https://forums.dabasdati.lv/viewtopic.p ... 74#p244574
Post by Simba » 12 Apr 2020 13:54
I just received a request from M.Strazda to post this comment:
GT:
Replica of "Oaks, Acorns, Gaya and Kaupo"
Birds do not live with the same feathers all their lives. They grow, wear out, fall out and grow new ones instead of the old ones. After obtaining the costume of an adult bird, which takes place at the age of 2-3 years (even this is not yet known exactly!), The black stork changes its feathers continuously throughout its life. Storks cannot afford to lose airworthiness by replacing "all feathers at once" (as is the case with some waterfowl species), so the feathers that are important for flying - feathers (large feathers) and angles (tail feathers) are gradually changing. Feather changing is an energetically very expensive process, as are laying eggs (for mom) and feeding babies (for both sexes). Probably, therefore, during the seasons when birds raise their young, there is no intensive change of feathers in nesting places. Rarely does a worn airplane or cornice fall out (and begin to grow back). In the off-nesting seasons, the feather change appears to be more intense in the nesting areas, but the main feather change apparently takes place in wintering areas where there is no other energy stress. One feather appears to have served the bird for at least two, possibly three years.
Feather that is older is less rigid and its ends become finned (because of worn hooks that hold the feather rays together). New feathers have smooth, flat ends. In the years when the birds are under a heavy load (a lot of children and probably not enough food for themselves), the feathers wear out much more
and therefore at the end of the season the bird no longer "looks after itself", even compared to the situation just a few months ago. Between seasons ("this year" compared to "last year" or earlier), part of the feathers have been changed for each adult bird, even if it is the same bird. Therefore, using the visual condition of the feathers (finned ends or not, broken grooves, etc.) as a criterion for identifying a bird is as productive as judging whether a famous singer is still the same person, based on the cut and / or outfit of her costume. colors every time you perform ... So far, there is only one surefire way to determine a bird 's identity - a ring on a leg, whether someone likes it or not.
We saw it with Kati and Karl II. They looked very different at the end of the season. The feathers around the eyes eg...