Combining band recovery data and Pollock's robust design to model temporary and permanent emigration

Capture-recapture models are widely used to estimate demographic parameters of marked populations. Recently, this statistical theory has been extended to modeling dispersal of open populations. Multistate models can be used t o estimate movement probabilities among subdivided populations if multiple sites are sampled. Frequently, however, sampling is limited to a single sit e. Models described by Burnham (1993, in Marked Individuals in the Study of Bird Populations, 199-213), which combined open population capture-recaptu re and band-recovery models, can be used to estimate permanent emigration w hen sampling is limited to a single population. Similarly, Kendall, Nichols , and Hines (1997, Ecology 51, 563-578) developed models to estimate tempor ary emigration under Pollock's (1982, Journal of Wildlife Management 46, 75 7-760) robust design. We describe a likelihood-based approach to simultaneo usly estimate temporary and permanent emigration when sampling is limited t o a single population. We use a sampling design that combines the robust de sign and recoveries of individuals obtained immediately following each samp ling period. We present a general form for our model where temporary emigra tion is a first-order Markov process, and we discuss more restrictive model s. We illustrate these models with analysis of data on marked Canvasback du cks. Our analysis indicates that probability of permanent emigration for ad ult female Canvasbacks was 0.193 ((SE) over cap = 0.082) and that birds tha t were present at the study area in year i - 1 had a higher probability of presence in year i than birds that were not present in year i - i.