Age effects and unequal sampling periods in seabirds

[Chris Jones]

I'm looking at analysing a 17-year dataset for a long-lived petrel species that is based on the banding records of a local ornithological society, i.e. it wasn't designed a priori for mark-recapture.

The simplified version is that adult birds have been banded during prospecting/bonding in April and again during the 'egg' stage in July. Chicks were banded at fledging in Dec./Jan. After fledging, birds return at around 4-5 years of age. I'm hoping to construct an 'age' model to estimate juvenile survival, but with adults sampled in, let's say, May and chicks banded in December the sampling periods (columns in PIM) don't line up.

Has anyone encountered this sort of issue before or could someone suggest a way around it, other than estimating a crude 'rate of return at age 4, or 5'?

I've RTFM, but could easily have missed a relevant comment. If I have done so, I apologise, but would appreciate it if someone could direct me to the appropriate section.