216 
Psyche 
[June-September 
of several females offered the same prey. In the three cases in which 
a male presented the same food item to three different females, 
copulation lengths were (a) 10.2, 7.8, and 0 min, (b) 15.7, 17.2, and 0 
min, and (c) 12.3, 3.8 and 0 min and the feeding phase lasted (a) 
10.2, 4.8, and 0 min, (b) 15.3, 14.8, and 0 min, and (c) 12.3, 3.8 and 0 
min. 
Table I. The relation between the estimated length of the prey offered a female as a 
nuptial gift and the time that she fed upon the prey and the duration of copulation. 1 
Size of 
gift 
N 
Mean time of 
feeding 
Range 
Mean time of 
copulation 
Range 
3-4 mm 
10 
0.2 min 
0- 1.8 
1.1 min 
© 
oo 
1 
o 
6-8 mm 
6 
3.6 
0-17.3 
6.2 
0-19.3 
10-14 mm 
4 
12.3 
10.2-15.3 
13.7 
10.2-16.8 
Correlation between size of prey and feeding time, r — 0.70, p < .01 
Correlation between size of prey and copulation time, r = 0.62, p < .01 
■Data collected from the first observed interaction between a male carrying a 
nuptial present and a female. 
Discussion 
The species of bittacids studied to date exhibit reasonably similar 
sexual behavior including the use of pheromones, nuptial gift giv¬ 
ing, female sampling of the present before copulation, and copula¬ 
tions of variable length but with means of about 10-20 min 
(Thornhill, 1977). An unusual feature of the mating behavior of 
Harpobittacus is the removal of the prey from the female by the 
male for a short period after the onset of copulation. In some other 
bittacids females feed continuously on the nuptial gift. The apparent 
struggle between copulating partners of H. australis for possession 
of the prey demonstrates the male and female interests are not 
identical. Perhaps the risk of prey thievery by females favors males 
that are cautious about relinquishing their valuable presents; per¬ 
haps they refuse to let potential mates feed until sperm have begun 
to be accepted by their partners. 
Sperm transfer in Hylobittacus apicalis is proportional to the 
duration of copulation (up to about 20 min) and it would not be 
surprising if this were also true for H. australis, whose females feed 
