Concealment from predators drives foraging habitat selection in brood-rearing Alpine black grouse Tetrao tetrix hens: habitat management implications
Natalina Signorell, Sven Wirthner, Patrick Patthey, Rebekka Schranz, Luca Rotelli & Raphäel Arlettaz
Declines of Alpine black grouse Tetrao tetrix populations have been linked to increasing disturbance by recreation and degradation of breeding habitat due to changes in land-use, especially abandonment of traditional farming practices. Appropriate forest, shrubland and grassland management may mitigate the negative effects of land abandonment. The habitat associations and trophic requirements of brood-rearing Alpine black grouse hens were appraised to inform effective habitat management policies. We measured the abundance, biomass and phenology of arthropods, a key food source for grouse chicks, in eight timberline habitat categories and performed a habitat selection analysis based on radio-tracking data collected from eight brood-rearing hens in the Swiss and Italian Alps. Arthropod biomass differed significantly between habitat categories and peaked in early summer due to a sharp increase of orthopterans (Saltatoria), an essential food source for Alpine black grouse chicks. Open grassland and grassy shrubland yielded the highest arthropod biomass, with Saltatoria dominating the sample. Yet, brood-rearing hens avoided open grassland opting for a mosaic of grassy shrubland with scattered trees. Chick-rearing hens apparently traded-off food abundance for reduced predation risk, i.e. habitats offering cover for concealment and escape from predators. These specific black grouse breeding habitat requirements inform about habitat management within Alpine timberline ecosystems. Managers should not restore extensive, homogeneous pasturelands. Instead, a complex heterogeneous habitat mosaic, consisting of patches of grassland and shrubland interspersed with scattered coniferous trees should be promoted.
Key words: Alpine timberline ecosystems, arthropod phenology, black grouse, breeding habitat selection, food abundance, habitat management, species conservation, Tetrao tetrix
Natalina Signorell, Sven Wirthner, Patrick Patthey & Rebekka Schranz, Institute of Ecology and Evolution, Division of Conservation Biology, University of Berne, Baltzerstrasse 6, CH-3012 Bern, Switzerland - e-mail addresses: natalina.signorell@bluewin.ch (Natalina Signorell); sven.wirthner@wsl.ch (Sven Wirthner); patrick.patthey@iee.unibe.ch (Patrick Patthey); re.schor@gmail.com (Rebekka Schranz)
Luca Rotelli, Parco Naturale Veglia-Devero, Viale Pieri 27, I-28868 Varzo, Italy - e-mail: l.rotelli@alice.it
Raphaêl Arlettaz, Institute of Ecology and Evolution, Division of Conservation Biology, University of Berne, Baltzerstrasse 6, CH-3012 Bern, Switzerland, Swiss Ornithological Institute, Valais Field Station, Nature Centre, CH-3970 Salgesch, Switzerland, and The Ecology Centre, University of Queensland, St Lucia, Queensland 4072, Australia - email: raphael.arlettaz@iee.unibe.ch
Corresponding author: Patrick Patthey
Received 2 April 2009, accepted 10 February 2010
Associate Editor: Ilse Storch
Wildl. Biol. 16: 249-257 (2010)
DOI: 10.2981/09-028
© Wildlife Biology, NKV
www.wildlifebiology.com
View (subscription only) or buy this article at: 