Hi Mardagosa,
Evan is completely correct that fitting models with time-varying individual covariates is limited in MARK, though there are some options outside of MARK.
If your experiment included recoveries of dead animals as well as the capture of live animals then you
can fit the trinomial model of Catchpole, Morgan, and Tavecchia (2008)(
https://rss.onlinelibrary.wiley.com/doi/abs/10.1111/j.1467-9868.2007.00644.x). Instructions are provided in Bonner (2012) (
https://besjournals.onlinelibrary.wiley.com/doi/10.1111/j.2041-210X.2012.00265.x).
If your experiment did not include dead recoveries then you can still fit this model by setting the recovery probability equal to 0. I call this the binomial model. There are some disadvantages to this model about which I have a manuscript in preparation, but you can do it.
Alternatively, if you are comfortable working outside of MARK then there are alternative methods I'd be happy to chat about this off the list and can provide further help if you want to send me an e-mail:
simon.bonner@uwo.ca.
Cheers!