80 The Birds of Cambridgeshire 



breeds or attempts to breed at intervals in or near Wicken 

 Fen, an area now strictly preserved by the County Council, 

 and possibly elsewhere, though no absolute case is on record 

 for other districts of late years. Migratory individuals are, 

 moreover, often met with by sportsmen in autumn, but the 

 bird's visits are quite irregular, for, while it may not be 

 observed in summer for several years in succession, it may 

 suddenly occur in numbers when circumstances are suitable. 

 A well-known case was during the 'vole-plague' of 1890-91, 

 on the Scottish border-lands. 



4. Circus cineraceus (Montagu). Montagu's Harrier. 



This scarce bird-of-prey still visits the neighbourhood of 

 Wicken Fen with some regularity. Owing to the fact of its 

 absence during the colder months, and the lack of game- 

 keepers in the Fens, it has a better chance of survival than 

 other members of its family, but it is not observed every 

 year in the county, and when observed does not invariably 

 breed with us. The food consists largely of reptiles, am- 

 phibians and insects, and, as in the case of Owls, any harm 

 that is done is much more than compensated by the destruc- 

 tion of noxious creatures. 



5. Ardetta minuta (Linn.). Little Bittern. 



There can be little doubt that this species has nested of 

 comparatively recent years on the Norfolk Broads, but as 

 regards Cambridgeshire the fact is less certain. Still it is at 

 least probable that a pair which were shot near Ely in the 

 spring of 184 . . , of which the male is still preserved in the 

 University Museum, were intending to breed with us. We 

 may therefore fairly infer that the Little Bittern was a more 

 or less regular migrant to our shores before the drainage of the 

 Fens, while the later instances of its occurrence give evidence 

 of a tendency to resume its former habits. 



