artifactual periodicity - data suitable for ctmm analysis?

[Alex Brunswick]

Hello all. The engagement in this group is awesome, and reading previous posts has really helped me understand this awesome package. I am a total beginner, and apologise if these are questions that are very simple.

I am studying the movement of shorebirds, during the non-breeding season in Western Australia. I followed the vignette and online materials to produce variograms and periodograms. All variograms follow a cyclic pattern similar to this variogram: 

 

I have interpreted this to support a stable daily movement pattern. However, the red diagnostic in the periodogram (below) suggests that this might be artifactual, due to an uneven sampling regime. 

The ensure I was on the right track I plotted the frequency of gps fixes per hour of day and found a daily pattern (due to battery consumption during low light times). 

Scheduled fixes are 6h apart; boost fixes (triggered when battery is high) are as lose as 30 s apart. 

In light of this irregular sampling regime, does it appear that this data is suitable for home range analysis using the CTSP framework? I believe that there are stable cyclic diurnal movements within the home range, between roosting and foraging sites. But, does my irregular sampling regime preclude me from using this package to explore that further? 

Thank you so much for your assistance. I hope to attend one of the ctmm workshops in my area if there is one in the future!

Kind regards

Alex Brunswick

[Christen Fleming]

Hi Alex,

No, this just tells you that the periodogram peaks may not be meaningful.

Best,

Chris