The birds lose weight to flee when beset by a … – cubasi

The birds lose weight and body mass to fly faster and escape their pursuers when they are harassed by a predator.
 

The birds lose weight and body mass to fly faster and escape their pursuers when they are harassed by a predator, according to investigations by an investigation conducted by ornithologists Museum of Natural Sciences in Barcelona.

The study, published in the journal ‘Journal of Ornithology’, has certified for the first time experimentally a hypothesis that ornithologists call “depending on the mass predation” is means that, in the presence of predators, some birds may voluntarily lose body mass to fly and run faster when risk being hunted.

As explained by researchers, although there have been many studies that have supported the hypothesis, never before had to do a scientific experiment to compare birds of the same species in the same place in two different situations. with presence or absence of predators

The authors of the research ornithologists have been Museum of Natural Sciences of Barcelona Jordi Pascual and Joan Carles Senar, who took the data into a permanent bird banding station located in Sarria in Barcelona.

There, during the Winter lives a colony of Luganos (Carduelis spinus), a small Finch Bird yellow, green and black color, of the family of finches, but also visit the bird station of the same species that are only transient, ie, are of step.

For five months, from mid-autumn to early spring, scientists captured over a thousand Luganos, which marked with rings and measured both its length, about 11 or 12 centimeters, as their body mass and breadth of its wings.

The research is based on 812 catches for 510 individuals (residents were caught more than once).

Checking hypothesis was favored because until January 19 did not observe the presence of any predator, and from day 20 saw the first hawk who settled in the area and every day hunting.

Thus, ornithologists had the ideal circumstances to test the hypothesis. one place with residents and passers birds of the same species and donut predator and another with his presence

The results indicated that the resident birds had had a . decreased body mass of about 9.75% in the donut predator and predator period with, and instead, the body mass of passers unchanged

The research was supported by other data: in similar periods in other years (1985-86 and 1989-89) did not presence of predators or loss of body mass was observed residents.

“This indicates that residents who know the risks, know to prepare losing weight while visitors, in an unfamiliar environment, where you spend a few hours or a few days, the presence of predators catch them unprepared and do not know a strategy “, as reported by the Museum of Natural Sciences.

According to the researchers, although the smaller body mass allows the birds fly faster and escape, may also hinder them find food.

Ornithologists see birds may use the time without predators to accumulate reserves and thus may lose after body mass without having a major impact on your state.

Although the study was done in the period from October 19, 1996 and March 22, 1997, to now it has not been published because data were not collected for this study, but for other research.

However, when researchers had the idea to test the hypothesis of body mass loss in the presence of predators recovered the data.