It’s a bird! No, it’s not, it’s a long-legged creature. Oh, But it got wings. Yes, but it runs like usual birds don’t do. Okay, it’s an ostrich.
Either this ostrich was chasing the cyclists or it just wants to keep up with them. But seriously, ostriches can be very aggressive when threatened, and may also attack if they feel the need to defend their territory or young. When attacking a person, ostriches deliver slashing kicks with their powerful feet, armed with long claws, which may result in serious injury.
I’m only glad that ostriches don’t have bicycles. Imagine how fast they’d go if they had one!