I have population data for 5 years for several species of birds and I would like to know whether the populations are growing, staying stable, or decreasing. I am using R.

So far, what I have been doing is creating a linear model of the count data (or log of the count data) by year and looking at the slope to determine if it is different from 0 and then at whether it is statistically significant (p-value less than 0.05). I think this is reasonable, but since it is technically a time series is there another test that would be more appropriate?

I am not positive that the population counts each year really are autocorrelated so maybe what I'm doing is fine? It is for birds migrating through an area and the number seen each year does not necessarily depend on the number that were seen the year before.

If anyone could provide some advice and if there is another test I should be performing, how to do it in R would be greatly appreciated!

Thanks.