We have come across this issue that there really is not a way to perform seasonal comparisons among low resolution (i.e. telemetry) movement data in a quantitatively rigorous manner (for example people often use seasonal MCPs).
Does anyone have ideas for how to compare low resolution movement data correctly between seasons or at least eliminate this issue from the literature?
Hi Colin,
How low-res are you talking? One thing our lab has considered in this case is to focus on landscape use (eg. area explored) as opposed to movement metrics (like distance traveled) because the area exploration will be less affected by the resolution of the dataset, particularly if you are using a convex hull algorithm.
Hi Matthew Montana McIntosh Good to hear from you! So we are typically seeing in the reptile telemetry literature folks are collecting variable time-lags between points between once per day to once per week. A lot of the data is inconsistently collected which is concerning to me. But let's use our work on king cobras as an example of on average 4 pinpoints per day spaced out throughout the diurnal hours of 0600-1800 as a starting point for the discussion since that was where my mind originally went when thinking about this question. If we wanted to say answer the question "do king cobras cover more area during breeding seasons?" which is inherently linked to "do king cobras move more in breeding seasons?" Do you think area explored is the right way to go about it?
Hi Colin,
Sorry for the slow reply -- I've been thinking a lot about your question. I study cow behavior and have seen others use area explored in the event of variable GPS time-lags. I think you'd find a lot in the literature about large ungulates that deals with this problem. That said, I think it would still be applicable to your cobra example in that you are tracking multiple snakes for multiple days throughout the breeding season (and perhaps across years, too?); I suspect that a daily MCP calculation for four fix locations per day between 0600-1800 would exaggerate the area explored, but would also offer a consistent metric between each snake and season. This way you could average the MCPs per season to see their general area explored. I think you could make a solid argument that a larger area explored would be facilitated by moving more. There is always the case that the animal is moving a lot in a small area and this would be the hardest thing to rule out, but I can't think of another metric that would account for the time-lagged dateset.
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