Condor, 81225-231 0 The Cooper Ornithological Society 1979

NEST INATTENTIVENESS AND ITS INFLUENCE ON DEVELOPMENT OF THE YOUNG IN THE

ALAN LILL

The optimal temperature range for avian a 198494 m altitudinal range; (b) Maroondah Catch- embryos and nestlings is usually narrow. ment area near Healesville, 57 km NE of , where research was conducted in a 0.62 km2 stand of Slight deviations from this range can retard mature Mountain Ash forest with a 334-790 m altitu- growth, and, if prolonged, induce abnormal dinal range on Mt. Riddell and in mixed-eucalyptus development and mortality (Lundy 1969). wet sclerophyll forest at Fernshaw. For the three sites Incubation and brooding rhythms general- mean annual rainfall ranges from 1,435 to 1,641 mm, mean daily maximal temperatures from 13.7-15.4”C ly restrict significant temperature devia- and mean daily minimal temperatures from 6.9-7.6”C. tions even during periods of inattention Mean daily maximal and minimal temperature ranges (Huggins 1941), and parents can also adjust for the months of June through September fall within levels of heat transfer during contact with the limits, 6.8-11.7”C and 2.84.5”C respectively (How- and nestlings (Drent 1973). Most ard and OShaughnessy’ 1971, Langford and OShaughnessy’ 1977). Snow occasionally falls at Ma- breeding at low temperatures main- roondah but rarely in Sherbrooke. tain fairly constant and early nestling The incubation regime was determined from 138.3 h temperatures through a high level of nest of observation, mainly while I was concealed, at and attentiveness, even when incubation and near to fourteen nests occupied by eleven different fe- males. The daytime brooding regime (i.e., when and brooding are uniparental (White and Kin- for how long nestlings were brooded) was determined ney 1974). from 67 h of concealed observation of six Sherbrooke The Superb Lyrebird (Menuru superba) and five Maroondah breeding attempts made by ten inhabits mainly wet sclerophyll and tem- females. Observations covered all daylight hours and perate rainforest in southeastern Australia. were spread over six breeding seasons. Internal temperatures (T,) of two eggs in ground Its domed nest is built at varying heights level nests were monitored in situ over several days from ground level to 18 m. The single-egg early in the incubation period using an implanted clutch is laid in mid-winter and hatches in transmitter which emitted 12F pulses at a predeter- late winter or early spring. Daytime am- mined, temperature-dependent rate. The unit was im- planted through a small opening cut in the shell and bient temperatures are around 10°C or low- resealed with an instantaneous bonding agent. The sig- er during the incubation and early nestling nals from this transmitter and a larger one located near periods, and both incubation and brood- ground level close to the nest to measure air temper- care are uniparental (Lill, unpubl. data). atures (T,) were monitored on a transceiver fitted with Tregallas (1921), Ward (1940) and Reilly a beat frequency oscillator operated by a concealed observer. Implantation times were 3 and 6-10 days (1970) have suggested that lyrebird incu- post-laying. Results were clear-cut and the species has bation does not begin immediately after protected status, so a sample size greater than two was egg-laying despite the prevailing low tem- deemed unjustifiable. peratures. Ward (1939), Reilly (1970) and Nestling core temperatures (Tnh) were taken by deep Robinson (1977 and unpubl. data) also in- cloaca1 insertion of a thermocouple linked to an elec- tronic thermometer. T, just outside the nest entrance dicate that the egg may be deserted for a was measured within 30 s of each Tnh reading. Usually long period daily once incubation has com- a series of readings was taken at intervals ranging from menced. Since the six to seven week incu- 1 to 120 min after a maternal post-brooding exodus on bation and nestling periods are very long for days l-10 or commencing at an arbitrary time from day 11 onwards. I obtained cooling curves for seven nest- a , the protracted nest recesses tak- lings, five of which were measured on two or more days. en by the unassisted female parent may lead At least one curve was obtained for each of the ten to marked cooling and retarded develop- daytime brooding phase days. ment of young. Here I explore this possi- Nestlings were weighed regularly and also when Tnb measurements were taken. Growth equations were fit- bility through the first detailed examination ted by Ricklef s (1967) method to the growth curves of of lyrebird incubation and brooding five known-age nestlings which fledged. Asymptote rhythms, and by monitoring embryonic and estimations and K values were generated by a com- nestling temperatures during maternal ab- puter program and t,,.,” (time taken for growth from lo- sences. 90% of the asymptote) values generated in turn from the K values.

STUDY AREAS AND METHODS RESULTS The two areas used from 1973 to 1978 were: (a) Sher- THE INCUBATION REGIME brooke Forest Park, an approximately 821 ha wet sclerophyll (Mountain Ash, Eucalyptus regnans) forest Full daytime incubation rhythms devel- reserve 37 km E of Melbourne (37”45S,’ 144”56E)’ with oped gradually and with varying latencies

~2251 226 ALAN LILL

N-56676567543 0600 cm0 no0 1100 12.00 13.00, !400 15.00 16.00 17.0 100 (3)(4)(4) (5)(4)(3) (41(4) (3)(3) (2) I EGGA GAY4 f ’ I \ fi 60- ', \ ii I ‘\. \,______,_._._._.___._._. _/‘-‘-‘-‘-~-~-- 3 40- \ la is t o*. 1 I I I I. 1.1 - \ OaW OS 00 1000 1100 1200 13.00 l4W 15.00 16.W 17.M

I 08.00 10.00 Ii.00 14.00 16.00 18.00 t- INCOMPLETE INCUBATION RHYTHM 3 i

$ N-3 6 8 11 9 10 8 6 8 7 6 3 (3) (5)(4)(6) (6) (6)(5)(d) (4)(4) (5)(3) 100

0600 09.00 WIM) 1100 1200 13fn 1400 15.00 1600 17.0 80 35 EGG B DAV’I-11 M- To 60 25.

20.

15. \‘ ,.: 10. N_. \,_,_~_,,._._\i_ ._._._._. - ._._._ ._._.- .i._._._ TO 5-

o--~. . I . I I I . I . 06.00 08.00 10.00 12.00 14.00 16.00 18.00 08.00 0900 1000 1100 12.W 13.00 14.00 15.00 1600 17.M: 30 . EGG B DAVE-1: FULL INCUBATION RHYTHM ... ..“X..’ FIGURE 1. Daytime incubation rhythm of Superb Lyrebird females. Graphs show average percentage of each daylight hour that females spent incubating. N is the number of observations for a particular hour from which the means were calculated. Numbers in paren- theses indicate the number of females observed for a particular hour. Means for the pre-08:OO and post-17:OO periods relate only to daylight segments of these pe- o-. I I . riods. Ten Sherbrooke and four Maroondah nests stud- 1400 15.00 16.00 1700 l%xJ 1600 1700 ied. 33. EGG B DAYG-10 EGG B MY9-13 25. .:. ;.

(mean c. 18 days) at six nests observed early 20. ,I. in the incubation period. During the incom- 15 .

plete incubation rhythm stage, females typ- 10 - .-._._._i_.,._, h._._._._._._._.‘ \ Ta Te ; ically left the nest following nocturnal in- Ta cubation within two hours after dawn and 5- did not return until middle or late afternoon 0 (Fig. 1). Three such recesses averaged 6.9 + FIGURE 2. The internal temperatures of two eggs 0.75 h and several incompletely timed ones during maternal recesses taken on several days in the were of similar length (Table 1). Females incomplete incubation phase. .-.-.- T, near the nest. typically returned to sit continuously ...... T, during incubation. - T, during maternal through the night 47-112 min before dusk. absence. The laying date of egg B was not exactly de- termined. Eggs were thus usually deserted for seven hours daily at mean daily maximum T,s‘ ranging from 8-10°C. DEVELOPMENT OF LYREBIRD YOUNG 227

TABLE 1. Duration of maternal recesses in the incubation stage.

Duration (min) of recesses begun= - stage of FIXWOO” Afternoon incubation

Absolute length 260; 71.5 j 57 ? 24.9 R 35-90 Complete incubation n 4 Minimal length! ’ xc 174.2 + 71.4 x 50 ? 29.8 regime R 77-335 R 5-85 (Day 19 onwards) n 13 n 5

Absolute length x 412 + 45 R 366.5 ? 456.5 Incomplete incubation n 3 Minimal length 251.3 ? 128.6 f 161.4 ? 68.9 regime ; 108-420 R 80-270 (Days l-18) n 4 n 6

Absolute length 43.5 Minimal length x 192.8 ? 131.8 23 Unknown incubation R 36-395.5 regime n 8

a Either recess began (absolute lengths) or timing of recess began (some minimal lengths) pre- or post-12:00. b Beginning andIor end of recess untimed. i‘ = mean f standard deviation; R = range; n = number of recesses timed. Computed only for samples P 3.

During the complete incubation stage (Fig. 2). On the second afternoon, resump- there were usually two recesses per day. tion of incubation induced a 0.24Wmin rise Morning recesses lasted from between in T, over 75 min. Both whole-day monitor- dawn and 09:30 to early afternoon (Fig. 1); ing sessions for egg B yielded similar re- incompletely timed ones ranged up to 335 sults to those for egg A except that on the min duration (Table 1). The second recess second day initial T, was 3°C lower and the generally began between 15:00 and 16:00 rate of cooling to T, much faster. In two fur- and averaged 57 + 24.9 min (range 35-90 ther afternoon monitoring sessions, T, of min, n = 4). Females usually incubated egg B rose 0.35 and 0.37Wmin respectively through the night, beginning one to two when the female resumed incubation. The hours before dusk. Occasionally this typical results show that in the incomplete incu- regime was varied by the interpolation of bation phase embryos were extensively ex- an extra incubation bout in the early morn- posed to low temperatures each day. Egg ing prior to the long recess, or by shortening cooling rates ranged from 0.065 to O.l”C/min of the long recess and advancing of the (mean O.O8I”C/min, n = 4) and heating rates afternoon recess. In the latter case the long from 0.222 to 0.367Wmin (mean 0.292W recess was still of three to four hours dura- min, n = 5). Over the same temperature tion. Just before hatching, recesses often be- range, both eggs heated up much faster when came shorter. Thus eggs were usually con- incubation resumed than they cooled down tinuously deserted for three to six hours in after maternal exodus (Table 2). the long recess during the complete incu- bation stage. Mean daily maximum T,s‘ at THE BROODING REGIME this time were 6-12°C in both study areas. Eggs hatched in August and September. The attentive index (mean percentage of the There was no obvious, consistent daytime average daylength incubated) for this stage brooding rhythm and daytime brooding was 45% (Lill, unpubl. data), well below the typical passerine range of 60-80% (Skutch 1962). TABLE 2. Cooling and reheating times of two eggs with implanted transmitters. INTERNAL EGG TEMPERATURES DURING Cooling MATERNAL RECESSES or heating Minutes Minutes Eggidw temperature taken to taken to T, near ground level was 10°C or less dur- measured range= cool reheat ing all six July daytime monitoring sessions. A; Day 5 9-28°C 225 75 On the two days it was monitored, T, of egg B; Day 7-11 9-26°C 290 60 A dropped from 29°C to 10°C in 2.6-3 h fol- B; Day 8-12 B-25°C 275 55 lowing maternal morning exodus and sta- BThese ran es are the closest possible approximations to the ranges between incu %atmn temperature and the lowest T, recorded during ma- bilized within l-3°C of T, after 3-3.25 h ternal absence. 228 ALAN LILL

TABLE 3. Duration of maternal daytime recesses in the daytime-brooding nestling stage.

Nestling Duration of recesses (min) age (days p&t-h&h- Absolute Minimal” ing) length length

1 35 2 16.6 ? 2.4” 14-19.5 4 3 40.3 + 11.5 29.5-60 6 4 26.5; 53 20; 28.5 5 R 54.2 + 43.3 38; 55.5 R 25.5-104 n 3 6 53.5: 77 7 4.5; 25 8 R 46-118

9 35.5; 42 ;; 53-182 n 4 10 72; 67

1-4h 34; 38 2.5 1-6 1 38.9 ? 19.5 R 6-31 CY 6b Go 30 60 R 20-76 n 3 n 7 MI NS. POST- MATERNAL EXODUS 5-8 x 32 2 12.5 20.5; 31.5 R 20-45 FIGURE 3. Tnb - T, (“C) at intervals following ma- ternal post-brooding departure. Exact or approximate n 3 nestling weight shown for each curve. Five nestlings a Beginning and/or end untimed. b Nestling ages only approximately known. (solid triangle, solid circle, solid square, crossed circle c For samples of three or more absolute lengths, mean ? standard de- and open square) were measured on more than one viation, range (R) and sample size (n) are given. For samples of three or day. Curves marked with open circles are for nestlings more minimal lengths, range and sample size are given. measured on only one day. Day 1 was hatching day. Readings taken on day X and X + 2 were for an unaged, mid-term nestling. Readings for Day 11 onwards com- menced at an arbitrary time as there was no daytime NESTLING TEMPERATURES DURING brooding. The curve for a 51 g nestling on Day 3 was MATERNAL ABSENCES obtained after flushing the mother following four hours The slopes of the cooling curves obtained of continual brooding from first light on a rainy day. Time of day at which each set of readings was begun for seven nestlings (Fig. 3) show a gradual is shown as M (pre-lO:OO), MD (lO:OO-14:00) or A improvement in thermoregulation up to (post-14:OO) to the right of each cell; the vertical order day 10 when nestlings were effectively en- of these symbols corresponds with the vertical order dothermic and daytime brooding ceased. At of their associated cooling curves. T,s‘ of 2-WC, Tnb fell 6-9°C after 30 min post-brooding exposure on days 1-4 and lo- 13°C after 60 min exposure on days 2, 4, 5, gradually decreased and ended on day 10 and 6. An hours’ exposure on days 9 and 10, when nestlings averaged 128 g (Lill, un- however, induced only a 2°C drop. Given publ. data). the duration of maternal recesses (Table 3), Twenty-nine brooding sessions spread 4-8°C drops in T,, must have been common over most daylight hours and recorded for on days l-6 and 12-13°C drops probably nestlings up to nine days old averaged 37 occurred during the longest recesses noted _‘ 21 min in length (range 13.5-126 min). for this nestling age. Mean duration of thirty-two maternal re- cesses was 39 + 20 min (range 14-104 min), NESTLING GROWTH RATES and several far longer recesses were record- The nestling period ranged from 41-44 to ed throughout the daytime brooding phase 54-55 days (best mean estimate 47 days). (Table 3). Mean daily maximal T,s‘ in the Mean hatching weight was 46 2 6 g (n = two study areas at this time range from 9- 11) and mean fledging weight was 571 t 63 15°C. Brooding constancy (percentage of g (n = 11) or 63% of the average adult (fe- the average daylength spent brooding) av- male) body weight. Since the converted eraged 42.1% over the ten days of daytime growth curves of five known-age nestlings brooding. which fledged are essentially linear (Fig. 4), DEVELOPMENT OF LYREBIRD YOUNG 229

ent measurements. Increased embryonic thermogenesis later in the incubation peri- od is probably insufficient to significantly counteract the degree of exposure recorded (MacMullan and Eberhardt 1953, Drent 1970). The Superb Lyrebirds’ attentiveness index is far lower than those of most pas- serines, tropical hole-nesters and unaided uniparental incubators (Skutch 1962), in- cluding many breeding at low T,s‘ (e.g., Capercaillie, Tetrao urogallus, 95%, Len- nerstedt 1966; Pink-footed Goose, Anser

1 10 20 30 40 1 10 20 30 40 50 fabalis brachyrynchus, 91.3%, Inglis 1977). High frequencies of predation on nests may AGE (DAYS POST- HATCHING) also have promoted selection for high levels of attentiveness in many , but although lyrebird nests are vulnerable and often de- o” 00 predated (Lill, unpubl. data), the known in- 8 volvement of ubiquitous, non-endemic nest predators clouds the issue in this species. The incubation regime and embryonic ther- mal environment of the Superb Lyrebird are unusual but not unique, even among low temperature breeders. Long nest re- 0 0 cesses resulting in low embryonic temper- atures occur regularly in some procellari- 00 iforms and galliforms (Barth 1949, Wester- skov 1956, Pefaur 1974). 1 10 20 30 40 1 10 20 30 40 50 Moderate exposure at 0-25°C slows de- velopment without inducing growth abnor- AGE ( DAYS POST- HATCHING) malities in chicken and possibly other avian FIGURE 4. Actual and converted growth curves for embryos, but significant exposure between five exactly-aged nestlings which fledged at Heales- 37°C (incubation temperature) and 27-25°C ville (1976-1977). Curves divided into two sets to fa- cilitate reading. Day 1 = day of emergence from egg. [physiological zero temperature (PZT) be- low which development ceases] causes ab- normal growth (Lundy 1969). If chicken and growth, though slow, was clearly logistic in lyrebird PZTs are similar, Figure 1 indi- form (Ricklefs 1967). K, the growth constant cates that daily exposure in this critical of the logistic equation, ranged from 0.105- range is fairly restricted and, by analogy, 0.122 (mean 0.117) for the five growth delayed development is probably the main curves; tlO_aoranged from 35.441.9 days, effect of egg neglect in lyrebirds. with a mean of 37.6. In birds, egg weight is positively corre- lated with duration of incubation period DISCUSSION (Rahn and Ar 1974) and adult body size THE INCUBATION REGIME AND (Huxley 1927), which in turn is inversely EMBRYONIC TEMPERATURES correlated with growth rate (Ricklefs 1968, T,s‘ of 25-29°C recorded towards the end of 1973). Thus lyrebirds should have a long in- nocturnal incubation are well below the 33- cubation period irrespective of daily embry- 38°C range documented for other species onic cooling. However, the larger corvids, during continuous egg contact by the incu- the closest to lyrebird size, have bating parent(s) (Drent 1970). The discrep- only approximately three-week incubation ancy probably stems from the transmitters’ periods (Witherby et al. 1938, Rowley weight, which must have ensured that it 1973). Moreover, from the relationship be- was always at the base of the egg, which is tween egg weight and incubation period in probably significantly cooler than at the ear- birds (Rahn and Ar 1974), a 29-30 day in- ly embryos’ topical position (Drent 1972). cubation period rather than the 50 days ob- The 3-6 h morning recess during the full served (Lill, unpubl. data) would be pre- incubation stage clearly leads to extreme dicted for the 62.9 g lyrebird egg. lowering of embryonic temperature, even if Significantly, Ward (1940) reported that a T, is a little higher than indicated by pres- newly laid lyrebird egg which was contin- 230 ALAN LILL uously incubated by a domestic hen been recorded in a few species (e.g., Wil- hatched after 28 days. This critical experi- sons’ Storm-Petrel, Oceanites oceanicus; ment should be replicated on a larger scale. Pefaur 1974; Snowy Owl, Nycteu scundi- Lyrebird eggs cooled more slowly during ucu; Barth 1949). However, too few studies maternal recesses than 100-g Herring Gull have combined detailed documentation of (Larus argentatus) eggs exposured at simi- the brooding rhythm with measurement of lar T,s‘ (Drent 1973). It is doubtful whether Tnb for us to know whether natural exposure nest insulation causes this slower cooling of young nestlings to a low T, is common. rate, since air temperature in the nest cham- While the degree of exposure documented ber is within 1°C of T, during incubation here may reduce the nestlings’ growth rate, and daytime brooding of nestlings (Lill, un- it seems insufficient to account entirely for publ. data). Incubating females spent nearly the extreme length of the lyrebirds’ nestling all their recess time foraging. Given the ne- period. Possibly the slow nestling growth cessity of six to seven hours foraging daily, rate evolved partly because it spreads out taking one long recess might keep T, out- the parental energetic load in a species side the detrimental intermediate tempera- where brood reduction is not possible tures for a greater percentage of the day (Ricklefs 1968, 1973). than several shorter recesses. This incuba- tion rhythm would be particularly adaptive SUMMARY when rates of egg cooling are relatively Incubation and brooding regimes of Superb slow. Lyrebird females were studied over six win- ter breeding seasons at two wet sclerophyll THE BROODING REGIME AND EARLY forest sites in southeastern Australia. Inter- NESTLING TEMPERATURES nal temperatures of two eggs were moni- The considerable exposure of ectothermal tored telemetrically over several days soon lyrebird nestlings to low temperatures dur- after laying. Core temperatures of young ing maternal recesses should reduce their nestlings were measured at intervals after growth rate. The additional insulation pro- maternal exodus during the first ten days vided by the domed and burrow nests of post-hatching, and some similar readings some species somewhat buffers nestlings were obtained for older, endothermic nest- against low T,s‘ during recesses and ad- lings. Growth curves were obtained and vances the age of effective endothermy growth rates determined for five known-age (e.g., Roberts 1940, Dunn 1976). But such nestlings. buffering does not seem to occur in lyre- The full incubation rhythm developed birds as indicated above, probably due to gradually and was characterized by a low the size of the nest entrance. As nestling (45%) attentive index and a three to six hour exposure is less extreme than embryonic morning recess. Internal egg temperatures exposure and endothermy is attained by fell and stabilized around ambient levels day 10, the effect of cooling on growth (approx. 10°C) for several hours daily during should be far less than in the incubation these long maternal absences. When incu- period. This prediction is supported by bation resumed, the egg reheated much Drents’ (1975) analysis of the nestling faster than it had cooled. growth rate-incubation period relationship Daytime brooding ceased ten days after in birds. The lyrebirds’ mean growth rate hatching when nestlings became endo- (K = 0.117) is unusually slow among pas- thermic. Mean recess duration during this serines. Nestling growth rate and adult brooding period was 39 min, but 45-60 min body size are inversely correlated in birds, recesses were common on days l-6. Nest- but comparing the lyrebird values with ling temperature measurements showed those for other passerines (Ricklefs 1968, that 4-8°C drops must have been common 1969) indicates that large body size does not during maternal absences and drops of I2- entirely account for the slowness of nestling 13°C characteristic of longer recesses early growth in this species. Similar growth rates in the ectothermic period. Nestling growth occur mainly among raptors and seabirds. curves were logistic, mean K being 0.117 The impact of chilling on growth rate is and mean tro.,,, 37.6 days. harder to assess for the nestling than the Comparative evidence suggests that re- embryo. Ectothermal nestlings of many tardation of embryonic growth is the main species can tolerate considerable experi- effect of daily egg neglect. One possible mental exposure to low temperatures (Daw- adaptive value of a single long recess rather son and Evans 1960) and marked lowering than several shorter daily recesses is ad- of T,, during natural parental recesses has vanced. The effect of cooling on nestling DEVELOPMENT OF LYREBIRD YOUNG 231

growth rate is harder to assess and probably bation rhythm of a Capercaillie (Tetrao urogullus less pronounced. L.) in Swedish Lapland. Oikos 17:169-174. LUNDY, H. 1969. A review of the effects of tempera- ture, humidity, turning, and gaseous environment ACKNOWLEDGMENTS in the incubator on the hatchability of the hens’ egg, p. 143-176. In T. C. Carter and B. M. Free- The Forests Commission of and the Mel- man [Eds.], The fertility and hatchability of the bourne and Metropolitan Board of Works permitted hens’ egg. Oliver and Boyd, Edinburgh. and facilitated the study on their properties and sup- MACMULLAN, R. A. AND L. L. EBERHARDT. 1953. Tol- plied meterological data. J. M. Cullen, G. Ettershank, erance of incubating eggs to exposure. J. J. Hansen, M. Hill, A. K. Lee, J. Sack and V. Kohout Wildl. Manage. 17:322-330. helped in various ways. I thank these authorities and PEFAUR, J. E. 1974. Egg neglect in the Wilsons’ Storm individuals for their assistance. Petrel. Wilson Bull. 86: 16-22. RAHN, H. AND A. AR. 1974. The avian egg: incubation time and water loss. Condor 76: 147-152. LITERATURE CITED REILLY, P. N. 1970. Nesting of the Superb Lyrebird in Sherbrooke Forest, Victoria. Emu 70:73-78. BARTH, E. K. 1949. Redetemperaturer og rugevaner. RICKLEFS, R. E. 1967. A graphical method of fitting Naturen (Bergen) 73:81-95. equations to growth curves. Ecology 48:978-983. DAWSON, W. R. AND F. C. EVANS. 1960. Relation of RICKLEFS, R. E. 1968. Patterns of growth in birds. Ibis growth and development to temperature regula- 110:419451. tion in nestling Vesper Sparrows. Condor 62:329- RICKLEFS, R. E. 1969. Preliminary models for growth 340. rates of altricial birds. Ecology 50: 1031-1039. DRENT, R. H. 1970. Functional aspects of incubation RICKLEFS, R. E. 1973. Patterns of growth in birds. II. in the Herring Gull. Behaviour Suppl. 17:1-32. Growth rate and mode of development. Ibis DHENT, R. H. 1972. Adaptive aspects of the physiol- 115:177-201. ogy of incubation. Proc. XV Int. Ornithol. Congr. ROBERTS, B. 1940. The life cycle of Wilsons’ Petrel (1970):231-256. Oceanites oceunicus (Kuhl). British Graham Land DRENT, R. H. 1973. The natural history of incubation, Exp. 1934-1937. Br. Mus. (Nat. Hist.) Sci. Rep. p. 262-311. In D. S. Farner [Ed.], Breeding biology 1: 141-194. of birds. National Academy of Science, Washing- ROBINSON, F. N. 1977. Environmental origins of the ton, D.C. Menurae. Emu 77: 167-168. DHENT, R. H. 1975. Incubation, p. 333420. In D. S. ROWLEY, I. 1973. The comparative ecology of Austra- Farner and J. R. King ]Eds.], Avian biology. Vol. lian Corvids. IV. Nesting and rearing of young to 5. Academic Press, New York. independence. CSIRO Wildl. Res. 18:91-129. DUNN, E. H. 1976. The relationship between brood SKUTCH, A. F. 1962. The constancy of incubation. size and age of effective homeothermy in nestling Wilson Bull. 74:115-152. House Wrens. Wilson Bull. 88:478-482. TREGALLAS, T. H. 1921. Notes on the lyrebird. Emu HOWARD, N. H. AND P. J. ~SHAUGHNESSY.‘ 1971. 21:95-103. First progress report Corranderk. Melbourne and WARD, J. E. 1939. In the haunts of the lyre-. Bull. Metropolitan Board of Works Report No. MMBW/ N.Y. Zool. Sot. 63:67-79. w/0001. WARD, J. E. 1940. The passing of the lyre-bird. Bull. HUGGINS, A. A. 1941. Egg temperatures of wild birds N.Y. Zool. Sot. 63:146-152. under natural conditions. Ecology 22:148-157. WESTERSKOV, K. 1956. Incubation temperatures of the HUXLEY, J. S. 1927. On the relation between egg- pheasant, Phasiunus colchicus. Emu 56:405420. weight and body-weight in birds. J. Linn. Sot. WHITE, F. N. AND J. L. KINNEY. 1974. Avian incuba- Lond., 2001. 36:457466. tion. Science 186: 107-115. INGLIS, I. R. 1977. The breeding behaviour of the WITHERBY, H. F., F. C. R. JOURDAIN, N. F. TICE- Pink-footed Goose: behavioural correlates of nest- HURST, AND B. W. TUCKER. 1938. The handbook ing success. Anim. Behav. 25:747-764. of British birds. Vol. I. Crows to flycatchers. With- LANGFORD, K. J. AND P. J. ~SHAUGHNESSY.‘ 1977. erby Ltd., London. First progress report North Maroondah. Mel- bourne and Metropolitan Board of Works Report Departments of Zoology and Psychology, Monush Uni- No. MMBW/W/0005. versity, Clayton, Victoria, Austruliu 3168. Accepted LENNERSTEDT, I. 1966. Egg temperature and incu- for publication 18 September 1978.