Starvation streak
Hunger strip or lack strip ( falknerspr . Grimale , engl. Hunger streaks or hunger traces ) denotes an occasional anomaly in the spring formation of almost all species. The causes of their development are discussed, but generally associated with deficiencies during feather formation.
Hunger streaks are about one millimeter wide, transparent fault zones of the feather, in the area of which the deposition of keratin was impaired during feather growth. The disruption can only partially affect a flag , it can extend over the entire flag, but it can also run over the inside and outside flag. It never runs parallel to the spring branches, but more or less at right angles to the spring shaft . Usually the hook rays are not fully developed in the area of the starvation streak , so that neighboring feather branches remain open. Starvation streaks can form a fracture zone, along the parts of the feather branches lying above or entire feather shafts break off, which in extreme cases can lead to inability to fly. Round fault zones, which are then referred to as starvation holes, are also less common.
Hunger streaks can occur in all bird species, especially young birds. Almost 10 percent of all spotted woodpecker hides examined for this phenomenon showed this feather damage. A temporary lack of food during feather formation is commonly assumed to be a trigger, but parasite infestation or stressful conditions can also play a role as causes. The latter is supported by the fact that a greater percentage of birds that were caught nestling or caught and ringed during juvenile moulting later showed this malformation of the feathers. The most recently hatched young birds also show this feather damage more frequently than their older siblings, which indicates both starvation episodes and states of stress.
Growth stripes, with which hunger stripes are sometimes confused, do not represent a disturbance, but are related to the different rapid growth of the feather during the day and night. Growth strips are not transparent and can only be seen by examining the feather at a certain angle in front of a light source.
Individual evidence
- ↑ Erritzøe (2006) p. 52
literature
- Johannes Erritzøe and Wolf-Dieter Busching: Thoughts on hunger stripes and similar phenomena in bird plumage. In: Contribution. Gefied.kd. Morphol. Vögel 12, 2006 pp. 52-65