Sunthorn Sotthibandhu

pp. 553 - 563

Abstract

The territorial behavior of the red-whiskered bulbul, Pycnonotus jocosus, was studied in the semiwild habitat of a bird farm compound in the District of Chana, Songkhla Province, the south of Thailand.
The male and female birds were bred and reared in the farm till they reached maturity following which they
were released to the wild. A mating pair was later formed and their territory established in the farm area.
A decoy was used to simulate a natural intruder to the defended area. Ten test stations were sited in the four
cardinal points of the compass and with reference to the farmhouse. The experiments were conducted during
the pre-nesting and nesting periods. It was found that territorial boundary was marked by the resident
male’s aggressive calls and threat displays to the decoy. The territory covered an area of approximately 0.3
hectare in which it was used for foraging and nesting. The size remained the same in both pre-nesting and
nesting periods, but the territorial behavior during the nesting period was evidently more vigorous than that
in the pre-nesting period. The intensities of territorial behavior had been hypothesized to be associated with
diurnal foraging rhythms. But the finding was contradictory to this prediction. There was no significant
difference in the intensity of territorial behavior (P > 0.05) at the three time regimes in the morning, at noon,
and in the afternoon. It was suggested that the resident bird’s aggressive behavior might be associated with
the degree of hunger pang.