1) Gruff is the eldest griffin in Griffonstone. As we were made aware in "Hearth's Warming Club", Grampa Gruff had no biological children, which got me thinking about bird biology. There is a South American bird called a rhea. They're polygamous cousins of the ostrich, and basically one male mates with up to twelve females, collects and broods the resulting eggs, and raises the young himself. Griffins could have a similar societal structure where one male is the designated "brooder" and his only job is to raise the kids. Brooders are selected by the other griffins, and they are forbidden to mate so they don't prioritize their chicks over the rest of the society's. Grampa Gruff was selected to become the brooder when he was about Gallus' age after his older brother was selected to be a breeding/soldier male. Gruff was visibly enthusiastic about the job and loved every single chick like a father would. Of course he was jealous of his brother and his parenting style wasn’t exactly positive, but he never lost a single chick beyond circumstances that were out of his control. The dud eggs and stillborn chicks always devasted him. However, as time wore on, and it was apparent that Gruff was the only one that even gave half a shit about Griffonstone, and he fell into a constant state of hysteric denial about how great his hometown really was. He aged to become the local raving, nagging griffon with annoyingly patriotic and repetitive stories. However, everyone tolerates him because he literally raised all of them. The polygamous nature of Griffin society is one of the last remaining aspects of the Old Kingdom and when a crazy, rambling griffin stands as the closest thing to a dad all of the griffins have, it's abundantly clear that the "one-brooder-system" needs to change. Griffonstone is basically an entire people with daddy issues.
Gruff has a slightly more obsessive relationship with Gallus because he was his last chick. Gilda suggested that Gruff finally retire from brooding, and convincing the old fool to do so was extremely difficult. He latched onto little Gallus, and he sees him as his biological son. But of course, being a griffin that has raised generations of children, he's not really sure how to be a real dad. So he just nags and bitches. After all, Gruff is just another result of a hive-like society aiming for efficiency and survival expectancy rather than emotional stability. Love and friendship is just kind of weird to them.
2) Griffon teeth allude me, so I just slapped some lion teeth in a beak. lmao. The problem with teeth is that they are a major hindrance to flight due to their weight, but then again, these creatures are half lion so what can ya do? So here's some biology mumbo jumbo. Griffins have hollow bones, just like birds. Even their lion parts have hollow bones. However, these bones are supported by air sacs and lightweight, fibrous musculature that still allows for flight and a powerful body. Unlike ponies, griffons do not have any sort of magic. No magic stones in their bodies that give them special advantages. They are naturally powerful and fearsome animals that are quite capable when they actually can be bothered to care about something. Now I bet you’re wondering, you fellow nature lovers: how do they do the nasty and make babies? Well, since mating is the one of the few activities the griffins still enjoy (shocker) they put quite a bit of effort into it. They host fertility banquets annually, preform elaborate aerobatic displays and generally try to present themselves as the coolest candidates for passing on their genes. Tsundere is apparently the hottest thing in town. Love is not a huge factor in this ritual, and although there are mated pairs here and there, even they aren’t exclusive. And yes, they have a hybrid reproductive system that develops soft eggs that are easier to pass through mammalian parts. No cloacas around here.
They do eat meat, and fish are their food of choice. Currently they rely mostly on wheat and other grain crops and many griffins in Griffonstone are overweight due to their poor diet.
Griffins formed flocks in ancient times. King Grover unified the flocks after finding the Idol of Boreas, segwaying the griffins into decades of peace and prosperity. However, as we know, the idol was stolen and after King Guto died, griffons lost their motivation to coalesce and became a greedy, unproductive lot. They emphasize material goods.
3) Finally, young griffins are at an interesting place in their lives. Gallus is the youngest male in Griffonstone, and as such, he was slated to be assigned to a role. However, Gilda and Gruff agreed that they would try something new with Gallus as not only a show of diplomacy with the Ponies, but also as an avenue into the new age of their culture. Young griffins go through something called "spotting out" where they molt their downy baby feathers into an intermediate stage of super spotty, frankly uncool and embarrassing, feathers until they finally molt into their mature plumage.
I'll likely add more to this later, but right now it's 4AM here and I gotta go to bed. Tell me your headcanons about griffins! I love these guys in the series, and applying my ameteur knowledge of birds was pretty fun for me!
I’m not sure she’s modeled after any particular bird, but she reminds me of some morph of a Yellow-rumped warbler or Dark-eyed Junco, or if you want to get exotic, a Noisy Miner. I tried finding birds with her main characteristics, but no bird is grey, has a white chin, and a yellow beak and legs.