360 ANNUAL, REPORT SMITHSONIAN INSTITUTION, 1930 



And on February 23, I find this: "No males in group 1 to-day. 

 Their attention is devoted to the builders in group 2." February 28 

 I quote further : " No males have been seen in group 1 since I can 

 remember." 



Although the males are such ardent and persistent wooers, they 

 exhibit no really pronounced sexual jealousy. Possibly its absence is 

 due to the excess in the numbers of females over males. But in the 

 small colony of 1928, when there were probably half as many males 

 as females and the competition for a mate should have been keener 

 than in the preceding years, no change was observed in the relations 

 of the males to one another. When several males (I have seen four) 

 court the same female simultaneously the situation is apparently 

 threatening. The birds whine excitedly and an attack seems im- 

 minent but at the worst it results in a pursuit in which one bird 

 retreats slowly before another, flying from limb to limb but not 

 usually leaving the nest tree. No notes are uttered — the whine seems 

 to be the only battle cry — there is no resistance and hence no fighting, 

 and the whole affair is quiet and dignified. On one occasion (Janu- 

 ary 26, 1927) one male drove a second from perch to perch and finally 

 out of the nest tree, then out of three other trees, and finally into the 

 forest where they were lost to view, but it was done quietly and 

 slowly. It is only the females that fight. 



THE SITE 



In the tree now occupied by the laboratory colony, the nest site 

 is a single terminal, "dripping" or downward pointing branch or 

 twig about the thickness of a lead pencil. Nests preserved from 

 the tree that fell show that its terminal branches had an upward 

 curve, creating, therefore, a short horizontal section at the turn 

 which offered a more favorable place of attachment for the nest 

 than is given by the branches of the tree now occupied. In any 

 event, the site should permit the nest to swing free without danger 

 of entanglements with near-by limbs even when, as sometimes hap- 

 pens, it is blown to an almost horizontal position. 



If the birds of a group arrive and work together they usually 

 build nests as near to one another as the available sites permit. The 

 selection of a site may be made at once and peacefully, it may cause 

 the display of some animosity accompanied by actual fighting, or 

 it may be the occasion of a remarkable performance extending over 

 several days. In the first instance, nest building proceeds at once 

 without friction and it is possible that these birds have been asso- 

 ciated before. In the second instance the birds grapple claw to 

 claw and, fighting with their bills, whirl downward like a single 

 bird with set wings extended. When within 10 to 20 feet of the 



