Apparent survival during the breeding season is lower for non-breeding than for breeding Semipalmated Plovers

For conservation to be effective, limiting factors in the annual cycle of the species need to be identified. We conducted regular resighting of breeding and presumptive non-breeding Semipalmated Plovers Charadrius semipalmatus at a sub-Arctic breeding ground study site near Churchill, Manitoba, Canada, to obtain an estimate of breeding season apparent survival using Cormack Jolly Seber (CJS) mark-resighting methods. Apparent 4-day survival was higher for breeders (0.990, CI_95%; 0.986–0.993) than for non-breeders (0.968, CI_95%; 0.950–0.980). Apparent survival rates did not differ between the sexes. Resighting probabilities for breeders ranged from 0.60–0.80 across the 10 observation intervals. Resighting probabilities for non-breeders were higher than expected, ranging from 0.30–0.55. Annualized estimates of apparent survival for breeders (0.409, CI_95%; 0.279–0.535) were lower than apparent annual survival estimates calculated from annual resighting efforts at the same study population. Given that parents need to take care of their clutch and offspring, they show high site fidelity during the breeding season, suggesting that the low estimates for apparent survival are likely due to mortality. Though these results may be useful to help identify population growth rate bottlenecks using full annual cycle models, additional work is needed to identify causes of mortality.