Combining MS trapping and telemetry data

[harding]

When I was first learning MARK, an experienced user told me I could use a dot notation (“.”) to merge radio telemetry and trapping data for multistate models. Specifically, there were times when a collared animal was not trapped during a trapping session, but was known to be alive because it was tracked by telemetry. However, because the animal was not captured, its state could not be determined. I used dots in the capture histories to denote this sort of occasion where an animal was known to be alive, but the state was unknown.

Based on a recent posting on this forum, I am now uncertain if this usage was correct. When running models using these histories, I did not get any error messages and the number of histories that MARK read was the same as the number in my input file.

If my usage was incorrect, can anyone suggest:
1) a better means of handling this sort of situation
2) how/if this coding might have influenced my results?

Fewer than 2% of the captures had a dot notation in their histories.

I could have sworn I saw this documented somewhere (in a help file, I thought) but now, of course, I can’t find what I thought I read!

Thanks in advance for any suggestions!

[bacollier]

harding,
I saw no one had answered so I thought I would take a shot. For future reference, questions like this is probably best posted under analysis and design questions as it is more general than RMark.

"Typically" the '." notation is used when the sampling was not conducted, i.e., if you are sampling over 5 day period and you don't get to point 4 one day, then you ch=101.1

I don't think that you did anything wrong, as your question is based on individual state (reproductive status, etc. I assume) and your use of the '.' notation acknowledges that you did not have state info for that time frame. I would not expect any MARK errors as the '.' just means not sampled, so MARK should not throw an error.

Now, as for how it might influence your results, not sure. Since using the '.', you did not technically sample in MARK parlance that individual during that occasion, so basically you did not collect any data. Now, how the telemetry data works in here I don't have a clear view of, but using the dot should not bias your estimates of state transitions imho and I don't think it will have too much impact on precision (unless, of course, the individuals with '.' are all due to difficult access or something like that).

Maybe this will spur additional discussion, especially if I am wrong

[harding]

Thank you for the response. Jeff Laake also discussed this with me off site and I believe I understand the correct usage of the dot notation now. FWIW, I reran the analysis without the dot notation (put 0's in place of dots and changed a collared group from Y to N so that p would not be fixed for those individuals) and found that although estimates for S and Psi changed some, the changes were very minor (at the 3rd or 4th decimal place for model averged estimates).

The telemetry data was primarily intended for a spatial analysis, but I incorporated what I could from that into the capture histories because it seemed a waste not to use all the information I had available for those individuals which were collared. Collared animals were all adults because they had to be heavy enough to wear collars, but other than that there were not any differences between collared animals and the general population.

Thanks again for the response. I was a bit horrified to think I had made an error, but very much relieved to find it didn't change the results in any meaningful way!