Missing Data in Mark-Resight IELNE

[mUltra]

I have a question about how to treat missing data. We conducted mark-resight surveys over 12 survey-units to estimate a bear population, using individually identifiable marks. We had one primary interval. We flew five times over 10 units but only four times over the other 2 due to the weather. Bears moved in and out of survey units during this primary interval, therefore we chose the Immigration-Emigration mixed Logit-Normal Estimator in Program Mark, which was also the model that has been used in the past to estimate bear population in the area. In other Mark-Resight models, I believe “missing data” would be entered as “. (dot)”. However in this model, “. (dot)” would make it look like those bears have emigrated from the survey units for the occasion, which would make the study area size for this occasion smaller (5/6 of other occasions). How should we treat these missing data? This model allows adding marks during a primary interval (in between secondary occasions), and we considered entering “. (dot)” and reducing the “Marked Superpopulation” for the occasion. But this would not account for missing data in unmarked bear number. Thank you in advance for your help.