“An experiment was conducted to observe the behavior (response) of two pairs of nesting Yellow-bellied Prinia (Prinia flaviventris) in long grass (lallang, Imperata cylindrica) environment, by replaying a pre-recorded song of the male prinia bird. Observations over the span of two weekends revealed that within minutes of playing the recording, one of the male bird would respond to its pre-recorded song by vocalising from a high branch (left). The male song was characterized by a clear and sharp “chip-cheererereup” usually delivered from a favorite perch when challenged while the female predominantly sings a “Tee-tirrata rak” from a brush or a long grass.
“During the initial nest building stage when the male birds were busy collecting nesting materials to construct their nests, normally built a foot or two above ground in the camouflage of lallang grass, the male would perform several nesting material ferrying services before resting on a high branch where it would perform its vocalisation sessions, each lasting approximately (maximum) a minute or two in the absence of pre-recording replay. When a pre-recorded male song was replayed, the male would rise to the challenge by displaying it vocal superiority apparently in an act to declare to the “invader” its territorial dominance. The male bird may challenge the song by vocalising from a brush, rest its voice by inflating its throat then continued with its session. These are represented by images shown below, left and right, respectively.
“On pre-recording cessation, vocalisation from the male would sustain for ~30s before the male retire and take shade in the long grass, sometimes located remote from the perch. At any one time, both males from both pairs would stay at a comfortable distance apart (~20m) from each other, even during the peak vocalisation sessions. Interestingly, only a single male from both pairs will respond to the pre-recording replay by vocalising from an open perch.
“When the pre-recorded song was first replayed during the initial nest building period, the male prinia bird was attracted by the replay and sang hopping from a remote branch to a near branch from tree to tree, in an apparent act to investigate the origin of the replay. With sustained replay, one of the nesting pair was observed to manifest visually unobstructed on bare branches and hopped-cum-flew in a direction remote from the nesting location. This strategy was perceived to be a tactic used to lure unwelcomed visitors away from the nest.
“After nest building activities ceased, the male vocalised less frequently from a high branch. Rather, in the presence of heightened human activities in the near vicinity of its nest, it would display a fly-ahopping from lallang to lallang, when a bassi wing tearing sound was clearly orchestrated and reverberated from 10m away afar.
“Clearly, the prinia birds observed exhibited behaviors that are cognitive in nature when they responded to artificial prinia song replay and that they could not differentiate between a pre-recording replay from a living bird. As nesting period deepens, such behavior appeared to be more subdued but in turn are replaced by wing-tearing ‘disgruntled’ sound instead.”
Images by Dr Jeff Lim: top, a male vocalising from high branch; above left, a male vocalising from brush; above right, male resting its inflated throat before resuming vocalisation from brush.
Jeff Lim (Ph.D)
28th May 2009
Postscript: These birds are pretty tough to observe even with a super telephoto with tc attached. As such, I have devised and used the recording replay strategy to entice them into manifesting themselves in clearer perspectives. Though i understand that such method may be frowned upon by purists, please be assured that the birds are breeding perfectly fine as of writing. However, a recent lallang pruning event initiated by NEA had caused the nesting birds to moved their nests deeper into the lallang “forest”, thus making observations even more challenged for these skittish birds – Jeff.