Recce is a way of conducting surveys without using a random design. So the good thing about them is they are easier to travel to / along, but the bad thing is they do not necessarily have a design associate with them, so inferences from them might be harder. There are papers comparing or at least including both recce and random transects. An example:
Morgan, D.; Sanz, C.; Onononga, J. & Strindberg, S. Ape abundance and habitat use in the Goualougo Triangle, Republic of Congo International Journal of Primatology, 2006, 27, 147-149
Hi, recce is simply a way of getting apriory knowledge about your study area before starting your study. It does not have a statistical apparatus for you to calculate abundance of any species since it is not among any kind of sampling techniques. Even though it is not very statistically sound way, what you could do is, map and mark the whole recce area through GPS and also mark GPS locations of your target animal. You could then calculate the encounter rate as no. of Ind. Per km.