480 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1914. 
These birds seemed to be especially favorable for my purpose 
because (1) they nest in rather compact colonies on the ground and 
in more or less open places so that many individuals can be seen 
and studied to advantage, and (2) their considerable size and largely 
white plumage make them among the best bird subjects for the 
indispensable photographic records. Furthermore, I had already 
had some experience with these birds, especially during July, 1907, 
when I visited a breeding colony at Gull Island in Lake Superior, 
near Marquette, Mich. 
On June 20, 1911, I made a preliminary exploring trip in Green 
Bay, starting from my headquarters at Ephraim, Wis. With the 
aid of a motor boat, the Strawberry Islands, the Sister Islands, and 
Hat Island were all visited during the day, and colonies of herring 
gulls were found breeding on all of these islands except at the largest 
of the Strawberry Islands (pl. 1, fig. 1), which supported a colony of 
ereat blue herons. 
As it did not seem practicable to attempt to live on any of the 
islands, I thought it best to stay at Ephraim and depend upon small 
boats for transportation whenever a visit was made to the gull 
colonies. Unfortunately, boats were not always available and the 
weather was not favorable on many days. Work was carried on at 
the Sister Islands on June 26, July 12, and July 15; at Middle Straw- 
berry Island on June 30 and July 29; and at Gravel Island July 18 
and 19. Another period was spent at Middle Strawberry Island 
beginning at 7.20 p. m., July 7, and ending the next day at 7.05 a. m. 
So much time was taken by preliminary studies that my experimental 
work at the breeding places was barely begun when the season ended. 
Other experiments were begun with some juvenal gulls which 
were taken from their nesting places to Ephraim and were kept in a 
pen (pl. 2, fig. 2). These birds were removed to Chicago in August, 
where experiments with them were continued for three years. Ref- 
erences will be made in this paper to observations made on these 
captive gulls. The work in Chicago was made possible through the 
kindness of Profs. Angell and Carr, of the department of psychology, 
in giving me outdoor cage accommodations. 
The only species of gull discussed in this paper except where 
otherwise stated is the herring gull. 
Like other observers, I found a tent or blind indispensable for the 
study of the birds at their breeding places. On approaching a 
breeding colony of gulls a wild panic begins, which does not cease so 
long as the intruder appears to be in the immediate vicinity. If a 
companion enters the tent with the observer and then goes out again, 
leaving the place, many birds, at least, fail to notice that only one 
of the two men has left, and they very soon resume their usual 
activities. 
