DISPERSION, SIZE AND ORIENTATION OF BOWERS OF THE GREAT BOWERBIRD Chlamydera nuchalis (PTILONORHYNCHIDAE) IN TOWNSVILLE CITY, TROPICAL QUEENSLAND
| Posted: |
05/08/2021 |
| Author(s): |
Clifford B. Frith, Dawn W. Frith, Jo Wieneke |
Eighty active Great Bowerbird
Chlamydera nuchalis bowers were examined of which 54 were
measured and 61 plotted in the suburbs of Townsville City, tropical E. Queensland, where the species
was reported by earlier authors to be absent or uncommon. The average number of years a bower
was known to have been in use at 54 sites was 4.4 (range 1-13, SD= 3.3) and seven of them were
known to be so for more than a decade. Mean nearest neighbour distance of 45 bowers was 790 m
(range 300-1 875, SD= 378.4). Of 54 bowers examined only four had a structure(s) additional to the
two parallel walls that constitute the avenue bower typical of this species. Bower shape, quality and
size are described and discussed. Compass orientation of the bower avenue was strongly biased
toward a NNW-SSE alignment, and 76% of bowers were orientated within 45° either side of the
N-S axis. While only 32% were within 45° either side of the E-W axis. The main display platform was
to the E half of the compass in 60% of 54 bowers. Sixty-three per cent of bowers had their main
display platform orientated within the quarter of the compass centred on the NNW-SSE axis. Compass
orientation of bower avenue and main display platform are discussed with respect to previously
observed biases and these findings are compared with data for other avenue bower-building bowerbird
species. A plausible explanation for observed orientations is that males orientate their bowers to
maximize advantageous illumination of their display decorations and postures during mornings of the
annual peak courtship season, but further studies are required.
>> Download Abstract |
File Size: 179KB
>> Download Complete PDF | File Size: 1MB
