data entry for spatial correlation model

[athimmay]

I'm little bit confused about how to set up the data for the spatial correlation model in program presence. I have read Hines et al., 2010 paper on the spatial correlation model and have searched on this forum, but I am obviously missing some important piece of information that everyone else seems to know about.

About my study: I had 7 transects ranging from 1.5-2.5 km along which I searched for sign at three different times (No. Occ/season = 3). I also measured vegetation characteristics along each transect. The transects were broken up into 30 m sections (each 30 m section is a site in the data form). This seems like a case for the spatial correlation model.

Question: Are each of my transect segments (in the spatial correlation model) actually an Occassion and I can only use information from 1 of my actual visits?
So if I had 50 transect sections I would have 50 occ/season?

Question: If the answear to the above question is no...then how do I input my data so the program knows which segments are adjacent to each other?

Question: Does theta refer to the probability that a segment is occupied conditional on whether the adjacent segment is occupied or does it refer to the probability of detection on a segment if the species was detected on an adjacent segment? In other words, does theta modify occupancy or detection probability?

Thanks in advance for your help!

[darryl]

The 'spatial correlation model' was devised for the situation where the repeat surveys of a 'site' are actually spatial rather than temporal, eg a single survey of a transect, but transect segments are the repeat surveys. Hence you set your data up accordingly with each column being each segment along your transect.

So you could estimate 'occupancy' of your transect separately for each visit using the segments as your repeat surveys, the first main question you need to deal with however is whether that is a biologically interesting question in the first place.

Cheers
Darryl

[ReneeLorica]

Darryl,

How do you set it up if you have 3 observers per survey?

[darryl]

Sorry, I don't understand your question. You need to give some details of your sampling.

[ReneeLorica]

Hi,

Sorry about that. I have another data set wherein the transects were divided into segments, mainly because there is more than one habitat type long a transect so I thought that's ecologically relevant. Each transect was sampled only once during each season but I wasn't sure how to set it up with detection data from 3 observers. If there was only one observer, is this how we should set it up in the Input Data Form?

Segment1 Segment2 Segment3
Transect1 0 1 0
Transect2 1 0 0

But what about if we have 3 observers? Sorry if the question is too elementary. Thanks very much.

[darryl]

Ok, we've gone across multiple threads now, but think I'm starting to catch on.

Did the observer all survey the transect at the same time, or quite different times? What type of species are you working with?

[ReneeLorica]

The way we set it up, each observer walks a different transect until all transects have been surveyed. The time difference between each observer walking a particular transect is just hours.

I'm working with the leopard cat in the Philippines.