November, 1920] 



The Canadian Field-Naturalist 



53 



crop than he would have done had the birds been 

 absent. This, I think explains the absence of 

 severe grasshrpper cutbreaks in the districts re- 

 ferred to. 



There are very few birds that do not take advan- 

 tage of a locust outbreak. Grouse find the insects 

 especially palatable and several people are now 

 learning to associate abundance of grasshoppers 

 with the rearing of large families of grouse and this 

 undoubtedly applies to several other birds. 



It is, however, to those birds which congregate 

 into flocks that we must look to most for help. I 

 have already mentioned gulls in this respect, another 

 is found in the crow. The crow is very fond of 

 grasshoppers at any time and as the evidence shows, 

 feeds its young largely upon them when they are 

 sufficiently numerous. Indeed it is no exaggeration 

 to state that a family of six crows would consume 

 at least three bushels of grasshoppers in a season 

 which would mean preventing about 9,000,000 of 

 the insects' eggs from being laid. 



In our grasshopper campaign of 1920 we ran 

 across many instances of crows gathering in lc;cust 

 areas for feeding purposes. They were especially 

 noticeable along roadways where fence or telephone 

 poles afforded convenient resting places for their 

 sentries. There is probably another reason for the 

 crows gathering along roadways which is explained 

 as follows: The outbreak of locusts referred to 

 was made up of several species of which two were 

 of special importance. These interestingly enough, 

 have a marked difference in their choice of breed- 

 ing sites, the one known as the Lesser-migratory 

 locust choosing stubble fields or areas of semi- 

 cultivation for egg-laying while the other, known 

 as the Road-side locust, (Camnula pellucida) pre- 

 fers the grassy road-sides for breeding purposes. 

 O.i account of this habit the last-named insect is 

 naturally massed within a comparatively small 

 space which the crows have learnt to take advan- 

 tage of. 



Returning to the contention that birds frequently 

 neutralize their usefulness in destroying noxious in- 

 sects by eating the parasites at the same time, we 

 have here at least a case where that was not so to 

 any marked extent. Parasites of adult grasshop- 

 pers have been of small importance owing to their 

 scarcity. Egg parasites, however, give far greater 

 premise of eventually bringing the insects under 



control. Here then we have a case where the des- 

 truction of adult locusts by birds will reduce the 

 possible egg supply and oblige the insect feeding 

 upon them to gather upon what remain, thus giving 

 a far greater assurance of reducing the pest quickly. 



I will conclude with one more example which, 

 though not conclusive, provides at least strong cir- 

 cumstantial evidence in favour of the birds involved. 

 Some twelve miles frcm my home at Treesbank, 

 Man., is a pretty little village surrounded by hills 

 and trees, where crows have bred rather freely in 

 the past. A few years ago, however, prominent 

 citizens of this place came to the conclusion that 

 the crows were greatly reducing the bird life, es- 

 pecially game birds, which the citizens looked upon 

 as their own special privilege to kill. In conse- 

 quence of this belief, these people inaugurated 

 crew-destroying competitions in which they formed 

 sides of equal number, those bringing in the great- 

 est number of crows and their eggs winning a prize, 

 which the losers had to pay. The result of this 

 annual competition in crow destruction has had a 

 marked effect upon crow life in the vicinity without 

 apparently producing very noticeable results in the 

 direction expected. What interests us here, how- 

 ever, is this. The district, which is a grain-growing 

 one, was infested by a severe and isolated outbreak 

 of grasshoppers last year, while surrounded areas 

 where crows had been protected escaped. As I 

 said above, this may be a coincidence, but since the 

 region is no more suitable for grasshoppers than 

 others nearby, such would hardly seem to be the 

 case. 



In the preceding remarks no effort has been made 

 to plead the cause of birds, the evidence has merely 

 been given as it was presented to me in the field. 

 I have said nothing of the aesthetic side, yet few 

 can depict anything more beautiful than a flock of 

 gulls following a ploughman, flying with their grace- 

 ful curves within a few inches of his head and 

 darting down with a characteristic little flutter to 

 pick up the insect newly exposed. To see them 

 flying over the lakes is equally pleasing, and we 

 ought surely to be thankful in realizing that such 

 perfect creatures are our friends. This can be said 

 with almost equal justice of many other birds, 

 which, if they are not as pleasing to look upon, 

 make up for that by a sweeter song or some other 

 characteristic which should endear them to us. 



