372 THE SENSE OF SMELL IN BIRDS. 



quently, my trap, always functioning through the summer, when the 

 safety of the settings makes it the most needed. I had relaxed my pre- 

 cautions a little, so that the trap often remained set until quite late in 

 the morning. But one day I found the trap had gone oti, and that 

 without catching a cat or a hedgehog, since there was no room for an 

 animal; and, on lifting it, 1 was disagreeably surprised to tind a female 

 tomtit whose nest was certainly not in that neighborhood. The deli- 

 cacy of her scent had caused her death. 



I am now going to give instances which will remove all doubt, if 

 any remains, of the great power of scent among birds. These obser- 

 vations relate to several kinds of birds which destroy slugs by search- 

 ing for them in the soil and making way with them, after boring into 

 the earth with their beaks till they come to the villainous larva. 



Among these species 1 may mention the rook {eorhean freux)^ the 

 magpie, and the blackbird {merle noi)% the onl}^ ones which I have 

 actually seen at this work. There are, very likely, others.* The serv- 

 ices that the two first thus render to agriculture are generally acknowl- 

 edged. In the case of the magpie they attentuate his misdeeds. 



In September, 1898, 1 used at all hours of the day to surprise several 

 magpies Avho always flew away from the same point on the lawn. My 

 attention was soon attracted to quantities of holes that they had evi- 

 dently made in the turf. Some strokes of the spade revealed young 

 larvae of May bugs [hannetons) several months old, 18S>8 being the 

 year of the Uranian cycle in the Department of the Oise. I counted 

 up to ten under one turf, and to-day there is an acre or so of the lawn 

 where the grass, eaten at the roots, has rotted and made a horrid spot 

 visible at a great distance. 



The magpies had been at work there, as the rooks work in the 

 meadows. Neither of them dig the holes they do with their strong 

 beaks on the mere chance of finding something; they go straight for 

 the larva they want; so that we have to admit that they scent it, not- 

 withstanding the layer of earth that covers it. 



I have said that the lilackbird does the same thing, a fact which I 

 believe was entirely unknown before 1897. But there always remains 

 an abundance of new facts for the observer of nature to discover. 



In the year named, during the month of June, 1 remarked in a 

 walk bordered on both sides with lilacs, numbers of little heaps of 

 earth that had been taken from holes, at the bottoms of several of 

 which could be seen a print agreeing perfectly in its dimensions with 

 the bodies of larvte of May bugs. At this time of the summer it is 

 not unusual to find these larvje reascending nearly to the surface of 

 the ground before redescending in July to the depth where they are 

 to remain until their nympheal metamorphosis is accomplished. 



^ I have strong reason to believe that the green -woodpecker {f gecine vert) hunts for 

 slugs in the same way; but I have, as yet, no positive proof of it. 



