Introduction
Contrastingly to a solo-top 
Warwick guide, jungle WW relies less on items and defense and more on offense (during the early levels) to maximise his usefulness. This is due to the masteries and runes taken to maximise jungling speed and minimise damage taken from minions. As you will be up against minions rather than actual opponenets, a jungling warwick is far less reliant on farm and items than his laning counterpart. Basically all you need is your ultimate to be an effective jungler as you won't be looking to stand toe-to-toe to fight the enemy team. Rather you will be using 
Infinite Duress to gank opponents, which even if cancelled before completion will effectively be a stun for your teammates to follow.
As such, during your short stay in a lane you want to take as much damage for your teammates whilst dealing maximum damage. Your enemy won't be able to focus you whilst your spending the majority of your time out of sight between jugnles, always moving around the map and this enables you to more agressive in comparison to solo-top WW. Your play-style should reflect this advantage during early and mid game. Late game your role will gradually develop into that of an off-tank, working over the enemy supports or carries.
Masteries
The defensive mastery tree provides the best jungling options in the form of extra armor, reduced damage taken from minions and health. Since minions deal physical damage rather than magic, the magic resist offered isn't your priority. As with most of the junglers and solo-top off-tanks that I play mercury treads are my preferred choice of boots, and the synergy they create with
Juggernaut
will hold you in great stead late game during drawn out teamfights with CC being thrown around left right and centre.
Runes
Your rune setup can further complement your jungle employing both offensive and defensive runes. Unlike my solo-top icon = warwick rune setup, magic penetration is fairly useless for jungling. Armor penetration quintessences will hold you in good stead early jungle and late game. Along with your marks you will be penetrating the majority of the minion's armor in the jungle, making it a quicker jungle basically. Flat armor seals provide defence to the only kind of damage you will be taking during the jungle phase (which is early game hence not armor per level). Finally magic resist per level glyphs are most viable as you won't be needing the magic resist early game, rather the greater per level magic resist.
Summoner Spells
Smite is a no brainer. It is possible to jungle without smite of course as Warwick is one of the stronger junglers in the game. Provides far quicker jungle though and extra gold with the
Summoner's Resolve
mastery.
Pro's and Con's
Self sustaining jungler
Built-in sustain
Not item dependent
Good ganking ultimate
Highly slippery and beefy late game
Weak ganker till ultimate at level 6
Relies on teammates to finish off ganks
Alternative items
Depending on the situation of the game, there are several alternate items which are viable for Warwick. If your team isn't lacking any damage, then selling 
The Bloodthirster, 
Wit's End etc or never buying them is an option. Defensive alternatives include: 
Thornmail for fed AD opponents, 
Warmog's Armor combined with 
Force of Nature for magic resist and excellent health regeneration to supplement your passive. 
Randuin's Omen and 
Frozen Heart are also nice alternatives to nullify AD carries which have gotten out of hand.
In terms of problematic AP carries and CC heavy teams, items such as 
Quicksilver Sash, 
Banshee's Veil and the Warmog's Armor/ Force of Nature combination are worth considering. I haven't tried the new 
Maw of Malmortius however from reading the stats on it, it seems viable also.
When it comes to improving your damage output (if your team is lacking damage) then discarding the early 
Spirit Visage and later 
Guardian Angel are options. Changing boots isn't really an option to 
Berserker's Greaves as this brings me to my other point about going down a more offensive path. Even if your team is crying out for damage, you must temper your response and build accordingly. Using 6 offensive items won't cut it as its too easy to focus down an AD WW, who doesn't pack any escapes or CC other than an ult which will be putting you more in harms way. Wit's End, 
Malady, 
Madred's Bloodrazor, The Bloodthirster, and 
The Black Cleaver are all suited to Warwick, more so than critical strike based damage with items such as 
Infinity Edge or 
Phantom Dancer.
Jungling
1. Begin at wolves by asking your teammates (mid) to damage them, whilst solo-top is watching blue's path for you. DO NOT use your smite on these minions by the way!
2. Follow this up by asking for a leash on blue, smiting the buff-holding golem only.
3. Cross over to wraiths, then on to red and finally 2 large golems near bot lane.
Its up to you when to return and buy, but you shouldn't 'B' unless you have enough gold to buy your 
Boots of Speed or madred's razor or both!!! Wards are necessary, particularly when the enemy team has a jungler capable of counter-jungling or defeating you in a jungle encounter.
After your initial levelling look to begin ganking, always picking an entry point which will both: disguise your approach from both creep waves (pay attention to your own minons' progress along a lane) and the champions themselves, as well as the entry point which will provide you with the most time to close distance. Pay attention to any information your laning partners provide on ward locations and any en masse MIA's as this usually means either a dragon run or a gank on you due to the enemy jungler's warding.
When it comes to counter-jungling personally I enjoy the odd foray into my opposite's home ground, however wards are always useful in maintaing vision and thus safety. Weigh up your own jungle speed and the awareness of their jungler when deciding on counter-jungling routes.
Summary
Thanks again for reading my second guide on Warwick, this time in his more traditional role as a jungling off-tank. More to come :)
Build Guide
Discussion (9)
Cloth Armor for the extra armor bonus is perfect for jungle 
Wriggle's Lantern. Both of which are key items for a quicker jungle and greater dragon control. A note on the lack of health potions taken at lvl 1: using the rune and mastery setup as detailed above will enable you to jungle without any potions (hence saving gold).
Last Whisper which is more suited to 
Riven's and 
Gangplank's.
