Red-tailed Black-Cockatoo (RTBC), South-Eastern
Subspecies
Calyptorhynchus banksii graptogyne
1.1 Population Surveys
Table 1. Population Surveys
| Survey |
Method |
Count |
Comment |
1980
(Joseph, L) |
39 days in field
driving through stringybark woodland & Buloke, plus community
survey; throughout year. |
160 |
“Estimate...little
better than a guess”.
“Generally uncommon, not rare”. |
| 1967-8,
(McCallum, I) |
Personal observation;
near Casterton, summer. |
550+/-100 (one
flock) |
|
1989,
(Joseph, Emison, Bren) |
Observations of
birds leaving roosting sites at 5 Crown Land blocks within 30
Km Edenhope; Feb-May. |
269 |
“Uncertain...
(total pop.) may number only between 500 and 1000 birds” |
| 1996
(Community Survey) |
90+ observers
randomly scattered across current known range; drive 500m, stop,
look/listen, drive on; August 24/5. |
436 |
Can hear c.300m
either side of track. |
| 1997 (Community
Survey) |
80+ observers
search as per 1996 survey; March 8/9. |
300 |
72% recorded from
Buloke in northern part of range. |
| 1998 (Community
Survey) |
Observers search
as per ‘97 &’96 but assigned to 49 grid squares
covering range; Feb. 28/March 1. |
392 |
No records from
Buloke. |
1998 (Hill/Burnard
et al.) |
Birds counted
returning to roost sites; August 8th |
634 |
Very large flocks
at selected roost sites |
| 1999 |
150 observers
search as per ‘97 &’96 but assigned to grid squares
covering range; Feb. 27/28. |
452 |
|
| 2000 |
170 observers
search as per ‘97 &’96 but assigned to grid squares
covering range; Feb. 26/27. |
686 |
|
Difficulties and advantages in surveying for RTBC
Advantages
• Large
• Noisy
• Often in flocks
• Buloke habitat open, with good visibility
• Range has good road/track access
• Roost together in winter
Difficulties
• Stringybark habitat dense and poor visibility
• Confusion in identification with Yellow-tailed Black-Cockatoo
• Range size difficult to cover with observers
• Stringybark “blocks” of habitat often extend >300m
from road/track
Survey methods, objectives and
times are so varied as to make comparison difficult, but there is
some comparability among the five, more recent, community counts
(436, 300, 392, 452 and 686, although volunteer search effort was
considerably higher for later counts). The August 8th 1998 roost-site
survey followed intensive field work to locate all known roosting
sites within the range.
Q.1 Arrive
at and justify a population figure for the RTBC using Table 1, and
including birds likely to be missed owing to survey difficulties
and shortcomings. 
Figure 1.
Ballarat School of Mines Students Preparing for the March 1998 Survey
Volunteer involvement is essential to the
Recovery Plan* and has enabled range-wide population surveys to
be carried out in recent years. (* The
plan estimates that a minimum of 2,070 volunteer days is required
to make the plan a success and improve the conservation status of
the RTBC).
|
