inter-specific and individual level. To verify this hypothesis we measured hemoglobin concentration in 875 waders from 14 species during their autumn migration through central Poland. In most of the species we found an increase in the hemoglobin levels along with increasing fat loads during the stopover period, which suggests that individual birds are able to elevate their oxygen-carrying capacity of blood prior to departure on a migratory flight. Positive relationship between hemoglobin concentrations of waders and their fat loads was confirmed at the inter-specific level by the comparative analysis of independent contrasts. Comparative analysis also demonstrated that hemoglobin concentrations were positively related with theoretical flight range and mean refueling rate during stopovers. The results indicate that species traveling according to the strategy of energy-minimization (short-distance migrants, low fat reserves, low refueling rates) have lower blood oxygen capacity in comparison to time-selected species (long-distance migrants, high fat reserves, high refueling rates). It remains uncertain whether high hemoglobin levels in long-distance migrants are a fixed evolutionary trait or a temporal physiological adaptation associated with carrying considerable fat load.

Low Oxygen-Carrying Capacity of Blood May Increase Developmental Instability of Molt in Migrating Waders

ABSTRACT. The degree of asymmetry in feather replacement may be considered a reliable measure of developmental instability of avian molt. Although empirical evidence exists for the fitness consequences of molt asymmetry, the proximate cause of asymmetrical molt remains unknown. We tested for the possibility of a link between asymmetry in feather replacement and hemoglobin concentration of first-year Common Snipe (Gallinago gallinago) during the partial postjuvenile molt. Advancement and symmetry of molt were determined for 637 first-year Common Snipe captured at Jeziorsko reservoir, central Poland, during autumn migration. We found that the probability of asymmetrical molt did not vary with date of capture (W = 1.66, P = 0.20), but Common Snipe with lower hemoglobin concentrations had a higher probability of asymmetrical molt (W = 5.22, P = 0.022). Because Common Snipe molt during migration, high oxygen-carrying capacity of blood is presumably necessary to meet aerobic demands of the tissues during long-distance flights. We suggest that under these conditions, low hemoglobin concentrations may lead to an acute organismal hypoxia causing disruptions in developmental homeostasis, such as asymmetrical feather replacement.

Plumage quality mediates a life-history trade-off in a migratory bird

BackgroundMoult is one of the most costly activities in the annual cycle of birds and most avian species separate moult from other energy-demanding activities, such as migration. To this end, young birds tend to undergo the first post-juvenile moult before the onset of migration, but in some species the time window for the pre-migratory feather replacement is too narrow. We hypothesized that in such species an increased investment in the structural quality of juvenile feathers may allow to retain juvenile plumage throughout the entire migratory period and delay moult until arriving at wintering grounds, thus avoiding a moult-migration overlap.MethodsThe effect of juvenile plumage quality on the occurrence of moult-migration overlap was studied in a migratory shorebird, the common snipe Gallinago gallinago. Ca. 400 of first-year common snipe were captured during their final stage of autumn migration through Central Europe. The quality of juvenile feathers was assessed as the mass-length residuals of retained juvenile rectrices. Condition of migrating birds was assessed with the mass of accumulated fat reserves and whole-blood hemoglobin concentration. Path analysis was used to disentangle complex interrelationships between plumage quality, moult and body condition.ResultsSnipe which grew higher-quality feathers in the pre-fledging period were less likely to initiate moult during migration. Individuals moulting during migration had lower fat loads and hemoglobin concentrations compared to non-moulting birds, suggesting a trade-off in resource allocation, where energetic costs of moult reduced both energy reserves available for migration and resources available for maintenance of high oxygen capacity of blood.ConclusionsThe results of this study indicate that a major life-history trade-off in a migratory bird may be mediated by the quality of juvenile plumage. This is consistent with a silver spoon effect, where early-life investment in feather quality affects future performance of birds during migration period. Our results strongly suggest that the juvenile plumage, although retained for a relatively short period of time, may have profound consequences for individuals’ fitness.

The first case of a major avian type C botulism outbreak in Poland.

SUMMARY Major outbreaks of avian type C botulism have been rarely reported from Central Europe. In this paper, we report the first severe outbreak of avian type C botulism in Poland. In 2011–12, two epizootics caused by Clostridium botulinum took place at Jeziorsko dam reservoir and affected an estimated number of 5500 birds in 2011 and 1600 birds in 2012. In total, 24 species of waterbirds were affected, including mainly waterfowl (37.0%), shorebirds (27.0%), rallids (25.7%), and larids (9.1%). Mallards (Anas platyrhynchos) and coots (Fulica atra) were most commonly represented among all affected species (27.5% and 25.0% of all recorded carcasses, respectively). Laboratory analyses confirmed the presence of type C botulinum toxin in the internal organs of paralyzed birds. This case study from the Jeziorsko dam reservoir demonstrates that this type of shallow-water habitat is especially prone to avian botulism outbreaks in the climatic conditions of Central Europe. RESUMEN Reporte de Caso—Primer caso de un brote severo de botulismo aviar del tipo C en Polonia. Brotes severos de botulismo aviar tipo C se han comunicado raramente en Europa Central. En este trabajo, se presenta el primer brote grave de botulismo aviar tipo C en Polonia. Entre los años 2011 al 2012, dos epizootias causadas por Clostridium botulinum se presentaron en la presa reservorio de Jeziorsko y afectaron a un número estimado de 5,500 aves en el 2011 y a 1,600 aves en el 2012. En total, 24 especies de aves acuáticas se vieron afectadas, principalmente se incluyen aves acuáticas (37.0%), aves costeras (27.0%), rálidos (25.7%) y láridos (9.1%). Ánades reales (Anas platyrhynchos) y fochas comunes (Fulica atra) estuvieron representados con mayor frecuencia entre todas las especies afectadas (27.5% y 25.0% de todas las canales registradas, respectivamente). Los análisis de laboratorio confirmaron la presencia de la toxina botulínica de tipo C en los órganos internos de aves paralizadas. Este estudio de caso de la presa Jeziorsko demuestra que este tipo de hábitat de aguas poco profundas es especialmente propenso a brotes de botulismo aviar en las condiciones climáticas de Europa Central.

Variation in Autumn Migration Strategy in the First-Year Wood Sandpipers Tringa glareola

Abstract. Wood Sandpipers are generally known to follow a time-minimization migration strategy on their autumn passage. We investigated whether the migration strategy adopted by first-year Wood Sandpipers is susceptible to temporal variations. Wood Sandpipers were trapped during the July–September period from 1997 to 2007 at the Jeziorsko reservoir, central Poland. Intra- and inter-seasonal variation in stopover length, refuelling rates, departure fat loads and flight range were investigated. There was a constant decline in the refuelling rates over the course of the migratory season, reaching 0.55 g/day at the end of August. Such low refuelling rates are considered typical of energy-minimizers. Despite showing high refuelling rates at the beginning of the season, first-year Wood Sandpipers left the stopover site with relatively low fuel reserves, resulting in a low potential flight range of about 1200 km, which suggested travelling in small hops — a trait characteristic of energy-minimizers. There was also considerable inter-seasonal variation in the adopted migration strategy. The results suggest that sandpipers caught at the beginning and at the end of the migratory season behaved as energy-minimizers, at least in some aspects of the migration strategy, unlike the intermediate migrants, which adopted a typical time-minimization schedule. These observations indicate that the migration strategies of waders may depend on the environmental conditions encountered en route and are thus likely to exhibit high intra- and inter-seasonal variation.