I was thinking about this days ago. And I wanted to talk about it here a little bit.
Whenever you hear some people bring up the big pack sizes reported in old stories whether it would be in a talk or on some random forum. It might become clear that perhaps a common belief is that if you expanded the habitat and increased the dhole population, you would see packs numbering in the 30s, even 40s. It's even thought by some that neighboring packs will temporarily merge together to create these big packs.
Ecologically speaking though, this is unlikely. Because the expansion of habitat would also mean more tigers on the landscape. The reason this makes dholes being commonly in groups numbering in the 30s is ecologically unfeasible comes down to one factor: Niche overlap.
If dholes were commonly in groups numbering in the 30s, they would have to hunt larger animals and tigers prefer hunting the largest ungulates they can safely bring down when they're available. So hunting bigger ungulates would create a bigger niche overlap with the tiger and thus, increase competition between the two species. For a large carnivore guild to successfully live together, the animals have to overcome the potential issues of competition while having to share the same resource, in this case, ungulate meat. While physical adaptations come into play, behavioral adaptations will also take place. Subordinate predators will either temporally or spatially or do both, avoid the dominant carnivores. Painted dogs do whatever they can to avoid high lion-density areas, even at the cost of having to live in areas with lower prey densities. Cheetahs will also hunt during the day and practice avoidance behaviors that allow them to use high-lion density areas.
Basically, predators (the smaller ones) do what they can to decrease competition with the bigger carnivores. That said, behaving in a way that increases a niche overlap with a larger co-predator makes no ecological sense. By being in smaller packs, the dholes end up preferring smaller prey animals than tigers and thus not only lower the odds of having their kill stolen from them, but it also reduces the nice overlap between the two. And every dietary study in India involving all 3 predators (tigers, leopards, and dholes) shows dholes hunting smaller animals than tigers. And this is probably why tigers have a stronger effect on dhole pack size than prey density does: Because you can higher prey densities with lots of smaller individuals within those populations.
