Wilson Phalaropes as Commensals
Wilson Phalaropes as Commensals.-Though a few species’ of birds such as Frigate Birds and Bald Eagles are well known for their parasitism on other birds, Wilson Phalarope (Steganopus tricolor) has not been previously reported, so far as I know, as a species whose food on occasion was provided through efforts of another species. On September 5, 1951, near Olmita, in southernmost Texas, I noticed about 50 Avocets (Recurvirostra americana) and 400 Wilson Phalaropes feeding in a large, shallow pond. The water was of such a depth that the Avocets could wade, but the phalaropes, with their shorter legs, had to swim. Evidently the feet of the Avocets were stirring up food from the bottom. Each Avocet was accompanied by, or sometimes completely surrounded by, a small cluster of swimming phalaropes, all excitedly pushing and crowding the Avocets and one another as they snatched at the food floating up from the bottom. Each of the Avocets was providing food for at least a few phalaropes, and one Avocet was providing for no less than 46. The Avocets did not seem to object to the robbery, if that is what it was, or to the crowding. No bird struck another ’ except accidentally in the scramble, and there were no quarrels or fights-GEORGE G. WILLIAMS, The Rice Institute, Houston, Texas, November 25,1952.
