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2.1 Breeding Biology
RTBCs are monogamous and probably pair for
life. They mature at four years. The female incubates the egg. The
male forages in surrounding stringybark or Buloke and returns to
feed the female and/or young in the evening.
Breeding Details
Breeding period: October - May.
Nest type: hollow, often in dead limb or tree.
Nest tree: Mainly River Red Gum Euc. camaldulensis (90.5% Joseph
1991). Nests have also been recorded in Yellow Gum, stringybark
and Manna Gum.
Clutch size: usually one.
Incubation period: 28 days.
Fledging period: 87 days.
Breeding frequency: probably once/year.
(HANZAB 1998)
 To
download the poster go to Poster.pdf
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Photo: T Burnard |
BREEDING HABITAT
Figure 6.
Typical RTBC Breeding Habitat
Project Officer Richard Hill checking
nest on River Red Gum plains near Edenhope, Victoria. Note:
such areas usually occur on more fertile and less sandy soils
than the stringybark rises and have thus been converted to
agricultural production.
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Richard Hill has summarised data on nest
context and found:
- 96% of nests have been recorded in Red
Gum on private land
- 88% “ “ “ “ dead trees
- Distance of nests from Brown Stringybark blocks >5
ha
| < 0.5km |
< 1km |
< 1.5km |
< 2km |
| 40% |
54% |
82% |
98% |
(Hill 1998)
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Table 2. Breeding Success (Hill 1998)
| Year |
Survey results |
Juveniles |
No.nests |
Breeding Success* |
| 88/89 |
304+ |
>15 |
12 |
n/a |
| 89/90 |
n/a |
n/a |
12 |
|
| 90/91 |
n/a |
n/a |
7 |
|
| 91/92 |
n/a |
n/a |
3 |
77 |
| 92/93 |
n/a |
n/a |
23 |
70 |
| 93/94 |
n/a |
n/a |
11 |
70 |
| 94/95 |
|
n/a |
n/a |
|
| 95/96 |
436 |
n/a |
n/a |
|
| 96/97 |
300 |
>10 |
2 |
|
| 97/98 |
385 |
>37 |
11 |
45 |
After
Joseph 1989; Emison & Caldow 1992, 1993, 1994; B. Clugston
pers. comm.
+ only part of range counted. *% of known nests which fledged
young. |
Q.11 From Table
2, calculate the average number of nests produced each year. 
Q.12 Calculate
the average breeding success of nests. Is this a high figure for
birds in general?
Q.13 Combine the
two previous answers to determine the average number of fledglings
produced each year.
Q.14 Compare the
above figure with those of the table for the numbers of juveniles
observed. Is there a discrepancy? If yes, why might this be? (Check
‘Breeding details’ and section 1.1).
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 Figure
7. Calibrating the “Peeperscope”
Left-right: Richard Hill, Graham Lewis
and Tim Burnard (Extension Officer). The Peeperscope is an
extendable pole with camera attached; it has greatly increased
the ease with which nests can be checked and is yielding valuable
breeding data.
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