Inspired by the pic earlier, today's #BirdsAtTea is the Hildebrandt's Francolin. Restricted to East Africa this attractive #bird is a favourite prey for virtually everything! I've seen them hunted by goshawks, servals & people: so how come they are still common? 1/5 #ornithology

Since everything likes to eat them, the demographics of game birds are well studied. In general, they have relatively large clutches (5-6 eggs for Hildebrant's) https://birdsoftheworld.org/bow/species/hilfra2/cur/introduction . If adults & chicks all survive, after a year we'd average 7.5 birds. 2/5

Obviously, many die: adult survival in francolins is essentially unknown (we know so little!), but let's guess about 40% for similar sized gamebirds https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1474-919X.2001.tb04176.x. That would leave an average of 1.2 adults, so a stable population needs 0.8 chicks to survive. 3/5

The remaining 4.7 chicks per pair are essentially spare: they'll either starve during the dry season, or (mostly!) will be eaten by something. Having larger clutches than other birds is the key to surviving if you're tasty, but also means sustainable harvests are possible. 4/5

The challenge with sustainable use is identifying the sustainable harvest while not depriving predators of their share: a rule of thumb is about half the surplus production, plus monitoring, as most predators are generalists https://www.jstor.org/stable/5465 . Pretty birds to watch too! 5/5