This is a Clapper rail screaming at her chicks who were in the grass nice and safe and she wanted them to stay there. If you have ever heard these birds, you will remember it. Besides the loud clapping sounds they are famous for, they also make a more bird like chirp which is also super loud.
Comments and suggestions welcome,
Morris
X-H2SXF500mmF5.6 R LM OIS WR lens500mmf/5.61/1400s1600 ISO+0.7 EV