multi-method models implemented in 'unmarked'?

[Alan Hitch]

Hello all,

I was wondering if single-season multi-method models have been implemented in the 'unmarked' package yet. I know they are in Presence and Mark.  I looked in the package literature but didn't find anything and just wanted to check here to see if I missed anything.

We surveyed for bats with mist net arrays paired with acoustic detectors and would like to model average detectability of each method for occupancy estimates.

Thanks for your help.

Alan Hitch

[Marc Kery]

Dear Alan,

would help to have a cite for the model. Do you mean Nichols et al. (2008) or Miller et al. (2011) ? If the former, then the answer is "no", if the latter then it is "yes" (this is called 'occuFP').

From what you say though I think it's the former. ----  But I wonder whether you can't just put all of your data into a single detection history for each site ? E.g., if you distinguish 10 occasions for mist-nets and 50 for the ARUs, then each detection history would have 60 occasions. You could then define an obsCov "method" that has value 1 for the first 10 occasions and value 2 for the remainder (or else code this two-group comparison as 0/1). Fitting that "method" covariate into p should give you an estimate of the per-occasion p's for mist nets and ARUs. Note that to make them perhaps as comparable as possible, you'd have to define the occasions in the same way for both, i.e., to have the same duration.

Or am I missing anything here ?

Best regards  --- Marc

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[Alan Hitch]

Hello Marc,

Thanks for the response.  You were correct I was referring to Nichols et al. (2008).  Thanks for the suggestion on combining the detection data and scoring each method as an obsCov.  I'll try that.  We structured the sampling design so both methods were surveying for the same amount of time.  They each have the same number of occasions.

Thanks again.

Alan

[gcsadoti]

Sorry, old question, but the multi-method/scale model of Nichols et al. (2008) can be run in RMark. Send me a pm if you need suggestions.

Giancarlo

[Sylvain Reydellet]

Hi everyone, 

I was wondering if there have been any news about the implementation of Nichols et al. (2008) multi-method model in unmarked. If not, @gcsadoti could tou give me any advice regarding the use of Mark ?

Thank you all

Sylvain

[Ken Kellner]

Hi Sylvain,

The goccu() function has been fairly recently added to fit the basic multi-scale model described in Nichols et al. (2008). I think whether this would work for multi-method data depends on your exact experimental design.

Ken

[Sylvain Reydellet]

Hi Ken, thanks for the so quick reply

I have 60 camera traps arranged in a grid, each cell is 1.5 x 1.5km. I'd like to define 4 or 6 cells as a single site. This site would then be occupied by 4 or 6 cameras, which would constitute my different detection methods.

Would it be interesting for the goccu() function ?

Thanks

Sylvain

[Ken Kellner]

Yes I think it would work. You'd have 4-6 of what unmarked calls "primary periods" per site, but rather than thinking of these as temporal replicates, they are spatial replicates (cells). Then within each "primary period"/cell presumably you'd have multiple detection periods.

unmarked will estimate an "availability" probability which would be the between-cell probability of detection, and "detection" probability which would be the within-cell detection probability.

Ken

[Sylvain Reydellet]

Okay I'll try this, thanks.

Even though I'm not sure to see how unmarked will deal with the "primary periods" that are really "primary site".

Sylvain