Fuel loss and flexible fuel deposition rates in a long-distance migrant

Most migrating birds alternate flight bouts with stopovers, during which they rest and replenish the fuel used during flight (refueling). The rate of refueling (fuel deposition rate, FDR) affects stopover duration, and hence is an important determinant of the overall time required for migration. Although environmental and endogenous factors affect FDR, the urge to refuel depends on the anticipated distance to be travelled and possibly also on the amount of fuel used during the flight preceding stopover. Combining a field study with a fasting–refueling experiment on long-term captive songbirds, we tested whether the extent of fuel loss prior to refueling indeed affects FDR. In the field study, we took a comparative approach and determined FDR in two subspecies of northern wheatear (Oenanthe oenanthe) that differ greatly in the distance flown, and thus the extent of fuel used to reach our study (stopover) site. As both winter in western sub-Sahelian Africa, they face the same remaining migration distance. We found that FDR was higher in the subspecies that uses more fuel to get to our study site. Solidifying this result, in the experiment on captive northern wheatears, we found that the extent of fuel loss as a consequence of fasting explained most of the variation in subsequent FDR. The observation that experimental birds losing little fuel did not maximize their FDR suggests there are costs to rapid refueling. Our study shows that FDR is shaped not just by current environmental and endogenous conditions but also by fuel loss prior to refueling.     

Understanding the effects of rainfall on elephant-vegetation interactions around waterholes

The distribution of surface water affects herbivore-vegetation interactions in arid and semi-arid regions. Limited access to surface water typically results in the emergence of vegetation gradients around natural and artificial water sources. In particular, African elephants can create large-scale gradients of woody vegetation. Understanding the dynamics of these gradients is of particular importance for the conservation of other, less mobile herbivores that depend on woody vegetation in areas close to water. While rainfall is known to be a key determinant of herbivore-vegetation interactions in dry areas, we only have limited understanding on how it impacts woody vegetation gradients around waterholes. To address this problem, we developed a deterministic simulation model that describes the interplay of rainfall, elephants and woody vegetation in the vicinity of waterholes. The model is based on elephant telemetry data and the ecological conditions in Etosha National Park (ENP), Namibia. We found that decreasing amounts of rainfall led to an increased degradation of woody vegetation, which was particularly severe in areas close to water. Based on this result we conclude that low rainfall was an important driver of recently observed patterns of vegetation degradation in ENP. More generally, rainfall appears to be a key factor that determines elephant-vegetation interactions and thus dynamics of woody vegetation gradients around waterholes. Using long-term rainfall data from ENP, we also demonstrate that an increase in the number of water sources during periods of low rainfall can mitigate the destructive impact of elephants in areas close to water. However, more research is required to assess the sustainability and effectiveness of rainfall-adapted strategies of artificial water provisioning in more detail. In particular it is important to investigate potential effects on elephant population dynamics.     

100 Jahre Lektinforschung — eine Bilanz

A hundred years of lectin research has led to the development of lectinology as an independent field of study. Although lectinology is in part related to immunology, fundamental differences exist. Lectins are important tools in biochemistry, histochemistry and clinical diagnosis. The essential in vivo function of lectins is to combine glycoconjugates. The function of lectins in microorganisms and in animals is partially known, whereas the function of lectins in plants is mostly unclear. Of special interest, now as before, are the toxic lectins of the ricin type consisting of an A-chain (N-glycosidase) and a B-chain (D-galactose-specific lectin).     

Environmental perspectives of pupils: the development of an attitude and behaviour scale

Summary The object of this study was to construct a measurement instrument to assess two different environmental world views of adolescents and, additionally, to address the adolescents' verbal commitment and actual behaviour. Using a multiple-choice questionnaire the instrument was designed to identify and measure the existing factors that underlie concern for ecological/environmental problems and behaviour towards environment/nature in the age group of 10 to 16 year old pupils. Within the traditional tripartite model covering cognitive, affective and behavioural components the study selected items that made up the majority of corresponding subscales from various previous studies. Using factor analysis the configuration of the scale's dimensionality was stated. Based on the responses of approximately 2000 Bavarian pupils, subscales were extracted via factor analysis and, subsequently, addressed to different segments of environmental concern ranging from attitudes to verbal commitment and actual behaviour. Correlation coefficients and the standardized Cronbach's -values were also surveyed. Additionally, a Kruskal-Wallis analysis was applied in order to locate the subscales' influences on sociodemographic variables such as gender and age and self-reported variables such as the pleasure of being a pupil and school performance. The further purpose of the present study is to provide the basis for follow-up comparisons of preferences and values in pupils within other countries.

---

Résumé Le but de la présente étude est la réalisation d'un système de mesure pour l'évaluation de différents niveaux de conscience par rapport à la nature et à la protection de l'environnement, ainsi que des comportements actuels ou envisagés. Le système de mesure s'appuie sur un questionnaire à choix multiples pour évaluer les différents facteurs qui déterminent les niveaux de conscience et les comportements correspondants chez les adolescents de 10 à 16 ans. Dans le cadre du modèle à trois niveaux, qui comprend des composantes cognitives, affectives et comportementales, un grand nombre d'items, en partie issus d'études antérieures, ont été sélectionnés pour former les sous-catégories nécessaires. La configuration des catégories a été garantie par une analyse factorielle.Sur la base des réponses d'environ 2000 élèves, des sous-catégories ont été définies, qui vont depuis les positions de départ jusqu'au comportement actuel. En outre, nous avons défini les coefficients de corrélation, ainsi que les valuers Cronback-Alpha, et une analyse des régressions a été effectuée, qui prend en compte les influences, par exemple, des variables sociodémographiques comme le sexe et l'âge, des résultats scolaires ou de la manière dont l'école est perçue par chacun.La présente étude représente la base aussi bien pour des investigations comparatives entre pays, que pour l'évaluation de l'influence d'un enseignement extra-scolaire adopté.

---

---

Dr. Franz Bogner is the senior author to whom correspondence should be addressed. Manfred Wilhelm is based at the Institut für Medizinische Statistik, Technische Universität, Ismaninger Straße 22, D-81675 München, Germany.     

Water and nitrate fluxes at a forest site in the North Tyrolean Limestone Alps

The water balance for the site Mühleggerköpfl in the North Tyrolean Limestone Alps has been established to a soil depth of 50 cm. The evaporation amounts to 42% and deep percolation is 58 % of the precipitation. The surface runoff was negligible and therefore the according nitrate fluxes as well. Soil water analysis revealed mean nitrate concentrations of 3 to 15 mg NO₃ L⁻¹, depending on soil depth. The nitrate concentrations at 50 cm soil depth and the associated percolation rates led to NO₂ ⁻N outputs of 15.9 kg NO₃ ⁻N ha⁻¹ in the year 1999 and 7.9 kg NO₃ ^∼N ha⁻¹ in the year 2000.