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agonzalez

overlapping stationary periods

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Hi everyone,

 

I'm working with data from Thrushes I tagged in their wintering grounds in Colombia. I'm a bit confused with the results from the stationary periods and I'll appreciate if someone can give me some feedback.

 

I attached the first table I got from: stationary.migration.summary(Result302_1e6, prob.cutoff = 0.1, min.stay = 3)

 

Mi first question is why would I get a stationary period when the period of stay was 0 days. Like in periods 4 and 14 in the table.

 

I got three periods during the breeding season (5,6,7). However the date of the three periods overlaps at some point. Here I'm not quite sure about the

departure/arrival during those periods or length of stay. Any advice?

 

When I plot the utilization distribution for the breeding grounds using the dates of period 5 I get two separated areas in the breeding grounds; one around period 5 and another around period 6 (north from 5). I believe this is because period 5 overlaps with period 6 but not sure what to do here...

 

Many thanks!

Ana

 

 

 

 

 

 

Summary stationary periods_Thrush 302_July 11 2017_Ana Gonzalez.docx

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  Hi Ana,

 This was not a bug this is just how function works. So I would not weight these resutls too high.

 

  When bird moves slowly points overlap a lot and function produces strange results. It is possible that there were additional stops on the way, but it is hard to tell for sure as there is strong overlap in locations.

 

  I would suggest you exclude all these short stops from the results, or make inference with 50% particles crossing some latitude.

For the breeding you can just select the area and find arrival times with find.times.distribution(Result, Spatial.Index)

 

   Hope it helps

And - if you have ideas on how to implement summary in a better way - let me know.

Cheers  

Eldar

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  Hi Ana, looks like a bug in the stationary.migration.summary(). Could you please send me the result object and I will try to debug the package (PS I am almost offline now, so do not expect much before early August).

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Hi Eldar,

 

Thanks so much for your reponse! I think you're right, this bird was moving quite slow and that might be why I got strange results.

 

I ended up using the results from "stationary.migration.summary" to help visualizing potential "long" stopover sites and then used "find.times.distribution" to determine arrival/departure from

stopovers, wintering and breeding sites. 

 

I just run another bird that migrated way faster and got way better results from "stationary.migration.summary". For dates inferences I'll use  "find.times.distribution" anyway as you suggested.

I also notice that the dates we get are the median dates... 

Thanks again!

Ana

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