Nahrungsökologie des Kormorans
Abstract
Great Cormorants inhabit coastal and inland freshwaters preying on fish, their main food source. In the Alpine foreland these birds initially were only overwintering, nowadays they have also established breeding colonies there. Although the feeding ecology of cormorants has been examined previously, important issues such as the actual spectrum of fish prey, and temporal, spatial or sex-specific variations in their feeding habits remain poorly addressed, mainly due to a lack of adequate methodology. The current proposal directly addresses these gaps of knowledge for cormorants in the Alpine foreland. Its aims are three-fold: 1. To assess the temporal and spatial variation in the trophic relationship between cormorants and their fish prey for both the overwintering and the breeding period. 2. To determine the characteristics of foraging grounds preferred by Great Cormorants in the Alpine foreland. 3. To examine if and how the feeding habits differ between male and female cormorants. There are five objectives to this three-year research programme: (i) to develop a DNA-based approach for identifying fish DNA in cormorant faeces and regurgitates (pellets) and to compare these outcomes with prey hard part analysis, (ii) to determine the diet of overwintering and breeding cormorants and to track temporal dietary changes in relation to fish phenology, (iii) to provenance the fish prey by analysing ear stones (otoliths) and to examine when foraging grounds are changed and how this is related to fish phenology, (iv) to assess the environmental parameters of preferred and avoided feeding grounds, and (v) to examine, based on molecular sexing of dietary samples, whether male and female cormorants differ in their feeding habits. Using a combination of non-invasive methods, feeding experiments and a two-year field study, this work will provide a detailed picture of the cormorant’s feeding ecology in the Alpine foreland. Aside from their ecological significance, the results obtained will provide a scientific basis for developing new management strategies for cormorant populations in Central Europe. Moreover, the molecular and micro-chemical methodology developed within this project will not be restricted to the analysis of cormorant-fish trophic interactions but it will also provide a new means for studying the feeding ecology of a wide range of other piscivorous vertebrates.
otoliths elemental pattern cormoran pellets mass spectrometry strontium food web
Publikationen
Project staff
Andreas Zitek
Dipl.-Ing. Dr.nat.techn. Andreas Zitek MSc.
andreas.zitek@boku.ac.at
Tel: +43 1 47654-31212
BOKU Project Leader
01.10.2011 - 30.09.2014
Thomas Prohaska
Ao.Univ.Prof. Dipl.-Ing. Dr.techn. Thomas Prohaska
thomas.prohaska@boku.ac.at
Sub Projectleader
01.10.2011 - 30.09.2014