First of all, there's - what? - a couple of hundred of them? Maybe it's the distortion of the square map of Galbar's sphere that's making their territory look bigger, but they must be pretty good at covering all that area.
Their tribal homeland is mainly based around the three sites they consider holy - Lake Grasidar, Old Bark-Tree, and the Solitary Mount. I have no idea how much land those three would take up, but I'm assuming the refined map will give us a better impression. For the moment, take the territory sizes with a pinch of salt - it's just mainly to show what there territory is relative to their sacred places.
Of course, perhaps I'm underestimating their capability. You mention that despite their bulk and propensity for staying together that they can run about as fast as a god damn cheetah for a solid ten minutes and then maintain the speed that might still trip a speed camera in an earthly suburb road.
Cheetah? I was basing their top speed on that of the extinct short-faced bear, which could go at speeds of 70 km/h. Cheetahs go at far faster than that, if memory serves me right. The top speed of a Treemind is 60 km/h
I mean, these guys have a lot of energy to be able to do that, I'm sure. They must work pretty hard for all that energy as well, seeing as it's frowned upon for them to kill animals. Those hunters have their work cut out to feed those meat-hungry folk.
It's only frowned upon for them to kill animals in the tribal homeland (see two inner circles on map), but it is permissible to hunt and kill on the hunting grounds. The hunting grounds are not considered part of the sacred homeland.
On the topic, what improves if one of these guys becomes a hero?
'All Heroes are, given potential conditions particular to individual gods, immortal' - All Treeminds are, unconditionally, mortal. Their life expectancy being 140
'All Heroes are impervious, to varying degrees, to attacks, poisons and magic' - All Treeminds are vulnerable to attacks, poisons and magic, with their fur semi-protecting against cutting strikes
'All Heroes have extraordinary strength, speed and stamina, the extent of this depending on their god and level' - Treeminds are bears and have similar speed, strength and stamina to bears. A level 1 hero is leagues and bound beyond them (see: Allure jumping hundreds of miles in one step).
'All Heroes can cast magic, the type and their proficiency with it depending on their god and the Hero's level' - Like most species, Treeminds have magical potential, but only Tree-Walkers actually practice it. Their magic is restricted to medicinal herbology. Most Treeminds are affected by the magic of the forest, making them around 1.5x faster at processing things than your average human (this is the same for all creatures that live int he Utmost North)
'All Heroes can Bless or Curse individuals, though the power of this grows with level and is not as powerful as a god's ability' - Treeminds can neither bless or curse individuals
'All Heroes can to a very limited extent, mould their direct surroundings to their will - an inherent kind of magic rather than a divine capability' - Treeminds cannot mould their surroundings to their will
'All Heroes can sense people, objects, creatures and gods, unless any of these are concealed, within their 100 metre radius' - Treeminds have the instinct of a bear and their connection with other Treeminds over short distances. They cannot sense people, objects etc. within any vicinity unless they can see, smell, or hear them.
'Moving on, wouldn't it be a little difficult to enforce the taboo on mating between non-parent pairs when they have super-speed?'
It's not a matter of enforcement for anyone, it's a custom upheld by the tribe as a whole. Their worldview makes it near impossible for anyone to even think of doing it. Try to step out of your modern human mentality, and enter the mentality of a Treemind living in the most sacred lands in existence. And their speed really isn't all that super: bears have great endurance, so being able to keep up their top speed for ten minutes is not huge, and their usual running speed is 40 km/h anyway, quite normal for bears. Their running is mainly used for getting from the homeland to the hunting grounds, and only hunters ever go to the hunting grounds.
Look, I understand that you're probably balancing these guys out by having their population being small. It's just that I get the feeling that some choices were made that don't seem to fit a theme or good reason.
Bears actually have a very slow rate of reproduction anyway, so I didn't really need to enforce the taboo. Taboo or otherwise, the Treemind population would be low. I think understanding the animal we are dealing with is important - bears aren't apes. You'll notice with the garinths that they're all about sex - sex for reproduction, sex for fun, sex to get to know each other better, sex because you made me angry and its the only way for us to sort things out again etc. it's a primate thing. Bears aren't really about that life.
do you have particular plans for these bears that tie this stuff together?
I don't think that, when you're creating a species whom you hope for others to interact with and develop ICly, you think of a long-term plot or plan that will make every single attribute of said species make sense. It's more about putting them out there, stating what makes them unique, and developing them. If you feel that the Treeminds are not a race that we can, as a group, really do anything with, then I'll be happy to get rid of them. The world has seen many strange and wonderful creatures over the ages, and many have died off.
Thanks for your detailed feedback though! Glad someone actually read through that xP if anyone has an opinion on them, please say. The fun for me was in creating them, I don't mind putting them to the side now that's over
Edit: I checked the Sheet and realised that I'd written mp/h instead of km/h. Sorry about that, I'm used to miles ^^'