crossbillAHM {AHMbook}R Documentation

Data from the Swiss Breeding Bird Survey MHB for European Crossbill from 2001 to 2012


The Swiss breeding bird survey ("Monitoring Häufige Brutvögel" MHB) has monitored the populations of approximately 150 common species since 1999. The MHB sample consists of 267 1-km squares that are laid out as a grid across Switzerland. Fieldwork is conducted by about 200 skilled birdwatchers annually, most of them volunteers. Avian populations are monitored using a simplified territory mapping protocol (also called spot-mapping West of the Atlantic), where each square is surveyed up to three times during the breeding season (only twice above the tree line around 2000 m elevation). Surveys are conducted along a transect that does not change over the years and is 4-6 kms in length on average.

The data frame crossbillAHM has the data for European Crossbill (Loxia curvirostra) from 2001 to 2012.

A variant of this data set for 1999 to 2007 only is included in package unmarked.




crossbillAHM is a data frame with 267 rows and 77 columns:

coordx, coordy

the x and y coordinates of the center of the quadrat; the coordinate reference system intentionally not specified.


the mean elevation of the quadrat, m.


percentage forest cover


the number of replicate surveys planned in the quadrat; above the tree-line 2, otherwise 3.

det011 to det123

1 if the species was detected in the quadrat, 0 otherwise; NA if the corresponding survey was not carried out; the first 2 digits indicate the year and the 3rd digit the survey.

date011 to date123

Julian date of the survey, 1 = 1st January; the first 2 digits indicate the year and the 3rd digit the survey; NA if the corresponding survey was not carried out.


Swiss Ornithological Institute


Kéry, M & Royle, J.A. (2021) Applied Hierarchical Modeling in Ecology AHM2 - 4.



# Extract data as site x survey x year arrays
ytmp <- as.matrix(crossbillAHM[, 6:41]) # matrix of detections
y <- array(ytmp, c(nrow(ytmp), 3, ncol(ytmp)/3))
datetmp <- as.matrix(crossbillAHM[, 42:77])  # matrix of Julian dates
date <- array(datetmp, c(nrow(datetmp), 3, ncol(datetmp)/3))

[Package AHMbook version 0.2.9 Index]