The moment my heart froze - first, a stranger approaches the nest, causing the female to get up (see above); then, the visitor lands close to the nest, and the female steps on the egg
A curious encounter occurred at 17:40. Before the intruder could be seen, the incubating female braced herself for his visit:
The visitor's feet can now be seen close to the top edge of the picture (don't be misled by the yellow band - la hembra would keep calm if this was el macho):