Magpies are notorious egg predators, but this bird 

 mistakenly attempted to make a meal of a golf ball. 



Maurice Tibbies; Survival Anglia 



North America's Magpies 



A magpie feeds on an elk carcass in Yellowstone National Park, Wyoming. 



Rod Planck: Photo Researchers, Inc. 



The black-billed magpies of Eurasia, 

 Africa, and North America belong to the 

 same species. Pica pica. They are nearly 

 identical in physical appearance, but the 

 North American subspecies (P.p. hudso- 

 nia) has a higher-pitched voice and is 

 somewhat smaller than its Old World coun- 

 terparts. The ecology of these Old and New 

 World magpies also differs. Ceremonial 

 gatherings and much of the associated com- 

 petitive behavior do not exist in North 

 America, probably because the magpies' 

 food, invertebrates, is patchily distributed. 



American black-billed magpies nest wher- 

 ever suitable habitat is found, often in prox- 

 imity to one another, but they forage away 

 from the nests on communal feeding 

 grounds. With no need to secure a year- 

 round nesting and feeding territory, compe- 

 tition for space and breeding opportunities 

 is much reduced. Interestingly, in its behav- 

 ior, America's black-billed magpie more 

 closely resembles the yellow-billed magpie 

 of Cahfomia, which is considered a sepa- 

 rate species (P. nuttali), than it does other 

 black-billed magpies.— Z B. 



lowed many magpies from hatching to 

 death. For every hundred chicks that 

 fledge, only ten survive to rear young, and 

 only one or two of these produce offspring 

 that survive to breed. Longevity is the key 

 to success. The longer an individual lives 

 and the more seasons it attempts to breed, 

 the greater the likelihood of its producing 

 offspring. Our most successful female 

 bred for six seasons and had seven young 

 that survived to breed. Our most success- 

 ful male lived eight years, but as far as we 

 could tell, produced only three breeding 

 offspring. However, this figure does not 

 take into account any young he may have 



fathered with females other than his mate 

 or, indeed, any paternity he may have lost 

 to other males in the race to get genes into 

 subsequent generations. 



The first step in this race, beyond sur- 

 viving the first year or two of life, is to 

 stake out a territory. By becoming an ini- 

 tiator of, or simply a spectator at, a gather- 

 ing, a nonbreeding magpie can assess the 

 competition and potentially learn enough 

 to wrest a territory from the owners. The 

 gatherings are neither great magpie mar- 

 riages nor mating celebrations, but arenas 

 in which the competitive business of 

 breeding begins. □ 



60 Natural History 3/94 



