My knowledge in statistics is horrifyingly rusty and I was wondering if anyone here might give me a hand.

I need to make a reasonable estimation on the absolute number of individuals in a population. The data I have available is the number of animals shot per year and the number of traffic accidents per year; data on how many is lost per year in disease and so on is available, but all observations indicate that human activities by far are the most significant factors in reducing the population.
Now, the population has been spreading at a very fast rate, most notably the traffic accidents have increased substantially in the last few years and the increase per year is also increasing. The reproduction rate per animal is also fairly high, so it's apparent that you'd need to do more than just calculate the percentage increase in animals shoot per year to draw a conclusion as to the winter population. We can call the winter population the net result per year, reproduction is limited to the spring and summer.

To round up, I certainly don't want anyone just giving me a solution to this, what I'm hunting after is good on-line material to read up on skills that might be useful to tackle it. Of course I'm also asking teachers and looking for good books on the subject, but consider yourself part of my internet sweep!
Thanks in advance for any assistance.