ENCOUNTER, SURVIVAL, AND MOVEMENT PROBABILITIES FROM AN ATLANTIC PUFFIN (FRATERCULA ARCTICA) METAPOPULATION

Several weaknesses in our understanding of long-lived animal populations have persisted, mainly due to a prevalence of studies of a single local population at the expense of multisite studies. We performed a multisite capture–mark–resight analysis using 2050 Atlantic Puffins (Fratercula arctica) banded as chicks on four islands (colonies) over 24 years in the Gulf of Maine, USA and Canada. Within program MARK, encounter, apparent survival, pre-breeding movement (PBM; annual movements between colonies prior to breeding), and natal dispersal (ND) probabilities were modeled as functions of age, colony, and several covariates. Information-theoretic model selection criteria and estimated model effect sizes were used to identify important effects and select models to estimate parameters. Encounter probabilities were extremely variable (0.10–0.95) and declined annually starting six years after bands were applied, due to changes in resighting effort, and band wear, respectively. Colony-dependent survival probabilities increased to a peak at age six years; arithmetic means from all colonies were: 0.70 for age 0–3, 0.78 for age 4, 0.81 for age 5, and 0.84 for age 6–8 years. Low adult survival (age ≥5 years) may reflect inclusion of breeding and nonbreeding adults in our sample or a bias due to band loss and illegibility. Consistent with a density-dependent prediction, the effect of colony size on survival was negative and acquired strong AICc support. However, this effect was inconsistent with strata effects in competing top models; the latter suggest that survival was lowest on the smallest island. The effects of origin and destination colony and origin colony size in PBM and ND probabilities resulted in important variation in these parameters. As few as 8% and as many as 57% of the puffins that we marked may have bred away from their natal colony, a signal of highly variable philopatry. Consistent with the conspecific attraction hypothesis, ND and PBM probabilities declined as the size of the origin colony increased. PBM probabilities were highest in the age 0–3 period, and these declined quickly with age thereafter. Strong colony and age effects in ND and PMB probabilities identify movement as a critical contributor to local population dynamics at our four study sites.

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