Black grouse cocks on lek sites

Photos: Arne Ader
Translation: Liis
Black grouse cock
 
 Black grouse
Teder      
 
In October the black grouse cocks are quite active in and around the display (lek) sites. On rare occasions the hens can be seen too but they behave rather passively. Day lengths are similar in September and in March and the sexual glands or gonads of the male birds increase under the influence of daylight time, bringing out lek behaviour. With more wintery weather the display or lek activity lessens but in fair and clement winter periods too the cooing or bubbling of the grouse cock can be heard, although no longer from the lek sites: to them they return again in March.

The cocks wear the proudly gleaming breeding or mating plumage already since a month. The lyre-shaped tail has eighteen or twenty black metallically gleaming feathers of different lengths. The three or four outmost feathers on each side are curved and longer than the feathers of the central part. Under-tail coverts are white. The brownish wings have a conspicuous white band. At the eyebrows of the cock are featherless areas that have swelled into half-globes from the effect of the sexual hormones.  

 
Black grouse cock


 

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