Influence of the spatial pattern of conserved lands on the persistence of a large population of red-cockaded woodpeckers Original Research Article

Spatial configuration of habitats can affect chances of survival for many rare species, especially those with low dispersal rates or large area requirements. The red-cockaded woodpecker (Picoides borealis) disperses relatively short distances and also requires large blocks of habitat — characteristics that make its populations especially sensitive to the distribution of its habitat across a region. We created conservation scenarios for a large population of red-cockaded woodpeckers based on acquisition of conservation easements on different properties, and we then estimated the probability of long-term persistence using Geographic Information System technology and a stochastic demographic model. We considered four broad conservation scenarios: (1) conservation of only those properties that currently have easements (Status quo); (2) random acquisition of additional conservation properties (Random); (3) strategic acquisition of additional conservation properties (Strategic); and (4) all properties that have red-cockaded woodpeckers gain protection (Total Protection). The data used in the analyses come from the sixth-largest population (ca. 180 groups), which occurs exclusively on private lands in the Red Hills region of north Florida and south Georgia. Chances of survival exclusively on existing easements were low unless large-scale improvements in habitat quality were realized. Easements acquired in random order also did not effectively conserve the large aggregations of active territories important to population persistence. Even when up to 20,000 ha of new easements were added randomly, densities and distributions of active territories generally remained critically over-dispersed. Random acquisition of easements did not approximate the additions of habitat based on biological criteria until 30,000 ha were added and an average of 60% of all clusters was conserved, and even then neighborhood sizes were roughly half the sizes of neighborhoods produced using biological criteria. Alternatively, use of biological criteria to select key properties with a total area <10,000 ha better approximated several spatial characteristics associated with population persistence. Overall, scenarios that provided the highest likelihood of long-term survival conserved core properties and expanded the population on existing easements through habitat improvement and intensive management techniques. This will require ca. 17,000 ha in new easements. We also suggest that management be used to augment populations on existing easements, particularly peripheral regions where populations of ca. 25 territories might eventually be established.