Movement of Individuals Among Populations

questions concerning analysis/theory using program MARK

Movement of Individuals Among Populations

Postby Fish_Boy » Wed Aug 24, 2022 2:48 pm

I have 4 populations that have been studied for ~21 years each. Typically when an individual moves between two populations (e.g., population A and B) I have migrated the encounter history from A to B. However, now I am wondering if it is more appropriate to leave the encounter history from A alone and start a new encounter in B for said individuals. These movements over the long term have been simple movements (e.g., straying) and not effective dispersal (e.g., breeding).

So my questions are:

1) do I continue to move individual encounter histories between A and B?
2) do I leave the individual in each A and B, with encounters unique to those populations?
3) do I start a new encounter for the individual in A and remove it's old encounter from B (using -1;)

Hopefully I have explained my issue sufficiently.
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Re: Movement of Individuals Among Populations

Postby ehileman » Thu Aug 25, 2022 2:32 pm

Not sure what sort of questions you are asking with these data, but assuming you have equal time intervals among sampling occasions it seems to me that keeping one distinct capture history for each animal but identifying what state (e.g., population A, population B, population C, population D or unobserved) an individual was in at the time of a given survey would be the most flexible approach.

Cheers,

Eric
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Re: Movement of Individuals Among Populations

Postby Fish_Boy » Thu Aug 25, 2022 3:09 pm

Eric thanks for the response... Yes for two populations A and B this worked up until recently, however, now A to B is a one way trip. For C and D there is free movement between them so your solution works.

I suppose for A and B the permanent emigration from A can be treated with -1 in the year it is captured in B and start a new encounter for it the immigrant to B?
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Re: Movement of Individuals Among Populations

Postby ehileman » Thu Aug 25, 2022 4:34 pm

Eric thanks for the response... Yes for two populations A and B this worked up until recently, however, now A to B is a one way trip. For C and D there is free movement between them so your solution works.

I suppose for A and B the permanent emigration from A can be treated with -1 in the year it is captured in B and start a new encounter for it the immigrant to B?


In that case, I wonder it may make the most sense to deal with permanent emigration from population A as mortality (i.e, leave the capture histories for the individuals this scenario applies to with pop. A and fill in all the trailing occasions after the last observation for these individuals with zeros). Then treat these individuals as a new immigrant in population B, which they are, and still use the multiple states for fishes from populations C and D. My two cents.
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