baycheck {UsingR}

Population estimate of type of Bay Checkerspot butterfly

Description

Estimates of the population of a type of Bay Checkerspot butterfly near San Francisco.

Usage

data(baycheck)

Format

A data frame with 27 observations on the following 2 variables.

year

a numeric vector

Nt

estimated number

Source

From chapter 4 of Morris and Doak, Quantitative Conservation Biology: Theory and Practice of Population Viability Analysis, Sinauer Associates, 2003.

Examples

data(baycheck)
plot(Nt ~ year,baycheck)
## fit Ricker model N_{t+1} = N_t e^{-rt}W_t
n = length(baycheck$year)
yt = with(baycheck,log(Nt[-1]/Nt[-n]))
nt = with(baycheck,Nt[-n])
lm(yt ~ nt,baycheck)