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 it in the article)

diet_smm.txt is a file with:

the small mammal  density computed by season (dt in the article, rough estimate of densities in number of individuals per ha for Apodemus spp., Myodes glareolus, Microtus arvalis, or weighted interpolated it 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