148 OBSERVATIONS ON BIRDS. 



It has been sometimes thought that rooks have 

 the power of discovering by scent, or some other 

 faculty, the prevalence in any particular pasture of 

 the grubs of the cockchaffer.* I should almost be 

 inclined to doubt this, from the circumstance that, 

 in the autumn of 1842, the field in front of my house 

 was so attacked by these grubs that a large quantity 

 of grass was completely destroyed; immense patches 

 appearing as if scorched; and it was under con- 

 sideration, whether it would not be necessary to 

 pare and burn the whole pasture, and lay it down 

 afresh; yet the rooks never found the grubs out. 

 From my proximity to a large rookery, the inha- 

 bitants of which were daily under my observation, 

 it was expected and confidently hoped each day that 

 the rooks would soon discover and extirpate the 

 enemy. To our surprise, not a single rook was 

 seen to alight on any of the bare places ; and, in- 

 deed, hardly a bird noticed in the field at all previous 

 to Christmas, when the grubs had worked deeper 

 from the approach of the cold weather, and were not 

 easily obtained. The size of the pasture was a little 

 less than three aeres. 



Dec. 30th, 1829. Feeling some desire to know 

 how rooks support themselves during severe frost, 

 like that we have now experienced for this fortnight 

 back, I caused one of these birds to be shot and 



* See Journ. of a Naturalist (3rd edit.), p. 179. See also 

 jS&e\$ Gleanings in Natural History, p. 62- 



