3. Why do some birds migrate,
and how do they fly
• Some birds migrate
because they are looking
for areas with access to
food.
• Norway is a good food
source for birds, and
especially in Borre
Vestfold. The waters in
Borre are an ideal place
for over 230 different
bird species. Borrewater
provides good food so the
birds can feed up
themselfes before winter
or migration.
• By flying in the plow
formation the birds
totally get 71% more
flying capacity.
08.04.2014
4. • Flocks of birds perform some aerial phenomena, which have amazed many of its viewers. This thesis
is a literature review, which concerns the three major questions of ‘When’, ‘How’ and ‘Why’ birds fly
in flocks. Flying flocks are roughly dividable in two types: ball shaped clusters and line formations.
Whereas cluster flying is commonly used throughout the year by groups of birds, for example while
transiting between their roosting and their foraging sites, formation flight is almost specifically used
for migration. The departure time of migration is a critical moment in the annual cycle of the bird.
The exact moment of departure is an optimization of several external and internal factors, including
migrating distance, energy reserves and weather conditions. Clusters have a three-dimensional
structure and tend to be rather disorganized. When a predator is nearby, clusters often start to
perform rapid manoeuvres. Previously believed to be coordinated by telepathy or electromagnetic
communication, due to high-speed filming scientists have determined that these manoeuvres are
initiated by one individual bird and followed by the rest of the flock. The individual fulfilling the role
of initiator changes from moment to moment. The most likely explanation for movement in a cluster is
a self-organization mechanism where each bird applies a few behavioural rules in response to local
information from neighbouring birds. There are different kinds of formations, ranging from an acute
V-formation to a U-shaped bow. Although the total energy saving is the same for different
formations, it differs for individual birds in the group. In an acute formation, the leader gains little
or no energy savings, while in a U-formation the energy savings are more egalitarian. A reason for
obtaining a specific formation may be related to kin-selection or reciprocity, although no empirical
evidence for this hypothesis has been found yet. Several specific reasons have been put forward for
birds to fly in clusters, mainly regarding predation prevention. These advantages include increased
predator detection, a dilution effect, physical protection of neighbours and a confusion effect. Two
hypotheses exist for a structured formation, like the well known V-shape. One is the aerodynamic
advantage hypothesis, in which birds conserve energy by taking advantage of the upwash vortices
created by the wings of the birds in front. The other is the communication and orientation
hypothesis, in which birds make use of their position for their combined orientation experience and
visual communication. These explanations are not mutually exclusive, and various studies have given
support to both of them. However, no conclusive evidence has been found for any of the both
hypotheses. There is still a debate going on between supporters and criticasters of both hypotheses
which remains unsolved upon till now. A review of the literature concerning the subject of flock flying
shows that the use (the ‘When’) and the organization (the ‘How’) of flock flying have been thoroughly
researched, which has led to a consistent view on these subjects. However, thorough research on the
main reasons for flock flying (the ‘Why’) has not given a clear view yet. Also behavioural aspects of
the organization and departure are still shrouded. These subjects still raise enough questions to
provide research options for years to come.
08.04.2014
7. • For thousands of years, homing pigeons were the most sophisticated
means of long-distance communication. The winners of the first
Olympics were announced by homing pigeon. Julius Reuter started his
news service with them. Cher Ami, an avian member of the U.S. Army
Signal Corps, received the Croix de Guerre in World War I after
completing a mission with a bullet in his breast.
• How do the birds find their way home? Decades of studies with frosted
lenses, magnetic coils or scent deprivation show they use pretty much
every clue available. The most difficult one for us to comprehend may
be the earth’s magnetic field. Birds see it, but what it looks like to
them, nobody knows. Work by Roswitha and Wolfgang Wiltschko in
Germany, among others, suggests that this sense relies on quantum
mechanics—that is, birds detect something happening in the eye at a
subatomic level. Light striking the retina seems to stimulate chemical
reactions that produce pairs of molecules with electrons that are
“entangled,” meaning they share certain quantum properties. One of
those properties, called “spin,” is affected by a magnetic field. That
effect could tell the bird which way is north.
• Charles Walcott of Cornell, who began studying pigeons in the 1960s,
says homing is “still a mystery”
08.04.2014
9. Why do some birds arrive
early and others late?
• The migrants comes back in different times during
the spring. The ones that are close, like Denmark, can
come early and return to Denmark if the weather is
not as they expected.
• For example the migration of the ”beek gees”
(nebbgjess), north in Denmark to Svalbard. We know
that they fly about 50-60 km/h, and so we can find
out from the the time they leave Denmark when they
will arrive in Borre.
08.04.2014
11. The birds who don’t migrate
• Birds survive the winter by first
thickening their feather layer , eating
berries and seeds that they
find.Through evolution their beek have
shortened and become thicker to suit
the climate. All birds fly longer or
shorter distances even if they don’t
migrate.
08.04.2014
13. Sometimes colours and other artefacts are
seemingly dangerous to the male bird. Still
they have it. Why?
• To be visible for the females and to
attract them.
08.04.2014
15. What is a bird and who are
their ancestors?
• The discovery that birds evolved from small carnivorous dinosaurs of the Late Jurassic was made possible
by recently discovered fossils from China, South America, and other countries, as well as by looking at old
museum specimens from new perspectives and with new methods. The hunt for the ancestors of living birds
began with a specimen of Archaeopteryx, the first known bird, discovered in the early 1860s. Like birds, it
had feathers along its arms and tail, but unlike living birds, it also had teeth and a long bony tail.
Furthermore, many of the bones in Archaeopteryx's hands, shoulder girdles, pelvis, and feet were distinct,
not fused and reduced as they are in living birds. Based on these characteristics, Archaeopteryx was
recognized as an intermediate between birds and reptiles; but which reptiles? In the 1970s, paleontologists
noticed that Archaeopteryx shared unique features with small carnivorus dinosaurs called theropods. All
the dinosaur groups on this evogram, except the ornithischian dinosaurs, are theropods. Based on their
shared features, scientists reasoned that perhaps the theropods were the ancestors of birds. When
paleontologists built evolutionary trees to study the question, they were even more convinced. The birds are
simply a twig on the dinosaurs' branch of the tree of life.
• As birds evolved from these theropod dinosaurs, many of their features were modified. However, it's
important to remember that the animals were not "trying" to be birds in any sense. In fact, the more
closely we look, the more obvious it is that the suite of features that characterize birds evolved through a
complex series of steps and served different functions along the way.
• Take feathers, for example. Small theropods related to Compsognathus (e.g., Sinosauropteryx) probably
evolved the first feathers. These short, hair-like feathers grew on their heads, necks, and bodies and
provided insulation. The feathers seem to have had different color patterns as well, although whether
these were for display, camouflage, species recognition, or another function is difficult to tell.
08.04.2014
