If the bird was just a little poisoned or something, if it recovered it was in a spot that would allow it to fly away if it could. It also was highlighted to people walking that it was an injured animal and nobody would step on it by accident not realizing what it was on the ground.

Predators can still take him/her very quickly. Especially predatory birds. They see it from above. They know that the bird is in a vulnerable position. Easy prey. The best thing to do probably would have been to take the bird home to a safe place, and to help him/her recover.

I hope that the bird recovered and survived.

Have a nice day. All the best. Greetings and much love from Hungary.