Allow me to draw you into a scenario a little bit. You've been hunting the Alaskan wilderness for a couple of days now in the early season of mid-August. You're at least a day or so from the nearest road and at least a day from anything that resembles civilization. Its unseasonably hot in the low 60s and maybe hitting a high of 70 at solar noon. The bugs are not too bad this year which means they won't drain a small dog in less time than it took you to read this far into the narrative but you're not going to sleep in the open either. Otherwise you seriously contemplate DEET poisoning as a possibility.
You look into the binos that have chaffed your neck for two straight days and there, just ambling out of the treeline is what you've been looking for- an honest 50" moose at a reasonable distance to launch a stalk. You launch your bid and a half hour later culminate your efforts in the silence between the thunder and the echo. Your comrades (and I do hope you have some along given what a bull moose weighs) pose for photographs with you and your marvelous hard won trophy but little do you realize that deep within that mountain of animal protein a complex biological chain reaction has just started taking place. The timer was tripped the moment this magnificent creature hit the ground and you have no idea how much sand is in the hourglass. Your next efforts in the field will not stop the sand but your actions can slow down the trickle of the grains allowing you to harvest all of this meat and get it safely home to grace your table and fill your freezer.
First things first- by all means pose for those photographs but please keep them tasteful, respectful and don't dally around about it. Once the eye glazes on the animal the photo will look bad- trust me on this. I could digress into a mini-tirade about trophy photo do's and don'ts at this point but I'll pass since we have more important matters to attend to.
That animal lying there is still at approximately the same temperature he was when he was alive and like all mammals has a whole host of wee beasties living inside him. Just because your well aimed bullet ended the bull's life doesn't mean those wee beasties were harmed in the slightest. In warm weather the stomach will start to distend as the flora of the gut continue to thrive upon your quarry's last meal and produce gas as a result. Now that your quarry is no longer farting subconsciously- that gas is building up pressure. Nothing is more difficult and fraught with potential disaster for meat care like attempting to field dress a bigger critter with a drum taught distended gut. So while your buddy puts away the camera, don your gloves and get out the gut hook before its really unpleasant. A lot of folks attempt to put off this step because it really is unpleasant but waiting will not make it more so and the "field dressing fairy" is away on other business. So please- using any method you find convenient, gut that critter.
And while you're gutting that critter do take all care not to rupture things you might find in there- namely the colon, bladder, and the ever expanding stomachs- you don't want any of this stuff on your plate. If you've been practicing your marksmanship and field skills properly the lungs will have been shredded as possibly is the heart. What that means is that you should have an enormous amount of blood in the carcass rolling about. Don't get freaked out but don't dawdle and get that hot blood out of the carcass right after the organs. As an aside, once you dress out a couple of critters that have been gut shot and determine that you'll have a mixture of blood, gastric juices, food matter and (God forbid) fecal material floating around in your carcass you will for darn sure practice your marksmanship in the off-season. This is where the phrase clean comes in but more on that later.
If all that came off right you will have a carcass minus the entrails but still wearing its fur and head. Back on Grampa's farm this is usually where the tractor or the pickup comes rolling up and you load the critter in the truck in the late October frost. But this isn't Grampa's farm- it's the backcountry of Alaska and Grampa's truck isn't coming. That marvelous fur coat your critter is wearing is keeping all that heat in the muscle tissue where a whole host of other wee beasties is starting the process of decay. Those wee beasties are also reproducing and the only way to stop them is cooling and the next step in that process is to get that fur jacket off.
There is more than one way to skin a moose but all of them entail a lot of moving big pieces, heavy lifting and awkward cutting so be careful. I like to take a tarp to spread out on the ground by the animal to lie pieces on and ensure meat doesn't fall on the ground. A real savvy hand can use the moose's own hide to this effect but a $9.00 tarp will work better. With a smaller animal you may be able to hang them whole for the skinning process but moose are too big and caribou tend to live on open tundra devoid of large trees so you'll work on one side, flip, then repeat. Another word about cleanliness- try to keep hair off the meat. Not only is loose hair stuck to meat a real pain when you butcher- it is also generally filthy given what animals will roll in and stomp in during the course of the day. Don't get freaked out by it but do make an effort to prevent it.
After several minutes ( OK a half hour or more) of this you'll have a side stripped clear of hide. Gather up some game bags (also called quarter bags some places) and get them ready. They should be clean and freshly laundered and prepared to have meat placed inside them. Bloodstained is a good sign they've been here before and are thus "experienced" but dirt covered is not. Remove the leg below the knee joint and cut of the quarter at the ball socket on the rear and shoulder on the front. Given the temperature you've undoubtedly attracted a number of flies and other insects by this point. Prior to bagging, spray the meat down liberally with a citric acid solution produced for such a purpose. This does a few things- it changes the PH of the meat's surface and retards bacteria growth, it slows or stops fly larvae development and it promotes "crusting" (that protective layer that forms on meat as the outer layer of meat dehydrates and the proteins leach out. This hardens into a layer on the surface. With a treated quarter placed in a clean bag then you should hang it up to promote airflow around it. Alternatively, place it upon brush so that air flows under it.
By the time you do this for four quarters on a bull moose, you'll certainly be aching and ready to take any shortcut you can. Don't fall prey to such temptations as you'll be rewarded for diligence later. A lot of folks will start boning out the neck and ribs at this point but I'd suggest not. Boned out meat has a lot of cuts and each cut is a potential place that foreign bacteria enters the tissue and promotes spoilage. A ribcage on bone can last several days under some pretty harsh conditions before spoilage sets in but a bag of boned out meat might not make the next sunrise before its turned. Not only that but meat attached to a boned structure (despite weighing more) carries and transports easier than a heavy bag of formless meat that's as impossible to strap down as a water balloon. If you bone out anything the neck meat should go into the "burger bag" where all the odds and ends pieces go but keep them as large as possible. On caribou I generally prefer to haul out the neck whole- a lot of the neck meat is simply wasted if boned out in the field.
So after several hours of backbreaking labor you should have (hung on a pole) 4 quarters, 2 ribcages, a neck, a burger bag, and a bag containing your tenderloins and backstraps hung on the meatpole. The savvy hunter will break camp and depart for civilization immediately but certain circumstances may prevent this (such as air taxi pickup). Rotate the meat in the bags to help promote even crusting and examine the meat at least twice a day and while you're at it- hit it with citric acid solution again for good measure. If it's very warm you might have reconsidered your shot but in case of hot weather submerging your meat in a creek while sealed in a plastic bag may be your only option. Be careful as waterlogged meat is ponderously heavy and very prone to spoilage. Your meat cache should also be protected from sun and rain while getting good airflow. Keep the meat dry.
So the basic rules are clean, cool and dry (where have you heard that before). Some additional thoughts are:
Cool the meat as quickly as possible, on cool weather hunts this is usually no serious problem but during warm weather the core temperatures of large pieces of meat can remain dangerously high for hours; promoting bacteria growth and early spoilage.
Keep the meat from freezing on cold weather hunts. Meat that has frozen in the field will be tougher than the boots on your feet. Those wee beasties working the meat to spoilage are also working it to tenderness. In the beef industry its known as aging but a deep freeze the first night brings it to a halt- particularly in small pieces or meat off the bone. A large quarter can sustain substantial low temperatures without freezing for a surprising amount of time. This process is known as cold rendering. It is something to avoid.
Keep the meat out of the sun. Direct sunlight can heat up the meat and prevent cooling.
Keep meat in the air. I once saw a photograph of a couple of float hunters who had ingeniously wrapped their meat in a blue tarp to keep it dry and I'm sure it worked great to that end. It also kept it a warm, moist mess and spoilage set in the first day. Do what you can to promote airflow around all the pieces. If you use heavy bags you may want to use cool and bug free periods (like during a good breeze) to remove the bag and let the wind blow directly on the quarters.
Use good game bags. I like heavy canvas bags that are durable and will stand up to sharp bones and heavy loads. Draw backs are sheer weight and size. A popular brand of lightweight game bag sold here tends to explode on contacts with pretty much anything and has a weave so generous that even the Jenny Craig flies can get through to work their heinous craft. These should be avoided at all cost unless you have a preference for dirty, maggoty meat. A new, lightweight synthetic gamebag is on the market that may proved the best of the breed for foot hunters but I haven't tried them yet.
Don't be afraid to pass an opportunity if the conditions aren't right. I passed on several caribou this year during some unusually hot and buggy weather. It would have made getting the meat out of the field precarious at best. I waited for a breezy day that hovered at freezing and was rewarded with perfect conditions to harvest my caribou without worry about spoilage or insects. The reward of taking an animal is the meat you carry home and to waste it is shameful in deed and may be criminal in certain jurisdictions.
So there you have an overview of field care of game meat. For a more detailed discussion I'd like to point you to my friend Larry Bartlett's excellent video- Project Bloodtrail as well as some of his other work that deals with proper field care of game meat in a wilderness setting.