I am carrying out camera trapping surveys to estimate the abundance and space use relationship of the medium sized carnivore in a protected area. I have done vegetation and ground cover surveys around each camera trap point. I have used 2 sq km grid design for deploying camera traps following the closure assumption of 60 days. I divided the study area into 4 blocks and performed camera traps for 15 days in each block containing 50 camera trap grids each. I have estimated the abundance of individual species for the entire study area using Royle-Nichole’s heterogeneity model using the program PRESENCE. Now to correlate with the habitat or ground cover data with the photographic record of these medium sized carnivores, which parameter should I use? May I use the photo captured rate of individual species captured at individual camera trap points with this habitat values or any other parameter should be considered.
Add the habitat and cover as covariates into occupancy models using PRESENCE. This will estimate occupancy (ratio of occupied sites) for each species modelling each species detectability and will tell you which covariates explain both.detectability and occupancies.
I think exactly as Christian. The occupancy and detection probability can explain the influence of habitat and antrophogenic variables upon distribution and abundance, and at the same time, it could permit detect some survey biases.
Hai, First of all regarding your sampling days, if you sample only for 15 days you tend to miss lot of captures, ie. you will not capture all the individuals in the area. you might worried about closure. if there is a behavioural response by animal for capture your closure test is not valid (read the otis etal papers on closure test). So increase the trapping days to capture all individuals in the area most probably you need to double the sampling period. In terms of habitat factors they broadly influence the presence of these carnivores. at your trap level the capture depends on movement of animals especially the large carnivores so check the capture rate of small carnivores in comparison with other species. Primarily the prey species abundance you might need to do sampling for rodents and other small mammals. this could primarily influence small carnivore movement.. remember Prey and predator avoidance is the key for their survival. regards
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