I am running a GAM on species detection data for the first time. I would like to see if there is any interaction between time of year and diel period for both male and female of this species. This is my first time using R so I am just looking for input on the following code for a GAM model/ if this is the right model to use?

> m4 <- gam(res_time_sec ~ s(julianday), data=species, method="REML")
> par(mfrow=c(2,2))
> gam.check(m4)

when I check the output there is obviously more to the story in terms of explanatory variables but I am just trying to get the basics down first!

Thanks a lot!