separating natural and hunting mortality

[Mark Trinder]

Hi all

I'm working on a heavily hunted population of greylag geese, for which some comprehensive analyses have been undertaken (Frederiksen et al, 2004) using Burnham combined live-dead models. I am trying to use the results of this analysis as well as data from a variety of other sources (population counts, partial hunting bag values) to provide parameters for population modelling. Currently the best estimate for survival (as modelled by Morten above) includes both hunting and natural mortality, but in order to explore the impact of changes in the level of hunting it would be nice to be able to partition the mortality out. So, my question is, if we have a combined survival estimate already (Burnham S), is it possible (and permissable) to derive a second survival estimate based on recovery data alone, and thereby find the natural survival rate as: total S/recovery S ?

Or would this approach, a- not work, and b-be statistically invalid?

cheers
Mark