Modeling the Local Abundance of Shorebirds Staging on Migration

Four key variables of migration that can be used to model the abundance of shorebirds at staging areas during an autumn or spring migration are described. They are Overlap, the average time birds stop over at staging areas; Compression, the total length of time that the migration takes; Volume, the total number of birds that pass through on migration; and Residency, the number of birds "resident" during the nonbreeding season. An iterative method is described that uses the four variables to estimate the total number of shorebirds staging during the course of a single migration. While specifically applied to shorebird migrations, the model may also be used to model the dynamics of any animal population stopping over at a staging area on migration.