An Assessment of Species-Area Relationships Using Ornithological Data

Summary

The concept of species-area relationships is reviewed, and a few models are discussed. Data on Royal Society for the Protection of Birds reserves (woodlands, islands, other habitats) fit the most frequently used model S = CA^Z where S is the number of species, A is the area, and C and z are positive constants.

An analysis of British Trust for Ornithology data for 30 woodlands over five years show no significant year to year variation in the species-area relationship. It is suggested that one of the most important factors in determining the constant z of the species-area relationship is the amount of time spent by the recorders in a wood during their Common Birds Census. Lack of time has probably led to incomplete sampling of larger areas.

What relevance does the species-area relationship have in studies of birds or their conservation? It is argued that the relationship is probably of more theoretical than practical importance, though it may be useful in thinking of conservation strategies.