minimum observations/sample size

[Constance Scholander]

Hello,

I have a few species which I am estimating the density of with the distsamp function in R. One of them only has 8 observations, another has 16 observations. The rest have more.

I thought I remembered reading somewhere a while ago the minimum number of observations using unmarked is 8, but I can't seem to find that again and annoyingly I didn't take a note of it. I was wondering if anyone knows if this is correct, and where I might find a reference for this?

Otherwise the only minimum observation I have to go on is from Plumptre, Sterling and Buckland (2013) 'Primate census and survey techniques', where they state a sample size of 30-40 as a minimum but that is for the Distance software. 

Thanks,

Connie