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Experimental studies have shown that individual wildfowl can shorten or skip moulting if the time between breeding and wintering is short; however, studies in wild birds are scarce. We tracked nine Common Shelducks Tadorna tadorna during the breeding and moulting seasons and determined the flightless time during moulting based on typical movement patterns. We found different movement patterns for two late-breeding females, suggesting that they skipped or shortened the moult of their flight feathers. These results provide a link between previous experimental studies and the situation in wild birds, likely reflecting an individual trade-off between the times allocated to moulting and breeding, respectively.

Fitness can be profoundly influenced by the age at first reproduction (AFR), but to date the AFR–fitness relationship only has been investigated intraspecifically. Here, we investigated the relationship between AFR and average lifetime reproductive success (LRS) across 34 bird species. We assessed differences in the deviation of the Optimal AFR (i.e., the species-specific AFR associated with the highest LRS) from the age at sexual maturity, considering potential effects of life history as well as social and ecological factors. Most individuals adopted the species-specific Optimal AFR and both the mean and Optimal AFR of species correlated positively with life span. Interspecific deviations of the Optimal AFR were associated with indices reflecting a change in LRS or survival as a function of AFR: a delayed AFR was beneficial in species where early AFR was associated with a decrease in subsequent survival or reproductive output. Overall, our results suggest that a delayed onset of reproduction beyond maturity is an optimal strategy explained by a long life span and costs of early reproduction. By providing the first empirical confirmations of key predictions of life-history theory across species, this study contributes to a better understanding of life-history evolution.

This chapter describes the structure of the project and the general methods applied in the study.

This chapter summarizes the main results of the study and recommends measures to avoid collisions of birds of prey at wind turbines.

Red Kites (Milvus milvus) are the second most often reported species in relation to collisions with wind turbines in Germany. Germany houses more than half of the world’s population of Red Kites and, therefore, has a high international responsibility for the protection of this species. The German Federal Ministry of the Environment, Nature Conservation and Nuclear Safety funded a field study to investigate why Red Kites and other birds of prey frequently collide with wind turbines, and which risk mitigation measures are most appropriate. The study took place in the core of the Red Kite global breeding range in Sachsen-Anhalt between 2007 and 2010. Ten breeding adult Red Kites were equipped with radio tags (seven birds) or GPS satellite transmitters (three birds). Each bird was tracked for one or two breeding and non-breeding seasons. Data on flight height and habitat preference were collected by visual observations. The collision risk was modeled in relation to the nest’s proximity to wind turbines. It was found that Red Kites spent most of their time close to their nests. Most (54%) of the fixes were located within a radius of 1000 m around nests. It is important to note that the data did not indicate displacement of Red Kites by wind farms. Red Kites frequently visited wind farms for foraging and spent about 25% of their flight time within the swept heights of rotors of the most common wind turbines present in the study sites. The probability of closely approaching a wind farm significantly decreased with the distance between wind turbines and nests. Furthermore, the collision probability model predicted a sharp decrease of collision risk with increasing distance from the nest. The results clearly indicate that implementing buffer zones around nest sites reduces collision risk.

Evidence for the occurrence of conspecific nest parasitism (CNP) in Pied Avocets Recurvirostra avosetta is presented. Clutches of more than four eggs had obviously been produced by more than one female but were incubated by only one pair each. Minimum estimates for the frequencies of parasitized clutches and parasitic eggs were 3.3% and 1.3% respectively. CNP increased in frequency in colonies with higher nest densities. The frequency of CNP was unaffected by the rate of nest failures early in the season. On average, parasitic eggs were laid earlier in the season than the majority of non-parasitic eggs. Parasitic Avocets usually deposited their eggs during the laying period of host nests. Parasitized nests had significantly longer incubation periods than unparasitized nests. Hatching success in supernormal clutches was insignificantly reduced compared with four-egg clutches. The annual breeding success of individuals with parasitized clutches was considerably (but not significantly) higher than those of non-parasitized individuals. This was probably due to the fact that parasites chose to deposit their eggs in dense colonies whose members had significantly higher breeding success than the individuals in loose colonies. In colonies with a high rate of CNP, the frequency of clutches of more than five eggs increased. These clutches had little chance of survival.

Due to the ‘double-clutch’ mating system found in the arctic-breeding Little Stint Calidris minuta , each parent cares for a clutch and brood alone. The resulting constraint on feeding time, combined with the cold climate and a small body size, may cause energetic bottlenecks. Based on the notion that mass stores in birds serve as an ‘insurance’ for transient periods of negative energy balance, but entail certain costs as well, body mass may vary in relation to climatic conditions and stage of the breeding cycle. We studied body mass in Little Stints in relation to breeding stage and geographical location, during 17 expeditions to 12 sites in the Eurasian Arctic, ranging from north Norway to north-east Taimyr. Body mass was higher during incubation than during chick-rearing. Structural size, as estimated by wing length, increased with latitude. This was probably caused by relatively more females (the larger sex) incubating further north, possibly after leaving a first clutch to be incubated by a male further south. Before and after correction for structural size, body mass was strongly related to latitude during both incubation and chick-rearing. In analogy to a similar geographical pattern in overwintering shorebirds, we interpret the large energy stores of breeding Little Stints as an insurance against periods of cold weather which are a regular feature of arctic summers. Climate data showed that the risk of encountering cold spells lasting several days increases with latitude over the species’ breeding range, and is larger in June than in July. Maintaining these stores is therefore less necessary at southern sites and during the chickrearing period than in the incubation period. When guarding chicks, feeding time is less constrained than during incubation, temperatures tend to be higher than in the incubation period, reducing energy expenditure, and the availability of insect prey reaches a seasonal maximum. However, the alternative interpretation that the chick-tending period is more energetically stressful than the incubation period, resulting in a negative energy balance for the parent, could not be rejected on the present evidence. The way in which energy stores are regulated in birds is often interpreted to be the result of a trade-off between the risk of starvation and certain costs

Amateure spielen in der wissenschaftlichen Ornithologie seit langer Zeit eine wichtige Rolle. In diesem Artikel, der auf einem vom Dachverband Deutscher Avifaunisten (DDA) auf der Jahrestagung 2000 der DO-G in Leipzig veranstalteten Symposium basiert, wird die Bedeutung von Amateur-Ornithologen fur die ornithologische Grundlagenforschung anhand einiger Beispiele aufgezeigt. Die Beitrage von Amateuren reichen von Gelegenheitsbeobachtungen — hierzu werden Ziele und Qualitatskriterien fur avifaunistische Jahresberichte vorgeschlagen — bis zu umfassenden populationsbiologischen Studien. Probleme bei der wissenschaftlichen Arbeit von Amateuren — oft die Veroffentlichung der bereits gesammelten Daten betreffend — werden genannt und Losungsmoglichkeiten angegeben. Ornithologische Vereinigungen, Schriftleitungen von Zeitschriften, Bibliotheken und die Vogelwarten leisten wichtige Beitrage zur Unterstutzung der Arbeit von Amateuren. Die Autoren laden zu einem Dialog uber weitere Fordermoglichkeiten ein.

In many colonial bird species there is considerable intraspecific variation in colony size and inter-nest distance (colony density). Possible causes of this variation and its effects on hatching success (survival of eggs) and breeding success (probability of a pair raising chicks) were studied in 48 Avocet Recurvirostra avosetta colonies in Schleswig-Holstein (Germany) between 1991 and 1996. Colony density was influenced by time of year and habitat (categories: island or mainland, close to or far from feeding grounds). Colonies on islands had the highest densities. When all available space at a colony site was used, colonies became very dense (mean nearest-neighbour nest distance less than 1 m). Colony size (number of clutches) was influenced by time of year, but not by habitat. Hatching success was low in high density colonies and in very low density ‘colonies’ (single nests) and high over a broad range of intermediate nest densities. The low success rate of single nests was caused by a very high predation rate, whereas the low success rate in very dense colonies was caused by a high rate of nest abandonment. Nest abandonment in very dense colonies was associated with a high level of aggressiveness among Avocets during the egg-laying period. Due to territorial behaviour, Avocets seemed to be expelled from the densest breeding sites. In very dense colonies, high frequencies of clutches of unusual size occurred due to conspecific nest parasitism. The number of Avocets taking part in attacks on potential egg predators was small and (in colonies of more than one clutch) depended neither on colony size nor on colony density. Despite a low hatching success in very dense colonies, individuals breeding in the densest colonies had significantly better chances of raising chicks than Avocets breeding in less dense colonies. Coloniality seemed to be obligatory for Avocets in order to ensure hatching success. The size and density of colonies seemed to be associated with the availability of suitable nesting habitats (islands).

Time-activity budgets of birds are known to be affected by many different factors. The aim of this study is to explain the intra-specific variation of activity patterns (in particular foraging activity) of one particular wader, the Avocet. Sixty-seven series of scan observations of 12 h to 12.5 h length were made at several sites on the flyway of the northwest European population and at various stages in the species’ annual cycle. In estuarine habitats the activity pattern was mainly influenced by the tide. As soon as the conditions allowed (neap tides) Avocets abandoned the tidal rhythm. No time of day effects on activity patterns could be detected. Activity patterns by day and at night were essentially the same, except during very dark nights (owing to artificial illumination at some of the study sites such nights were a rare event), when foraging activity was reduced. The breeding season induced considerable changes of the activity patterns, including a reduction of foraging time to less than 20% of the budget at the end of the breeding season. Outside the breeding season, activity patterns were mainly influenced by the type of food (fish: reduced foraging time, Chironomid larvae: prolonged foraging time), by temperature (increase of foraging time with decreasing temperature), by windspeed (reduction of foraging time at wind speeds above 10 m/s) and by the darkness of the previous night (compensatory feeding after dark nights).

Growth of mass and linear body dimensions (bill, tarsus and wing length) was studied in the Little Stint Calidris minuta at several locations on the Taimyr Peninsula, Siberia (73°–76°N) in 1983–94. Little Stints fledged at near-adult body mass, at 15 days of age. Growth followed an S-shaped pattern which was best described mathematically by a logistic curve. Curves of this type showed that growth was similar between study sites and years, although there were differences in mass development during the first days after hatching, perhaps related to weather conditions. When the logistic growth curve was used, K L (the standard measure of maximum growth rate) was 0.285. Conversion of this parameter to another S-shaped curve, the Gompertz curve which has been widely used to describe wader chick growth, yields K G = 0.194. This is higher than predicted from an allometric relationship based on 15 other precocial wader species, and might be related to the Little Stint's high latitude breeding range.

Der Energieumsatz sechs brutender Sabelschnabler wurde mit doppelt-markiertem Wasser in einer Brutkolonie am Rande des Nordfriesischen Wattenmeeres im Jahre 1994 untersucht. Die Sabelschnabler wiesen eine Energieumsatzrate von durchschnittlich 5,04 W (Standardabweichung (±0,33 W) auf. Dieser Wert betragt lediglich das 2,3fache des aufgrund allometrischer Beziehungen (Kersten &Piersma 1987) berechneten Basalstoffwechsels. Der mittlere Wassergehalt der Versuchsvogel betrug 66,8 % (SD±2,4 %). Die Wasseraufnahme streute sehr stark und zeigte mit durchschnittlich 178 ml/Tag (SD±48 ml) sehr hohe Werte. Sabelschnabler mit niedrigem Gewicht (Weibchen) hatten hohere Wasseraufnahmen und Wassergehalte als Vogel mit hohem Gewicht (Mannchen). Ein Vergleich mit anderen Arten last vermuten, das die Hohe des Energieumsatzes brutender Watvogel sehr stark durch die geographische Lage ihres Brutgebietes bzw. die damit zusammenhangenden energetischen Kosten fur die Thermoregulation beinflust wird.

Shelducks, Oystercatchers, Grey Plovers, Knots, Dunlins, Bar-tailed Godwits, Curlews, Spotted Redshanks, Redshanks, and Greenshanks showed a tidal rhythm of time-activity budgets on the Wadden Sea coast during the non-breeding season. Ringed Plovers and Ruffs did not react to the tidal rhythm. Night-time feeding could be observed in most species. Differences in the time-activity budgets of the species were related to body mass and size of food particles. Inter-site comparisons revealed that technical constructions for coastal protection influenced the activity rhythms of the birds.

Gene flow promotes genetic homogeneity of species in time and space. Gene flow can be modulated by sex-biased dispersal that links population genetics to mating systems. We investigated the phylogeography of the widely distributed Kentish plover Charadrius alexandrinus. This small shorebird has a large breeding range spanning from Western Europe to Japan and exhibits an unusually flexible mating system with high female breeding dispersal. We analysed genetic structure and gene flow using a 427-bp fragment of the mitochondrial (mtDNA) control region, 21 autosomal microsatellite markers and a Z microsatellite marker in 397 unrelated individuals from 21 locations. We found no structure or isolation-by-distance over the continental range. However, island populations had low genetic diversity and were moderately differentiated from mainland locations. Genetic differentiation based on autosomal markers was positively correlated with distance between mainland and each island. Comparisons of uniparentally and biparentally inherited markers were consistent with female-biased gene flow. Maternally inherited mtDNA was less structured, whereas the Z-chromosomal marker was more structured than autosomal microsatellites. Adult males were more related than females within genetic clusters. Taken together, our results suggest a prominent role for polyandrous females in maintaining genetic homogeneity across large geographic distances. © 2012 Blackwell Publishing Ltd.

Besides the well estabished countings of breeding birds, the monitoring of breeding success in a selection of sites seems to be the most promissing method for improving the knowledge on the population processes of Avocets. Measuring the breeding success does not take much time and does usually not involve any disturbance to the birds. Measuring mortality rates can only be done by ringing, which involves catching and hence disturbing the birds. Colour-ringing of a relatively small number of adults and chicks per annum will be sufficient to notice whether drastic changes in mortality and recruitment rates occur, provided enough working-time can be devoted to checking colour rings in and before the breeding season. Studies of turnover rates at resting sites seem to be impractical at present. The main emphasis in winter should be to fill the gaps in knowledge at the southern end of the flyway.

Egg size variation in the Pied Avocet Recurvirostra avosetta was studied at seven breeding colonies on the North Sea coast of Schleswig-Holstein in Germany in 1999. A total of 999 eggs from 283 clutches were measured during the whole breeding period. Egg size was very variable and most variance was due to differences between clutches. Eggs within a clutch were relatively uniform in size. Size differences due to laying order could not be detected. Egg size did not differ between four-egg and three-egg clutches. Egg size, clutch size and the length of the incubation period decreased as the season progressed. Egg size and chick size at hatching were positively correlated. Received 31 July 2000, accepted 20 November 2000.

In intertidal habitats, Dunlins (Calidris alpina), like other shorebirds, spend most of the time around high tide roosting on the ground. Occasionally, however, Dunlins remain airborne at high tide and fly over the sea rather than sitting in saltmarshes. Here I describe over-sea flocking in Dunlins on the German Wadden Sea coast and try to analyze factors associated with this behavior. Over-sea flocking occurred at only one site, the Jadebusen, where it was recorded on 5 out of 35 occasions. Over-sea flocking was associated with the absence of safe (poorly or non-vegetated) roosting sites, the presence of tall trees close to the site and the presence of raptors, suggesting that over-sea flocking is a reaction of Dunlins to high risks of surprise attacks by raptors. Received 20 March 2000, accepted 8 May 2000.

An analysis of wing length data of wintering Meadow Pipits has shown that the population wintering in the north of the range consists mainly of males and in the major (southern) part of the wintering range the sex ratio is more or less even. Meadow Pipits wintering in the north showed a midwinter weight peak, whilst those wintering in the south did not. Mean winter weights were correlated with mean January temperatures of wintering sites.

Beobachtungen zur Brutbiologie einer zu einem Teil farbig beringten Population des Wiesenpiepers in Nordwestdeutschland (1975–1981) ergaben

On 23.7. 1977a colour-ringed first-year Meadow Pipit was observed feeding nestlings of a third brood of more than two-year-old parent Meadow Pipits for at least three times. The first-year Meadow Pipit had hatched about 1.5. 1977 in a nest about 3100m off the place where it helped feeding.