Flying north

The Grey Geese are flying to the north. A well-known annual returning signal of the spring turning towards summer. Their flying habit in a "plow formation" has been described by Roar Solheim in 2009, but I have made my own translation of his text from Fuglevennen.no

When birds fly in formation called "the plow", it's not the plow-formation that is of interest to the birds. It is the location of each bird in relation to the bird ahead that is crucial. 

When the bird flies behind the rear wing-tip of the bird ahead,  the reduced air resistance may be about 20%. and a lot of energy is saved. Therefore large flying birds (geese, cranes, storks) fly after each other in a diagonal line. When birds fly behind each wing-tip to another, it could form a plow-formation. It must be many birds in each of the "wings" to make a equilateral plow. therefore the "plow" is from time to time warped out. 

Occasionally the leading bird drop back, so a new bird must take over the leading role as a "helping hand". (You see the same system performed in bicycle-racing.)

Roar Solheim (01/11/2009)

Maybe the photo is not good enough, and my iPhone not a bird-watcher´s dream tool, but click on the photo and try to count the numbers of noisy birds flying over my cottage this afternoon.