On the lookout

Animals in nature must be on the lookout constantly.  In a herd of horses a few individuals can sleep while there are those who stay on the lookout. On the Osprey nest the female is on the lookout 24/7. The male visits only occasionally, and rarely stays any longer. Today he was there and they were cackling loudly. There was something flying above the nest. The chicks are such an easy catch on the bare open nest!