Non-independent sites, spacing for variably mobile species

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Non-independent sites, spacing for variably mobile species

Postby katyg » Tue Aug 22, 2017 1:19 pm

I have a design question that involves 4 camera grids separated by a minimum of 150 m ranging to 3.5 km (measured from closest edge of grid). 10 camera stations within each grid are spaced 35-70 m apart. This is part of a larger study on Black Bears, where behavior, movement, and habitat use are already being assessed through GPS collared individuals. The primary purpose of the camera data is to evaluate black bear activity in beechnut stands within 1 km of the wind energy development footprint pre- and post-development. Camera data has already been collected for the pre-development phase, from Oct-Dec 2016 and Apr.-May 2017, when bears forage in beechnut stands. My question moving forward pertains to the extremely spatially autocorrelated data inherent in this study design. Given the focus on black bears, there is no hope for independence of sites with camera stations spaced at 35-70 m. I cannot think of a way around this huge violation, except for a complete redesign of the camera grids and spacing, at which point I would be left with just the post-construction data to make use of. This might not be a big deal, since I could always compare data from 2 grids set up in proximity to the wind energy development and 2 grids away from it (in similar habitat of course). Alternatively, could I use the pre-construction data as an index of activity (I am assuming this is similar to use rather than true occupancy) and compare activity levels pre- and post-construction? I am assuming the huge independence of sites violation still makes it impossible to reach biologically meaningful conclusions regarding activity levels though.....I would appreciate any ideas on this! I am trying to think of useful ways that this camera study can supplement the GPS collar data, but am stumped by the spatial autocorrelation, and have trouble justifying another camera spacing that may suffice if the current camera design setup is completely overhauled. given extremely variable food driven movements of black bears (ranging from ~2 - >100 sq. km).
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