SwissEagleOwls {AHMbook}R Documentation

Territory-level, multi-state detection/nondetection data for Eagle Owls in Switzerland


Multi-state detection/nondetection data stem from more or less opportunistic surveys in a total of 274 territories of the Eurasian Eagle Owl (Bubo bubo), the largest owl in the world, between 2007 and 2016 (10 years). Sites are all over Switzerland and represent the complete list of sites where a territorial Eagle Owl was ever detected during this period. For site/year combinations with more than 20 observations, 20 were randomly selected for inclusion.

The data set recognizes four observed states: 'nondetection', 'detection of single bird', 'detection of a pair without breeding evidence' and 'detection of a pair with confirmed breeding'; these being the classical criteria of bird atlases for possible, probable or confirmed breeding. For the analysis in the book, the last two are aggregated into a single state 'Pair'.




SwissEagleOwls is a list with 2 elements:


a data frame with a row for each of the 5974 observations and the following columns:

  • site_name : a numeric site ID.

  • year : the year of the observation.

  • jdate : the Julian date of the observation (1 = Jan 1st).

  • y : the observed state: 0 = species not detected; 1 = detection of a single bird; 2 = detection of a pair without evidence of breeding; 3 = detection of a pair with evidence of breeding.


a data frame with rows for 274 1x1km quadrats containing the sites, and the following columns:

  • site_name : the numeric site ID, corresponding to site_name in the obs data frame.

  • region : codes for six regions of Switzerland.

  • elev : the elevation of the center of the quadrat, m.

  • forest : proportion of the quadrat covered by forest.

  • slope : the slope of the quadrat in degrees.

  • roads : total road length in the quadrat, m.


Swiss Ornithological Institute


Kéry, M. & Royle, J.A. (2021) Applied Hierarchical Modeling in Ecology AHM2 - 6.



[Package AHMbook version 0.2.9 Index]