Spring is the nesting and reproduction period of most of the birds. From each nest on the trees, under the roofs, in the cavities, an incessant pigalio comes out and many small open beaks are glimpsed waiting for food. But where do the feces of the new births end? Birds must keep the nest clean from the abundant dejections that produce their chickens and, in many species, parents take away a real “staff bag” fecal bags, mucous membraneswhite or transparent with a dark termination, which are promptly eliminated by the parents, a bit like it happens for newborns diapers. This strategy, used by most sparrows such as chinses and breasts but also by peaks, thrushes and swallows, allows you to prevent the diffusion of pathogens and avoid the call of any predators.
How a faecal bag is made
Birds do not eliminate urine and feces separately: all refusal substances are expelled in a single semi-liquid solution. THE pulles of most sparrows (scriccioli, cades or breasts), but also of other birds such as peaks, towers, swallows and swallows are able to produce directly in the intestine, of fecal bags more or less oval form that allow you to encapsulate the excrements. In the case of nidiaceans the dejections are enclosed in one mucous membrane, White or transparent with a dark termination in order to be visible to parents. Each bag, hermetically closed, is expelled directly from the cloaca (the terminal part of the intestine), ready to be taken away by the parents.
The chickens of some species lift the rear in the air at the time of the production of the faecal bag in order to show it nowothers deposit him on the edge of the nest, still others shake to get him out. Generally, they await the arrival of adults for expulsion, so that the bag can be taken immediately. The nidiaceans produce their “diaper” shortly after feeding: an experimental study highlighted that Almost all bags are produced after meals. This synchronization with meals is important because if the bag is expelled when the parents are far away, the nest could be contaminated or it could recall predators.
The advantages of the faecal bag
A dirty nest is a nest very dangerous It is unsuitable for breeding the offspring. The constant cleanliness is part of the most important parental care to prevent contamination and diseases of nidiaceans. The continuous production and removal of fecal bags is a winning evolutionary strategy for various reasons:
- Avoid the olfactory call of any predators;
- The mucous membrane of the island bag e It does not make pathogen bacteria come out present in the intestine of birds (antimicrobial function);
- The chickes dejections do not smear the nest and can be brought quickly and effectively;
- In some phases, they represent one immediate source of nourishment For parents engaged in the care of offspring.
How the bag is removed
The bags can be ingested by the parents Or take away from the nest, but this depends on the species and the stadium for development of the Pullo. The newborn chicks are not very efficient in digestion and therefore many nutrients remain in their dejections. In this first phase, Adults ingest fecal bags So as to obtain a double energy advantage: they use them as a semi-deigitous food resource and avoid flight effort to take them away.
When the chickes begin to grow, the intestinal absorption of the substances improves and “the diapers” become larger and less nutritious, At this point the parents cannot swallow them and take them away. Of course, “throwing the garbage” is a tiring activity for parents. The bigger the bag, the more it is short flight that the adult performs to throw it away.
Research conducted in the Kentucky on 30 Cin of Carolina nests (Poecile Carolinensis) made it possible to evaluate who, between males and females, engage more in throwing away “the garbage” of the fecal bags. THE male They eliminate more fecal bags per hour than females, but this is because they visit the nest more frequently to feed the chickens; A bag is also thrown to each visit.
