For 3 years now a mallard duck has returned to its nest every spring to lay its eggs. The nest is well camouflaged in a compost area and when sitting on its clutch of eggs it blends in with the background surround and thus very difficult to observe unless you knew it was there. If you pass by it the duck is totally stock still.
Several weeks ago it had a clutch of 9 eggs. Every few days I would carefully pass it by. Then one day the duck was no londger on its nest. The eggs, bright white, were well exposed. I thought the duck might have gone walkabout to stretch its legs... The next day the same situation. On the third day no duck, all eggs intact but two were missing. No cracked, broken or shell remnants in sight. Looking around I saw the dead body of the duck tucked away a feet from the nest. It showed no sign of a violent death or attack by raptor. Given that the eggs had been exposed to chilly nights and windy days I assumed the eggs were passed possible incubation. Several days later I noticed that the remaining eggs had been covered completely with grass/straw and on the top were some downy feathers. On my next visit I was stunned to see another duck sitting on the nest. On my approach it flew away and revealed the eggs in the nest. To my amazement another 6 or so eggs had been laid amongst those of the original eggs. Thus in the nest were about six newly laid eggs together with the orginal 7 "dead" eggs.
Has anyone any explanation for this bizarre series of events
What caused the demise of the original duck
Why cover the eggs and who would have done this
Why lay eggs in a anothers nest when it could have built its own
Could it be that the second duck was in fact the mother of the first batch
How did the original duck die and why were the exposed white eggs not taken by a fox or rat etc etc
Any suggestions appreciated