University of Natural Resources and Life Sciences, Vienna (BOKU) - Research portal
Gewählte Master / Diploma Thesis:
Stella-Marie Weber
(2015):
„Untersuchung der Reproduzierbarkeit von Präsenz-Absenzdaten von Birk- und Auerhuhn in Abhängigkeit von Habitatstrukturen".
Master / Diploma Thesis - Institut für Wildbiologie und Jagdwirtschaft (IWJ),
BOKU-Universität für Bodenkultur,
pp 68.
UB BOKU
obvsg
- Abstract:
- Analyses of presence-absence data are widely used in wildlife biological issues. Indirect signs like droppings or feathers play a decisive role in the study of wildlife-habitat relationships, especially for those animal species which are hard to observe directly or susceptible to disturbances. The visibility and the detectability of these signs are affected by many factors including vegetation characteristics. Until now, the reproducibility of presence-absence data had been scarcely investigated for Capercaillie and Black Grouse. This study addresses the reproducibility of presence-absence data for Black Grouse and Capercaillie in different habitat structures. For this investigation, proportions of sample plots with indirect signs of presence between 30% and 34%, naturally occurring in Austrian habitats, were simulated by artificially deposing intestinal droppings. Contingency analysis and logistic regression were used to analyse the simulated dropping counts, also considering influence of vegetation characteristics on count data. During the study, a total of 111 Black Grouse faecal samples and 174 Capercaillie faecal samples were exposed on a sample grid. Results showed that out of the 111 Black Grouse faecal samples, 38.3% of droppings on open ground, 26.6% of droppings lying on vegetation and 4.7% of droppings lying under vegetation were retrieved successfully. As for Capercaillie (174 faecal samples) 68.5% of droppings lying on open ground, 82.1% lying on vegetation and 31.7% lying under vegetation were found successfully. Therefore presence -absence data could successfully be reproduced for Capercaillie with a retrieval rate of 62% but were only moderately reproducible for the Black Grouse with a retrieval rate of 28.2% It is evident that the low retrieval rates of droppings lying under vegetation compared with those lying on open ground or lying on top of vegetation illustrate the influence of vegetation structures on data reproducibility. Rich ground vegetation significantly impairs the successful finding of indirect Black Grouse and Capercaillie signs. In the given study, reproducibility of presence-absence data did not differ between experts and novice persons, proving that novices are qualified for pellet count work for both the Black Grouse and Capercaillie after training.
- Beurteilende(r):
- 1.Mitwirkender: Nopp-Mayr Ursula