Island Size and Bird Extinctions
In a study of the Krunnit Islands archipelago, researchers presented results of extensive bird surveys taken over four decades. They visited each island several times, cataloguing species. If a species was found on a specific island in 1949, it was considered to be at risk of extinction for the next survey of the island in 1959. If it was not found in 1959, it was counted as an “extinction”, even though it might reappear later. This data frame contains data on island size, number of species at risk to become extinct and number of extinctions.
case2101
A data frame with 18 observations on the following 4 variables.
IslandName of Island
AreaArea of Island
AtriskNumber of species at risk
ExtinctNumber of extinctions
Scientists agree that preserving certain habitats in their natural states is necessary to slow the accelerating rate of species extinctions. But they are divided on how to construct such reserves. Given a finite amount of available land, is it better to have many small reserves or a few large one? Central to the debate on this question are observational studies of what has happened in island archipelagos, where nearly the same fauna tries to survive on islands of different sizes.
Ramsey, F.L. and Schafer, D.W. (2002). The Statistical Sleuth: A Course in Methods of Data Analysis (2nd ed), Duxbury.
V\"ais\"anen, R.A. and J\"arvinen, O. (1977). Dynamics of Protected Bird Communities in a Finnish Archipelago, Journal of Animal Ecology 46: 891–908.
str(case2101) logit <- function(p) log(p/(1-p)) plot(logit(Extinct/Atrisk) ~ log(Area), case2101)
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