Different survey methods as sampling occasions

[Saolaseeker]

It's suggested on page 162 of 'Occupancy Estimation and Modelling' that it would be possible to use alternative survey methods as equivalent to repeat sampling occasions. So k would be the number of survey methods used. I'm wondering if this has ever been tried. Does anyone know or have any thoughts?

[darryl]

It's suggested on page 162 of 'Occupancy Estimation and Modelling' that it would be possible to use alternative survey methods as equivalent to repeat sampling occasions. So k would be the number of survey methods used. I'm wondering if this has ever been tried. Does anyone know or have any thoughts?

The key is whether the survey methods are independent or not. If all the methods are run concurrently at pretty much the same point then independence may be a concern because if you detect the species in one of the devices, the probability of detecting them in the other devices may be different than if you hadn't detected it (eg the same animal may stumble around and get detected in all devices on the same day). If there's some separation of the devices within the same sampling unit such that it's unlikely to get all device triggered by the same animal then you'd be less concerned about independence.

I know some people have tried it with small carnivore surveys in the US, although they also had temporal replication as well. In that case, Jim Nichols, Jim Hines and Larissa Bailey have been working on an extension of the methods to account for a form of lack of independence.

Darryl

[rlong]

Hi,

We used multiple methods within an occupancy framework to estimate occupancy and detectability for 3 carnivores. We had 5 sampling occasions with 3 corresponding to surveys of the site with detection dogs (these were temporally separated surveys), and the remaining 2 corresponding to a remote camera and hair snare at the site. The paper was published recently in JWM (Long et al. 2007a; see reference below) along with a second paper in the same issue that just looked at the dog results (Long et al. 2007b). In the papers we do address independence issues to some extent. Both papers dealt primarily with the detectability end of things. A final manuscript is in prep that will report on the occupancy results.

Best,

Robert

Long, R. A., T. M. Donovan, P. MacKay, W. J. Zielinski, and J. S. Buzas. 2007a. Comparing scat detection dogs, cameras, and hair snares for surveying carnivores. Journal of Wildlife Management 71:2018–2025.

Long, R. A., T. M. Donovan, P. MacKay, W. J. Zielinski, and J. S. Buzas. 2007b. Effectiveness of scat detection dogs for detecting forest carnivores. Journal of Wildlife Management 71:2007–2017.