Barn owl diet and prey fluctuations in the Jura mountains, eastern France

Based on pellet collection, the diet of the Barn Owl (Tyto alba) was studied over a 8-year period in the Jura mountains, eastern France, during two population surges of its main prey (common vole, Microtus arvalis and montane water vole, Arvicola amphibius); Small mammals were sampled by trapping and index methods. Results have been published in the Canadian Journal of Zoology (Bernard et al. 2010). Dominique Michelat collected Barn Owl pellets and identified prey items, Pierre Delattre, Jean-Pierre Quéré Jean-Pierre Damange and Patrick Giraudoux sampled small mammals. Patrick Giraudoux managed the data.

Small_mammals_trapping.txt  is the file of the raw trapping results for small mammals (instant abundance index i_t in the article)

diet_smm.txt is a file with:

• the small mammal  density computed by season (d_t in the article, rough estimate of densities in number of individuals per ha for Apodemus spp., Myodes glareolus, Microtus arvalis, or weighted interpolated i_t for the other species)
• the ratios of each category of prey items on the total number of items collected in the church tower of three sites, Levier, Chapelle d'Huin and Le Souillot.

For details see the material and methods of the article.

FILE DESCRIPTION

diet_smm.txt

• date, year and season: year on two digits, then P, E, A, H respectively for Printemps (Spring), Été (Summer), Automne (Autumn), Hiver (Winter)
• at_t, abundance index of Arvicola amphibius (ex A. terrestris)
• ap_t, rough density estimate of Apodemus sp.
• cg_t, rough density estimate of Myodes glareolus
• ma_t, rough density estimate of Microtus arvalis
• sa_t, relative abundance of Sorex spp.
• n_l, number of prey items at Levier
• ma_p_l, ratio of M. arvalis prey items at Levier
• at_p_l, ratio of A. amphibius prey items at Levier
• apcg_p_l, ratio of Apodemus spp. or Myodes glareolus prey items at Levier
• sa_p_l, ratio of Sorex spp. prey items at Levier
• au_p_l, ratio of other prey items at Levier
• n_ch, number of prey items at Chapelle d'Huin
• map_ch, ratio of M. arvalis prey items at Chapelle d'Huin
• at_p_ch, ratio of A. amphibius prey items at Chapelle d'Huin
• apcg_p_ch, ratio of Apodemus spp. or Myodes glareolus prey items at Chapelle d'Huin
• sa_p_ch, ratio of Sorex spp. prey items at Chapelle d'Huin
• au_p_ch, ratio of other prey items at Chapelle d'Huin
• n_ls, number of prey items at Le Souillot
• ma_p_ls, ratio of M. arvalis prey items at Le Souillot
• at_p_ls, ratio of A. amphibius prey items at Le souillot
• apcg_p_ls, ratio of Apodemus spp. or Myodes glareolus prey items at Le Souillot
• sa_p_ls, ratio of Sorex spp. prey items at Le Souillot
• au_p_ls, ratio of other prey items at Le Souillot

Small_mammals_trapping.txt

• date, trapping period: digit 1-2, year; digit 3-4, month. Example: 8704 = April 1987.
• n_traplines_f, number of traplines in forest
• ap_f, average number of Apodemus spp. captured in forest
• cg_f, average number of Myodes glareolus captured in forest
• sa_f, average number of Sorex spp. captured in forest
• n_traplines_hfb, number of traplines in hedges and forest borders
• ap_hfb, average number of Apodemus spp. captured in hedges and forest borders
• cg_hfb, average number of Myodes glareolus captured in hedges and forest borders
• sa_hfb, average number of Sorex spp. captured in hedges and forest borders
• n_traplines_g, number of traplines in grassland
• ma_g, average number of Microtus arvalis captured in grassland
• sa_g, average number of Sorex spp. captured in grassland

SmallMammalSamplingArea.kml kml file locating the small mammal sampling area