Which supports can jungle effectively? We've seen Soraka jungle on ggChronicle tournament, which was doing pretty well. Allistar jungle is actually common, but what else? What do you think about Janna ad jungle? Or maybe even Taric?
A number of the supports have the ability to clear the jungle successfully.
Stonewall008's Jungler Tier List (Fiora Edition): (Note this link has all jungling characteristics so you can see their indvidual traits)
God Tier – Lee Sin, Udyr, Skarner, Trundle, Maokai, Nocturne
Tier 1 – Shaco, Rammus, Shyvana, Alistar, Jarvan, Dr Mundo, Nautilus, Malphite, Amumu, Cho Gath, Gangplank, Master Yi
Tier 2 – Riven, Sejuani, Jax, Xin Zhao, Wukong, Olaf, Nunu, Renekton, Tryndamere, Fiddlesticks, Volibear, Warwick, Fiora
Tier 3 – Shen, Singed, Kayle, Pantheon, Twisted Fate, Janna, Kennen, Blitzcrank, Taric, Sion, Ezreal, Twitch, Soraka, Karthus, Cassiopeia, Ziggs, Fizz, Leona, Heimerdinger, Brand, Eve
Tier 4 – Yorick, Poppy, Karma, Nasus, Gragas, Irelia, Malzahar, Sivir, Galio, Akali
Tier 5 – Viktor, Mordekaiser, Graves, Orianna, Garen, Ahri, Talon, Urgot, Kog Maw
For tiers G to 2 - the placement is more important towards indicating "who is better" but less so for tier 3. In tier 3, just think of it in brackets as the champions here are more flawed and harder to argue. You can say the higher tier 3 are better than the lower tier 3 though. For Tier 4 and 5 it's pretty much wishy washy.
He has a hard CC and an armor reduction which are nice tools for gank attempts. However, He lacks any sort of gap closer.
She has a knockup and a slow which are nice for gank attempts. The shield could help if things go wrong.
I guess she could perform reverse ganks? Bam, healed an ally and then strut back into the jungle?
Once she has her ultimate she might could gank successfully. Before then it would rely on the lane having CC and damage.
He is actually a really popular jungler in Europe. The jungler for CLG.eu, Snoopeh, is known for his Alistar jungler. Here is a video of him playing it.
I couldn't find a video from season 2 with his clear times, but he is an extremely safe jungler. By that I mean, he has good HP throughout his jungle but is not particularly fast since he lacks the AoE abilities of the more popular junglers.
Most of them are vulnerable to being counter jungled since most higher tier jungles have the ability to outduel or escape from them.
Overall, their clear times are horrible when compared to the top tier junglers. For example Udyr with his slowest form, Tiger, has a clear time of 3:40. Phoneix, the most efficient form, clocks in at 3:30. So, no for the most part they cannot jungle effectively.
For any champion to be an effective jungler, there are several criterias that champion have to meet.
To be an effective jungler that can clear the jungle without having to recall every other camp, a champion needs to start out with a relatively decent armor base stat. All the creeps in the jungle deal physical damage and as such, if you armor is too low, you will inevitably take too much damage. For the most part support champions do not start with very high base armor. Sona for example only starts with 8 + 3.3/lvl armor.
Another trait of an effective jungler is having sustained and/or aoe damage to take down the creeps quickly. These junglers will usually focus the biggest creep in that camp and usually by the time they have killed that big creep, the aoe should have mostly killed the smaller creeps. Think about Riven, Shyvanna, Rammus, Amumu for a moment. Supports for the most part will be unable to deal enough damage to be able to clear the camps fast enough to keep up in gold and exp and still be able to gank.
Ability to Gank
This I believe is the most important attribute of a good jungler. A good jungler needs to be able to gank well. This means the champions has to have a minimum of 1 crowd control OR have very high burst damage. Usually the crowd control and the damage from the support is not as effective as some of the common jungler.
Of course there are always some exceptions to this. As you have seen, Alistar is a relatively decent jungler. He has decent base armor and his passive gives him AoE damage while his Triumphant Roar will heal him up and give him a lot of sustain. His Headbutt and Pulverize skills are very valuable crowd control that can work very well in ganks.
Soraka, however in my opinion, is a horrible jungler. It's true she can heal up and spam Starcall to clear the jungle. But at level 1, her clear time is pretty horrible. And I can't really imagine what she can actually do during a gank? The best she can do is probably silence someone and provide a tiny slow with red buff. But there are definitely way more effective junglers than soraka.
Besides all the points I have used above, the most important point is the fact that if the support is jungling, the utility of the support is not very well utilized. A support is generally there to provide vision and protect a carry through the use of auras and heals/shields. If you are jungling, noone but the support will benefit from these auras (think Taric's armor boost, Soraka's Magic Resist boost, and Sona's Armor and Magic Resist boost).
If you are purely asking whether a support can do it, then yes, they all can do it. Every champion in the game can do it. They might need an armor heavy rune page and/or the traditional cloth + 5 health pot build, but it can be done. They might even need to get a super leash from their team and go back really early before clearing the jungle to heal.
Now, if you are asking about which supports can jungle well, it kinda depends on what you mean by supports. Support champions have changed so much and many supports no longer provide sustain to their lane really. Nunu used to be one of the best junglers for his counterjungling ability, but since switched to support role. Nunu still jungles effectively, just the counter jungling has decreased with the shorter respawn times of the small camps. Gangplank has been used in every role except AP Carry including support. His abilities still are like an upgraded version of Nunu, without the Attack speed debuff, but his dominance in the solo top role seemed to have made his support days over. Nautilus is another champ that has been seen in support and jungle and top even. I won't bother talking about the medley of champions that were found in the "support role" within blind pick normal games. Incidentally, if you think blind picks are the only "troll" in picking random champs for support, Nhat Nguyen, support player for Epik Gamer has played nearly every single champ in the support role, including support Yorick, support Heimerdinger, and others.