[R] Mixed-effects model for overdispersed count data?

[Marie-Hélène Hachey]

Hi,

I have to analyse the number of provisioning trips to nestlings according to a number of biological and environmental factors. I was thinking of building a mixed-effects model with species and nestid as random effects, using a Poisson distribution, but the data are overdispersed (variance/mean = 5). I then thought of using a mixed-effects model with negative binomial distribution, but I have 2 problems:
 
1- The only package building mixed models with neg. bin. distribution I found is the package glmmADMB but I have a hard time understanding the output. Anyone knows of a R package with an output that gives p values?
 
2- Two people I asked advice to told me that I should use either a mixed-effect model with a Poisson distribution (the random effects will take care of the overdispersion) OR a glm using neg. bin. distribution but not both at the same time, which would be unnecessary. 
 
Any advice is welcome!
 
Thank you
 
Marie-Helene Hachey
M.Sc. student
Universite Laval, Quebec