328 U. S. NATIONAL MUSEUM BULLETIN 211 



1936, I watched about 25 Brewer's blackbirds feeding on spilled 

 grain on the snow. I was seated in a parked car a few feet away. 

 During the whole of this time, an adult male marsh hawk tried to 

 catch one, and at each strike the blackbirds in danger would shift a 

 couple of feet, easily dodging the raptor, pick up a few more grains 

 and dodge the next blow. The blackbirds rose only a few inches from 

 the ground each time. None was ever caught, though there were some 

 near misses, and I suppose the hawk succeeded eventually." Bond 

 (1947) has found the remains of a Brewer's blackbird at a marsh 

 hawk's nest near Watsonville, Calif. 



"It is a well known trait of the Brewer Blackbird to badger large 

 birds such as hawks and crows," writes Grinnell and Storer (1924). 

 The list of those animals harried or mobbed by this species is extensive 

 and includes the great blue heron (Ardea herodias) (Bond, MS.), 

 snowy egret (Egretta thula), white-tailed kite (Elanus leucurus), 

 horned owl, pygmy owl (Glaucidium gnoma), weasel, gray squirrel 

 (Sciurus griseus), cats, dogs, and humans. Attacks by the blackbird 

 may be made singly or in groups. An incident of an attack on a 

 sparrow hawk (Falco sparverius) taken from my notes will suffice to 

 illustrate the manner of single attack on a flying bird: "Monterey 

 County, June 13, 1948 — A male Brewer's swooping at a sparrow 

 hawk, seemingly making contacts on the lower back or tail. Would 

 fly rapidly from behind and a little above, catch up to the hawk, sail 

 down on it and seem to make contact uttering the squawk at the same 

 time. At this moment the hawk would twist in flight, seemingly in 

 order to evade the blackbird." These attacks, although seen several 

 times on that day, did not seem to extend very far beyond the limits 

 of the nesting colony. La Rivers (1944) mentions a sparrow hawk 

 killing a Brewer's blackbird that was harrying it. Allan R. Phillips 

 (MS.) says that on June 14, 1936, he "took a young male from a spar- 

 row hawk that was carrying it away, pursued by adult blackbirds, so 

 Falco sparverius is an occasional enemy of the young." 



The sharp-shinned hawk has been observed to be mobbed by 

 blackbirds. The warning note was uttered by several members of 

 the river-mouth colony on May 23, 1945, as several other Brewer's 

 blackbirds pursued a sharp-shinned hawk flying away and at some 

 distance from the colony. A group of about five redwing and/or 

 Brewer's pursued a pigeon hawk, on September 25, 1945, at the river- 

 mouth colony. At first a much larger group of about 25 of both 

 species of blackbirds hovered about a pine where the hawk was perched. 

 When the hawk took flight the five took after it, pursuing from a 

 little above the hawk. Once the hawk turned and swooped upward 

 toward its pursuers, who immediately turned back for a short way, 



