Diet selection of lesser white‐fronted geese Anser erythropus at a spring staging area

• Published in: Ecography
• Main Authors: Markkola, Juha, Niemelä, Marika, Rytkönen, Seppo
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2003
• Subjects: Anser erythropus; lesser white-fronted goose
• Online Access: http://dx.doi.org/10.1111/j.0906-7590.2003.03576.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.0906-7590.2003.03576.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.0906-7590.2003.03576.x

We studied diet selection of the globally threatened lesser white‐fronted goose Anser eythropus at a spring staging area on the island of Hailuoto (64°00′N, 24°45′E), off the western coast of Finland. We determined the diet using droppings, which were collected in late May, when the geese had left the area and migrated northwards. The sample potentially comprised of ejecta from 31 different individuals. Plant idengification was based on visual determination of epidermal fragments. A total of 100 droppings were sampled using a point quadrat method. We calculated the percentage of each idengified taxon in each dropping and related this to the availability of the corresponding taxon in the meadow. We measured preference for each taxon using Chesson's electivity index (ɛ i ) and tested them by bootstrap resampling. The diet contained 9 taxa of the ca 40 available. Almost all dietary items were Monocotyledons (99.9%), mostly grasses (88.7%) including Festuca rubra (43%), Phragmites australis (30%) and Calamagrostis stricta (13%). Only Phragmites (ɛ=0.73, p=0.000), Festuca (ɛ=0.52, p=0.004) and possibly Triglochin palustris (ɛ=0.70, p=0.125) were preferred, all other species were avoided. All preferred species were quite common and other goose species exploit them too. The lesser white‐fronted geese preferred large natural meadows that were five times broader than an “average” Bothnian Bay meadow. All forms of mowing and grazing management benefit the restoration of lesser white‐fronted goose habitats at the landscape level. Festuca and especially Triglochin benefit from such management. Reeds, Phragmites , whose spread has been the main cause of coastal meadow deterioration, can be controlled by management, but can also be maintained among other vegetation if mowing is less frequent or grazing not too intensive.