grazing {GLMsData}

Bird abundance in grazing areas

Description

The density of understorey birds at a series of sites in two areas either side of a stockproof fence

Usage

data(grazing)

Format

A data frame with 62 observations on the following 3 variables.

Birds

the number of understorey birds; a numeric vector

When

when the bird count was conducted; a factor with levels Before (before herbivores were removed) and After (after herbivores were removed)

Grazed

which side of the stockproof fence; a factor with levels Reference (grazed by native herbivores) and Feral (grazed by feral herbivores, mainly horses)

Details

In this experiment, the density of understorey birds at a series of sites in two areas either side of a stockproof fence were compared. Once side had limited grazing (mainly from native herbivores), and the other was heavily grazed by feral herbivores, mostly horses. Bird counts were done at the sites either side of the fence (the Before measurements). Then the herbivores were removed, and bird counts done again (the After measurements). The measurements are the total number of understorey-foraging birds observed in three 20-minute surveys of two hectare quadrats.

Source

Personal communication from Martine Maron.

References

Alison L. Howes, Martine Maron and Clive A. McAlpine (2010) Bayesian networks and adaptive management of wildlife habitat. Conservation Biology. 24(4), 974–983.

Examples

data(grazing)
plot( Birds ~ When, data=grazing)