The extra weight males raised pigeons on the hierarchical ladder

Biologists watching the flock of pigeons, found that among these birds there is a stable hierarchy, which strictly depends on the body weight of the bird. When
pigeons artificially weighted, hanging weights to them, birds raise their
status in the group. However, this applied only to males, say the authors
the study, published in Biology Letters.

Many animals that live in groups, there is
hierarchy, which is reflected in the priority of access to food and females. At that time
as high ranking individuals receive priority, low-ranking
the group members have to compete for resources. However, in different
communities the hierarchy can be both stable and unstable, so the question
about what determines the position of individuals on the social ladder, and how
to change for different kinds of animals have solved in different ways.

Studying a hierarchy among birds, scientists from the Royal
veterinary College University of London for three years watched
a group of domestic pigeons (Columba
livia). They recorded data three times per year, at different points in the annual life
cycle of birds. The group consisted of nine adult females and eight males,
which differed in mass and size. Based on observations, the researchers placed
birds in rank. It turned out that regardless of the time of year, in the group
there is no established hierarchy, and is dominated by the massive bird.
As a rule, they behave most aggressively, pushing smaller
relatives, and get access to the most resources first.

To find out what determines the behavior of the dominant individuals
– size, weight, or character traits, the researchers conducted a simple
experiment. A year and a half of observations to nine the smallest doves
tied weights, therefore making them heavier than an average of 12 percent (this change reflects a real change in the average mass of birds during the year). Increase
mass affect the behavior of experimental males they immediately started to behave
more aggressive, and quickly changed their position in the group, turning from
outsiders in the dominant species. For potjazhelevshie females nothing
changed. However, when the weights are removed, the birds returned to their usual
position the bottom of the hierarchy.

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