TY - JOUR A1 - Schlägel, Ulrike E. A1 - Mädlow, Wolfgang T1 - All-season space use by non-native resident Mandarin Ducks (Aix galericulata) in northeastern Germany JF - Journal of ornithology / publ. by Deutsche Ornithologen-Gesellschaft N2 - Patterns of space use are often subject to large temporal and individual-level variation, due to seasonality in behaviour and environmental conditions as well as age- or sex-specific needs. Especially in temperate regions, seasonality likely influences space use even in non-migratory birds. In waterfowl of the family Anatidae, however, few studies have analyzed space use of the same individuals across the full annual cycle. We used a resident population of Mandarin Ducks (Aix galericulata) in northeast Germany to study their year-round space use in relation to season, sex, and age. We marked 172 birds with colour rings and surveyed relevant water bodies for re-encounters for several years. As space-use patterns we derived home ranges from minimum convex polygons and the number of water bodies used by individual birds. Our analysis revealed that individuals shifted their space use between seasons, in particular extending their home ranges during the non-breeding season. Between years, in contrast, birds tended to show season-specific site fidelity. Sex differences were apparent during both breeding and non-breeding season, males consistently having larger home ranges and using slightly more water bodies. No difference was found between first-year and adult birds. Our study demonstrates that mark-resighting can provide valuable information about space use in species with suitable behaviour and readily accessible habitat. In such cases, it may be a valid alternative to more expensive GPS-tracking or short-term manual radio telemetry, particularly within citizen-science projects. N2 - Raumnutzungsmuster von Vögeln zeigen häufig große zeitliche und individuelle Variationen in Abhängigkeit vom saisonalen Verhalten und von Umweltbedingungen, aber auch alters- und geschlechtsspezifischen Ansprüchen. In gemäßigten Klimazonen können jahreszeitliche Einflussfaktoren die Raumnutzung auch von nicht ziehenden Arten bestimmen. Für Entenvögel (Anatidae) liegen bisher jedoch nur wenige Studien vor, die die Raumnutzung von Individuen über den gesamten Jahresverlauf hinweg betrachten. Wir untersuchten die ganzjährige Raumnutzung einer Standvogel-Population der Mandarinente (Aix galericulata) in Abhängigkeit von Jahreszeit, Geschlecht und Alter der Vögel. Wir markierten 172 Vögel mit Farbringen und kontrollierten mehrere Jahre lang die relevanten Gewässer, um Ringablesungen zu erzielen. Zur Analyse der Raumnutzung ermittelten wir Minimum-Convex-Polygone und die Anzahl der von den einzelnen Individuen genutzten Gewässer. Unsere Auswertung zeigte, dass die von den Vögeln genutzten Aktionsräume sich mit den Jahreszeiten veränderten. Insbesondere vergrößerte sich das besuchte Gebiet außerhalb der Brutzeit. Beim Vergleich mehrerer Jahre tendierten die Vögel zu einer saisonspezifischen Gebietstreue. Geschlechterunterschiede zeigten sich sowohl innerhalb als auch außerhalb der Brutzeit, wobei die Männchen stets größere Gebiete und eine größere Zahl an Gewässern nutzten. Zwischen Vögeln im ersten Lebensjahr und Adulten wurden keine Unterschiede gefunden. Unsere Untersuchung zeigt, dass Farbberingungsprogramme wertvolle Informationen zur Raumnutzung bei Arten liefern können, deren Verhalten dafür geeignet ist und die in gut zugänglichen Lebensräumen vorkommen. In diesen Fällen kann die Farbberingung eine geeignete Alternative zur teureren GPS- oder manuellen Telemetrie sein, vor allem wenn die vereinte Kraft von Amateurornithologen in die Untersuchungen einbezogen werden kann. KW - Anatidae KW - Aix galericulata KW - Home range KW - Site fidelity KW - Movement KW - Seasonality Y1 - 2021 U6 - https://doi.org/10.1007/s10336-021-01932-7 SN - 2193-7192 SN - 2193-7206 VL - 163 IS - 1 SP - 71 EP - 82 PB - Springer CY - Berlin ER - TY - JOUR A1 - Eccard, Jana A1 - Fey, Karen A1 - Caspers, Barbara A. A1 - Ylönen, Hannu T1 - Breeding state and season affect interspecific interaction types indirect resource competition and direct interference JF - Oecologia N2 - Indirect resource competition and interference are widely occurring mechanisms of interspecific interactions. We have studied the seasonal expression of these two interaction types within a two-species, boreal small mammal system. Seasons differ by resource availability, individual breeding state and intraspecific social system. Live-trapping methods were used to monitor space use and reproduction in 14 experimental populations of bank voles Myodes glareolus in large outdoor enclosures with and without a dominant competitor, the field vole Microtus agrestis. We further compared vole behaviour using staged dyadic encounters in neutral arenas in both seasons. Survival of the non-breeding overwintering bank voles was not affected by competition. In the spring, the numbers of male bank voles, but not of females, were reduced significantly in the competition populations. Bank vole home ranges expanded with vole density in the presence of competitors, indicating food limitation. A comparison of behaviour between seasons based on an analysis of similarity revealed an avoidance of costly aggression against opponents, independent of species. Interactions were more aggressive during the summer than during the winter, and heterospecific encounters were more aggressive than conspecific encounters. Based on these results, we suggest that interaction types and their respective mechanisms are not either-or categories and may change over the seasons. During the winter, energy constraints and thermoregulatory needs decrease direct aggression, but food constraints increase indirect resource competition. Direct interference appears in the summer, probably triggered by each individual's reproductive and hormonal state and the defence of offspring against conspecific and heterospecific intruders. Both interaction forms overlap in the spring, possibly contributing to spring declines in the numbers of subordinate species. KW - Rodents KW - Aggression KW - Seasonality KW - Space use KW - Winter biology Y1 - 2011 U6 - https://doi.org/10.1007/s00442-011-2008-y SN - 0029-8549 SN - 1432-1939 VL - 167 IS - 3 SP - 623 EP - 633 PB - Springer CY - New York ER - TY - THES A1 - Liesenjohann, Thilo T1 - Foraging in space and time T1 - Nahrungssuche unter variablen zeitlichen und räumlichen Bedingungen N2 - All animals are adapted to the environmental conditions of the habitat they chose to live in. It was the aim of this PhD-project, to show which behavioral strategies are expressed as mechanisms to cope with the constraints, which contribute to the natural selection pressure acting on individuals. For this purpose, small mammals were exposed to different levels and types of predation risk while actively foraging. Individuals were either exposed to different predator types (airborne or ground) or combinations of both, or to indirect predators (nest predators). Risk was assumed to be distributed homogeneously, so changing the habitat or temporal adaptations where not regarded as potential options. Results show that wild-caught voles have strategic answers to this homogeneously distributed risk, which is perceived by tactile, olfactory or acoustic cues. Thus, they do not have to know an absolut quality (e.g., in terms of food provisioning and risk levels of all possible habitats), but they can adapt their behavior to the actual circumstances. Deriving risk uniform levels from cues and adjusting activity levels to the perceived risk is an option to deal with predators of the same size or with unforeseeable attack rates. Experiments showed that as long as there are no safe places or times, it is best to reduce activity and behave as inconspicuous as possible as long as the costs of missed opportunities do not exceed the benefits of a higher survival probability. Test showed that these costs apparently grow faster for males than for females, especially in times of inactivity. This is supported by strong predatory pressure on the most active groups of rodents (young males, sexually active or dispersers) leading to extremely female-biased operative sex ratios in natural populations. Other groups of animals, those with parental duties such as nest guarding, for example, have to deal with the actual risk in their habitat as well. Strategies to indirect predation pressure were tested by using bank vole mothers, confronted with a nest predator that posed no actual threat to themselves but to their young (Sorex araneus). They reduced travelling and concentrated their effort in the presence of shrews, independent of the different nutritional provisioning of food by varying resource levels due to the different seasons. Additionally, they exhibited nest-guarding strategies by not foraging in the vicinity of the nest site in order to reduce conspicuous scent marks. The repetition of the experiment in summer and autumn showed that changing environmental constraints can have a severe impact on results of outdoor studies. In our case, changing resource levels changed the type of interaction between the two species. The experiments show that it is important to analyze decision making and optimality models on an individual level, and, when that is not possible (maybe because of the constraints of field work), groups of animals should be classified by using the least common denominator that can be identified (such as sex, age, origin or kinship). This will control for the effects of the sex or stage of life history or the individual´s reproductive and nutritional status on decision making and will narrow the wide behavioral variability associated with the complex term of optimality. N2 - Das Verhalten von Tieren ist das Ergebnis eines kontinuierlichen Anpassungsprozesses im Laufe der Evolution einer Art und damit der Veränderung der Umgebung in der es lebt und der Interaktion mit anderen Arten. Dies wird besonders deutlich im Verhalten von potentiellen Beutetieren, ihre Strategien beinhalten meist ein möglichst unauffälliges Verhalten im Zusammenspiel mit reduzierter Bewegung und möglichst guter Tarnung. Dementgegen stehen essentielle Bedürfnisse, wie zum Beispiel die Nahrungssuche, die Verteidigung von Ressourcen (zum Beispiel Territorien, Futterstellen) und die Suche nach Paarungspartnern. Beutetiere leben also in einem Spannungsfeld indem sie Ihr Verhalten optimieren müssen. Hierbei stehen die Ernährung, erfolgreiche Verpaarung und andere Chancen auf der einen Seite, die Vermeidung von Begegnungen mit Prädatoren auf der anderen. Vor allem Kleinsäuger sind häufig als Beutetiere mit einer Vielzahl von Prädatoren aus der Luft und auf dem Boden konfrontiert. Sie müssen für die verschiedenen Bedrohungen adaptive Verhaltensanpassungen bereit haben und in der Lage sein, auf die optischen, olfaktorischen oder akustischen Signale, die die Gefahr durch Prädatoren anzeigen, mit plastischen Verhaltensmustern zu reagieren. Die vorliegende Dissertation beschäftigt sich mit bisher als Konstanten behandelten Faktoren und untersucht anhand von Verhaltensexperimenten mit wilden Wühlmäusen (Microtus arvalis) folgende Fragestellungen: - Wie verhalten sich Tiere, die einer homogenen Risikoverteilung ausgesetzt sind, zum Beispiel weil ihr Prädator genauso gross ist wie sie, im gleichen Habitat lebt und es keinen sicheren Ort gibt? - Mit welchen Anpassungen reagieren Tiere, wenn sie gleichzeitig verschiedenen Prädatoren ausgesetzt sind? - Wie unterscheiden sich die Nahrungssuchstrategien von Männchen und Weibchen? - Wie verhalten sich laktierende Weibchen, die einer permanenten, indirekten Gefahr, z.B. durch einen Nestprädator ausgesetzt sind? Die Ergebnisse der verschiedenen Versuche in künstlichen Arenen und Aussengehegen zeigen, dass die Mäuse in der Lage sind, adaptive Verhaltensanpassung an homogenes Risiko und verschiedene Prädationstypen abzurufen. So sind sie in der Lage, Luft- von Bodenprädatoren zu unterscheiden und jeweils das Verhalten zu zeigen, dass die größtmögliche Sicherheit mit sich bringt. Die simultane Kombination von verschiedenen Prädatoren bewirkt hierbei additive Effekte. Gibt es keine Auswahl zwischen Habitaten, sondern nur unterschiedliche homogene Risikolevel, reagieren sie auf steigendes Risiko immer mit verminderter Aktivität und konzentrieren ihre Nahrungssuche auf weniger Futterstellen, beuten diese dafür jedoch länger aus. Die Wertigkeit von Futterstellen und alternativen Optionen verändert sich also mit dem Risikolevel. Ähnliches zeigt sich auch in den unterschiedlichen Futtersuchstrategien von Männchen und Weibchen. Die untersuchte Art ist polygyn und multivoltin, dementsprechend verbinden die Männchen mit ihrer Nahrungssuche Aktivitäten wie die Suche nach Paarungspartnern und unterscheiden sich die Aktivitätsmuster zwischen Männchen und Weibchen. Zusätzlich zeigen die Ergebnisse, das laktierende Weibchen in der Lage sind, das Risiko für sich und für Ihre Jungen abzuschätzen, wenn sie mit einem Nestprädator (Sorex araneus) konfrontiert werden. Für die Interaktion zwischen diesen beiden Arten ist jedoch die Saison (und damit die Ressourcenlage), in der sie sich begegnen, von entscheidender Bedeutung. Wühlmäuse reagieren mit entsprechenden Verhaltensanpassungen zum Schutz des Nestes um die Überlebenschancen ihrer letzten Würfe im Herbst zu erhöhen. Die vorliegende Arbeit konnte grundsätzliche Probleme der antiprädatorischen Verhaltensanpassung von Beutetieren klären und wichtige Faktoren der Entscheidungsfindung unter Prädationsdruck analysieren. Sie zeigt, dass Tiere das Risiko in ihrer Umgebung nicht unbedingt über direkt Signale wahrnehmen, sondern ihre Verhaltensstrategien einem empfundenen Gesamtrisikolevel anpassen. Dies ermöglicht ihnen, adaptive Strategien zu verfolgen, auch wenn sie keine Auswahl an sicheren Habitaten haben. Sie zeigt auch die unterschiedliche Wahrnehmung von Risiken durch Männchen und Weibchen, die durch die unterschiedlichen mit der Aktivität zusätzlich wahrgenommenen Chancen verknüpft zu sein scheint. Zusätzlich wurde der Einfluss des reproduktiven Status (z.B. laktierend), sowie der Ressourcenlage (z. B. je nach Saison) nachgewiesen. KW - Nahrungssuche KW - Microtus KW - Wühlmaus KW - Prädation KW - Optimalität KW - Predation KW - Microtus KW - Optimality KW - Seasonality KW - Foraging Y1 - 2010 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus-48562 ER - TY - JOUR A1 - Fechner, Carolin A1 - Hackethal, Christin A1 - Höpfner, Tobias A1 - Dietrich, Jessica A1 - Bloch, Dorit A1 - Lindtner, Oliver A1 - Sarvan, Irmela T1 - Results of the BfR MEAL Study BT - in Germany, mercury is mostly contained in fish and seafood while cadmium, lead, and nickel are present in a broad spectrum of foods JF - Food chemistry: X N2 - The BfR MEAL Study provides representative levels of substances in foods consumed in Germany. Mercury, cadmium, lead, and nickel are contaminants present in foods introduced by environmental and industrial processes. Levels of these elements were investigated in 356 foods. Foods were purchased representatively, prepared as consumed and pooled with similar foods before analysis. Highest mean levels of mercury were determined in fish and seafood, while high levels of cadmium, lead, and nickel were present in cocoa products and legumes, nuts, oilseeds, and spices. The sampling by region, season, and production type showed minor differences in element levels for specific foods, however no tendency over all foods or for some food groups was apparent. The data on mercury, cadmium, lead, and nickel provide a comprehensive basis for chronic dietary exposure assessment of the population in Germany. All levels found were below regulated maximum levels. KW - Total diet study KW - BfR MEAL Study KW - Metals KW - Contaminants KW - Unprepared and KW - prepared foods KW - Regionality KW - Seasonality KW - Organic and conventional type of production Y1 - 2022 U6 - https://doi.org/10.1016/j.fochx.2022.100326 SN - 2590-1575 VL - 14 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Heim, Olga A1 - Schröder, Assja A1 - Eccard, Jana A1 - Jung, Kirsten A1 - Voigt, Christian C. T1 - Seasonal activity patterns of European bats above intensively used farmland JF - The astrophysical journal : an international review of spectroscopy and astronomical physics ; Part 2, Letters N2 - Bats are top insect predators on farmland, yet they suffer from intensive farmland management. Here, we evaluated the seasonal activity patterns of European bats above large, arable fields and compared these patterns between ecologically distinct bat species. Using repeated passive acoustic monitoring on a total of 93 arable fields in 2 years in Brandenburg, Germany, we surveyed the activity of different bat species between early spring and autumn. We then used generalized additive mixed models to describe and compare the seasonal bat activity patterns between bat categories, which were build based on the affiliation to a functional group and migratory class, while controlling for local weather conditions. In general, the affiliation to a bat category in interaction with the season in addition to cloud cover and ambient air temperature explained a major part of bat activity. The season was also an important factor for the foraging activity of open-space specialists such as Nyctalus noctula but showed only a weak effect on species such as Pipistreilus nathusii which are adapted to edge-space habitats. Across the seasons, habitat use intensity was high during the period of swarming and migration and low during the energy demanding period of lactation. Seasonal patterns in foraging activity showed that open-space specialists foraged more intensively above agricultural fields during the migration period, while edge-space specialists foraged also during the energy demanding period of lactation. We conclude that the significant seasonal fluctuations in bat activity and significant differences between bat categories in open agricultural landscapes should be taken into consideration when designing monitoring schemes and management plans for bat species in regions dominated by agriculture. Also, management plans should be directed to improve the conditions on arable land especially for bat species which would be classified as narrow-space foragers such as Myotis species. (C) 2016 Elsevier B.V. All rights reserved. KW - Agricultural intensification KW - Seasonality KW - European bat species KW - Functional bat group KW - Migration KW - AgroScapeLabs Y1 - 2016 U6 - https://doi.org/10.1016/j.agee.2016.09.002 SN - 0167-8809 SN - 1873-2305 VL - 233 SP - 130 EP - 139 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Santana, Lucineide Maria A1 - Weithoff, Guntram A1 - Ferragut, Carla T1 - Seasonal and spatial functional shifts in phytoplankton communities of five tropical reservoirs JF - Aquatic ecology : the international forum covering research in freshwater and marine environments N2 - Trait-based approaches have become increasingly important and valuable in understanding phytoplankton community assembly and composition. These approaches allow for comparisons between water bodies with different species composition. We hypothesize that similar changes in environmental conditions lead to similar responses with regard to functional traits of phytoplankton communities, regardless of trophic state or species composition. We studied the phytoplankton (species composition, community trait mean and diversity) of five reservoirs in Brazil along a trophic gradient from ultra-oligotrophic to meso-eutrophic. Samples at two seasons (summer/rainy and winter/dry) with a horizontal and vertical resolution were taken. Using multivariate analysis, the five reservoirs separated, despite some overlap, according to their environmental variables (mainly total phosphorus, conductivity, pH, chlorophyll a). However, between the seasonal periods, the reservoirs shifted in a similar direction in the multi-dimensional space. The seasonal response of the overall phytoplankton community trait mean differed between the ultra-oligotrophic and the other reservoirs, with three reservoirs exhibiting a very similar community trait mean despite considerable differences in species composition. Within-season differences between different water layers were low. The functional diversity was also unrelated to the trophic state of the reservoirs. Thus, seasonal environmental changes had strong influence on the functional characteristics of the phytoplankton community in reservoirs with distinct trophic condition and species composition. These results demonstrate that an ataxonomic trait-based approach is a relevant tool for comparative studies in phytoplankton ecology. KW - Functional traits KW - Plankton KW - Seasonality KW - Tropical system KW - Diversity indices Y1 - 2017 U6 - https://doi.org/10.1007/s10452-017-9634-3 SN - 1386-2588 SN - 1573-5125 VL - 51 SP - 531 EP - 543 PB - Springer CY - Dordrecht ER - TY - JOUR A1 - Liesenjohann, Thilo A1 - Liesenjohann, Monique A1 - Trebaticka, Lenka A1 - Sundell, Janne A1 - Haapakoski, Marko A1 - Ylonen, Hannu A1 - Eccard, Jana T1 - State-dependent foraging: lactating voles adjust their foraging behavior according to the presence of a potential nest predator and season JF - Behavioral ecology and sociobiology N2 - Parental care often produces a trade-off between meeting nutritional demands of offspring and the duties of offspring protection, especially in altricial species. Parents have to leave their young unattended for foraging trips, during which nestlings are exposed to predators. We investigated how rodent mothers of altricial young respond to risk of nest predation in their foraging decisions. We studied foraging behavior of lactating bank voles (Myodes glareolus) exposed to a nest predator, the common shrew (Sorex araneus). We conducted the experiment in summer (high resource provisioning for both species) and autumn (less food available) in 12 replicates with fully crossed factors "shrew presence" and "season." We monitored use of feeding stations near and far from the nest as measurement of foraging activity and strategic foraging behavior. Vole mothers adapted their strategies to shrew presence and optimized their foraging behavior according to seasonal constraints, resulting in an interaction of treatment and season. In summer, shrew presence reduced food intake from feeding stations, while it enhanced intake in autumn. Shrew presence decreased the number of visited feeding stations in autumn and concentrated mother's foraging efforts to fewer stations. Independent of shrew presence or season, mothers foraged more in patches further away from the nest than near the nest. Results indicate that females are not investing in nest guarding but try to avoid the accumulation of olfactory cues near the nest leading a predator to the young. Additionally, our study shows how foraging strategies and nest attendance are influenced by seasonal food provision. KW - Myodes glareolus KW - Optimal foraging KW - Sorex araneus KW - Nest protection KW - Seasonality KW - Interference Y1 - 2015 U6 - https://doi.org/10.1007/s00265-015-1889-x SN - 0340-5443 SN - 1432-0762 VL - 69 IS - 5 SP - 747 EP - 754 PB - Springer CY - New York ER -