Maybe this paper can come in handy for this case

http://www.cof.orst.edu/leopold/class-reading/Lima%201998.pdf

Regards

If the predator population is negligible, are you sure that Lotka-Volterra is the best way to go, since it is meant to explicitly model competition and/or predator-prey dynamics?

If you are trying to model population dynamics in a system where there is negligible impact from predators (or competitors), perhaps just a basic Leslie Matrix approach would be more appropriate.

However, assuming these ungulates are relatively long-lived, do you have a lot of historical data on the system? If you are just starting to collect demography data on a long-lived species, especially ones who reproduce repeatedly, year after year, it could take you a lifetime to collect enough data to really have an appreciable understanding of their population dynamics.

I agree with Kevin that about the use of a Lotka-Volterra model for a predator-prey system that is really just a prey system (i.e. the predators are negligible.) A matrix model would probably be the simplest way to go, though the modern usage of matrix models (such as those used by Tim Coulson and others) are far from simple. Perhaps you could clarify why you want to use Lotka-Volterra?