Chlamydera guttata carteri from North West Cape 
are almost identical (Table 1), there being no 
significance between them (f =1.119, P > 0.1 and t = 
0.163, P > 0.1 respectively). The wing and tail 
length of North West Cape birds are much shorter 
than those of birds from the Hamersley Range 
immediately to the east, however, and the 
differences are significant (t = 10.417, P < 0.001 and 
t = 2.089, P = 0.05 respectively). Differences in wing 
and tail lengths of the North West Cape birds 
compared with those of both the Hamersley and 
Murchison areas combined (Table 1, Figure 1) are 
also significant (f = 10.072, P < 0.001 and t = 2.471, 
P < 0.02 respectively). 
DISCUSSION 
We agree with the current view that there is no 
justification for taxonomically distinguishing 
between populations of C. guttata of the Hamersley 
Range and Murchison River areas (Figure 2). Birds 
from the former may be on average slightly more 
brownish in the throat and darker on the crown; 
however Museum of Victoria specimens HLW 6772 
and 6774 (subadult and adult male respectively) 
from the Hamersley Range are all but identical to 
specimens HLW 1137 and 1138 (subadult and adult 
male respectively) from the East Murchison in 
throat, crown, upperparts and all other plumage. 
Measurements of birds from these two areas are 
similar (Table 1) and show no significant 
difference. We do note that a number of species 
show geographic variation between west and east 
Murchison (R. E. Johnstone in lilt.). 
It is clear from results presented in Table 1 and 
above that the seven birds from the North West 
Cape of Western Australia are on average 
significantly smaller than those from the adjacent 
Hamersley Range area (including Onslow and 
Sherlock River) in wing length (8%) and, to lesser 
extent, tail (4%) and tarsal length (5% shorter), 
while their bills are only fractionally smaller and 
therefore are disproportionately long and broad 
relative to overall body size. Inexplicably, the 
original description of C. g. carteri (Mathews 1920) 
includes the statement "and the bill smaller [than 
C. m. subguttata]", and a subsequent description 
(Carter and Mathews 1920) stated that the "bill of 
this new subspecies is distinctly smaller, and about 
5 mm shorter [than in C. m. subguttata]". 
The lilac nuchal crest feathers of the North West 
Cape birds are all far shorter than those of birds 
from elsewhere, and the crest thus forms a far 
narrower band. They were not measured, but the 
shorter crest is nevertheless clearly apparent 
(Figure 2). The crown coloration and markings of 
birds from North West Cape differ obviously from 
those on birds of adjacent areas. This is significant 
because speciation in bowerbirds is typically 
emphasized by marked differences in crown 
229 
colour. Examples of this are differences between 
the catbirds Ailuroedus crassirostris and A. melanotis 
within Australia and between subspecies of A. 
buccoides and of Chlamydera lauterbachi in New 
Guinea. Likewise, crest size differences among the 
gardener bowerbirds, Amblyomis, of New Guinea 
reflect speciation in this genus (Gilliard 1969, 
Schodde and McKean 1973, Frith and Frith in 
press). These examples support the argument that 
the population of C. guttata that is apparently 
confined to the North West Cape area (Blakers et 
at. 1984, Storr 1984, Ford 1987a, Kendrick 1993) has 
differentiated at least subspecifically. 
The degree of morphological differentiation of C. 
guttata carteri from conspecifics to the east and 
southeast is far greater than that between the 
populations of the Hamersley Range and on the 
Murchison River (see above. Table 1, Figure 1) to 
which Schodde (in Schodde and Tidemann 1986) 
was alluding when indicating the species to consist 
of "one or two races" (Schodde in litt.). It is greater 
than the difference between the far more 
extensively distributed, mid-central and mid- 
western Australian populations of C. guttata. The 
difference between C. g. carteri and C. g. guttata is 
not unlike the degree of differences found between 
the long and presently recognised subspecies 
within C. nuchalis and C. lauterbachi (Gilliard 1969, 
Cooper and Forshaw 1977), notwithstanding that 
Schodde (in Sibley and Monroe 1990) doubted the 
validity of subspeciation within the latter species. 
In view of the above, C. guttata carteri Mathews 
of the North West Cape should be recognised as a 
subspecies until such time as further collecting 
and/or genetic studies demonstrate otherwise. 
Storr (1986), Blakers el al. (1984) and Kendrick 
(1993) clearly indicated the isolated nature of the 
North West Cape bowerbird population. That its 
geographical range is so limited is of considerable 
interest on a continent where this is rarely the case 
for avian laxa at any level (Keast 1961). Storr (1984) 
noted ten bird species (one non-passerine and nine 
passerines) with populations isolated on the Cape 
Range of the North West Cape. In acknowledging 
and discussing the Cape Range as a minor 
geographical isolate. Ford (1987a) noted it is 
separated from rangelands in the Pilbara by a 
water barrier (Exmouth Gulf) and a lowland 
vegetated with open scrub steppe. Ford (1987b) 
shortly thereafter named the isolated population of 
Grey Shrike-thrush on the Cape Range of North 
West Cape as the diminutive subspecies 
Colluricincla harmonica kolichisi. 
Because the female AMNH 679152 specimen is 
dated 6 August 1916, it clearly cannot be the type 
of C. maculata nova designated by Mathews (1920), 
as he specified in his description a female collected 
on "August 7th, 1916". Thus the type must be one 
of the two females collected on 7 August and now 
