Maybe the males were just easier to catch. Did they ever think of that?
Color, size, and in mammals it might be horns. The females hide in the bird kingdom. The females in predators can be the hunters but males usually dominate. Hunt elk and a cow generally leads the herd and a bull travels along keeping his harem together. I figure the collectors of the specimens got what they could and didn’t worry about human idiocy from the future. JMO