Family FALCONIDAE. 

 Circus cyaneus (L.) — Hen-Harrier. 



(Plate 100, fig. a-c). 

 (Snouckaert: Avifauna Neerlandica, p. 63, No. 151). 



Colour of surface of shell : 



Colour of spots: 



Average dimensions: 

 Average weight of shell: 

 Texture of shell: 

 Shape : 

 Nest: 



Site of nest: 



Number of eggs: 

 Breeding season: 

 Duration of Incubation: 



white, with a more or less bluish sea-green 

 tinge; when light shines through the egg- 

 shell it shows through green. 



havana-brown (light greenish yellow, ac- 

 cording to VON RlESENTHAL). 



44.7 X 34.9 millimetres. 



2.4 grams 



fine-grained. 



mostly rounded ; sometimes oblong-ovoidal. 



consists of vegetable materials, sometimes 

 lined with hair and feathers. 



on the ground in cornfields and grass-land; 

 also sometimes on dry spots in bogs. 



4—5, sometimes 6. 



May— June. 



about 3 weeks. 



