No recaptures within sessions

[quokkasRcool]

Hello,

I am trying to run density analysis with Density 5.0 using ML SECR.

I am using trapping data for quokkas trapped at eight different sites and at each site, I have trapped for eight sessions (seasons) with four occasions within each session.

My problem is that in some of my high density sites, I have no recaptures within some of the sessions (eg. Grassland 2, session 4), and I keep getting the message "No data for initial values", when I try to analyse the data.

I have set the minimum number of recaptures to 0 in ML SECR Options, and I have also selected between sessions model on the ML SECR page.

I was wondering if there is any way I can run a density analysis of sessions with no recaptures at all?

Thank you very much for your time.
Regards,

[murray.efford]

Hi QuokkasRcool

I can't remember right off how Density handles multisession data with no recaptures in some sessions, but it should be possible to fit this model. Have you tried setting starting values manually? (Select manual initial values on the Options | ML SECR page). If it's only a problem with initial values that should fix it.

Incidentally, in the soon-to-be released version 2.9.5 of the R package 'secr' you can nominate the session X that will be used to compute initial values (details = list(autoini = X)), and a pre-release version is on the Density webpage.

Murray (my real name)

[quokkasRcool]

Hi Murray,

Thank you so much for your fast response and for your help.

I will give that a try and see how we go.

Thanks again.

Veronica.