This paper investigates how different prioritizations of species for conservation can affect both the number of breeding individuals that receive protection and the distribution of conservation attention among different types of habitat. I use as a study example three red lists of the avifauna of Kanton Zürich in northern Switzerland. Species are weighted based on their placement in different red list categories to represent
differences in species’ relative conservation value. I examine howtheseweightings affect the number of breeding pairs benefiting from increasing conservation effort. Conservation effort is defined as the number of ranked land parcels that receive conservation attention, be it through habitat enhancement, protection, or other measures. I rank parcels’ conservation value based on the number of weighted breeding pairs estimated
for each parcel.Not surprisingly, the number of category-1, -2 and -3 breeding pairs that receive benefits varies greatly when different red lists are used. Changes in the relative conservation value of species in different categories influences both the number of breeding pairs and the number of parcels to receive conservation attention. The effect of increasing conservation effort on the number of breeding pairs and the proportion of each landscape type receiving attention also vary when different red lists and relative conservation values are used to determine conservation priorities. Use of the ‘official’ red list published by a governmental body (Bundesamt für Umwelt, Wald und Landschaft, Bern, Switzerland) results in more emphasis on conservation in agricultural landscape than did use of either of the other two lists. The process of prioritization of
sites for conservation should evaluate the effects of variation in both the relative conservation value of species and species categorization that may arise due to incomplete data and variation in opinion.