The Common Crane is one of the largest birds in Europe with a wingspan of 2 meters and a weight of 4 - 6 kg. Overall plumage is a nearly uniform grey with long legs and neck. Adults are distinguished by the black and white contrast to the neck and head, marked with a bright red spot and young Cranes have a brownish plumage that they keep for a year that gradually changes to adult plumage. On the ground they appear to have a fluffy puffed up tail that is actually formed by the last wing feathers that are very elongated.
Cranes are very sociable and gregarious during their migration and wintering when they can form very large groups, especially on the ground which can be many tens of thousands. They are however extremely territorial when nesting.
Breeding grounds are situated principally in Russia, Finland, Sweden, Norway and the Baltic countries where large solitary nests using dry grass are constructed on the ground situated in large areas of marsh or swamp forests that can occupy up to several hundred hectares.
Here a couple will produce one or two eggs in May that take about 4 weeks to hatch.
Shortly after hatching, the chicks are able to follow their parents and sneak into the swamp in search of insects, molluscs and small vertebrates which then make up the bulk of their food. Thereafter, they consume more plants: tender herbs, aquatic plants and berries. The young start to take to the air at around two months between mid July and August when they have to prepare for their first migration when they will stay with their parents until their return in the spring. Sexual maturity isn’t actually achieved for between 3 and 5 years when, assuming they find a partner, they pair for life.
In August and September thousands of cranes gather on the Swedish island of Oland from here they can cross the Baltic sea to the Island of Rügen where the birds gather in October with more on the German mainland. The birds move through with continuous arrivals and departures, birds staying perhaps two or three days, possibly longer. As with all things natural nothing is precise and much is determined by weather and temperature. It is access to food on the ground that is most important both during their migration and where they over winter. What we can say is that the main migration is spread from October to December with small local movements from September and possibly continuing sporadically until early Spring and that therefore the “migration” is both gradual and partial, spread out over several months with them wintering at various locations stretching from north-eastern France (Lorraine and especially Champagne) to Morocco with various locations in between, however the majority will end up in Spain with most of them in the large wintering areas of Extremadura.
Although this site is concerned with France it should be mentioned that to the East there is another European migratory route taking birds through the Great Hungarian plain then southward from Hungary that is generally described as crossing the Balkan Peninsula on two routes: one over the Adriatic Sea, and a second, more easterly route via Bulgaria, Greece and the Aegean to North and East Africa.
The map shows the principle breeding zones and the migratory corridors.
Most estimates of flight speed puts them at between 40 to 80 km/h (depending on the wind). On at least one occasion I have followed a flock on a straight road at 80 to 90 km/h.
On migration they will fly by night and by day with altitudes between 200 to 1000 meters. This is quite important and worthy of note as this height clears the wind generators at 150 metres although in practice they may occasionally drop below this height before circling and regaining altitude.
Starting in late January the Spring migration starts with some small movements, sometimes being reversed due to cold weather but once it gets underway it is a far more rapid affair with all the urgency that breeding brings with it. This tends to peak in March with the route being slightly shifted to the east, however the same areas are used during stops although many will cross France non stop in a day.
In Sweden, lake Hornborgasjon in April becomes the main assembly site before the adults disperse to their nesting sites. The fantastic ballet show of the Cranes during their courtship at Hornborga is famous throughout Europe. This same ballet can be seen between pairs here in France when on the ground, especially so just prior to flying North, although not on such a large scale.
With a west European population of 250,000 and a total European population of 400,000 they are relatively OK but, (there is as always a BUT), issues remain with serious threats principally habitat loss and lack of winter feeding grounds.
Hunting and destruction of nesting sites (dry marsh) were sufficient to eliminate the breeding Crane populations of the southern half of Europe between 1880 and 1965.
Transformation of over-wintering sites by deforestation where Spanish oak acorns provided the main food supply.
Dependence on increasingly large scale agricultural production resulting in poisoning and infertility caused by the massive use of hazardous chemicals - nothing really new there!
Drainage and exploitation of northern forests destroying parts of their nesting areas.
Agri-environmental conservation measures that had been put in place decreasing again.
The Common Cranes primarily use large lakes and reservoirs as dormitories and eat in the fields around, especially in corn stubble in the Autumn which is increasingly turned in following harvest.