ASPECTS OF THE BEHAVIOUR AND ECOLOGY OF
THE WHITE COCKATOO (Ca c a t u a g a l e r i t a ) AND GALAH
CC. roseicapilla ) IN CROPLANDS IN NORTH-EAST NEW SOUTH WALES
BY
Su s a n No s k e
Thesis submitted for the degree of Master of Science at The University of New England, Armidale, New South Wales.
MAY 1980 I certify that the substance of this thesis has not already been submitted for any degree, and is not being
currently submitted for any other degree.
I certify that any help received in preparing this
thesis, and all sources used, have been acknowledged in
this thesis. ill
ACKNOWLEDGMENTS
In 1977 a project to study parrots as pests on the sunflower crops in north-east New South Wales, was initiated by Mr. R.J.S. Beeton formerly of the Department of Zoology and Dr. P.J. Jarman of the Department of Ecosystem Management, University of New England. Together with studies undertaken by four students from the Department of Ecosystem Management and one student from the Faculty of Rural Science, this study from the Department of Zoology forms part of that overall project. I thank these people for helpful discussions in the initial planning stage. Travel expenses were funded by a grant from the Oilseeds Marketing Board of New South Wales, to whom-I am thankful. This study was undertaken while in receipt of a Commonwealth Post- graduate Research Award, and I acknowledge the facilities provided by the Department of Zoology. To my supervisor Dr. H.A. Ford, I extend thanks for his guidance and help in the preparation of this manuscript. I am grateful to landowners at Swan Vale and Wallangra to whose properties I had access. Special thanks are offered to Mr. D. Castledon of "Glen Eisle", Mr. W. Anderson of "Hillview" and Mr. H. Witts of "Taveuni", for their willingness to provide information on bird damage. My gratitude includes Mr. and Mrs. M.G.M. Woods, formerly of "Warrawee" Swan Vale, for their valued friendship and hospitality. I am particularly indebted to Mr. Woods for his keen interest and help in field work, and for many useful discussions related to this work. .... I appreciate the generosity of Mr. J.E. Courtney of "Ashgrove" Swan Vale, in sharing his extensive knowledge of Australian parrots, for information about local species, and for access to his banding data on Galahs. I am very grateful to Mr. S. Ferrier for advice and help with statistical data analysis, and to Mrs. V. Watt for typing this thesis. Ms. S. Bowen of the Botany Department, University of New England identified some plants and seeds. I am deeply indebted to my husband Richard, for his adept shooting and agile tree-climbing, for his willing help in preparing this thesis, and for his encouragement. SUMMARY
In agricultural areas of New South Wales several species of
parrots are pests to grain growing, causing damage to sunflower crops in
particular. This problem was the subject of several studies by students
of the University of New England. This thesis deals with the behaviour
and ecology of the White Cockatoo and Galah, two of the most significant
bird pests. I studied these two species for two and a half years in two
- areas—(Swan-Vale-and Wallangra) on the North-west Slopes of New South ___
Wales. Small mixed farms predominate at Swan Vale while Wallangra is in
a region of larger farms with more intensive cropping.
I recorded all facets of the behaviour and ecology of the White
Cockatoo, as this species has not previously been studied. Observations
of the Galah were restricted to social and feeding behaviour as two
previous studies have concerned this species.
The individual and social behaviour of the White Cockatoo and
Galah were very similar, and comparable with those of other species of
Australian cockatoos and parrots. Both species were gregarious, flocking
throughout.the year for most daily activities. The birds fed in the
early morning and late afternoon, resting in the foliage of trees during
the middle of the day. At night they roosted communally under the foliage
of trees at relatively permanent sites.
At both field areas the number of White Cockatoos was greatest in
the non-breeding season, from February to August, when they frequently
formed large flocks (of up to 800 birds at Wallangra). The number of
birds was lowest during the breeding season; birds were then more dispersed
and feeding aggregations were relatively small (less than 100 birds at
Wallangra). Birds which remained during the breeding season were considered
to represent a sedentary population which included breeding adults as well V
as non-breeding birds. The absence of a substantial proportion of the winter population during the breeding months, strongly suggested the existence of mobile populations which probably consist of young birds and possibly non-breeding adults. The movements and behaviour of these flocks during the breeding season is not known. The seasonal pattern of population fluctuations and flocking tendencies of the
Galah parallelled those of the White Cockatoo.
The breeding season of the White Cockatoo extended from August to
January. Pairs nested in large tree hollows which they maintained ... throughout the year. Nests were usually in large old trees, either scattered over a large area or concentrated in small forest stands as at Wallangra. There were non-breeding birds present during spring, and nestling success was relatively low (about one fledgling per pair).
Humans and goannas were responsible for most nest predation of the
White Cockatoo.
White Cickatoos and Galahs fed mainly on grain crops and less frequently on native and modified (exotic) pastures. Fifty-nine White
Cockatoos and 103 Galahs were collected and their 'crops' examined.
White Cockatoos ate sunflower, and sorghum seeds almost exclusively in autumn and winter, and these seeds formed a major part (40-70% by dry weight) of the diet of the Galah in these seasons. Both species ate wheat, barley and oat seeds, particularly in spring and summer, when
they comprised about 40% and 25% of the diets of White Cockatoos and
Galahs respectively. Seeds from native and especially modified
grassland comprised about 55% of the White Cockatoo's diet in spring
and summer, but less than 4% in autumn and winter. Such seeds were more
prevalent in the diet of the Galah. More seeds from native and exotic
plants were eaten by both species at Wallangra than at Swan Vale.
The formation of large flocks of cockatoos in autumn and winter
coincided with the period of apparent relative scarcity of native and v±
exotic seeds. However this was also the time when sunflower and sorghum crops were available. Consequently it was these crops which received the greatest damage from birds. Theoretical calculations of grain intake by the cockatoos and potential crop yields at each field area, revealed that less than 5% of overall crop yield was consumed by these birds each year.
However, damage was not evenly distributed-over the field areas, and appeared to be of greater economic significance to the individual small landholder, than larger agricultural concerns.
A combination of careful farm management, with the retention of uneconomic stubble areas for the use of the birds, or specially planted
"decoy" crops; and of improved sunflower agronomic practices (e.g. early planting, reduced period of seed susceptibility to damage) could alleviate damage to both summer and winter crops. Only provision of alternative food sources would effectively remove birds from standing crops, and more cooperation between farmers living within the home ranges of cockatoos is necessary. Such practices of damage control would ideally suit both farmers and birds. vii
CONTENTS
Page
ACKNOWLEDGMENTS i ii
SUMMARY iv
LIST OF TABLES x
LIST OF FIGURES xii
CHAPTER 1. INTRODUCTION
..1.1. Birds as pests to agriculture 1
1.2 Australian research 6
1.3 The birds 9
CHAPTER 2. METHODS
2.1 Field areas 12
2.2 Field observation 14
2.3 Shooting 19
■;2.4 Trapping and dyeing 20
2.5 Plant and seed collection 21
2.6 Bird 'crop' analysis...... - 21
;2.7 Data analysis 21
SECTION A . ':THE:WHITE COCKATOO (CACATUA GALERITA)
CHAPTER 3. HABITAT
3.1 Habitat preferences 23
3.2 Habitat use 30
3.3 Specific use of some habitat features 30
CHAPTER 4. INDIVIDUAL AND SOCIAL BEHAVIOUR
4.1 Introduction 32
4.2 Modes of locomotion 32
4.3 Maintenance ______33---
4.4 Effects of weather 35 Page
4.5 Allo-preening 37
4.6 Threat and alarm -39
4.7 Longevity and mortality 40
4.8 General flock behaviour 42
4.9 "Sentinel" behaviour 43
4.10 Roosting 44
4.11 Vocal communication 44
CHAPTER 5. SOCIAL ORGANIZATION AND DAILY ROUTINE
5.1 Population size and organization 51
5.2 Flock sizes and activities 58
5.2.1 Seasonal 58
5.2.2 Diurnal flock activity 65
CHAPTER 6. FEEDING ECOLOGY
6 .1 Feeding periods 72
6.2 Food availability 75
6.3 Food eaten 81
6.4 Selection of feeding sites 94
CHAPTER 7. BREEDING BEHAVIOUR
7.1 Pair behaviour 99
7.2 The nest 100
7.3 Laying and incubation 108
7.4 The nestling 108
7.5 The fledgling 116
7.6 Proportion of adults breeding 117
7.7 Breeding success 118
SECTION B . ' THE GALAH'(CACATUA ROSEICAPILLA)
CHAPTER 8 . HABITAT
8.1 Habitat pref erences 122
8.2 Habitat use 122 Page CHAPTER 9. SOCIAL ORGANIZATION
9.1 Population size and organization' 126
9.2 Flock behaviour and daily routine 131
9.3 Breeding 133
CHAPTER 10. FEEDING ECOLOGY
10.1 Feeding habits 135
10.2 Feeding periods 135
10.3 Food availability 136
10.4 Food eaten 141
SECTION C .■ THE WHITE COCKATOO AND GALAH - COMPARATIVE BEHAVIOUR, ECOLOGY AND PEST STATUS '
CHAPTER 11. COMPARATIVE BEHAVIOUR AND ECOLOGY
11.1 Comparisons between the White Cockatoo,
Galah and other cockatoos 149
11.2 Comparison of the White Cockatoo and
Galah with other Australian parrots 155
11.3 Environment, social organization and
potential pest status 159
CHAPTER 12. THE WHITE COCKATOO AHD GALAH AS PESTS TO GRAIN CROPS IN NORTH-EAST NEW SOUTH WALES
12.1 Crop damage 165
12.1.1 Crop selection 165
12.1.2 Patterns of crop damage 168
12.1.3 Crop seed intake 170
12.1.4 Degree of crop damage 177
12.2 Control of crop damage 184
CHAPTER 13. CONCLUSIONS 190
REFERENCES 194 APPENDIX A 205
APPENDi ’ B 208 X
LIST OF TABLES
Page 1. Major references on bird pest research 2
2. General description of the two field areas 15
3. Specific habitat composition 24
4. Areas of the four major habitats within the range of White Cockatoos at both field areas 29
5. Habitat use by the White Cockatoo 31.
6. Number of times White Cockatoos responded to predators 41 'hunting' in their vicinity
7. Vocalizations of the White Cockatoo 48
8. Seasonal differences in flock sizes of White Cockatoos 61
9. Daily activity of White Cockatoos each season 68
10. Major and minor feeding by White Cockatoos 74
11. White Cockatoo feeding 'bird hours' in each feeding period at: a. Swan Vale and b. Wallangra 76
12. Foods eaten by White Cockatoos in various parts of Australia 83
13. Gross energy values of some seeds present at Swan Vale and Wallangra 9 3
14. Nest trees used by White Cockatoos at Swan Vale and Wallangra 101
15. Breeding success of the.White Cockatoo 109
16. Habitat use by the Galah 124
17. Major and minor feeding by Galahs 138
18. Galah feeding 'bird hours' in each feeding period at Swan Vale 139
19. Foods eaten by Galahs in various parts of Australia 142
20. Behavioural comparison of the Galah and White Cockatoo 150
21. Social continuum of some Australian parrots 156
22. Metabolic requirements of White Cockatoos and Galahs for certain activities 171
23. Daily metabolic requirements of White Cockatoos and Galahs 172 xi
Page 24. Daily crop seed intake (dry weights) of White Cockatoos and Galahs 174
25. Dry weights of cockatoo 'crops' full of pure crop seed 175
26. Daily crop seed intake (g/day at 15% moisture) of White Cockatoos and Galahs 176
27. Crop damage potential of White Cockatoos and Galahs at Swan Vale and Wallangra 179 xii
LIST OF FIGURES
Page
1. Distribution of the White Cockatoo and Galah in Australia 10
2. Location of the two field areas, Swan Vale and Wallangra, 1 ^ in north-east New South Wales
3. Monthly rainfall at Swan Vale, Wallangra and Inverell 16
4. Minimum and maximum monthly temperatures at Swan Vale and Wallangra ^
5. Diurnal variation in preening 36
6. Monthly changes in the reinforcement of pair bonding 38
7. Times at which White Cockatoos arrive at roost area and settle to sleep, at Swan Vale and Wallangra 45
8 . Awakening times for White Cockatoos at Wallangra Site A 46
9. Sonographs of nine White Cockatoo calls 50
10. . fiange of the White Cockatoo population at Swan Vale 52
11. fiange of the White Cockatoo populations at Wallangra Site A and B ^
12. Number of White Cockatoos at the two field areas each month 54
13. Population structure of the White Cockatoo 57
14. Mean and range of flock sizes of White Cockatoos throughout the year at both field areas 59
15. Distribution and mean of flock sizes each season at a. Swan Vale and b. Wallangra 60
16. Distribution of White Cockatoo individuals in flocks of 1-5 each month at Swan Vale and Wallangra 63
17. Dispersion of White Cockatoos within their ranges at a. Swan Vale and b. Wallangra 64
18. Daily routine of the White Cockatoo 66
19. Daily activities of White Cockatoos each season at Swan Vale 67
20. Diurnal fluctuation in mean flock size of White Cockatoos each season at a. Swan Vale 1977 and b. Wallangra 1978 70 xiii
Page 21. Mean and range of flock sizes of White Cockatoos in the three main activities - feeding, flying and perching - each season for 1977 and 1978 at a. SwanVale and------b. Wallangra 71
22. White Cockatoo feeding periods ^3
23. Dry weights of White Cockatoo 'crops' throughout the day 77
24. Seasonal flock sizes of White Cockatoos participating in morning and afternoon feeding periods at each field area 78
25. Native and exotic grass seed cycle at the field areas 80
26. Food availability - monthly changes in the composition of cultivated land at a. Swan Vale and b. Wallangra 82
27. Use of feeding areas by White Cockatoos at a. Swan Vale and b. Wallangra 87
28. Monthly seed composition of White Cockatoo 'crops' at a. Swan Vale and b. Wallangra 90
29. Distances flown by White Cockatoos from roosts to feeding areas at a. Swan Vale and b. Wallangra 95
30. Feeding areas used by White Cockatoos at Swan Vale each year 96
31. Feeding areas used by White Cockatoos at Wallangra each year 97
32. Nest attendance by White Cockatoos throughout the year 107
33. Growth of White Cockatoo nestlings 114
34. Inferred home ranges of Galah populations at Swan Vale and ,...... Wallangra Site A 123
35. Total population numbers and mean and maximum flock sizes of Galahs present each month within the Swan Vale home range ' 127
36. Monthly fluctuations of Galah. numbers within five home ranges in north-east New South Wales 129
37. Galah feeding periods 137
38. Dry weights of Galah 'crops' throughout the day 140
39. Use of feeding areas by Galahs at a. Swan Vale and b. Wallangra 145 xiv
Page 40. Monthly seed composition of Galah 'crops'1 at
a. Swan Vale and b. Wallangra 147
41. Flock sizes of eight species of Australian parrots
in three activities (flying, perching and feeding) 158
42. Establishment of White Cockatoos on two sunflower
crops in 1977 at Swan Vale 166
43. Selection of crops by White Cockatoos and Galahs at
a. Swan Vale and b. Wallangra 167
44. Amount of crop seed eaten from standing crops by White
Cockatoos and Galahs at
a. Swan Vale and b. Wallangra 178
45. Patterns of bird numbers, population composition,
cropping and native seed cycles, within a permanent
home range of White Cockatoos and Galahs in
north-east New South Wales 191