Ostsee

Observing cranes without disturbing them

This is how a leaflet published by the National Park Authority of Vorpommern describes in a few words on how to approach cranes. For ages this stately bird has been drawing through our region twice a year.

Contribution:
Brigitte Hildisch in Cooperation with Dr. Helga Konow, National Park Authority Vorpommern

The Grey crane - Grus grus

Crane Characteristics of the Grey Crane
The Grey crane (Grus grus) is one of the largest migratory birds in Europe, for its body size can be as high as 1.20 meters. The bird got its name from the slate-gray plumage colours. The colour of the head appears in black and white tones. What strikes is a bright red, featherless stain on the head. Its wing span reaches as far as 2.20 meters. There’s almost no difference in sexes regarding weight or size. Male birds can reach a weight up to 7 kg, females up to 6 kg.
Being in the air you will easily recognize a crane from its flying style. For one thing it is the long neck craned forward and for the other one it is the long legs that let no doubt about which bird it is. In flight the legs are significantly longer than the crane’s tail.

Bird migration in spring and their "dancing"
Depending on the weather conditions already in mid-February the first cranes brush against the Federal state of Mecklenburg-Vorpommern. They are on their return flight to their breeding homeland. Then around late March or early April there will be a good chance of watching the last few cranes heading north. Such a group of incoming birds often shows only a small number of cranes. The reason why is: they stay for a short break, merely to refuel before crossing the Baltic Sea. In really good weather conditions they will fly non-stop further north and thus without any additional food intake. The sight of cranes flying in an arrow-shaped formation high in the sky is something that one will experience on different shores of the Baltic Sea coast. And their trumpet-like cries fill the air. On some days observers are especially lucky because they will become witnesses of early mating rituals as of their mating dance. Here the birds strut around each other, turn or nod with their heads. Their wings are impressively set up in a semicircle to unveil the splendor of the plumage. This dance is accompanied by loud trumpet-like calls. But the peak of the mating ritual, the mating itself, will only be reached later after having occupied their breeding territory.

The crane’s breeding ground
For about 80 per cent of cranes the breeding grounds are places in a wetland like in water-rich swamp forests, marshes or places at the Scandinavian banks of lakes which have silted up. For the remaining 20 per cent the breeding grounds are places in Poland or in the Baltic Republics, namely in corresponding habitats. Following a rule cranes almost ever return to their traditional breeding grounds.

Breeding and rearing of the birds
Cranes are ground-nesting birds. They build their nests in the wetlands with water depth between 30 to 60 cm to protect their eggs and later on the young birds from predators such as wild boars or foxes.
A crane’s nest can have a diameter of more than one meter. Normally it is made from the different plant materials and remains a permanent "construction site" during the rearing period.
After 29 till 31 days the birds hatch out of green-brown speckled eggs. Often one will find two eggs in one nest. The parents in turn take care of the breed. To find food the cranes are often forced to cover long distances. Cranes are precocials.
The young birds grow up swiftly and already after a time span of 10 weeks they have acquired the ability to fly longer distances. Cranes can reach a flying speed of over 100 km per hour (75 mph). To save power during long flights cranes often travel long distances by gliding. Then the birds keep an average speed of about 60 km per hour (45 mph).

Grey crane Food sources
Juvenile birds feed on insects, as well as frogs, worms and snails. Later on crops as grain, maize or potatoes will become part of their food intake but also berries and buds. The spot where they find their food are sparse deciduous forests, especially beech forests, and the open grassland. In autumn the remains of crops in the harvested fields become an additional source of food. With their rather short beaks the cranes take their food in a goose-like kind. So everything that is found by them lies on the surface of their respective feeding place.

The reproduction of cranes
In their third year of life cranes are sexually mature. As early as one or two years before maturity the birds search for a suitable breeding territory and they even begin to build their nests.

Sleeping and gathering place
The Federal State Mecklenburg-Vorpommern is inhabited by cranes a second time each year. Especially there is the Ruegen-Bock-Kirr region, the largest area for birds to rest and gather in Central Europe. It is the autumn season when the cranes arrive for their migration to the south. At this time of the year social interaction in the crane’s behaviour becomes even more important and can be seen fully used to good effect.
Gathering places encompass lakes and rivers with stretches of shallow water. Thus the birds can almost safely sleep at night. When predators approach in the dark the cranes will hear them making sounds when crossing the waters. Preferred sleeping places are occupied in the mudflats in front of Pramort and the island of Kirr. Each year about 60.000 birds have a rest at this spot.
Conservationists from the National Park Authority keep an eye on this unique habitat to let the birds rest in an undisturbed way. To find food the cranes fly on the nearby mainland.
People are always welcome as observers but should never be noticed as an intruder by any crane.

The bird migration in autumn
The majority of cranes migrates further south at the end of October or at the beginning of November. In good "flying" weather you can experience true mass starts. High up in the air the birds form a wedge, with the more experienced ones right in front. They set off to Southern Europe or North West Africa, to places where they will stay during the winter season. On their way the birds cover distances of thousands of miles, to reach countries as France, Spain or Portugal. The total distance from the breeding grounds to the winter accommodations is between 2000 and 6000 km. Well-organized stages are essential for survival as well as undisturbed rests. Any disturbance means a loss of power due to additional lift ups in this case. Smaller groups of birds that can withstand a mild winter remain in Germany. If sleeping places in the water freeze over or snow covers the fields the birds will leave, however, the chosen places for some time.

Crane observation

For the crane observation it is best to choose the autumn migration. One reason for it is the long duration of their resting period lasting for a few weeks. As cranes belong to the diurnal birds, being most active in the morning or evening hours, the chances of watching them are really good at these times of day. It offers the opportunity of watching them while they take on their food or fly back to their sleeping places. So where can I watch cranes?

Crane-Group

Who wants to learn more about the life of these shy and watchful birds, their resting places or about the current numbers of birds just staying in this area should not miss the Crane Information Centre in Groß Mohrdorf, a German facility established for the protection of cranes.
Wherever you go on a crane tour do not forget: Watch without disturbing them.

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