Hello,
I'm using camera traps to estimate the abundance of male white-tailed deer. The plan is to use the branched-antler pattern of male deer as distinct natural marks and analyze the data in a mark-recapture framework. Here is the problem: Some photographs are too poor of quality to use in the analysis: You can tell the animal has branched-antlers (e.g. carries a unique mark); however, the photo is not clear enough to evaluate whether the individual is a new individual or a recapture.
In the literature, it appears that where researchers are relying on natural markings and encounter this problem they exclude those photographs that are ambiguous. This approach seems problematic. You are either throwing away recaptures or worse, initial captures of unique individuals.
Are there analytical solutions for dealing with photographic data where you know an animal is marked, but cannot evaluate it's identity. I know the mark-resight methods allow for recording recaptures of unidentifable marks when estimating abundance. However, in the present case, there are no "unmarked" bucks. They all have antlers. I also know some closed-population models allow you to introduce a parameter to account for misidentification. However, I don't believe this solves the current problem.
In short, I'm looking for a mark-recapture analysis that accounts for records of unidentifiable marks.
Thanks,
mark