Error in sum(fac_random) : invalid 'type' (character) of argument and paired sample size issue

[naalipalo]

I have a dataset that i am struggling with how to approach handling. I have >1500 animals, with 2 samples per individual. The samples come from 2 places on the claw, thus trying to get a seasonal component. However, Im not seeing if there is a way to deal with paired samples unless individual is included as a random effect. I see the alligator example, but I don't have a "continuous" variable to account for a time change between samples.

I was hoping to assess the differences between the two segments of the claw and then if they are not capturing significantly different diets, I only need to use 1 which would reduce the sample size from ~3,000 down to ~1500 and then I could subset out geographic, sex, age, etc. With random effect being ~1500 individuals, this is going to take an exorbitant amount of time to run. Wont it? it will have to create a model for each individual? Am I missing other ways to deal with paired samples? Is there a way to modify the jags model to account for that?

Suggestions on how to deal with paired samples would be extremely helpful