I'm trying to modelize the diving depth of birds according to categorical (sex, age class: adults/subadults) and conitnuous parameters (temperature, salinity). The frequecy distribution of this data looks like this: many many many dives between 0-50m deep, some between 50-100m deep and few between 100 and 300 m.

As I have repeated measures on the same individuals, I used linear mixed models to find the best factors that explain the varaibility within the data. To do it, I used the lmer function of the lme4 packages in R program. This is an example of models that was been fitted:

fm2 <- lmer(depth ~ 1 + patch+(1|Ident), data, REML=F)

The figures attaches show the plot of the residuals of the models according to the fited data as well as the normality of the residuals. I wonder if we can conclude that this model respected the assumptions of the linear mixed model.

If not, I am also asking which will be the best model to apply on those data. I look for the poison distribution with a log link function. Which would be a nice idea? If not, waht would you recommand to me?I try to log the data and this not improve the fit of the data.

Thanks in advance, your help, any help, will be appreicated.

Alex.