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Monday, 22 June 2015

Journal of Ornithology - Volume 156, Issue 3, July 2015

Journal of Ornithology

Volume 156, Issue 3, July 2015


Effects of breeding habitat and field margins on the reproductive performance of Skylarks (Alauda arvensis) on intensive farmland
M. W. Kuiper 1  , H. J. Ottens 2, 3, J. van Ruijven 1, B. J. Koks 2, G. R. de Snoo 4 and F. Berendse 1
(1)Nature Conservation and Plant Ecology Group, Wageningen University, PO Box 47, 6700 AA Wageningen, The Netherlands
(2)Dutch Montagu’s Harrier Foundation, PO Box 46, 9679 ZG Scheemda, The Netherlands
(3)SOVON Dutch Centre for Field Ornithology, PO Box 6521, 6503 GA Nijmegen, The Netherlands
(4)Institute of Environmental Sciences, Leiden University, PO Box 9518, 2300 RA Leiden, The Netherlands

Field margin management is a common measure employed in Europe to support farmland bird populations. In this study we found and analysed 237 nests of the Skylark Alauda arvensis in the Netherlands over a period of 6 years to determine the effects of arable field margins and breeding crop on nest-level reproductive success. Additionally, the effect of field margins on predation was investigated and food availability in crops and field margins was compared. Neither clutch size, nest survival nor nestling body weight were improved by field margin availability, irrespective of the breeding crop used. However, the choice of breeding crop had important effects. Nestling weight was significantly lower in cereals than in grassland and lucerne, corresponding with the low prey densities present in cereals. Nest survival was lowest in grassland due to frequent silage cutting. Predation rates were highest in cereals but were not affected by field margin proximity. The highest reproductive success was achieved in lucerne, which was mown twice a year and retained a suitable height for breeding throughout the breeding season. We conclude that field margins are not sufficient to maintain a Skylark population in this intensively farmed area. The presumably more subtle effects of increased food availability cannot compensate for the high nest failure rates resulting from agricultural operations and predation. In this and similar areas, the provisioning of safe nesting habitat throughout the breeding season is essential to improve breeding performance. Our research suggests that this can be achieved by reducing the frequency of silage cutting on grassland and by increasing the surface area of lucerne.

Vegetation structure and inter-individual distance affect intake rate and foraging efficiency in a granivorous forager, the Eurasian Skylark Alauda arvensis
Thibaut Powolny 1, 2  , Cyril Eraud 1, Jean-Daniel Masson 2, and Vincent Bretagnolle 2
(1)Office National de la Chasse et de la Faune Sauvage (ONCFS), Carrefour de la Canauderie, 79360 Villiers en Bois, France
(2)Centre d’Etudes Biologiques de Chizé, Centre National de le Recherche Scientifique (CNRS), 79360 Villiers en Bois, France


Animals gain benefits from group living through increased probability of predator detection, dilution of individual risk and confusion of predators during attack. A further benefit involves larger groups in which individuals may further decrease the amount of time spent being vigilant, while maintaining the probability of predator detection by allocation of this extra time to foraging activities. Living in groups or flocks, however, also incurs costs, e.g., by increasing inter-group competition, with negative impacts on intake rates. Our aim was to investigate the trade-offs between the costs of competition and the benefits of group living in contrasted habitats. For prey species that rely on sight for detecting predators, vegetation structure may influence the perceived predation risk. Hence, we experimentally examined the combined effects of vegetation height and inter-individual distance on foraging time, intake rate and foraging efficiency in a granivorous species, the Eurasian Skylark (Alauda arvensis). Our experimental results based on temporally captive birds indicate that time devoted to foraging decreased with increasing inter-individual distance, but was unrelated to cover height. Conversely, increasing both vegetation height and distance with other group members did translate into a foraging disadvantage, i.e. reduced intake rate as well as foraging efficiency. Overall, our results show that both vegetation structure and inter-individual distances modify patch profitability, and therefore provide another example of how flock dynamics can influence the trade-off between vigilance and foraging.

Habitat management varying in space and time: the effects of grazing and fire management on marshland birds
Thomas Oliver Mérő 1  , László Lontay 2   and Szabolcs Lengye l, 3  
(1)Nature Protection and Study Society - NATURA, Milana Rakića 20, 25000 Sombor, Serbia
(2)Aggtelek National Park Directorate, Tengerszem oldal 1, Jósvafő, 3758, Hungary
(3)Department of Tisza River Research, Centre for Ecological Research, Danube Research Institute, Hungarian Academy of Sciences, Bem tér 18/c, Debrecen, 4026, Hungary


Freshwater wetlands and marshes with extensive reed beds are important hotspots of biological diversity, but in the absence of proper management, they are subject to biotic homogenisation. We assessed the impact of spatiotemporally variable management by cattle grazing (for 4 years) and late-summer burning (1 or 3 years before the study) on both songbirds and non-passerines in a previously homogeneous reed bed. We surveyed birds using a combination of line transects and point counts in a quasi-experimental design comprising six treatment levels. Management increased both the diversity of marsh habitats and the diversity of bird species. The species richness and abundance of non-passerines (ducks and geese, wading birds, gulls and terns, rails, coots and grebes) was higher in recently burned than in unburned or old-burned patches. Species richness of farmland songbirds was higher in grazed than in non-grazed patches, and the richness and abundance of reed songbirds was higher in unburned, old-burned, and grazed patches than in recently burned patches. Total Shannon diversity and evenness of birds was lowest in areas with the most intensive treatment (patches grazed and twice-burned), whereas Simpson diversity was highest in these areas. Non-managed patches had fewer species and individuals of all groups except reed songbirds. The proportion of old reed was low in recently burned and grazed patches, and was similarly high in all other treatment areas. No other property of reed stands was influenced by management, and both the allocation and the effect of management were independent of water level. Spatiotemporally variable management by cattle grazing and late-summer burning may thus simultaneously benefit several groups of birds. The effect of burning alone disappeared in 3 years, even in the presence of grazing; thus it must be repeated every 2–3 years. We conclude that both management actions are necessary to establish and maintain highly diverse habitats for marshland bird communities.

Bluethroats Luscinia svecica namnetum offset landscape constraints by expanding their home range
Laurent Godet 1  , Matthieu Marquet 2, Marie-Christine Eybert 3, Elisa Grégoire 1, 2, Sarah Monnet 1, 2 and Jérôme Fournier 4, 5
(1) Le laboratoire LETG-Nantes-Géolittomer (CNRS-UMR 6554), Nantes University, BP 81227, 44312 Nantes Cedex 03, France
(2)Parc Naturel Régional de Brière, 214, Rue du chef de l’île, Ile de Fédrun, 44720 St-Joachim, France
(3)Joint Research Unit ECOBIO (CNRS-UMR 6553), University of Rennes 1, Campus de Beaulieu, Bât. 25, Avenue du Général Leclerc, 35042 Rennes Cedex, France
(4)Le Laboratoire de BOREA (CNRS-UMR 7208), French National Museum of Natural History, 75231 Paris Cedex 05, France
(5)CRBPO (Research Center for the Bird Banding Populations), French National Museum of Natural History, 75005 Paris, France


The highly fragmented landscape structures of coastal salinas are known to result in decreased terrestrial bird abundance, species richness and diversity but to promote original assemblages dominated by specialist species, such as the Bluethroat Luscinia svecica namnetum. This species is mainly found at the core of these salinas, where the landscape characteristics are a priori the most hostile for terrestrial birds. The aim of this study was to test whether individuals of a specialized species like the Bluethroat may offset such landscape constraints by expanding their home ranges. We therefore radio-tracked 21 males in 2013 and 2014 in the salinas of the Marais du Mès (Parc Naturel Régional de Brière, Western France). The data of the 18 best-monitored males were used to carry out a hierarchical partitioning of variance to test the relative influence of landscape characteristics, individual characteristics and distance to other males on their home-range sizes. We found that landscape characteristics were the factors that best explained home range sizes. Home-range sizes were significantly smaller in diversified landscapes composed of tidal creeks and salt-marsh patches and tended to be larger in landscapes dominated by the aquatic matrix consisting of water ponds. The results of this study demonstrate that although a few bird species are able to select a priori hostile landscapes, they can offset such constraints by expanding their home-range size.

Factors affecting growth parameters of White Stork nestlings in eastern Algeria
Naouel Benharzallah 1, Abdelkrim Si Bachir 2, Fayçal Taleb 1 and Christophe Barbraud 3  
(1)Department of Natural and Life Sciences, Faculty of Exact Sciences and Natural and Life Sciences, University Mohamed Khider of Biskra, 07000 Biskra, Algeria
(2)Department of Natural and Life Sciences, Faculty of Sciences, University of El Hadj Lakhdar, 05000 Batna, Algeria
(3)Centre d’Etudes Biologiques de Chizé, UMR7372 CNRS/Univ. La Rochelle, 79360 Villiers-En-Bois, France


Survival and reproduction of young can be affected by growth parameters. It is thus important to estimate intraspecific growth rate variability and environmental factors affecting growth to better understand the dynamics of populations and the potential impacts of environmental changes. Growth parameters of White Stork (Ciconia ciconia) nestlings were estimated in eastern Algeria, in the southern part of the species’ range. A total of 2,756 measurements of 65 nestlings from 18 nests were taken for body mass, and tarsus, wing and bill lengths. Individual growth data were used to investigate the effects of nest occupation date, laying and hatching dates, clutch size, number of hatchlings, productivity, hatching order, and brood reduction on nestling growth patterns. Body mass and bill length growth rates were lower in the studied population than in a more northerly White Stork population. This supports the hypothesis of a geographic variation in intraspecific growth parameters. Chicks from nests occupied early reached higher asymptotic body mass but tended to grow more slowly. However, chicks from late arriving birds compensated for the difference in body mass and wing length by higher growth rates. Wing length was significantly affected by asynchrony and hatching order. Last hatched chicks had larger asymptotic wing lengths, lower wing growth rates and longer growth periods. Wings of nestlings from highly asynchronous broods grew faster but took more time to attain the inflection point. Brood reduction had a negative effect on nestling bill length at hatching. Chicks from nests with little brood reduction had a longer bill at hatching than nestlings from nests with high brood reduction.

Natural nest-sites of Great Tits (Parus major) in a primeval temperate forest (Białowieża National Park, Poland)
Marta Maziarz 1  , Tomasz Wesołowski 1, Grzegorz Hebda 2 and Marta Cholewa 1
(1)Laboratory of Forest Biology, Wrocław University, Sienkiewicza 21, 50 335 Wrocław, Poland
(2)Department of Biosystematics, Opole University, Oleska 22, 45 052 Opole, Poland


Knowledge of the breeding ecology of the Great Tit Parus major is vast, but almost exclusively concerns birds using nest-boxes. Information on birds nesting in natural conditions is scant. Here, we present the results of the first thorough study on natural nest-sites of the Great Tit. The data, including descriptions of nest-cavity location and dimensions, were collected during 39 breeding seasons in the primeval forest of Białowieża National Park (BNP), Poland. With an excess of available tree-cavities providing a diverse choice of nesting options, Great Tits nested mainly in non-excavated, very deep and spacious cavities with elongated, narrow openings, placed at intermediate heights in living tree trunks. Different sets of tree species were used in different habitats. The pattern of nest-site utilisation by Great Tits in BNP overlapped with that recorded in other areas, but showed niche separation from other non-excavating hole-breeders in BNP. This indicates that Great Tits have core nest-site preferences, which have probably evolved in response to selective forces such as, e.g., risk of predation, flooding, sufficient nest illumination and/or efficient air ventilation.

Flexibility in foraging strategies of Brown Skuas in response to local and seasonal dietary constraints
Ana P. B. Carneiro 1, 2  , Andrea Manica 1, Wayne Z. Trivelpiece 3 and Richard A. Phillips 2
(1)Department of Zoology, University of Cambridge, Downing Street, Cambridge, CB2 3EJ, UK
(2)British Antarctic Survey, Natural Environment Research Council, Madingley Road, High Cross, Cambridge, CB3 0ET, UK
(3)Antarctic Ecosystem Research Division, Southwest Fisheries Science Center, National Oceanic and Atmospheric Administration, La Jolla, CA 92037, USA


The Brown Skua Stercorarius antarcticus lonnbergi is an opportunistic species that displays a high degree of flexibility in foraging tactics. We deployed global positioning system (GPS) and immersion (activity) loggers on breeding Brown Skuas of known sex, body size and condition at Admiralty Bay, King George Island with the aim to examine the impacts of spatial and seasonal fluctuations in prey availability on movement and foraging behavior. We also investigated whether reversed sexual size dimorphism (females larger than males) in this species leads to differences between sexes in foraging behavior and whether this or other factors contribute to variation in breeding success. Analysis of the GPS data highlighted the high degree of plasticity in foraging behavior among individuals. Although most Brown Skuas were flexible in their feeding tactics, this was not enough to ensure a successful breeding season, as few pairs fledged chicks. During early chick rearing, Brown Skuas spent most of their time on land, feeding almost exclusively on penguin chicks. By late chick rearing, when the availability of penguins had diminished, Brown Skuas supplemented the food obtained on land by traveling to the ocean. All foraging trips to sea occurred during daylight, mostly during the early morning. Despite marked sexual size dimorphism, we failed to find any difference in foraging tactics between males and females. Furthermore, although laying date affected the number of chicks hatched (earlier pairs were more successful), no relationship was found between breeding success and male or female body size, condition or degree of dimorphism within pairs.

Analyses of Black Grouse (Tetrao tetrix) faeces with infrared spectroscopic methods
Sebastian Url 1, Manfred Schwanninger 2 and Ursula Nopp-Mayr 1  
(1)Department of Integrative Biology and Biodiversity Research, Institute of Wildlife Biology and Game Management, University of Natural Resources and Life Sciences, Vienna, Gregor Mendel Straße 33, A 1180, Vienna, Austria
(2)Department of Chemistry, Institute of Wood Science and Technology, University of Natural Resources and Life Sciences, Vienna, Muthgasse 18 A 1190, Vienna, Austria

In recent years, the Fourier transform infrared spectroscopy (FT-IR) was used to assess the diet, digestibility or nutritional values of food items of ruminants. However, it has never been used to analyse the diet of grouse species. Commonly used methods have so far been direct observations of birds and microscopical analyses of droppings. The sample preparation and comparison of microscopical analyses is a highly time-consuming procedure. The comparison is based on morphological structures of epidermal cells, like the shape of cells, stomata or trichomes. In contrast, the sample preparation for the FT-IR and the subsequent measuring is simple and quickly done. We investigated the diet of Black Grouse (Tetrao tetrix L.) in two study areas with infrared spectroscopic methods comparing summer and winter droppings’ content with plant reference material. The study areas are located in the provinces of Salzburg and Upper Austria, Austria. In our study, samples were measured in the mid- and near-infrared range. We tried to determine the dominating content of faecal samples at species, genera or family level or at least to assign samples to one of four main plants groups (i.e. woody plants, heathers, herbs and grasses). Our results showed a dominance of Larix decidua within the group of woody plants in both areas and, within the group of heathers, a dominance of Calluna vulgaris and Rhododendron hirsutum in one study area. Partially, our results are in marked contrast to other studies conducted in the Alps, as Vaccinium myrtillus was not detected in the samples. For further methodological studies, faecal sampling over larger areas, larger samples of plant reference material (including seeds and other parts of plants at different seasons), taking more samples per dropping and synchronous comparisons of microscopic analyses as well as FT-IR spectroscopy, are recommended.

Disentangling the drivers of change in Common Teal migration phenology over 50 years: land use vs. climate change effects
Matthieu Guillemain 1  , Claire A. Pernollet 1, 2, Grégoire Massez 3, François Cavallo 1, Géraldine Simon 2 and Jocelyn Champagnon 2, 4
(1)Office National de la Chasse et de la Faune Sauvage, CNERA Avifaune Migratrice, La Tour du Valat, Le Sambuc, 13200 Arles, France
(2)Centre de Recherche de la Tour du Valat, 13200 Arles, France
(3)Les Marais du Vigueirat, Mas Thibert, 13200 Arles, France
(4)Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, A.P. 70-275, 04510 México D.F., Mexico


A large body of research has accumulated on the impact of climate change on wildlife movements and distributions, especially for migratory birds. We used large ringing datasets for the Common Teal (Anas crecca) from the Camargue, southern France, to compare historic (from 1956–1975) spatiotemporal patterns of teal recovery with those seen in modern (2002–2012) years and assess whether the migration phenology of these ringed birds and their use of the Camargue as winter quarters has changed. Because teal are short-distance migrants (i.e., they breed in northern Europe and winter north of the Sahara), they would be predicted to delay their autumn migration in response to climate change. Conversely, ring recoveries showed that teal are now arriving much earlier: a stable 80 % of the recoveries were made locally in the Camargue each week between mid-November and late January in the modern dataset, whereas this percentage was only 53 % on average in the older data, and the proportion of recoveries made locally in the Camargue gradually increased through the autumn and winter until late January. This suggests that Camargue habitats have changed markedly and become more attractive to teal compared to other potential wintering areas, consistent with known changes in local habitat management practices and improvements in the body condition of the birds. Despite the fact that global climate change will likely be one of the main drivers of wildlife distribution over the long term and at large spatial scales, local habitat management should not be overlooked, as it can increase habitat attractivity to migratory birds.

Migration distance and breeding latitude correlate with the scheduling of pre-alternate body moult: a comparison among migratory waders
Pedro M. Lourenço 1, 2   and Theunis Piersma 2, 3
(1)Centro de Estudos do Ambiente e do Mar (CESAM)/Museu Nacional de História Natural e da Ciência, Universidade de Lisboa, Rua da Escola Politécnica 58, 1250-102 Lisbon, Portugal
(2)Animal Ecology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, PO Box 11103, 9700 CC Groningen, The Netherlands
(3)Department of Marine Ecology, NIOZ Royal Netherlands Institute for Sea Research, PO Box 59, 1790 AB Den Burg, Texel, The Netherlands

Moult is an important maintenance activity that should be carefully timed within the annual cycle. Many birds perform a pre-alternate moult of body feathers some time prior to the breeding season. In migrants, the timing of the pre-alternate moult coincides with the migration from wintering to breeding areas. In this study, we used visual plumage scores collected on the Continental Black-tailed Godwit Limosa limosa limosa in Portugal and The Netherlands to establish that the pre-alternate body moult of these birds during the northward migration between West Africa and The Netherlands takes place only in staging areas in the Iberian peninsula from late January to late February. A comparison of the moult strategy of these godwits with that of 20 other migratory wader populations (13 species) revealed that the former had a rather uncommon moult schedule which was more characteristic of populations with rather short migrations that breed at lower latitudes. We argue that this unusual moult schedule can be explained by a combination of ecological opportunity and proximate and ultimate trade-offs (hormonal incompatibly and maximization of plumage quality vs. time spent on migration, respectively).

Evaluation of aerodynamic parameters from infrared laser tracking of free-gliding white storks
Heinrich Eder 1  , Wolfgang Fiedler 1, 2   and Markus Neuhäuser 3  
(1)Max Planck Institute for Ornithology, Am Obstberg 1, 78315 Radolfzell, Germany
(2)University of Konstanz, Universitaetsstrasse 10, 78457 Konstanz, Germany
(3)Fachbereich Mathematik und Technik, RheinAhrCampus der Hochschule Koblenz, Joseph-Rovan-Allee 2, 53424 Remagen, Germany

Free-flight paths of White Storks (Ciconia ciconia L. 1758) were tracked using a modified laser rangefinder system (Vector IV) based on a 1550-nm diode laser. Field measurements were taken of two flocks comprising approximately 100 adult storks in all. Tracking data allowed mathematical reconstruction of their spatial trajectories using a ground-mounted GPS-based system. Atmospheric influences were accounted for by performing regular observations of ground wind speed and temperature and evaluating recorded trajectories with respect to local disturbances. A model was created by splitting the speed polar into three subspeed polars based on typical wing configurations: “soaring” (V = 7.5–10 m/s), “gliding” (V = 10–14 m/s), and “fast flight” (V = 14–19 m/s). Subspeed polars for a reference stork were derived from 60 measured data couples of sinking speed and forward speed. Multiple regression analysis was used to determine both the induced and noninduced proportionality coefficients. Morphometric data, such as wing span, wing area, and aspect ratio, were collected from 58 photogrammetric examinations. PC-connected outdoor scales provided the body masses of 36 storks from the investigated flocks. Wing loading and aspect ratio vs. forward speed were evaluated to estimate the induced drag factor k. For lift coefficients (C L) of 1.2–1.6, characterizing the range for a fully open primary cascade, k lies between 0.70 and 0.96 at a confidence level of 95 %. Our findings show agreement with the theoretically predicted k values for cascaded wing tips.

How to hatch from the Common Cuckoo (Cuculus canorus) egg: implications of strong eggshells for the hatching muscle (musculus complexus)
Marcel Honza 1  , Kateřina Feikusová 1, Petr Procházka 1   and Jaroslav Picman 2
(1)Institute of Vertebrate Biology, Academy of Sciences of the Czech Republic, Květná 8, 60365 Brno, Czech Republic
(2)Department of Biology, University of Ottawa, Ottawa, ON, Canada


One of the most obvious adaptations to the brood parasitic mode of reproduction is the formation of eggs with unusually strong shells, which apparently reduce chances of egg breakage during laying and puncture ejection attempts of parasitic eggs by the hosts. We tested a hypothesis that strong eggshells of the Common Cuckoo, Cuculus canorus, may have also led to a stronger hatching muscle, musculus complexus. First, the Cuckoo hatching muscle had a higher density of fibers than that of the similarly sized Great Reed Warbler Acrocephalus arundinaceus chicks; and second, the cross-sectional area of fibers of the hatching muscle was smaller in the Cuckoo than in the Great Reed Warbler. We propose that the increased density of muscle fibers in the Cuckoo facilitates hatching out of structurally strong eggshells because chicks possessing this trait should be able to exert greater pressure on the shell during the hatching process. Our results are consistent with the hypothesis that the higher density of fibers in the musculus complexus represents another adaptation facilitating hatching from unusually strong parasitic eggs that has presumably evolved during coevolution involving the Cuckoo and its hosts.

Roles of phenotypic and genetic characteristics in the social mating pattern of Silver-throated Tits (Aegithalos glaucogularis)
Jianqiang Li 1, 2, 3  , Lei Lv 2, Pengcheng Wang 2, Zhengwang Zhang 2 and Yong Wang 2, 3
(1)College of Nature Conservation, Beijing Forestry University, Beijing, 100083, China
(2)Ministry of Education Key Laboratory for Biodiversity Sciences and Ecological Engineering, College of Life Sciences, Beijing Normal University, Beijing, 100875, China
(3)Department of Biological and Environmental Sciences, College of Agriculture, Life, and Natural Sciences, Alabama A&M University, Normal, AL 35762, USA


Choice of mating partners may affect fitness. Both phenotypic and genetic traits have been shown to play roles in the mating processes of animals. We investigated the roles of phenotypic and genetic characteristics in the patterns of social mating in the Silver-throated Tit (Aegithalos glaucogularis), a sexually monochromatic species that exhibits sexual size dimorphism, rarely sings, does not occupy territories, and has a relative low level of extrapair paternity. To explore the role of phenotype traits, we tested for assortative mating based on the sizes of seven morphological traits. To explore the role of genetic traits, we tested for assortative mating with respect to genetic heterozygosity (the heterozygous mate hypothesis) and whether birds mated with genetically dissimilar individuals (the compatible mate hypothesis). We found significant correlations between paired individuals for bill length and body length, indicating possible assortative mating based on these two traits. In contrast, genetic heterozygosity was not correlated between paired individuals, and the mean relatedness of the mates was not significantly different from that of randomly mated individuals, which do not support the idea that Silver-throated Tits assortatively mate with heterozygous individuals or choose genetically dissimilar mates. Also, individual heterozygosity was not reflected in the measured morphological traits, as no correlation was detected. Neither the individual heterozygosity nor the relatedness between mates was correlated with reproductive performance measures, including clutch size, brood size, and number of fledglings. However, we found that clutch size increased with female body length, which could explain the benefit to males of mating with larger females. Taken together, while our current data failed to provide evidence for an effect of genetic characteristics on the social mating pattern of Silver-throated Tits, the results suggest that phenotypic traits are likely associated with their mating pattern.

Intra-specific plasticity in parental investment in a long-lived single-prey loader
Eric W. M. Stienen1  , Allix Brenninkmeijer2   and Wouter Courtens1
(1)Research Institute for Nature and Forest, Kliniekstraat 25, 1070 Brussels, Belgium
(2)Altenburg and Wymenga bv, Suderwei 2, 9269TZ Feanwâlden, The Netherlands


Seabirds exhibit considerable behavioural flexibility in foraging investment in order to meet the nutritional needs of their chicks during variable environmental conditions. Although regulation of offspring provisioning is generally thought to be related to species-specific constraints imposed by central place foraging, some studies suggest different responses within the same species linked to local differences in foraging conditions. Under adverse conditions, seabirds are expected to be less flexible because they must secure their own survival chances first before investing in current reproduction. Short-ranging single-prey loaders are expected to show large intra-specific variation in time spent on foraging because their mode of foraging is energetically expensive, and because they face restricted possibilities to increase the numerical prey input to the colony compared to multiple prey loaders. In this study, we examined if and how the single-prey loading Sandwich Tern Thalasseus sandvicensis varies colony attendance based on the nutritional status of their chick as well as parental body condition in two study colonies. The proportion of time that a chick was left unattended at the colony negatively correlated with chick body condition, suggesting that the parents tried to counterbalance poor feeding conditions by investing more time in foraging. Energy transport rates to the chicks (corrected for time spent away from the colony) and body condition of the chicks were similar in both colonies. However, at Zeebrugge, where adults were in poor body condition, parental non-attendance was much lower than on Griend, even when chicks were in poor condition. Still, our results suggest that parental nest non-attendance in Sandwich Terns is merely a corrective response to food loss to kleptoparasitic gulls in order to meet the nutritional status of the chick, although an effect of adult body condition could not be excluded.

To fledge or not to fledge: factors influencing the number of eggs and the eggs-to-fledglings rate in White Storks Ciconia ciconia in an agricultural environment
Ute Eggers 1, 2  , Michael Arens 3, Mario Firla 4 and Dieter Wallschläger 1
(1)Eco-Ethology, University of Potsdam, Maulbeerallee 2a, 14469 Potsdam, Germany
(2)Plant Ecology and Nature Conservation, University of Potsdam, Maulbeerallee 2, 14469 Potsdam, Germany
(3)White Stork Carer, Rural District Salzwedel (Saxony-Anhalt), Vienau, Germany
(4)White Stork Carer, Rural District Genthin (Saxony-Anhalt), Ferchland, Germany


Numerous studies have explored the relationship between environmental factors and White Stork Ciconia ciconia reproduction, mainly expressing breeding success as the number of fledglings. Nonetheless, one of the most critical life-history stages in birds falls between egg-laying and fledging, and identifying the factors causing offspring mortality during this period provides valuable knowledge. We quantified the number of laid White Stork eggs and the proportion of eggs that turned into fledglings in an agriculture-dominated region in Eastern Germany. Moreover, we identified the factors among land cover, weather and arrival dates, which influenced these two reproductive measures the most, and analysed the monitored mortality causes. On average, four eggs were laid per nest, and 57.8 % of the eggs turned into fledglings. The number of eggs laid was best explained by the negative effect of the arrival date of the second stork, while the percentage of eggs that turned into fledglings was more dependent on weather: most important parameters were mean temperature in the fifth and seventh weeks after the assumed breeding start (i.e. around the assumed hatching date), and the number of consecutive days with precipitation when nestlings are assumed to be approximately 3 weeks old. In an agricultural environment, weather effects that potentially disturb food availability might be more important than effects directly affecting the survival of White Stork offspring. The most frequent observed mortality cause, nest fights, furthermore revealed the relevance of intraspecific competition in the study population.

The influence of phenology on double-brooding and polygyny incidence in the Sedge Warbler Acrocephalus schoenobaenus
Tadeusz Zając 1  , Wojciech Bielański 1, Adam Ćmiel 1 and Wojciech Solarz 1
(1)Institute of Nature Conservation, Polish Academy of Sciences, al. Mickiewicza 33, 31-120 Kraków, Poland


There is growing evidence that the fitness of birds in temperate zones depends strongly on the match between the timing of breeding and local phenology. We have analysed data collected from a 15-year study on a Sedge Warbler (Acrocephalus schoenobaenus) population in its natural habitat. The highly skewed distribution of arrival dates of males indicated that they competed intensely to be the earliest arrivals. The distribution of mating dates, unlike arrival dates, was not skewed, rather it formed a bell-shaped distribution. Because females arrived much later, they could not base their mating choices on the arrival dates of males. Females, however, could use male song repertoire, a trait we found to be correlated with male arrival date. Double-brooded females mated early in the season, exactly within the peak of mating date distribution. Polygynous females, on the other hand, mated later in the season, choosing high-quality older males which had arrived significantly earlier. Male territory quality did not differ between double-brooded and polygynous females, nor did the quality of the territories occupied by an individual female change during her lifetime. Although longer lifespan and double-brooding influenced a female’s fitness over the course of her lifetime, polygyny had no significant effect. We conclude that Sedge Warbler females do not compete for territorial resources, but they do prefer to mate with high-quality early-arriving males. Polygyny is an effective strategy used by females to compensate for their late arrival and breeding onset, since they pair with high-quality males.

Frequent within-pair copulations during incubation in Northern Lapwings Vanellus vanellus are consistent with the sperm competition hypothesis
Miroslav Šálek 1  
(1)Department of Ecology, Faculty of Environmental Sciences, Czech University of Life Sciences Prague, Kamýcká 129, 16521 Praha 6, Czech Republic


Social partners of some bird species copulate during the incubation period; explanations for this include strengthening social bonds and/or reducing the risk of extra-pair paternity in consecutive clutches within the same season. According to current opinion, Northern Lapwings Vanellus vanellus exhibit this behavior, uncommon in shorebirds, in order to strengthen social bonds. Based upon field observations at 36 nests, I found that mating frequency increased after cessation of male incubation bouts, i.e., after the male had been unable to guard the female and prevent opportunities for extra-pair mating. This pattern is consistent with the sperm competition hypothesis: increased rates of copulation may be a way of devaluing the sperm of possible competitors and a strategy to secure paternity in subsequent clutches, which Northern Lapwings frequently lay throughout the breeding season. This explanation extends the previous interpretation of the frequent mating of Northern Lapwings during the incubation period.

Interspecific competition and nest survival of the threatened Red-headed Woodpecker
Barbara Frei 1  , Joseph J. Nocera 2 and James W. Fyles 1
(1)Department of Natural Resource Sciences, McGill University, Macdonald Campus, Sainte-Anne-de-Bellevue, QC, H9X 3V9, Canada
(2)Ontario Ministry of Natural Resources, Trent University, Peterborough, ON, K9J 7B8, Canada

The cavity-nesting Red-headed Woodpecker (Melanerpes erythrocephalus) is a once common, but now threatened, species across most of its range. Although several drivers for the species’ decline have been suggested, few have been quantitatively tested and still little is known of the Red-headed Woodpecker’s breeding ecology. From 2010 to 2011, we monitored 60 Red-headed Woodpecker nests across a variety of habitats in southern Ontario to estimate the species’ nest survival near the northern edge of their range where populations are rapidly declining. We investigated the relevance of a suite of meteorological, biotic, temporal, and habitat-based drivers on woodpecker nesting success. The frequency of European Starlings (Sturnus vulgaris) sightings near active woodpecker nest sites was the strongest factor influencing Red-headed Woodpecker nest survival. Logistic-exposure nest success assuming constant survival (68 %) dropped significantly (to 13 %) when the frequency of Starling sightings was considered. More than a third of nest failures were suspected to be the result of aggressive cavity takeovers by Starlings, and nests with Starlings present were almost four times more likely to fail than nests without. Red-headed Woodpecker nest survival early in the breeding season appeared depressed, perhaps as a result of interference competition with Starlings. Nesting success increased with the availability of snags and dead branches, which may increase foraging opportunities and parental attentiveness at the nest, leading to more effective nest defense. This research is contrary to previous reports that Starlings do not negatively affect North American primary cavity nesters, and demonstrates the importance of considering multiple ecological, temporal, and spatial factors when determining threats for species-at-risk.

Is income breeding an appropriate construct for waterfowl?
Adam K. Janke 1  , Michael J. Anteau 2, Nicholas Markl 1, 4 and Joshua D. Stafford 3
(1)Department of Natural Resource Management, South Dakota State University, Brookings, SD 57007, USA
(2)US Geological Survey, Northern Prairie Wildlife Research Center, Jamestown, ND 58401, USA
(3)US Geological Survey, South Dakota Cooperative Fish and Wildlife Research Unit, Department of Natural Resource Management, South Dakota State University, Brookings, SD 57007, USA
(4)South Dakota Department of Game, Fish and Parks, Webster, SD 57274, USA


Breeding birds use a range of nutrient accumulation and allocation strategies to meet the nutritional demands of clutch formation and incubation. On one end of the spectrum, capital breeders use stored nutrients acquired prior to clutch formation and incubation to sustain metabolism during reproduction, while on the opposite end, income breeders derive nutrients solely from exogenous sources on the breeding grounds. Blue-winged Teal (Anas discors) are an ideal candidate to test for adoption of an income strategy among migratory waterfowl because of their small body size, temperate breeding range, and timing of reproduction relative to pulses in nutrient availability within breeding habitats. We collected migrating and pre-breeding Blue-winged Teal (n = 110) during the warmest spring in over a century in the southern edge of the species’ breeding range, which produced ideal conditions to test for adoption of an income breeding strategy among migratory waterfowl. Regression analyses revealed that females accumulated protein and fat reserves early in follicle development and appeared to mobilize at least some reserves coincident with the onset of clutch formation. Accumulation and subsequent mobilization of nutrient reserves was inconsistent with adherence to an income breeding strategy and suggested breeding Blue-winged Teal used capital (albeit locally acquired) for reproduction. Our results add to existing knowledge on the ubiquity of endogenous nutrient reserve accumulation prior to and during reproduction by waterfowl, perhaps suggesting endogenous nutrient reserves are universally used for clutch formation or incubation to some degree. If indeed Blue-winged Teal and other waterfowl universally use capital for breeding, research and conservation efforts should shift from evaluating whether an income breeding strategy is used and focus on when and where necessary capital is acquired prior to clutch formation.

Geographic variation in White-throated Sparrow song may arise through cultural drift
Scott M. Ramsay 1   and Ken A. Otter 2
(1)Department of Biology, Wilfrid Laurier University, Waterloo, ON, N2L 3C5, Canada
(2)Ecosystem Science and Management Program, University of Northern British Columbia, Prince George, BC, Canada

Geographic variation in song may arise to facilitate assortative mating among locally adapted individuals or to increase ability to communicate within local neighbourhoods. Alternatively, geographic song variation may be functionally neutral, emerging as a by-product of idiosyncrasies of founder effects and song learning in peripheral populations. We studied differences in the terminal notes of songs in White-throated Sparrows (Zonotrichia albicollis) in a peripheral population found west of the Rocky Mountains. Unlike the common triplet of notes found in terminal strophes of the main distribution of this species in eastern North America, birds in Prince George, British Columbia, Canada, had terminal notes composed of doublets. We mapped song variation on an east–west transect through central Alberta, Canada, but were unable to find a sharp division between areas where the terminal notes shift; instead, we found evidence of a cline of increasing frequency of doublet endings from east to west. We performed playback experiments of local versus foreign song types in populations where doublet terminal strophes (Prince George, BC) versus triplet terminal strophes (Algonquin Park, ON) predominate. We found a significant difference between the populations, with the western birds responding more strongly overall than the eastern birds, and males in both populations responding more strongly to the doublet-ending song type. Our results do not support the origination of regional variation to discriminate among local populations, but are consistent with neutral cultural shifts.

The influence of social dominance on calling rate in the Large-billed Crow (Corvus macrorhynchos)
Noriko Kondo 1, 2   and Mariko Hiraiwa-Hasegawa 1
(1)Department of Evolutionary Studies of Biosystems, The Graduate University for Advanced Studies, Shonan Village, Hayama Kanagawa, 240-0193, Japan
(2)Japan Society for Promotion of Science, Sumitomo-Ichibancho FS Bldg., 8 Ichibancho, Chiyoda-ku, Tokyo 102-8472, Japan


Individual animals of social species that form dominance hierarchies use status signals to advertise their dominance status to conspecifics. Bird species often have a visual status signal known as a “badge of status.” However, the hierarchies of some social species are fluid, and dominance status may change depending on the composition of the group. In such situations, vocal signals are more suitable as a status signal because they are readily modifiable by the signaler. In this study, we investigated the relationship between social dominance rank and calling rate in the Large-billed Crow (Corvus macrorhynchos) by observing a captive flock of Large-billed Crows and determining the dominance rank of each individual. The number of vocalizations each individual produced during the study period were also recorded. Our results revealed that there was a clear linear dominance hierarchy within the flock and that more dominant crows produced sequential-note calls more frequently than their subordinate counterparts. Contact call rate, however, was not affected by dominance status. These results suggest that sequential-note calls function as status signals in groups of Large-billed Crows.

Age-related change in carotenoid-based plumage of the American Redstart (Setophaga ruticilla)
Kristen L. D. Marini 1, Ann E. McKellar 2, Laurene M. Ratcliffe 3, Peter P. Marra 4 and Matthew W. Reudink 1  
(1)Department of Biological Sciences, Thompson Rivers University, Kamloops, BC, Canada
(2)Environment Canada, 115 Perimeter Road, Saskatoon, SK, Canada
(3)Department of Biology, Queen’s University, Kingston, ON, Canada
(4)Migratory Bird Center, Smithsonian Conservation Biology Institute, National Zoological Park, Washington, DC, USA


Plumage colouration serves a variety of functions for birds, including conspecific signalling, crypsis, and predator–prey interactions. Though much research has been conducted on colour changes in species with delayed plumage maturation, where birds do not exhibit definitive adult plumage until their second breeding season or later, relatively few studies have examined how plumage colour changes once definitive adult plumage has been attained. In this study on male and female American Redstarts (Setophaga ruticilla), which exhibit male delayed plumage maturation, we used reflectance spectrometry to evaluate carotenoid-based tail colour changes over 11 breeding seasons, examining both within-individual and population-level changes. At a population level, males in their first breeding season in definitive adult plumage had a feather hue that was more orange-shifted than birds in their second year in adult plumage, and marginally, but not significantly, more orange-shifted than birds in their third year in adult plumage. Within-individual analysis of males recaptured in subsequent seasons also revealed a shift away from orange towards a more yellow feather hue as individuals aged. Within individuals, red chroma was highest for males in their second year in adult plumage, but it showed no population-level effects. At the population level, female redstarts in their first breeding season displayed plumage with a higher red chroma and a lower brightness than birds in their second breeding season, potentially as a result of differences in the timing and conditions of moult (first-year bird tail feathers were grown in the nest). For adult males and females, there was no difference in plumage colouration between birds that returned to the study site compared to those that failed to return. Together, our results suggest that within-individual change rather than differential survival best explains our findings. We suggest that studies examining age-related colour changes are critical for understanding the evolution of complex signalling systems, such as that of American Redstarts.

Experimentally reduced male ornamentation increased paternal care in the Barn Swallow
Masaru Hasegawa 1   and Emi Arai 2
(1)Department of Evolutionary Studies of Biosystems, The Graduate University for Advanced Studies, 1560-35 Kamiyamaguchi, Hayama-machi, Miura-gun 240-0115, Kanagawa, Japan
(2)Division of Ecology and Evolutionary Biology, Graduate School of Life Sciences, Tohoku University, Sendai, Japan

It has recently been demonstrated that male ornaments feedback on their physiological state and this is expected to be followed by behavioral alterations in paternal care. However, only a few studies have shown the effects of experimental manipulation of ornamentation on paternal care behavior. The present study investigated the effects of experimental manipulation of the size of a male ornament, the red throat patch, on the feeding rates of nestlings by male and female Barn Swallows (Hirundo rustica gutturalis). First, we observed a dynamic change in male throat patch height during the breeding season, indicating that behavioral alterations in response to changes in throat patch height may be beneficial for male Swallows. Second, males with an experimentally reduced throat patch, but not their mates, fed their nestlings significantly more often compared with control individuals. In addition, we found a significant interaction between treatment and male body size: i.e., the effects of a reduced throat patch height varied depending on male body size. Among males with a reduced throat patch, male feeding rate increased with body size, but this was not the case in control males. This interaction is consistent with the idea that small males have low behavioral flexibility, and might contribute on positive correlation between throat ornamentation and male body size, given that behavioral flexibility is adaptive. The current finding indicates that males can increase paternal care in response to a seasonal decrease in ornamentation and this differential behavioral flexibility among males may facilitate the honesty of ornamentation.

Effects of immune supplementation and immune challenge on bacterial assemblages in the avian cloaca
Kevin D. Matson 1, 2  , Maaike A. Versteegh 1, Marco van der Velde 1 and B. Irene Tieleman 1
(1)Animal Ecology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, P.O. Box 11103, 9700 CC Groningen, The Netherlands
(2)Resource Ecology Group, Department of Environmental Sciences, Wageningen University, P.O. Box 47, 6700 AA Wageningen, The Netherlands


Relationships between avian physiology and bacterial assemblages in the cloaca are poorly understood. We used molecular techniques to analyze cloacal swabs from pigeons that were subjected to two immunological manipulations: lysozyme supplementation and endotoxin challenge. From the swabs, we derived ecological indices of evenness, richness, and diversity of bacterial assemblages. Challenge led to changes in evenness that depended on supplementation. When analyzing these changes, we neutralized the effects of a possible statistical artifact by including the starting values as a covariate. Repeatability calculations suggested that swabbing reliably captured the evenness but not the richness or diversity of bacterial assemblages in the cloaca.

Patterns of year-to-year variation in haemoglobin and glucose concentrations in the blood of nestling Pied Flycatchers Ficedula hypoleuca
Michał Glądalski 1  , Joanna Skwarska 1, Adam Kaliński 3, Mirosława Bańbura 2, Marcin Markowski 1, Jarosław Wawrzyniak 1, Piotr Zieliński 4 and Jerzy Bańbura 1
(1)Department of Experimental Zoology and Evolutionary Biology, Faculty of Biology and Environmental Protection, University of Łódź, Banacha 12/16, 90-237 Lodz, Poland
(2)Museum of Natural History, Faculty of Biology and Environmental Protection, University of Łódź, Kilińskiego 101, 90-011 Lodz, Poland
(3)Department of Teacher Training and Biological Diversity Studies, Faculty of Biology and Environmental Protection, University of Łódź, Banacha 1/3, 90-237 Lodz, Poland
(4)Department of Ecology and Vertebrate Zoology, Faculty of Biology and Environmental Protection, University of Łódź, Banacha 12/16, 90-237 Lodz, Poland


Physiological tools can be used to identify the sources and consequences of stressors on animals. Understanding the influences of variation in habitat quality and anthropogenic disturbance on organism condition and health may improve future management and conservation. We present results concerning variation in haemoglobin and glucose concentrations in the blood of about 14-day-old nestling Pied Flycatchers Ficedula hypoleuca in central Poland over a 4-year period, 2011–2014, in a deciduous forest. The most important findings of the study are: (1) the concentration of haemoglobin and glucose of the nestlings from the same brood tended to be consistently similar, with much variation occurring among broods; (2) repeatability of haemoglobin concentration was higher than repeatability of glucose concentration; (3) mean levels of haemoglobin and glucose varied among years; (4) haemoglobin and glucose concentrations were negatively correlated; and (5) there was a positive relationship between haemoglobin levels and breeding success.

A hybrid snipe Gallinago gallinago × G. media found in the wild
Jacob Höglund 1  , Stein Are Sæther 1, 2, Peder Fiske 2, David Wheatcroft 1 and John Atle Kålås 2
(1)Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236 Uppsala, Sweden
(2)Norwegian Institute for Nature Research (NINA), P.O. Box 5685, Sluppen, 7485 Trondheim, Norway

A hybrid snipe male was observed and caught in 2009 in the Norwegian mountains. We report behaviour, vocalizations, morphology, and genetic data for this bird. Mitochondrial and nuclear DNA sequences revealed that the hybrid had a great snipe mother and a common snipe father. The hybrid was intermediate in most measured morphometric traits and showed some intermediate plumage characteristics. The behaviour was similar to that of a great snipe—it displayed and vocalised at a great snipe lek for more than a week. The song was somewhat reminiscent of a great snipe's, but lacked the frequency-modulated whistles that are part of the great snipe song, consisting of more rapid click notes of a narrower frequency spectrum. This is the only putative hybrid that we have found among the more than 4,400 adult individuals we have examined between 1986 and 2014 at great snipe leks in Norway, Sweden, Poland, and Estonia. Common snipes invariably occur near these sites. Reports on putative hybrids among snipe species are very rare, and we question the validity of previous claims. This is the first where the parental origins—and, indeed, the hybrid status—have been unequivocally determined. We speculate on how a great snipe female, known for being extremely choosy about mating, came to mate with a common snipe male. We also note that, although perhaps behaviourally more likely, physical constraints on chick development (caused by the smaller egg size of the common snipe and larger body size of the great snipe) might prevent any successful male great snipe × female common snipe hybridisation—a possible example of an unidirectional post-zygotic barrier.

Intergeneric hybridization between Common Redstart Phoenicurus phoenicurus and Whinchat Saxicola rubetra revealed by molecular analyses
Silje Hogner 1  , Albert Burgas Riera 2, Margrethe Wold 2, Jan T. Lifjeld1 and Arild Johnsen 1
(1)Natural History Museum, University of Oslo, Blindern, P.O. Box 1172, 0318 Oslo, Norway
(2)Lista Bird Observatory, Fyrveien 6, 4563 Borhaug, Norway


Hybridization between members of different genera is relatively rare in nature. Here, we present the first molecular evidence of an intergeneric hybrid within the avian Muscicapidae family. The suspected hybrid was captured at Lista Bird Observatory, Norway, in September 2013. Molecular analysis of the mitochondrial COI gene showed that the mother of the hybrid was a Whinchat, while two intronic sequences revealed that the father was a Common Redstart. Molecular sexing showed that the hybrid was a male. A detailed phenotypic description of the hybrid is presented together with the parental species. Documenting hybridization is increasingly feasible using molecular methods and provides important information to studies of species borders, reproductive barriers and the process of speciation. We emphasize the importance of securing solid documentation (photos and morphometrics) and DNA samples (from feathers or blood) whenever suspected hybrids are captured in the wild.

A primitive heron (Aves: Ardeidae) from the Miocene of Central Asia
Andrzej Elzanowski 1   and Nikita V. Zelenkov 2  
(1)Museum and Institute of Zoology, Polish Academy of Sciences, 64 Wilcza Street, 00-679 Warsaw, Poland
(2)Borissiak Paleontological Institute, Russian Academy of Sciences, Profsoyuznaya ul. 123, Moscow, 117997, Russia


A robust quadrate from the Middle Miocene of Mongolia represents a new genus of Ardeidae that combines the similarities to Nycticorax and Tigrisoma, both of which have been recovered in basal positions in recent phylogenies of the Ardeidae, and to cf. Pikaihao from the Middle Miocene of Africa. The confluence of mandibular facets on the medial condyle and pterygoid condyle in the new genus, Nycticorax, and cf. Pikaihao is likely to be symplesiomorphic, as it is shared with nearly all other waterbirds (except for the Ciconiidae), including the immediate outgroup (Threskiornithidae). However, the medial supraorbital crest is a likely synapomorphy of the new genus and cf. Pikaihao. The similarities to Trigrisoma support its basal position, as recovered from molecular sequences and proposed by a pre-cladistic morphological analysis. Since both the night herons and Tigrisoma have heads that are proportionally much larger than those of the large day herons, it appears that the Ardeidae started their evolution with relatively heavy heads, which may have contributed to the origins of the family-specific head retraction in flight.

Mercury concentrations in primary feathers reflect pollutant exposure in discrete non-breeding grounds used by Short-tailed Shearwaters
Yutaka Watanuki 1  , Takashi Yamamoto 1, 2, Ai Yamashita 1, Chihiro Ishii 3, Yoshinori Ikenaka 3, Shouta M. M. Nakayama 3, Mayumi Ishizuka 3, Yuya Suzuki 1, Yasuaki Niizuma 4, C. E. Meathrel 5 and R. A. Phillips 6
(1)Graduate School of Fisheries Sciences, Hokkaido University, Minato-cho 3-1-1, Hakodate 041-8611, Japan
(2)Arctic Environment Research Center, National Institute of Polar Research, Midori-cho 10-3, Tachikawa 190-8518, Japan
(3)Graduate School of Veterinary Medicine, Hokkaido University, Kita-18 Nishi-9, Sapporo 060-0818, Japan
(4)Faculty of Agriculture, Meijyo University, Shiogamaguchi 1-501, Tenpaku-ku, Nagoya 468-8502, Japan
(5)LaTrobe University, Wodonga, VIC, 3086, Australia
(6)British Antarctic Survey, Natural Environment Research Council, High Cross, Madingley Road, Cambridge, CB3 0ET, UK


We measured mercury concentrations ([Hg]) and nitrogen stable isotope ratios (δ15N) in the primary feathers of Short-tailed Shearwaters (Puffinus tenuirostris) that were tracked year-round. The [Hg] were highest in 14 birds that used the Okhotsk and northern Japan Seas during the non-breeding period (2.5 ± 1.4 μg/g), lowest in nine birds that used the eastern Bering Sea (0.8 ± 0.2 μg/g), and intermediate in five birds that used both regions (1.0 ± 0.5 μg/g), with no effects of δ15N. The results illustrate that samples from seabirds can provide a useful means of monitoring pollution at a large spatial scale.

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