Morphologie einiger Zweigsänger (Aves: Sylviidae) Nordasiens

Morphologische Daten von Zweigsängern Sylviidae sind nur spärlich publiziert. Basierend auf Beringungstätigkeit in drei Regionen Nordasiens (Ussurien, Baikalsee und Zentralkasachstan) präsentieren wir Flügellängen, Teilfederlängen der achten Handschwinge, Tarsuslängen, Schwanzlängen und Gewichtsmessungen von 27 Zweigsängerarten aus 6 Gattungen. Außerdem zeigen wir flügelmorphologische Profile basierend auf Einzelfedermessungen des Handflügels für 15 Arten aus 5 Gattungen. Von allen untersuchten Arten zeigte der Koreabuschsänger Cettia canturians den rundesten Handflügel, während der Wanderlaubsänger Phylloscopus borealis den spitzesten Handflügel (mit langen Handschwingen 6-8) zeigte. Für einige Arten waren Tests auf Unterschiede in den Messwerten zwischen den Regionen möglich. Wander- und Dunkellaubsänger Phylloscopus fuscatus unterschieden sich nicht zwischen den Fangorten, während am Baikalsee gefangene Gelbbrauenlaubsänger Phylloscopus inornatus kleiner, aber schwerer waren als Individuen aus Ussurien. Auch Klappergrasmücken Sylvia curruca unterschieden sich in Tarsus- und Schwanzlängen, aber nicht in Flügelmorphologie zwischen den Fangregionen Baikalsee und Zentralkasachstan. Die präsentierten Ergebnisse zeigen, wie innerhalb relativ kurzer Fangzeiträume interessante morphologische Daten gesammelt werden können.Data on the morphology of warblers belonging to the family Sylviidae have only scarcely been published. Here we present data on maximum wing chord, length of the 8th primary, tarsus length, tail length and body weight of 27 species (from 6 genera) of Sylviidae. The data are based on ringing activities in three regions of Northern Eurasia (Ussuriland, Lake Baikal and Central Kazakhstan). For 15 species (from 5 genera) we also show wing tip profiles based on measurement of individual feathers of the outer wing. Of all species studied, the Korean Bush Warbler Cettia canturians showed the bluntest wing tip, while the arctic warbler Phylloscopus borealis showed the most pointed wing (with long primaries 6-8). For a number of species we compared morphological measurements between regions. Arctic and Dusky Warblers Phylloscopus fuscatus did not differ in measurements between sites, while Yellow-browed Warblers Phylloscopus inornatus caught at Lake Baikal were smaller but heavier than individuals caught in Ussuriland. Furthermore, Lesser Whitethroats Sylvia curruca differed in tarsus and tail length, but not in wing morphology between Lake Baikal and Central Kazakhstan. The results show how interesting morphological data can be collected within relative short periods of ringing activity

Drift-correction techniques for scale-adaptive VR navigation

Scale adaptive techniques for VR navigation enable users to navigate spaces larger than the real space available, while allowing precise interaction when required. However, due to these techniques gradually scaling displacements as the user moves (changing user's speed), they introduce a Drift effect. That is, a user returning to the same point in VR will not return to the same point in the real space. This mismatch between the real/virtual spaces can grow over time, and turn the techniques unusable (i.e., users cannot reach their target locations). In this paper, we characterise and analyse the effects of Drift, highlighting its potential detrimental effects. We then propose two techniques to correct Drift effects and use a data driven approach (using navigation data from real users with a specific scale adaptive technique) to tune them, compare their performance and chose an optimum correction technique and configuration. Our user study, applying our technique in a different environment and with two different scale adaptive navigation techniques, shows that our correction technique can significantly reduce Drift effects and extend the life-span of the navigation techniques (i.e., time that they can be used before Drift draws targets unreachable), while not hindering users' experience