Does Oiling History affect survival, and does this effect interact with seasonal severity?
Methods and Data: Harlequins were captured while flightless in August or September and radio-transmitters were surgically implanted into their abdomens. Once-weekly aerial surveys occurred to document whether ducks were alive or dead. (See Esler’s paper for details and citations regarding censoring). Harlequins were monitored for 26 weeks each winter for 3 years. A priori, years were pooled to allow sufficient power to detect oiling effects. The 26-week winter was divided into three seasons (early [9 weeks], mid [8 weeks], and late [9 weeks]). Thus, there were 6 groups for analysis. 6 Groups (remember which number corresponds to which area/season) • Early Winter – Oiled Area • Mid Winter – Oiled Area • Late Winter – Oiled Area • Early Winter – Unoiled Area • Mid Winter – Unoiled Area • Late Winter – Unoiled Area Data Format There are multiple ways that data can be input to MARK for this analysis. In a model without individual covariates, the simplest way for a known-fate analysis is as
