1914] Grinnell: Mammals and Birds of tin Colorado Valley 119 



Herodias egretta (Gmelin) 

 American Egret 



Met with only in one place, the recently silted-in area above the 

 Laguna Dam. About five miles north of Laguna, on the Arizona side 

 and about one half mile back from the river, were extensive shallow 

 lagoons sprinkled with numerous water-killed mesquites. Here herons 

 found seclusion and feeding grounds. April 22 to 25 we frequently 

 saw individuals of the egret, to the number of three at one time: but 

 because of the deep mud and water we were unable to stalk them. 

 Usually they were seen in flight from one portion of the bog to 

 another; one, however, was seen perched on a dead mesquite, preening. 



We were told that in summer, after the overflow begins subsiding, 

 there is a large influx of white herons and ibises from the south. This 

 would appear to be accounted for by the abundant food-supply in the 

 way of fish left in the drying ponds as the river lowers. This con- 

 stitutes a local condition, therefore, serving to modify the seasonal 

 movements of these birds. 



There is in the Museum a skin (no. 4492) taken by J. G. Cooper 

 at Fort Mohave. January 9, 1861. 



Butorides virescens anthonyi (Mearns) 



Anthony Green Heron 



First seen April 24, five miles above Laguna. Thenceforth com- 

 mon all along the river below, and up to the time of our departure. 

 May 15. As far as observed up to the latter date the species was still 

 in migration. We found no evidences of breeding. Seven specimens 

 were taken, nos. 12645-12651, from Potholes, near Yuma, and near 

 Pilot Knob, all on the California side. 



Nycticorax nycticorax naevius (Boddaert) 

 Black-crowned Night Heron 



Eight specimens secured (nos. 12637-12644). Three, taken March 

 25 and April 20, are immatures in the streaked plumage; tin- rest 

 are in more or less perfect adult plumage. 



Since one individual was seen February IS. near The Needles, 

 it is probable that the species winters in the region, though sparingly. 



