subspecies identification bias?

[Eldar]

I have marked individuals from 2 subspecies that are not always identifiable and going to model survival of one of them. For some of the individuals we were able to distiguish subspecies on recapture only.
The question is: if we identified subspecies not on the first occasion is it possible to inculde it into the analysis from it's first capture or should we start only from the capture when identification happen?
Thanks,
Eldar

[cooch]

I have marked individuals from 2 subspecies that are not always identifiable and going to model survival of one of them. For some of the individuals we were able to distiguish subspecies on recapture only.
The question is: if we identified subspecies not on the first occasion is it possible to inculde it into the analysis from it's first capture or should we start only from the capture when identification happen?
Thanks,
Eldar

Sure -- see papers by Nichols, Pradel and the other usual suspects on 'uncertain sex' determination (amounts to much the same as what you've described). Capture a bird as young, but sex not known (no sexual size dimorphism, so gender assignment not possible). Catch them later, and determine sex (where sex on subsequent recapture is determined by breeding state or some proxy which is a fair indicator of sex).

For starters,

Nichols, James D., William L. Kendall, James E. Hines, and Jeffrey A. Spendelow. 2004. ESTIMATION OF SEX-SPECIFIC SURVIVAL FROM CAPTURE–RECAPTURE DATA WHEN SEX IS NOT ALWAYS KNOWN. Ecology 85:3192–3201.

[Bill Kendall]

Evan is correct that the unknown sex papers are directly analagous to your problem. For software to analyze such data there is LOLASURVIV (www.mbr-pwrc.usgs.gov/software), or you could use more general tools like E-SURGE or MARK. See my recent comments in the thread on uncertainty in disease modeling for how MARK could be used.

[Eldar]

Thanks, but how would you advice to model only one subspecies (sex)? E.g. we have males and females but we can model males only? - so after identification animal will go in the focus group or outside dataset..

[Bill Kendall]

I'm not sure of the question here. If you can only analyze data for males, then you run males only through the unknown state models (in your case it is unknown subspecies instead of unknown sex). If you have males and females you can treat them as groups, in the usual way.