VOL. 17 (2) JUNE 1997 71

AUSTRALIAN WATCHER 1997, 17, 71 -80

Male Superb , with Eastern Yellow Robin watching. Plate 6 Photo: L.H. Smith

Building a Viable Lyrebird Population

by L.H. SMITH, 36 Duke Street, Kew, Victoria 3101

Summary Available data are used to prepare a model showing how a Superb Lyrebird Menurp novaehol/ondiae population grows, under prescribed conditions, as the annual breeding proceeds from an initial population of breeding . On the assumption that breeding of the initial stock ceases after their first progeny begin to breed (in their eighth year), the model shows that an egg-to-breeder success rate of about 22% would suffice to establish a viable Lyrebird population. For growth to occur, a higher success rate would be necessary. If the success rate for the egg-to-chick stage is x % and that for the chick-to-fledgling stage is y%, the value of z, the fledgling-to-breeder success rate required to establish a viable population, may be calculated from the formula z = 22/xy%. The effects of and forest conditions are discussed. The strong growth of the Lyrebird population in Tasmania, where there are no Red Foxes Vulpes vulpes, is used to demonstrate what is required in mainland Australia to achieve the higher values of x, y and z which are prevalent in Tasmania: namely, vigorous and efficient fox-control programs and appropriate management of Lyrebird habitats.

Introduction The decline in the population of the Superb Lyrebird Menura novaehollandiae in Sherbrooke Forest, Victoria, has been attributed to the combined effect of predation and the deterioration of the forest environment caused by the unimpeded accumulation of forest litter and the uncontrolled proliferation of native plants such as ground-ferns, wire-grass, shrubs, trees, etc. The loss of access to its food , which the Lyrebird derives AUSTRALIAN 72 SMITH BIRD WATCHER from the forest floor, has been exacerbated by invasions of exotic species such as English ivy, wandering jew, violets, holly, sycamores, blackberries, etc. The closure of walking and fire-protection tracks has precluded the adoption of appropriate management practices designed to ameliorate conditions, thereby compounding the hazards confronting the Lyrebird (Smith 1994). The Lyrebird lays only one egg each year and there is only one clutch (Lill1986, Reilly 1988, Smith 1988). Lack of data on the events preceding egg-laying precludes further consideration of that aspect here, but Reilly (1970) and Lill (1979a,b, 1980) have provided data on the incubation of the egg and the growth of the chick into a fledgling, and Smith (1982) has described the development of the fledgling into a mature Lyrebird. It is thus possible to construct a model to demonstrate what is involved in the development of a viable Lyrebird population, under certain conditions listed below. Some of the assumptions made may not be realised in practice, but an analysis of the factors involved in the production and interpretation of the model will provide useful guidance in the formulation of any plan to manage an area reserved (not necessarily exclusively) for the preservation of the Lyrebird. There are at present no such 'guidelines'.

Lyrebird populations At any given time, the Lyrebird population in a particular area will consist of breeding females, breeding males, immature male and female of various ages and, possibly, mature males and females not directly involved in breeding. The status of such birds within the community changes from year to year, but the total number of birds can increase only through the annual breeding success of the mature females (provided that the number of breeding males is adequate), on a sustainable basis. There are no reliable statistics on Lyrebird populations (Smith 1994), but there is abundant evidence that, before Australian forests gave way to various forms of 'development', Lyrebirds were numerous. Over 150 years ago, Gould (1848) found himself 'surrounded by these birds'. Haydon (1846) was woken 'by the singing of several '; Aflalo (1896) described how, within a few months, two enterprising brothers in New South Wales obtained '500 dozen pairs of tails for sale', by shooting. Campbell (1900) provided further evidence of the abundance ofLyrebirds in earlier days. Conditions within the forests must then h'ave been more favourable to the Lyrebird; predation was apparently not a major problem before the wide dispersal of the introduced Red Fox Vulpes vulpes (O'Donoghue 1931, Rolls 1984). Keast (1969) stated that the indigenous mammalian fauna was low in predators, and Lill (1980) concluded that 'predation was unlikely to have been a significant mortality factor ancestrally'. Food must also have been abundant and readily accessible to sustain strong Lyrebird populations throughout the bird's range. Studies on avian population densities in other countries show that, in general, the richer and more varied the food resources of an environment the denser its bird population (Welty 1982).

Food requirements The Lyrebird's diet consists of worms, grubs, centipedes, scorpions, land yabbies, 'hoppers' (Talitrus sp.), spiders, etc., which are obtained from the forest litter and soil (Robinson & Frith 1981, Smith 1988, Barker & Vestjens 1990). The lack of data on the Lyrebird's daily food requirements, yield of food per hectare and the significance of habitat quality in the economy of the Lyrebird, render it difficult to formulate firm conclusions regarding the survival of the Lyrebird in the wild. VOL. 17 (2) JUNE 1997 Building a Lyrebird Population 73

The range of the Superb Lyrebird embraces a wide variety of habitats including and eucalypt forests (Blakers et al. 1984). I have observed Lyrebirds in the dry open forest of Central Gippsland and north-eastern Victoria, in the dry sandstone areas around Sydney and in the dry ridges of the of the Blue Mountains in New South Wales. In the Mount Buffalo area, some mounds where male birds display had the fine tilth of those of Sherbrooke Forest, whereas others consisted of coarse gravel. Bell (1976) described Lyrebird habitats in which mounds (reflecting the nature of the terrain) varied in composition from soil and humus to pebbles and quartzite. In such cases, it is more difficult for Lyrebirds to obtain sufficient food to meet their needs than it is in the moister soils of the fern gullies of other areas. Lyrebirds must be able to obtain sufficient food to sustain themselves, but there is a limit to the amount of energy which can thus be expended without detriment to breeding efficiency. Female Lyrebirds need extra food to compensate for the energy consumed in supporting their young.

Longevity Few data exist on the longevity of birds. It is necessary to distinguish between 'potential longevity' as realised by captive birds and actual longevity achieved by birds in the wild. Welty (1982) listed ages attained by many species of banded wild birds, ranging from 18 to 42 years, whereas others lived 5 to 16 years. In the wild, birds are exposed to a wide range of environmental factors including predation, the absence of which favours captive birds, which may live for 50 years. Birds having delayed breeding are long-lived (Ford 1989). The fact that the Lyrebird requires about 7-8 years to mature and the female lays only one egg each year suggests that this species may have a propensity for longevity and that, under the conditions which prevailed before white settlement, a lifespan in excess of20 years was not uncommon for Lyrebirds, in the wild. There is evidence to support this view. For example, a free-ranging 'pet' Lyrebird lived on a farm in Gippsland for about 20 years before being shot (Godfrey 1905). The celebrated 'Timothy' lived in Sherbrooke Forest for about 25-26 years; his successor 'Spotty' was about 21-22 years old when he died. Two female Lyrebirds exhibited in the Adelaide Zoological Gardens died at the age of 19-20 years (Smith 1988). One of my 'friendly females' nested regularly near Sherbrooke Falls from 1947 to 1960; she was therefore about 20 years old (possibly older) when I last saw her. Chisholm (1960) described a pair of captive Lyrebirds which died as a result of an accident, at the age of 15 years. On the other hand, many of Sherbrooke's Lyrebirds died at an earlier age, almost certainly the result of predation. 'Red' (1958-67), R/R(1959-68), W/W(1960-68) and R/B(1959-68) were among the casualties.

Age at maturity The male Superb Lyrebird acquires his adult tail plumage at the age of7-9 years, but the age at which he first mates is not precisely known (Smith 1988). A captive female Lyrebird in New South Wales successfully reared her first chick in her ninth year (Chisholm 1960), and a female Lyrebird in Sherbrooke Forest, banded as a nestling in 1963, produced her first chick in 1970. For the purposes of this exercise, it is assumed that both sexes begin to breed in their eighth year.

Sex ratios Information on sex ratios for Lyrebirds is not available. The demonstration by Kenyon (1972) that one male Superb Lyrebird mated with several females during one breeding season suggests that there might have been an excess of females in that -.1

""'" I Table 1

Theoretical growth of Lyrebird population as breeding proceeds (see text) Year No. breeding Total no. No. chicks Total no. Total no. No. immature Lyrebirds of different ages Lyrebirds mature produced immature Lyrebirds at end at end of breeding season (F + M) Lyrebirds Lyrebirds of breeding . season 1st yr 2nd yr 3rd yr 4th yr 5th yr 6th yr 7th yr 8th yr 8th N + rN N + rN N N 2N + rN N 9th N + rN N + rN N 2N 3N + rN N N Vl lOth N + rN N + rN N 3N 4N + rN N N N ~ 11th N + rN N + rN N 4N 5N + rN N N N N ->-3 12th N + rN N + rN N 5N 6N + rN N N N N N I :I: 13th N + rN N + rN N 6N 7N + rN N N N N N N 14th N + rN N + rN N 7N 8N + rN N N N N N N N 15th N + rN N + rN N 8N 9N + rN N N N N N N N N Original Lyrebird population ceases breeding

Breeding of progeny begins 15th 0.5N + 0.5rN N 0.5N 7.5N 8.5N 0.5N N N N N N N N 16th N + rN 2N N 7.5N 9.5N N 0 .5 N N N N N N 17th 1.5N + 1.5rN 3N l.5N 8N liN l.5N N 0.5N N N N N N 18th 2N + 2rN 4N 2N 9N 13N 2N l.5N N 0.5N N N N N 19th 2.5N + 2.5rN 5N 2.5N l0 .5N 15.5N 2.5N 2N l.5N N 0.5N N N N

20th 3N + 3rN 6N 3N 12.5N 18.5N 3N 2.5N 2N l.5N N 0.5N N N C::l 21st 3.5N + 3.5rN 7N 3.5N 15N 22N 3.5N 3N 2.5N 2N 1.5N N 0.5N N ~> 22nd 4N 4rN 8N 4N 18N 26N 4N 3.5N 3N 2.5N 2N l.5N N 0.5N - + I Oc::: ~Vl >>-3

>-3~ :I:-(')!:"" tn> ~z VOL. 17 (2) JUNE 1997 Building a Lyrebird Population 75 particular area at the time, but the generality of polygamy for the species has not been established (cf. , however, Lill 1980). This aspect is not relevant in the present context, because the number of chicks produced in a given year will depend on the number of breeding females , provided of course that each female realises her potential . Studies on 14 species of wild birds revealed that, in eight cases, the percentage of males was in the range 52-59; in five cases, it was 60 to 80 and, in one case, it was 33 (Welty 1982). For the purpose of this paper it is assumed that the ratio of breeding males to breeding females is r (-'1).

Model of population growth The foregoing provides a basis for developing a demographic model to indicate what is entailed in establishing a viable Lyrebird population, under certain conditions. For the purpose of the exercise, it is assumed that the original population consisted of N breeding females and rN breeding males, that equal numbers of chicks of both sexes were produced each year, and that there were no casualties (i.e. no infertile eggs and no losses to predation or natural causes). Assuming that the original breeding birds were in their respective eighth years, N chicks would be produced in that year and in each succeeding year for a total of eight years. The growth of the Lyrebird population during that period and beyond, along with the number in each age group, is shown in Table 1, which becomes the model for analysis.

Discussion The conditions prescribed as a basis for Table 1 are known to be, in varying degrees, unrealistic. Although some Lyrebirds are known to have lived for long periods (20 years or longer), others have died younger. Even if such birds lived long enough to begin breeding, some died soon after. Lyrebird 'R' mated in his ninth year, but disappeared in his tenth year. In 1942, in Sherbrooke Forest, a containing an egg was destroyed by a heavy fall of snow. I have found at least six containing eggs which had been incubated for the full period but which proved to be infertile. Hindwood (1960) and Reilly (1970) have had similar experiences. It has already been mentioned that not all Lyrebirds commence breeding in the eighth year, and some birds live and breed beyond the sixteenth year, which could enhance the chances of building a viable Lyrebird population. The regular breeding schedules implicit in Table 1 are virtually impossible to achieve under natural conditions. Losses of Lyrebirds, irrespective of age or sex, are caused by predation and other factors (Lill1980, Smith 1994). In 1956, the egg of the 'friendly female ' was broken and the contents extracted by a small which tunnelled through the rear ofthe nest. Similar experiences have been reported by Lill (1980) and from East Gippsland (0. Bassett pers. comm.). Lyrebirds have been killed by motor cars (Smith 1988). Whatever the cause, any interruption to the breeding pattern on which Table 1 is based will impede the building of a Lyrebird population. The foregoing shows that the production and development of a Lyrebird population is beset with many hazards. Nevertheless, the events on which Table 1 is based serve as a model .from which certain conclusions may be drawn.

Survival rates In addition to those events which precede egg-laying, there are three recognisable stages in the production of a breeding Lyrebird. The percentage of eggs which produce chicks in a given year is defined as the 'egg-to-chick success rate' (x) ; likewise the AUSTRALIAN 76 SMITH BIRD WATCHER

percentage of chicks which reach the fledgling stage is the 'chick-to-fledgling success rate' (y). If the 'fledgling-to-breeder success rate' is z%, the 'egg-to-breeder success rate' will be xyz% . For the Lyrebird population to survive, it would be necessary for the number of breeding Lyrebirds to be maintained at least at the same level (N + rN) as it was when the original stock began to breed. Under the conditions implicit in Table 1, the first group of N + rJ\l.breeders ceases breeding after having produced 8N chicks. Thus, out of a total of 8N, at least N + rN must survive to become breeders. If r = 1, the required overall success rate (xyz) will be 2§; if r = 0.5, the value of xyz would be 19%. For purposes of discussion, it is assumed that xyz = 22% (that is, r = 0.75). Because the egg and the chick (nestling) remain in fixed positions (in the nest), it is possible to obtain values for x andy over a period (Reilly 1970). Obtaining values for z under field conditions would be virtually impossible because of the mobility of the immature birds and the length of time involved. However, if the two stages represented by x and y are combined to represent the success rate for the egg-to­ fledgling stages, it becomes possible to calculate the value of z corresponding to assigned values of x andy, from the formula z = 22/xy. If other values, e.g. 25 or 30, are assigned to xyz, representing higher egg-to-breeder success rates, the corresponding values for z may be calculated from the formula z = 25 (or 30)/xy. It thus becomes possible to construct a series of curves showing the relationships between the nesting success rate (i.e. the egg-to-fledgling success rate) and the fledgling-to-breeder success rate required to achieve an assigned value for the egg­ to-breeder success rate (Figure 1). If the plot of xy vs z falls on the curve AA, the Lyrebird population will be sustained but will not grow. If the plot falls above the curve AA, the population will grow. If the plot falls below the curve AA, the population will not be viable. In studies in Sherbrooke Forest during 1958-65 (Reilly 1970), x had a value of 86.4% and the corresponding value for y was 63% . Thus xy = 54% . To achieve a value of 22% for the egg-to-breeder success rate, the fledgling-to-breeder success rate (z) would require to have been 22 X 100/54 (= 41)%. No data are available on this aspect. Lill (1980) studied reproductive success rates and nest predation of the Superb Lyrebird in the Maroondah Catchment Area during 1976-78 and in the south-eastern part of Sherbrooke Forest during 1973-76. He recorded 'egg success rates' of 11-20% and concluded that the recruitment rate was 0.1-0. 2 fledglings per breeding female annually. This is below the limit for viability. The Lyrebird is not indigenous to Tasmania but, during the period 1934-49, a total of 11 mature males and 11 mature females was introduced from the mainland (Fleay 1952). Eight of each sex were released in Mount Field National Park and, in 1945, three of each sex were released at Hastings Caves, about 80 km farther south. Two of the male birds are known to have died in Mount Field National Park but, from the remainder, many strong populations have developed in both areas. Although no 'hard statistics' on breeding success are available, the evidence pertaining to the growth of the Lyrebird in Tasmania is irrefutable (Sharland 1944, 1952; Wall & Wheeler 1966; Reilly 1988; Smith 1988). For this to have occurred, it would have been necessqry to achieve a breeding success rate (xyz) in excess of the minimum of 22 % postulated in the foregoing and to have maintained such a result over a long period. The plot of z vs xy (if such data were available) would fall above the curve AA in Figure 1. VOL. 17 (2) JUNE 1997 Building a Lyrebird Population 77

100

90 80

70 A

60 z "1. 50 40

30 xyz. 30 xyz 25 20 xyz 22

10

0 xy%

Figure 1. Combinations of success rates at different stages of the breeding cycle required to achieve designated values for the breeding success rates of the Superb Lyrebird, under prescribed conditions (see text). x (%) = egg-to-chick success rate y (%) = chick-to-fledgling success rate xy (%) = egg-to-fledgling success rate (nesting success rate) z (%) = fledgling-to-breeder success rate xyz (%) = designated egg-to-breeder success rate

The reasons underlying the differences between the results of Reilly and Lill, and the remarkable success of the Lyrebird in Tasmania, invite closer analysis. The life of the Lyrebird in the wild is influenced by environmental factors and predation. The most significant environmental factor is adequate supply of food which is accessible to Lyrebirds.

Forest environment If the number of Lyrebirds in the original population had remained constant at N + rN for eight years, the daily food requirements would have remained constant during that period. However, the prescribed conditions require that N chicks be produced in each year of their breeding lives; therefore additional food is required each year. The relationship between the number of Lyrebirds and their food requirements is implicit in Table 1, which shows that, even before the recruits to the population have begun to breed, the food requirements of the breeding birds and their progeny will have increased about fivefold. The extra food must come from AUSTRALIAN 78 SMITH BIRD WATCHER the same source as that which sustained the original stock. Though it is highly probable that there will be some losses among the younger birds (and possibly among older ones), it is clear that the growing population will make greater demands on the available food resources and any deterioration in the latter will adversely affect the Lyrebird population. Any management plan must ensure that the forest environment is not permitted to deprive the Lyrebird of its basic food requirements. Information on the q,uantity of food and its accessibility to Lyrebirds in the Maroondah Catchment Area is not available, but my general knowledge of the area suggests that the condition of the forest was not responsible for the low success rates reported by Lill. I do not think that the conditions in Sherbrooke Forest at the time would have had a significant adverse effect on either Lill's or Reilly's results. Sharland (1944) stated that conditions in Tasmania 'would appear to be most favourable for breeding' of the Lyrebird. The wide dispersal of the Lyrebird in Tasmania, over the past 50-60 years, suggests that the forest environment has been favourable.

Predation The risk of predation during the egg-to-chick stage (6-7 weeks) is probably lower than that during the chick-to-fledgling stage (6-7 weeks), because of the higher noise and odour levels, and the greater visibility of the female at or near the nest, during the second stage. During the third stage, the immature birds (as well as mature birds), although mobile, are exposed to great risk because of their vocal and display activities, and the need to feed at ground level, over a period of about 7.5 years. In the areas where Lill worked, no predator-control measures were taken. Lill (1980) found that predation accounted for 79% of the chicks that failed to fledge. Predation accounted for total 'nest-young' losses of 82% and 75% respectively in the two areas where he worked. Those parts of Sherbrooke Forest relevant to Reilly's data (1970) had the benefit of a vigorous and successful fox-poisoning campaign which commenced a year before Reilly's work began and continued for about a year after it ceased (Smith 1994). Lill (1980) recognised that predation was a 'relatively insignificant' factor in Reilly's high success rates during 1958-65, but exerted a greater influence on nesting success records from 1967 to 1972 (RAOU Nest Record Scheme). It seems relevant that several banded Lyrebirds which had survived through the duration of the fox-poisoning campaign died, almost certainly as a result of fox predation, soon after the cessation of the fox-poisoning. These birds were R ('Red') 1958-67, RIB (1959-68), R/R(1959-68) and W/W (1960-68). Kinnear et al. (1988) found that destruction of foxes resulted in increased rock­ wallaby populations. Welty (1982) gave many examples which show that mammalian predators greatly depress avian breeding success rates and that removal of predators substantially increases such rates. It is difficult to escape the conclusion that the fox is the Lyrebird's most significant predator; this view is supported by the successful introduction and expansion of the Lyrebird in Tasmania, from which the fox is absent (Smith 1988).

General The foregoing indicates that, under the prescribed conditions, an egg-to-breeder success rate of 22% could maintain a viable population of Lyrebirds. This figure should not be held too rigidly, because there are some assumptions (age at which breeding commences, sex ratios, regularity of breeding of females, etc.) on which full VOL. 17 (2) JUNE 1997 Building a Lyrebird Population 79 information is not available. However, even without such information, the growth of the Lyrebird population in Tasmania demonstrates that, under favourable forest­ environment conditions and very low levels of predation, breeding success rates can be obtained which are in excess of the minimum required to maintain a viable bird population. If the success rates x and y reported by Reilly (1970) could be raised from 86.4 to 90% and from 63 to 70% respectively, the fledgling-to-breeder success rate required to produce a viable population could be reduced from 41 to 35% . Figure 1 shows various combinations of x, y and z which could maintain or increase the Lyrebird _population, provided that breeding conditions were maintained at the required levels, through the adoption of appropriate strategies in the management of the forest environment. Although, for the purposes of this exercise, the original breeders (N + rN) were assumed to cease breeding (and were no longer included in the calculations, i.e. were in effect dead) after eight years, some birds ('Timothy', 'Spotty' and a ' friendly female') in Sherbrooke Forest are known to have continued to breed beyond that time. Table 1 shows that, under the prescribed conditions, by the time the last progeny of the original breeders had begun to breed, the total Lyrebird population could have increased about sevenfold and the number of breeding birds could have quadrupled. Thus, although predation of the Lyrebird is unlikely ever to be completely eliminated in mainland Australia and there will be losses to natural causes and accidents, in building a viable Lyrebird population the benefits of appropriate forest management and predator-control practices would be enhanced by the propensity of the Lyrebird for longevity.

Conclusions and synthesis Following the laying of the egg, there are three stages in the life of the Superb Lyrebird, namely the egg-to-chick, chick-to-fledgling and fledgling-to-breeder stages. Breeding begins in about the eighth year. If the success rates for the three stages are x, y and z%, respectively, the success rate for the egg-to-breeder stages will be xyz%. This paper has shown how, under specified conditions (which may not all be fully realised in practice), a model may be produced illustrating the growth of a Lyrebird population after breeding commences in the eighth year of the breeding stock consisting of N females and rN males. On the assumption that N chicks are produced each year, the model shows that, for the breeding population derived from the progeny of the original breeders to attain the value N + rN, the value of xyz would need to be (N + rN)/8.5N, which, if r = 0.75, equals 22%. Values of xyz in excess of22 would result in growth of the population. From the model it can be deduced that the food requirements of the growing population could increase to about five times that of the original breeders. Lill (1979a,b) found that, in areas where fox-control measures were absent, the value of xyz was 11-20%, which would not maintain a viable population under the prescribed conditions. However, Reilly (1970) found that, in an area where fox control had been practised for about a year before observations were begun and maintained throughout the relevant period (seven years), the value of xy was 54%, which implies that a value of 41 for z would suffice to maintain a viable population. The Lyrebird is not indigenous to Tasmania but, during 1934-49, Lyrebirds were introduced from mainland Australia. The strong growth of many Lyrebird populations in Tasmania is attributed to the absence of the fox from that state and the availability of adequate food accessible to the Lyrebirds. This paper provides values for the breeding success rates required to produce a viable Lyrebird population, and defines the conditions which must be fulfilled in order to achieve the required values: namely, fox control and appropriate habitat management. AUSTRALIAN 80 SMITH BIRD WATCHER

Acknowledgements I thank three referees for helpful advice, Dr Mark Elgar and Dr David Baker-Gabb for comments on an earlier draft, and Dr Mark Burgman and Charles Todd for their interest. I am indebted to Mr Stephen Debus and Mrs Julia Hurley for their help in the preparation of this paper, and Mrs Susie Debus for typing it onto computer disk. References Aflalo, F.G. (1896), A S/v!tch of the Natural History of Australia, author, London. Barker, R.D. & Vestjens, W.J.M. (1990), The Food of Australian Birds, 2. , CSIRO, Melbourne. Bell, K. (1976), 'Song of the Superb Lyrebird in New South Wales with some observations on habitat', Emu 76, 59-63. Blakers, M., Davies, S.J.J.F. & Reilly, P.N. (1984), The Atlas of Australian Birds, Melbourne University Press, Melbourne. Campbell, A.J. (1900), Nests and Eggs of Australian Birds, facs. edn, Wren, Melbourne. Chisholm, A.H. (1960), The Romance of the Lyrebird, Angus & Robertson, Sydney. Fleay, D. (1952), 'Transporting Lyrebirds to Tasmania', Vic. Nat. 69, 60-63. Ford, H.A. (1989), Ecology of Birds, An Australian Perspective, Surrey Beatty, Sydney. Godfrey, I. (1905), 'Domesticated lyrebird', Emu 5, 33-34. Gould, J. (1848), The Birds of Australia, vol. 3, author, London. Haydon, G.H. (1846), Five Years in Australia Felix, author, London. Hindwood, K.A. (1960), 'Two eggs and second eggs in Lyrebirds' nests' , Aust. Bird Watcher 3, 94-%. Keast, A. (1969), 'Evolution of rnarnrnals in southern continents. VII. Comparisons of the contemporary rnarnrnaJian faunas of the southern continents' , Q. Rev. Bioi. 44, 121-167. Kenyon, R.F. (1972), 'Polygyny among Superb Lyrebirds in Sherbrooke Forest Park', Emu 72,70-76. Kinnear, I .E., Onus, M.L. & Brornilow, R.N. (1988), 'Fox control and rock-wallaby population dynamics', Aust. Wild/. Res. 15, 435-450. Lill, A. (1979a), •An assessment of the male parental investment and pair bonding in the polygamous Superb Lyrebird', Auk 96, 489-498. --(1979b), 'Nest attentiveness and its influence on the development of the young in the Superb Lyrebird', Condor 87, 225-231. --(1980), 'Reproductive success and nest predation in the Superb Lyrebird', Aust. Wild/. Res. 7, 271-280. -- (1986), 'Time-energy budget during reproduction and the evolution of single-parenting in the Superb Lyrebird', Aust. J. Zoo/. 34, 351-371. O'Donoghue, J.G. (1931), 'Notes on the Victorian LyrebirdMenura victoriae', Vic. Nat. 28, 149-157. Reilly, P.N. (1970), 'Nesting of the Superb Lyrebird in Sherbrooke Forest, Victora', Emu 70, 73-78. -- (1988), The Lyrebird - A Natural History, New South Wales University Press, Sydney. Robinson, F.R. & Frith, H.J. (1981), 'The Superb Lyrebird Menura novaehollandiae at Tidbinbilla, A.C.T.', Emu 81, 145-157. Rolls, E.C. (1984), They All Ran Wild, Angus & Robertson, Sydney. Sharland, M.S. (1944), 'The Lyrebird in Tasmania', Emu 44, 64-71. -- (1952), 'The Lyrebird in Tasmania', Vic. Nat. 69, 58-59. Smith, L.H. (1982), 'Moulting sequences in the development of the tail plumage of the Superb Lyrebird Menura novaehollandiae', Aust. Wild/. Res. 9, 311-330. -- (1988), The Life of the Lyrebird, Heinemann, Melbourne. --(1994), •A critical analysis of the factors responsible for the decline of the Superb Lyrebird Menura novaehollandiae in Sherbrooke Forest', Aust. Bird Watcher 15, 238-249. Wall, L.E. & Wheeler, R.J. (1966), 'Lyrebirds in Tasmania', Emu 66, 123-131. Welty, J.C. (1982), , Saunders College, New York. Revised 10 April 1996 •