General doubts

[Angelica]

Hello,

I am just starting to get into the SECR world and some doubts have released. I am analyzing an ocelots data from a camera trapping survey with a single station array. The photographs were grouped according to the side of the animal (right or left) and this is the information: Right side = 39 occasions, 7 captures, 4 individuals; Left side = 35 occasions, 12 captures, 10 individuals.
1.Each size was considered as a session, is this ok?
2.Can I choose the same buffer in both sessions?, the trap layout is the same, but the RPSV is different (right side = 10778.9 m; left side= 8301.5 m)
3.I know I am analyzing small sample sizes, then I have to choose the appropriate model based on the AICc criterion. However, when I run the ML SECR model for each “session”, the AICc criterion was calculated for the left side but not for the right one. Does this means the right data is better than the left one? Do I choose only the right data to continue the analysis?
4.When I use the IP SECR model, it just doesn’t work, the results are NA for all the parameters.
5.What should I do when I have more than 150 occasions? Can I run models with more than 150 occasions in secr R?
6.About secr (R), where should I save my trap layout and capture data files? I haven’t been able to select the directory.

Thank you for your attention, any help will be very useful.

[murray.efford]

Hello Angelica
I'm afraid you do not yet have enough data for capture-recapture analysis of any sort. Lack of 'recaptures' (only 3 right, 2 left) explains the behaviour of AICc and IP SECR. There is no reason to use IP SECR with photographic data.
1. This might work, but violates independence assumptions and has not been tried before, to my knowledge. Combining data from left and right sides is not an option in secr just now (I do know people have been developing nonspatial methods for this, and an option may appear in secr next year, but to use it you would need more data).
2. Yes - the buffer width just has to be big enough, and 40000m would do for both.
3. See above. You cannot expect sensible results without more data.
4. See above.
5. There is no hard limit on number of occasions in secr, but for clarity you may want to combine occasions with reduce.capthist (e.g. myCH10 <- reduce(myCH, by = 10)).
6. setwd()
Murray

[Angelica]

Prof. Efford,

Thank you for your response, mine a little late but very grateful.