Q: As with hunting any animal, it starts with using the animal's own signs to track them. Fortunately wild pigs, more so than many other game animals, leave a variety of signs as to where they have been and where they might be going. Regardless of how you choose to hunt, it won't be any use unless you've got a general idea of where the pigs will be. The first (and likely the first to come to mind) to look for are pig tracks, hoof prints, in the ground. They are near-circles with a slight indent at the front. You can distinguish them from deer tracks by the deer tracks' pointed end. Tracks going straight up a steep incline are a sure sign of wild pigs; other animals usually climb hills at an angle. Another sign of wild pigs will be their droppings. They come in clumps, with the size depending on the age of the animal. Using a rubber glove, you can examine them for some idea of where the pigs are feeding. Wild pigs often dig into the ground, looking for roots and other plant life to eat. Look out for sizable troughs in the ground, usually many in a small area. Wild pigs will also make indents in the ground near ponds or other still water. If you're near either, look out for what look like artificial holes with splattered water and mud around. If you see trees with bark removed in spots, or find hair on a tree, it's probably a sign of wild pigs; they scratch their itches by rubbing themselves on trees. If you're already an avid hunter of deer or other game, you may have a hunting blind or stand which you like to use. Using a blind to hunt pigs is a viable choice, but not necessarily the best one on account of the pigs' highly mobile nature. Hunting from a blind is good choice, however, if you know the area well. Be sure to have a good spot. Either near an obvious food or water source, you need to set up your stand where the pigs will at some point want to return to. You'll want to be downwind of where the pigs will eventually be, in order to avoid them catching your scent. One of the biggest benefits to hunting from a blind is it reduces the chance you'll have to face a wounded boar. You can use a store-bought pig call to lure pigs that you know are close. The best calls will be those which replicate a piglet's squeal, especially useful when a female is traveling with her young. You can also hunt from a blind by setting up where you think the pigs may be running from other hunters. Perhaps the most traditional way to hunt pigs is to follow their tracks and signs, and take position once you've found them. This is certainly (in theory at least) one of the quicker methods to hunt pigs, as you'll always be on the move unless you have pigs in sight. Provided you're up for a hike as well as a hunt, tracking to hunt may be your best option. Because hoofprints are so vital to this method of hunting, it's best to try and plan tracking hunts after a rainfall. The mud makes for a great environment in which to hunt wild pigs. If you know an area with heavy pig activity, plan a path which makes a circle around this area and move forward with every rotation. Tracking pigs is perhaps the most viable option if you're hunting only with a friend or two. Too large of a group would spook pigs you're trying to stalk. All of the other methods will require some tracking, but this is the only one which requires some surprise. Once you know you're near a group of pigs, do your best to become as quiet as possible. It's best to shoot from a static position for the best (and most humane) shot. Given enough people with the right transportation (some sort of all-terrain vehicle usually), you can put numbers to your advantage when hunting wild pigs. Essentially you'll be spreading out to cover a wider area, as well as provide a greater chance of flushing out any hogs hanging around. Like hunting from a blind, you'll want to have a good understanding of the land you'll be hunting on. This will help you decide just how to organize your group with the landscape. Most likely you and your fellow hunters will spread out in a line, each person relatively far from the next (twenty or so meters). Unfortunately this method won't always result in a kill for yourself, but definitely increases the chances of multiple kills significantly. Alternatively, you can have one group of hunters find a spot to sit, stationary. If you know the area of high activity, locate one group on the far side away from the others, and have them push forward in a line to flush the pigs out towards the stationary hunters. More than any other method of pig hunting, you'll need to be incredibly aware of the direction of your shot, and absolutely sure there's nothing but foliage behind the pig you hope to shoot. Shooting a fellow hunter is an unfortunate but not totally unlikely consequence of group hunting. Though not necessarily the choice for beginners (as you'll need a trained dog), hunting with dogs is more likely to yield results. Trained dogs will find the scent of the pigs and track them until they get one cornered; the dogs will bark so that they too can be found, and the pig dispatched. More than the other methods of hunting, hunting with dogs will require a bit of fitness, on account of needing to follow the dogs a bit of a brisk pace. Again, any dog used for this should be well-trained. Specifically, they should know to only chase the pigs and to avoid engaging them no matter what. Wild pigs, especially cornered, can be very dangerous. If hunting with dogs is something you're very interested in, it is possible to find dogs that come already trained, provided you find the right breeder. Consider buying some body armor for any dog you use to hunt pigs. They usually come in a few pieces (one for the neck, torso, etc.); this armor can really make a difference if a dog happens to be attacked directly.
A: Look for the signs of wild pigs. Hunt using a stand or blind. Track and stalk the game. Hunt using your group. Hunt alongside dogs.

Q: Figure out the boundaries of the region for which you want to know the population density. Think about why you want this number. Perhaps you want to find the population density of your country, your city, or your neighborhood. You will need to find the total area of this place: usually in feet, miles, meters, or kilometers. Odds are that someone else has already measured and surveyed this area. Look for census data, read an encyclopedia, or run a web search. Find out whether the area has any set boundaries. If not, you'll need to define them yourself. A neighborhood, for instance, may not be listed in the census, so you'll need to draw the borders yourself. Short of counting the population yourself, you'll need to find an up-to-date record of how many people live in this area. Start by running a web search for the population of the place say, the city of Houston, Texas. Look for the most recent census data for a relatively accurate number. If you are looking for the population of a country, the CIA World Factbook is a good source. If you are calculating the population density for an area that has not already been recorded, you may need to count the population yourself. This might include a colloquially-defined urban neighborhood, for instance, or a population of kangaroos in a section of the Australian Outback. Try to get as accurate a number as possible. If you plan to compare one area against another, make sure that all of your numbers use a common unit of measurement. For instance, if one county is listed in square miles and another is listed in square km, you will need to convert the area of both countries into either square miles or square km. For easy Imperial-to-metric conversions, visit http://www.metric-conversions.org.
A:
Define the area. Determine the population. Balance your data.