Jan., 1922 13 
MAGPIES VERSUS LIVESTOCK: AN UNFORTUNATE NEW 
CHAPTER IN AVIAN DEPREDATIONS 
By S. STILLMAN BERRY 
WITH TWO PHOTOS 
region, as he has done in the case of much of the territory of our 
western states during the last half century, one of the first results 
of the impact is an inevitable severe dislocation of the whole nice dynamic 
equilibrium existing in the life relations of the myriad of humbler animals 
and plants endemic in the area. Some of these, unable to meet the new condi- 
tions involved in the introduction of so all-invading a competing or conflicting 
organism as man, never recover from their first reverses and sink rapidly into 
extinction. Others linger on, continuing a losing battle in the face of ultimate 
defeat until perhaps man himself rouses in interested admiration to temper the 
odds against them. Still others are able to maintain themselves in the old way 
without much discomposure, while a fourth class meet the invader half way and 
by divers quaint counter-adaptations to the human environment attain such pow- 
ers of survival as to hold their own willy-nilly, the pleasure of omnipotent man 
in large degree to the contrary notwithstanding. The detection, observance, 
and recording of these secondarily acquired adaptive habits form by no means 
the least profitable field open for investigation by the biologist in any new 
country. In the older regions, it is true, these changes still present themselves 
at intervals, but no doubt less frequently, and the complete history of the 
transformation in any given case is generally more difficult to trace. 
Viewed in this light the few observations here recorded possess a some- 
what wider significance than the mere recognition, in the economic sense, of 
‘another pest’’, although whether the modifications of habit noted will ever 
become permanently established or sufficiently widespread to be considered a 
specific part of ‘‘picine’’ ecology, only the future will reveal. 
It is well known that magpies, like their relatives, the jays, habitually de- 
vour, not only coarse seeds, berries, and insects of many species, but also small 
mammals, the eggs of other birds, and all too often, alas, the young birds 
themselves. Likewise they are and doubtless lone have been energetic scav- 
engers demolishing carrion with a speed and assiduity that their human ob- 
servers can scarcely envy. Yet we do not generally think of them as raptorial 
in habit, at least in any major sense, and to find them becoming so tempers our 
natural indignation at their bloodthirstiness with surprise at their ready apti- 
tude in learning to adapt themselves thus readily to so new a source of food. 
The frequenting of the backs of animals, especially the various ungulates, by 
magpies and other birds has ever been a commonplace observation, but while 
the knowledge that magpies may resort to such situations for the purpose of 
preying directly on the animals themselves has been the little treasured prop- 
erty of western stockmen for some time, little seems to have found its way into 
print regarding the birds’ assumption of so malevolent a habit. 
It was in July, 1912, that the writer had his first experience with an attack 
by magpies (Pica pica hudsonia) upon one of the larger mammals, in this in- 
= civilized man extends his domain into an hitherto unoccupied 
