VERY INTERESTING INFORMATION by Dr. Māris Strazds
(GT later - done, corrected)
https://forums.dabasdati.lv/viewtopic.p ... 11#p388011
M = mātīte/Female
1.
You CANNOT determine the age of black storks by plumage, including the colour of the head, bill and legs. It is as wise as judging that, say, a person with a crooked/hooked nose is older than a person with a short and pointed nose.
Birds up to the age of 2 can be distinguished by their appearance, but then they don't breed.
2. Technically, a bird of breeding age (which is all the birds in the cameras) CAN breed. The minimum age at which a young F is known to have laid an egg is a full 2 years (third calendar year).
No F in the nest, which is in adult bird plumage, is too young to lay an egg.
3.
A fertilized egg is not enough for F to lay an egg. Most of the weight and volume of the egg is made up of nutrients, which F must "provide" in a very short time. The egg is formed within 48 hours.
If there is not a sufficient amount of high-quality food available at this time, it is possible that the eggs are not formed simply because there is nothing to create them from (but it is known that birds can not nest because they "don't want to", just like people, not all of them have children ).
A good indication of how good F's condition is is the length (and frequency) of her droppings - a well-fed bird has a droppings jet well over 1m long (rough estimate, from photos and webcam images), i.e. longer than her own height.
If everything seems fine with that, then there are probably other reasons for not nesting, which cannot be seen in the cameras.