Breeding success in Brent in relation to individual feeding opportunities during spring staging in the Wadden Sea

Brent Geese Branta bernicla individually marked with inscribed leg rings were intensively watched from permanent towers on the saltings of the island Schiermonnikoog in the Dutch Wadden Sea during the spring staging period April- May 1982 when 3,000 used the area. By observing geese on plots with enhanced vegetation (biomass, protein content) as a result of fertilizer treatment, it was found that individuals on the improved sites fought more and walked more slowly. The position of the marked individuals in relation to the total feeding minutes accumulated by the flock as the group grazed past the tower was determined by making use of a radial system of counting plots. Individuals tended to be consistent in their relative timing in the grazing sequence, and the highest rate of interaction and lowest pacing rate was found just behind the leading edge of the flock, in the second quartile of feeding minutes, and by inference birds in this sector experienced the best feeding conditions. Status of the males (proportion of interactions won) was highest for individuals habitually in this sector, and observation of the same birds in the fall revealed the highest incidence of breeding success (pairs accompanied by young) for this group. A number of measures reflecting a good food supply (low pace rate, highest percentage feeding times, and highest number of bites per step) were found to correlate positively with male status supporting the conclusions from the grouped data presented in relation to the grazing sequence. Though a causal relation cannot be proved from such correlations, we interpret these findings to indicate that males of high status can provide their mates with enhanced feeding opportunities, resulting in accumulation of more body reserves in the spring, and a heightened probability of successful breeding. Females subsequently found to prove successful had a larger proportion of Triglochin maritima in their spring diet but a larger sample of droppings will be needed to substantiate this hint of a difference of diet in birds of the same flock

Breeding success in Brent in relation to individual feeding opportunities during spring staging in the Wadden Sea

Brent Geese Branta bernicla individually marked with inscribed leg rings were intensively watched from permanent towers on the saltings of the island Schiermonnikoog in the Dutch Wadden Sea during the spring staging period April- May 1982 when 3,000 used the area. By observing geese on plots with enhanced vegetation (biomass, protein content) as a result of fertilizer treatment, it was found that individuals on the improved sites fought more and walked more slowly. The position of the marked individuals in relation to the total feeding minutes accumulated by the flock as the group grazed past the tower was determined by making use of a radial system of counting plots. Individuals tended to be consistent in their relative timing in the grazing sequence, and the highest rate of interaction and lowest pacing rate was found just behind the leading edge of the flock, in the second quartile of feeding minutes, and by inference birds in this sector experienced the best feeding conditions. Status of the males (proportion of interactions won) was highest for individuals habitually in this sector, and observation of the same birds in the fall revealed the highest incidence of breeding success (pairs accompanied by young) for this group. A number of measures reflecting a good food supply (low pace rate, highest percentage feeding times, and highest number of bites per step) were found to correlate positively with male status supporting the conclusions from the grouped data presented in relation to the grazing sequence. Though a causal relation cannot be proved from such correlations, we interpret these findings to indicate that males of high status can provide their mates with enhanced feeding opportunities, resulting in accumulation of more body reserves in the spring, and a heightened probability of successful breeding. Females subsequently found to prove successful had a larger proportion of Triglochin maritima in their spring diet but a larger sample of droppings will be needed to substantiate this hint of a difference of diet in birds of the same flock

Review and principles of PPP-RTK methods

PPP-RTK is integer ambiguity resolution-enabled precise point positioning. In this contribution, we present the principles of PPP-RTK, together with a review of different mechanizations that have been proposed in the literature. By application of S-system theory, the estimable parameters of the different methods are identified and compared. Their interpretation is essential for gaining a proper insight into PPP-RTK in general, and into the role of the PPP-RTK corrections in particular. We show that PPP-RTK is a relative technique for which the ‘single-receiver user’ integer ambiguities are in fact double-differenced ambiguities. We determine the transformational links between the different methods and their PPP-RTK corrections, thereby showing how different PPP-RTK methods can be mixed between network and users. We also present and discuss four different estimators of the PPP-RTK corrections. It is shown how they apply to the different PPP-RTK models, as well as why some of the proposed estimation methods cannot be accepted as PPP-RTK proper. We determine analytical expressions for the variance matrices of the ambiguity-fixed and ambiguity-float PPP-RTK corrections. This gives important insight into their precision, as well as allows us to discuss which parts of the PPP-RTK correction variance matrix are essential for the user and which are not

Magnetic catalyst bodies

After a discussion about the importance of the size of the catalyst bodies with reactions in the liquid-phase with a suspended catalyst, the possibilities of magnetic separation are dealt with. Deficiencies of the usual ferromagnetic particles are the reactivity and the clustering of the particles. A procedure to produce more suitable magnetic particles is to deposit a nickel± iron precursor on a support and to obtain small metal particles by reduction. Subsequently the metal particles are encapsulated in layers of graphitic carbon by exposure to methane at 700°C. Exposure to methane at lower temperature leads to growth of carbon fibrils, which can be controlled by raising the temperature. The alumina support is dissolved in hydrochloric acid. The magnetic properties of nickel-iron alloys prevent clustering of the ferromagnetic particles

Distributional theory for the DIA method

The DIA method for the detection, identification and adaptation of model misspecifications combines estimation with testing. The aim of the present contribution is to introduce a unifying framework for the rigorous capture of this combination. By using a canonical model formulation and a partitioning of misclosure space, we show that the whole estimation–testing scheme can be captured in one single DIA estimator. We study the characteristics of this estimator and discuss some of its distributional properties. With the distribution of the DIA estimator provided, one can then study all the characteristics of the combined estimation and testing scheme, as well as analyse how they propagate into final outcomes. Examples are given, as well as a discussion on how the distributional properties compare with their usage in practice

Factoren die de overleving van weidevogelkuikens beïnvloeden

Uit onderzoek naar de effectiviteit van het huidige weidevogelbeheer komt telkens naar voren dat er voor de ontwikkeling van een beter beheer op een aantal punten nog onvoldoende kennis aanwezig is over factoren die van belang zijn voor de overleving van weidevogelkuikens. Die ontbrekende kennis spitst zich toe op de invloed die weer, voedsel en beheer op de conditie en daarmee op de overleving van kuikens hebben. Een deel van de vragen kan alleen worden beantwoord door nieuw opgezet veldwerk, maar een deel kan wel beantwoord worden op grond van nieuwe analyses en bestaande datasets . De belangrijkste uitkomsten van die analyses worden hieronder beschreven

Samenwerkingsproject Frysk Ynformaasjesysteem Greidefûgels : voorstudie

In de provincie zijn veel mensen op de een of andere manier betrokken bij bescherming of het monitoren van weidevogels. Helaas blijkt dat de gegevens die door al die mensen zijn en nog steeds worden verzameld elkaar niet altijd aanvullen. De provincie zou hier graag verandering in aanbrengen en heeft daarvoor een samenwerkingsverband opgericht waarbij alle partijen die weidevogelgegevens verzamelen zijn betrokke