CSIRO PUBLISHING www.publish.csiro.au/journals/emu Emu, 2004, 104, 1–6

The breeding ecology and behaviour of a colour-marked population of Brown Falcons (Falco berigora)

Paul G. McDonald

School of Botany and Zoology, Australian National University, Canberra, ACT 0200, Australia. Email: [email protected]

Abstract. This study took advantage of a large, closely monitored colour-banded population of Brown Falcons to describe aspects of this species’ breeding ecology and behaviour over three consecutive years. Both pair members aggressively defended territories throughout the year from conspecifics and other species alike. Males performed territorial displays more frequently than females, which rarely displayed unprompted. Strong differences in the types of parental care provided by each sex were evident, with females contributing most to incubation, brooding and feeding of nestlings and fledglings. Males, on the other hand, provided most of the food to both females and broods, from well before the first eggs were laid until nestlings were 2–3 weeks old. Prey deliveries were more frequent early in the morning and late in the evening; however, remains of larger prey were cached, presumably to provision the offspring more regularly throughout the day.

Introduction Details of the study site (Baker-Gabb 1982, 1984a) and population, which included 44–49 breeding pairs, have been described elsewhere Despite being one of Australia’s most commonly encoun- (McDonald 2003a, 2003b; McDonald et al. 2003). tered raptors (Blakers et al. 1984), the behaviour and breed- Falcons were captured with bal-chatri and modified goshawk traps ing biology of the Brown Falcon (Falco berigora) has (see Bloom 1987 for details), fitted with a unique combination of colour received little scientific attention. In the most comprehensive bands approved by the Australian Bird and Bat Banding Scheme and released at the point of capture. During frequent visits to the study site studies to date, Baker-Gabb (1982) monitored up to 25 pairs banded birds were actively sought, identified and their behaviour noted. in southern Victoria over three seasons and Mooney (1976) When found, nest trees were climbed daily until clutches were described several aspects of the behaviour of captive indi- complete. If not observed directly, laying dates of first eggs were viduals. However, this work is largely confined to unpub- estimated using either a formula based on egg weight (P. Olsen, lished theses. Bollen (1993) published descriptions of the unpublished data) or, if eggs hatched, by backdating using an average incubation period of 36 days (this study) and estimating chick age from behaviour from one pair, while Debus (1991) described two formulae based on wing length (McDonald 2003b). Nests were visited displays of a single male and Olsen and Olsen (1980) have weekly after hatching to determine nestling periods and the number of described nest-defence behaviour in response to human birds successfully fledged from each nest. At ~4 weeks of age nestlings intruders. Additional information on the Tasmanian popu- were fitted with colour bands. Following fledging, the length of post- lation has been provided by Mooney in Cade (1982) and fledging parental care was determined by visiting the nest area bi-weekly. If fledglings could not be located in three successive visits Marchant and Higgins (1993). The latter also contains a they were deemed to have successfully reached independence. During review of additional anecdotal evidence. the breeding seasons of 2000 and 2001 intensive assessments of This study, as part of a larger investigation into the breed- parental roles at the nest were conducted using surveillance cameras ing biology and life-history strategies of Brown Falcons, throughout the nestling stage. Small cameras with infrared lights (Model 43150674; Radio Parts Group, Melbourne) were placed at nests took advantage of a large, colour-banded population to for 48-h periods throughout the nestling phase. Cameras were powered investigate and describe additional behaviours of birds of by deep-cycle batteries (Besco N70T; Battery World, Canberra) and known sex and background. In addition, footage from nest- connected to time-lapse video-recorders (Hitachi VT1200E; Radio surveillance cameras over two seasons allowed a detailed Parts Group, Melbourne) run at one-eighth normal speed; this examination of the degree of sex-role partitioning during minimised visits to the nest tree to 24-h intervals to change batteries and tapes. The behaviour of parent birds and offspring was then noted on parental care. subsequent viewing of video footage.

Materials and Methods Statistical analyses The study was conducted between July 1999 and June 2002 ~35 km Goodness-of-fit tests were used to assess the significance of differences south-west of Melbourne, at the Western Treatment Plant, Werribee in prey-delivery rates throughout the day as well as sexual differences (38°0′S, 144°34′E), adjacent to Avalon Airport (38°2′S, 144°28′E) and in the recorded frequency of each display type. Where appropriate, small areas of surrounding private land, a total area of ~150 km2. Yates’ corrections for continuity were used (Zar 1996). One-way

© Royal Australasian Ornithologists Union 2004 10.1071/MU02042 0158-4197/04/010001

2 Emu P. G. McDonald

ANOVAs and linear regressions were used to assess yearly differences torial disputes, usually given with much calling. Equal in the duration of various phases of parental care. The methods used in numbers of males and females were observed performing this project was approved by the Australian National University Animal this display. Another apparently territorial display was Experimentation Ethics Committee (F.BTZ.02.99). observed in 11.1% (total n = 126) of observations, with Results falcons flying in a series of large, undulating ‘U’ shapes, Agonistic interactions giving quick wingbeats during upsurges, again with much calling and usually while rolling from side to side with the Both members of Brown Falcon pairs aggressively defended wings held in a half-closed position, particularly during territories from intraspecific intruders of either sex through- descents. More rarely, this display was performed while out the year, although agonistic interactions were more flying at a constant elevation in a figure-of-eight pattern. common and were of a longer duration between July and U-displays were given significantly more often by males November (the breeding season, see below). Interactions χ2 (85.7%, total n = 14, c = 5.21, P = 0.02); females were often escalated into physical contact between birds, with observed giving this display on just two occasions (both perched combatants observed jumping to the ground to avoid times in the company of a displaying male). U-displays were being struck by conspecifics on seven occasions. Talon- usually performed over a male’s own territory during/follow- presentation displays were also common and, in one extreme ing agonistic interactions, with neighbouring males observed case, two females locked talons and spiralled downwards giving this display while soaring 200 m apart. Typically, 20 m in a ‘cartwheeling’ flight, completing four full revolu- U-displays were given at great height, often culminating in tions before releasing their grip close to the ground. spectacular, steep and rapid descents to nest trees, with marked side-slipping and frequent calling throughout. After Territorial and courtship displays birds returned to perches following territorial disputes, occa- Displays were also frequently encountered throughout the sionally both members of a pair would continue to call, year, becoming more frequent from July to November. Of a raising their wings above their back, fully outstretched, while total of 126 displays given by banded birds, ‘side-slipping’ facing the direction from which the intrusion came. At dusk was the most frequently observed (62.7%). During this males would fly around their territory with fast wing beats display birds would rotate rapidly from side to side while in giving single, sharp ‘ack’ calls, with the ‘arrrrrk-ark-ark’ a gliding descent, often from great height, with wings held call often heard during this and all other displays. stiffly behind their back, alternatively displaying their dorsal and ventral plumage. Males were usually more exaggerated Courtship feeds and copulation behaviour than females in their movements, often using strong winds to The first courtship feeds of the season were recorded in perform the display in a stationary position above their mid-July each year. Males would bring prey, house mice eventual perch, rotating through an axis of up to 270° with (Mus musculus) in all cases identified (n = 13), towards each turn. This display was usually given by both sexes upon females with fast, exaggerated wing beats, frequently giving landing near the nest tree or returning to perches following ‘arrrrrk-ark-ark’ calls and performing the side-slipping agonistic interactions. Females (40.5%) were observed display before landing. Females responded with trilling calls giving this display less frequently than males (59.5%, n = 79, or occasionally a sharp ‘kark’, taking the prey from males’ χ2 c = 2.86, P = 0.09). In all cases, females were prompted in beak to beak or, less often, with her talons. Copulation was some manner before giving the display, whereas males often observed following a courtship feed on only one occasion performed displays alone. For example, following territorial (6.7%, total n = 15). Females initiated copulation on 27.8% disputes, females would usually follow males back to perches, of all occasions that it was witnessed (n = 18), by giving usually 3–5 m behind. Upon landing, males routinely gave the short, sharp monosyllable calls, bowing their heads forwards side-slipping display, with females following suit with fewer, and lifting up their tail and rump. After this behaviour males smaller rotations. The only other occasions when females would approach the female and land upon her back before were recorded side-slipping was after they were flushed from copulation (lasting 5–7 s) ensued. Less often, both sexes nests or released following capture (both these contrived would perform this bowing display prior to, and immediately situations were not included in figures presented above). In after, copulation. contrast, males frequently gave this display outside of these situations and in areas away from the nest. Duration of, and the partitioning of, parental care among Other displays observed include mutual soaring (16.7%, the sexes total n = 126), where both members of a pair would soar Incubation lasted 35.8 ± 0.8 days, based on six eggs found on within 50 m of each other, and a variety of stoops and soaring the day that they were laid and subsequently hatched. Nest- displays accompanied by quick, flickering wing beats while ling periods, obtained for 60 nestlings, did not differ between the birds rolled from side to side in flight (9.5%, total the 2000 and 2001 breeding seasons (F1,58 = 0.77, P = 0.39), n = 126). This faster wingbeat seemed to be confined to terri- averaging 41.5 ± 0.5 (s.e.) days. Nestling periods were

Brown Falcon breeding behaviour Emu 3

unaffected by nestling sex (F1,54 = 1.08, P = 0.30), hatch Prey delivery and the feeding of nestlings order (F2,54 = 0.35, P = 0.71) or the interaction between the There were two distinct peaks in frequency of delivery of two (F2,54 = 0.43, P = 0.65). Likewise, post-fledging parental prey to nests over the course of the day (Fig. 1): the first at care periods were not influenced by sex (F1,37 = 0.21, P = 0600–0800 hours, just after sunrise, and the second just prior 0.65), hatch order (F2,37 = 0.09, P = 0.92) or their interaction to sunset. Deliveries during the middle of the day were less (F2,37 = 1.11, P = 0.34). The duration of post-fledging paren- frequent. Differences in the number of prey items delivered tal care was identified for 46 fledglings, being quite variable χ2 to nests throughout the day differed significantly ( 16 = (range: 7–70 days), lasting on average 27.9 ± 2.3 (s.e.) days. 87.5, P < 0.0005). Deliveries of four of the five different Yearly differences were again not apparent (F1,44 = 0.46, P = dietary groups taken by pairs within the study site – lago- 0.83); however, chicks that fledged later in a given season morphs, small ground prey, small birds, large birds and 2 received shorter periods of post-fledging parental care (R = reptiles (see McDonald et al. 2003 for definitions), as well as 0.29, F1,44 = 18.30, P < 0.0005; duration of parental care prey that could not be identified, followed the same general [days] = 227.9 – 0.6 [Julian date fledged]). No such seasonal daily pattern (all P < 0.05, data not presented) (Fig. 1). Large decline was apparent for the nestling period (F = 1.26, P = χ2 1,58 birds were the exception ( 7 = 10.7, P = 0.15), although this 0.27). Over one-quarter of fledged young failed to reach is likely an artefact of low sample size. Nestlings were often independence (28.1%, n = 64); all remains recovered indi- fed from cached prey remains before sunrise; final daily cated that predation by either red foxes (Vulpes vulpes) or feeds were often conducted after sunset. During rain periods feral cats (Felis catus) was responsible for these deaths. prey deliveries were rare. Strong sex-role partitioning was apparent throughout the First-hatched birds were not fed until the day after hatch- breeding season. Females rarely hunted from ~2 weeks prior ing, although nestlings hatched later in the sequence were to laying the first egg, staying close to the eventual nest site. fed earlier, as they received food during the eldest chick’s In this period males supplied females with most of their food first feed. When feeding young, females generally ate the with courtship feeds, as described above. After laying, intestines, feet, fur, large bones and feathers of prey items, females assumed most incubation duties and, in all cases giving progressively larger and coarser pieces of prey to nest- observed except one, incubated/brooded during the night. lings as they grew. Once nestlings were two weeks old Three males were observed incubating clutches; in two of females began giving smaller prey items to them whole. At these nests incubation was monitored over a 24-h period with this age chicks could either swallow the prey in its entirety or a surveillance camera. During this time, one male provided break off smaller pieces unaided. Chicks were brooded con- 45.4% of the 610 min of incubation during daylight hours, stantly until 10–14 days old, coincident with the develop- with the longest stint lasting 92 min. However, at the other ment of a thick woolly down (McDonald 2003b). When not nest monitored the resident male did not incubate at all, indi- brooding, females usually remained perched within 100 m of cating considerable individual variation in this trait. the nest, although this distance increased as nestlings’ aged. After hatching, males occasionally brooded young, but at Females were generally within sight of young until they a much lower frequency than during incubation. Instead, males supplied most of the food for both the brood and the 110 Lagomorphs Small ground prey female until chicks were 2–3 weeks old, when females again 100 Small birds Large birds resumed hunting. Males usually brought prey to a tree next 90 Reptiles Unidentified prey to the nest site with similar behaviour to that observed during 80 courtship feeds. When a male arrived with food, which was 70 usually decapitated, females retrieved prey directly from 60 their partner, usually in a tree close to the nest, before distri- 50 buting food among the brood. If prey remained after chicks 40 were satiated, remains were usually either eaten by the 30 female or cached, often in a disused corvid nest near where 20 transfers took place. If females were absent from the nest

Prey items delivered to nests 10 area males would drop the prey item into the nest and leave; 0 if chicks were unable to break up the prey themselves, 8-21 females would usually retrieve it upon their return. Only one 04-06 06-08 08-10 10-12 12-14 14-16 16-18 1 male was ever observed feeding nestlings; this occurred Time of day (24 hours) when he brought prey to the nest while the female was Fig. 1. The timing of prey delivery to Brown Falcon nests monitored already feeding one nestling. After unsuccessfully offering 24 h per day with nest-surveillance cameras. Legend indicates category the prey to the occupied female, the male proceeded to feed of prey item delivered, according to five dietary groups defined by the second nestling himself. McDonald et al. (2003) and unidentified prey.

4 Emu P. G. McDonald achieved independence, responding to perceived threats, breeding on the study site, namely Black-shouldered Kites such as my presence, more quickly than males. Nestlings (Elanus axillaris), Black Kites (Milvus migrans), Whistling were still brooded overnight until ~25 days old, when Kites (Haliastur sphenurus), Brown Goshawks (Accipiter feathers had emerged over much of their bodies (McDonald fasciatus), Little Eagles (Hieraaetus morphnoides), Swamp 2003b). Females slept in the nest until their chicks fledged. Harriers (Circus approximans), Nankeen Kestrels Once fledged, young on several occasions roosted in a corvid (F. cenchroides) and Australian Hobbies (F. longipennis). nest close to their nest tree; however, fledged offspring were Defence was most intense and prolonged against Wedge- not observed returning to the natal nest. tailed Eagles (Aquila audax). This latter species was often When females arrived at the edge of the nest with prey, swooped at by both sexes with much calling and fast wing nestlings older than seven days would jostle for position beats, similar to those used in territorial interactions with closest to the female, with birds older than three weeks gen- other Brown Falcons. Often, when eagles soared to a height erally holding out their wings to keep brood mates away from of 100 m or so, as many as three pairs of falcons would food. In larger broods nestlings at the back of nests pushed display and direct swoops at them. Despite this interspecific their way forwards closer to the female; however, bills or aggression, nests of Australian Hobbies and Whistling Kites talons were not used against other siblings. Older nestlings were both observed within 50 m of Brown Falcon nests and intercepted food from the female more easily than younger that of a Wedge-tailed Eagle within 250 m. Interspecific nestlings as they had a longer reach. Once satiated, chicks agonistic interactions between these close-nesting pairs were would sit back down on their tarsi, allowing hungrier chicks rarely observed unless intruders flew directly at the falcon’s to move forwards and receive any remaining food. When nest. Of the other raptor species on site, only Black- nestlings began breaking prey up into manageable pieces by shouldered Kites were observed initiating attacks against themselves, nestmates would use their bills and talons to Brown Falcons. This species did so frequently throughout the attempt to grab prey from each other. Once all prey was con- entire year. One Brown Falcon was observed taking a sumed, nestlings that were not being brooded huddled recently caught mouse from a kite in an act of mid-air klepto- together during periods of cool weather or lay on their side parasitism. with legs stretched out during hotter parts of the day. When begging, fledglings assumed a similar posture to Discussion females receiving courtship feeds, with the head and Displays, aggression and breeding behaviour shoulders held low and forwards, wings slightly open, the body parallel to the ground and the tail lowered, giving a trill- Throughout the entire year both sexes of Brown Falcon pairs ing call throughout. Both sexes delivered prey to fledged aggressively maintained territorial boundaries, with physical young, but males did so more often. Most food was given to contact between combatants frequently recorded. The high fledglings whole; however, occasionally large prey would level of agonistic interactions in this population may reflect still be broken up for recently fledged birds. In one case a the high density of breeding birds present in the study area; fledgling, recently independent, begged with fledglings from in two of the three years that this population was monitored c another brood and received food from the male territory densities were the highest on record (M Donald et al. 2003). holder. This brood parasitism was observed over several days Given this, on-site territories are likely to be highly sought without any sign of aggression from the territory owners. after and this perhaps may explain the level of agonistic Likewise, recently independent young were also observed interactions observed. The intersexual displays observed begging from territory-holding birds other than their parents were similar to those that have been described previously in December and January, without any sign of aggression (Baker-Gabb 1982; Debus 1991; Bollen 1993; Marchant and towards the intruding young. Higgins 1993). However, by monitoring a population of Fledglings normally drifted further and further away from banded birds this study was able to determine that females the nest area before obtaining independence of their own displayed less frequently than males. This was particularly accord; however, parental aggression was observed in two evident in examination of side-slipping and U-displays, with cases. An adult female tail-chased and swooped her young in females rarely giving these displays unprompted. the week prior to independence, striking them on two occa- In contrast, females were frequently involved in agonistic sions. In another instance, an adult male flew very fast and disputes, with the one case of a ‘cartwheeling’ flight involv- straight at his begging fledgling 300 m away. A tail chase ing two females. These flights in raptors are considered by ensued, with the adult bird pulling out of the chase after the some researchers to be primarily aggressive in nature fledgling landed in a small tree. (Simmons and Mendelsohn 1993). This was apparently so in two recorded cases of male Tasmanian Brown Falcons cart- Interspecific interactions wheeling (Mooney in Simmons and Mendelsohn 1993), An area of up to 500 m from the nest site was aggressively although Hollands (1984) reported one instance involving a defended by both sexes against corvids and other raptors male and female apparently related to courtship. The incident

Brown Falcon breeding behaviour Emu 5 reported in this paper appears aggressive in nature as it activities, feeding young and remaining close to the nest, involved two females from adjacent territories, occurred in presumably to protect offspring. This sex-role differentiation the approximate area where these territorial boundaries met has been noted in most other raptor species (Newton 1979; and both individuals returned to the centre of their respective Marchant and Higgins 1993; Olsen 1995). territories after the interaction. Prey deliveries to nests peaked in late afternoon and early Courtship feeding was commonly observed before the in the morning, just after sunrise. This is in keeping with laying of eggs in this population, and this behaviour has been results previously reported for several pairs of Brown described previously by Baker-Gabb (1982). The sole use of Falcons observed from hides (Baker-Gabb 1984b; Marchant house mice as prey during courtship feeds is interesting and Higgins 1993). The comparatively low delivery rate given the wide range of prey taken by the population observed by Bollen (1993) may be a consequence of most (McDonald et al. 2003). Perhaps heavier prey items do not watches being undertaken in mid-afternoon, a period of allow males to perform the side-slipping display when infrequent prey delivery in this study. Female Brown Falcons delivering prey to females, overriding any advantage of frequently cached larger prey items if chicks could not delivering a larger biomass. Alternatively, delivering smaller consume them in one sitting. Caching behaviour has been amounts of food more frequently throughout the day, thus noted previously in some Brown Falcons (Mooney 1982; increasing the number of interactions between members of a Bollen 1993; Marchant and Higgins 1993); this study pair, may cement pair bonds and help coordinate repro- demonstrates that the practice is widespread and common ductive activities more efficiently than less frequent deliver- throughout the entire breeding season. Caching has also been ies of larger prey (Hamerstrom 1979; P. Olsen, personal observed in many other falcons (Holthuijzen 1990; Cameron communication). and Olsen 1993), where its main function is apparently to The high level of nest defence directed at other raptor reduce hourly fluctuations in food availability. This is likely species by Brown Falcons has been commented upon previ- to apply to Brown Falcons, as cached prey was usually used ously (Baker-Gabb 1982; Marchant and Higgins 1993), to feed offspring immediately prior to sunrise and after dark, although this study extends the list of species repelled. Some periods when hunting was not likely to be successful. This pairs nested in relatively close proximity to other raptors, strategy regularised food intake, particularly early after with a subsequent reduction in the area defended around hatching when feeds were comparatively small and frequent, nests, demonstrating that interspecific aggression did not similar to the situation reported in Peregrine Falcons (F. pere- limit nesting opportunities. Aside from corvids and some grinus) (Cameron and Olsen 1993). small passerines, Black-shouldered Kites were the only The feeding of fledged offspring from another brood, or species routinely observed behaving aggressively towards brood parasitism/adoption, has not previously been reported Brown Falcons, with these small kites the only raptor in Brown Falcons, although the behaviour has been noted in recorded in the falcon’s diet (McDonald et al. 2003). One instance of kleptoparasitism was also recorded between a many other bird species, including several raptors (Bustamante and Hiraldo 1989; Frumkin 1989). The high Brown Falcon and Black-shouldered Kite. Despite Brown c Falcons being known pirates of many other species (Baker- density of the population studied (M Donald et al. 2003) Gabb 1984a), this is apparently the first reported instance of may bring recently independent offspring into contact with kleptoparasitism from a Black-shouldered Kite. other broods more often than usual. If adults could not recog- nise their own fledglings, this behaviour would increase the Parental care and sex-role partitioning likelihood of brood parasitism occurring, although the Yearly differences in the time devoted to parental care of ultimate factors driving this behaviour remain unclear nestlings and post-fledging young might have been expected, (Bustamante and Hiraldo 1989). according to the prevailing conditions and subsequent sur- Thus the breeding behaviour of Brown Falcons appears vival prospects of young (Korpimäki and Lagerström 1988; very similar in many respects to that of other species of Hakkarainen and Korpimäki 1994; Verhulst and Hut 1996). Falco, although vocalisations and territorial displays were However, none of these relationships were apparent. The one given more frequently than is typical (cf. Marchant and significant relationship observed was a seasonal decline in Higgins 1993). While this may be an artefact of the dense the period of post-fledging parental care, a trait that has been population studied, other Brown Falcon populations, which described in other raptors (e.g. Bustamante and Hiraldo are distributed more sparsely, also vocalise and display 1990). frequently (P. Olsen, personal communication). As Brown Distinct sex-role partitioning during parental care was Falcons occur at a high density throughout their range, also evident, with males supplying most of the food prior to particularly for a large falcon (Blakers et al. 1984), this the eggs being laid until chicks were old enough to control behaviour may be a mechanism by which territory bounda- their own body temperature. Females, on the other hand, ries can be maintained and enforced with little risk of injury undertook most of the incubation and, particularly, brooding to combatants. 6 Emu P. G. McDonald

Acknowledgments Frumkin, R. (1989). Egg quality, nestling development and dispersal in the sparrowhawk (Accipiter nisus). Journal of Raptor Research 23, I thank Melbourne Water, Avalon Airport, Werribee CSR 123. Readymix, the Avalon Mountain View Quarry and various Hakkarainen, H., and Korpimäki, E. (1994). Does feeding effort of private land owners for allowing access to their land. Penny Tengmalm’s Owls reflect offspring survival prospects in cyclic food Olsen, Andrew Cockburn and David Baker-Gabb provided conditions? Oecologia 97, 209–214. valuable advice and supervision throughout the project. Hamerstrom, F. (1979). Effect of prey on predator: voles and harriers. Auk 96, 370–374. Penny, David and Rob Heinsohn greatly improved an earlier Hollands, D. (1984). ‘Eagles, Hawks and Falcons of Australia.’ version of this manuscript; Andrew generously partially (Thomas Nelson: Melbourne.) funded the camera setups. Sidney McDonald and Robert Holthuijzen, A. M. A. (1990). Prey delivery, caching, and retrieval rates Phillips helped put the cameras together. The Australian Bird in nesting prairie falcons. Condor 92, 475–484. and Bat Banding Scheme provided bands used in this study. Korpimäki, E., and Lagerström, M. (1988). Survival and natal dispersal of fledglings of Tengmalm’s Owl in relation to fluctuating food An ANU Graduate School Scholarship supported me conditions and hatching date. Journal of Animal Ecology 57, throughout the project, which was also partially funded by 433–441. Stuart Leslie Bird Research Awards, a Cayley 2000 Memo- Marchant, S., and Higgins, P. J. (Eds) (1993). ‘Handbook of Australian, rial Scholarship, Birds Australia VicGroup Research Grants New Zealand and Antarctic Birds. Volume 2: Raptors to Lapwings.’ and the Joyce W. Vickery Scientific Research Fund. (Oxford University Press: Melbourne.) McDonald, P. G. (2003a). 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