Absolutely. I vaguely knew they had more than a pair but the size of the group surprised me. They make a great exhibit, even if the wind was keeping them indoors most of the time on this particular day. Every so often one popped outside for a minute or two but it soon retreated back!
It's certainly most of the group, but I couldn't swear it was all of them - it was more or less impossible to get the window for long enough to do a proper count!
My little booklet of callitrichids informs me that the usual group size in the wild is typically 4-8 individuals, rarely up to 20. So 10 or so is a big group, but not an unnaturally big one.
I think the smaller captive groups are mostly due to limited availabilty of animals (and/or space!), though in the UK bigger groups are far from unknown - such as the large group of Geoffroy's Marmosets at Chester.
