162 BULLiiTIN 191, UNITED SIATES NATIONAL MUSEUM 



magpies by vigorous pursuits. Two magpies watched in February were 

 greatly concerned over a golden eagle that perched near their nest, and 

 they tried repeatedly to drive it away. Special animosity is directed to- 

 ward sparrow hawks in the vicinity of the nest, as if the magpies recog- 

 nized the intent of these intruders. In one instance great effort was put 

 forth to drive away two hawks from a nest, but when a western blue- 

 bird lit on a limb close to the nest, the magpie paid no attention to it. 

 Once when a red-shafted flicker lit close to a magpie nest, the owner 

 came immediately and drove it away. Similar effort has been watched 

 with respect to California woodpeckers near occupied nests. 



Other members of the Corvidae are treated with special enmity 

 whenever one approaches a magpie nest. Magpies are able to drive away 

 California jays ordinarily, but sometimes these smaller birds display 

 an extra degree of persistence in refusing to leave the nest tree. Crows 

 near a magpie nest arouse special activity, and they are driven away if 

 it is possible. Sometimes they refuse to be driven and even turn on 

 their pursuers and drive them from the site of their own nest. Once 

 a nesting magpie attacked an intruding meadowlark with such fierceness 

 that the two fell for 20 feet, or halfway to the ground, before the smaller 

 bird escaped and fled with notes of alarm. 



Defense of a nest site more than ordinarily effective against intrusion 

 by a crow was noted on a morning early in February. A pair of mag- 

 pies was discovered in a large valley oak, about a hundred feet from 

 their nest site, where they had driven a crow to seek shelter in a thick 

 clump of branches. One magpie would make a dash at the crow and 

 retreat, and then the other would move toward it, but each took care 

 to keep out of range of the crow's bill. Several times the crow dashed 

 out after one or the other of the magpies, but always it retreated back 

 to the protection of the limbs. This was kept up for 3 or 4 minutes, 

 until four more magpies came, when the crow gave up, moved to the 

 outer part of the tree, and then flew away. The magpies then dis- 

 persed. 



Another incident in another year but in the same group of trees 

 concerned a crow carrying a twig for its nest, which it had pulled from 

 a blue oak about 80 feet from a new magpie nest. The pair of magpies 

 kept such close watch of the crow and dashed toward it so frequently 

 that it was unable to leave the tree with its stick. Finally, it placed 

 the twig on a limb and tried to drive the magpies away, but this was not 

 successful and it was forced to leave the tree without its twig. 



Nearly all the examples of defense of nest site included in this section 

 occurred in early stages of nest-building, before the start of incubation. 

 When this stage is reached, the magpies seem too much occupied with 



