Development of maximum metabolic rate and pulmonary diffusing capacity in the superprecocial Australian Brush Turkey Alectura lathami: an allometric and morphometric study

The Australian Brush Turkey Alectura lathami is a member of the Megapodiidae, the mound-building birds that produce totally independent, "superprecocial" hatchlings. This study examined the post-hatching development of resting and maximal metabolic rates, and the morphometrically determined changes in pulmonary gas exchange anatomy, in chicks during 3.7 months of growth from hatchlings (122 g) to subadults (1.1 kg). Allometric equations of the form y=aM(b) related gas exchange variables (y) to body mass (M, g). Metabolic rates were measured with open-flow respirometry (mL O2 min(-1)) of chicks resting in the dark and running above the aerobic limit on a treadmill. Resting metabolic rate (RMR=0.02 M(0.99)) and maximal metabolic rate (MMR=0.05 M(1.07)) scaled with exponents significantly above those of interspecific allometries of adult birds. However MMR was below that expected for other species of adult birds in flapping flight, consistent with the Brush Turkey's ground-dwelling habits. Total lung volumes (mL) increased faster than isometrically (V(L)=0.0075 M(1.19)), as did the surface area (cm(2)) of the blood-gas barrier (S(t)=7.80 M(1.23)), but the data overlapped those of adult species. Harmonic mean thickness of the blood-gas barrier was independent of body size (mean tau(ht),=0.39 microm) and was about twice that expected for flying birds. Diffusing capacity (mL O2 min(-1) kPa(-1)) of the blood-gas tissue barrier increased faster than isometrically (Dto2=0.049 M(1.23)); in hatchling Brush Turkeys, it was about 30% expected for adult birds, but this difference disappeared when they became subadults. When compared to altricial Australian pelicans that hatch at similar body masses, superprecocial Brush Turkeys had higher MMR and higher Dto2 at the same body size. A parallel allometry between MMR and Dto2 in Brush Turkeys and pelicans is consistent with the concept of symmorphosis during development.     

Patterns of growth and heterochrony in moundbuilders (Megapodiidae) and fowl (Phasianidae)

Megapode hatchlings are "superprecocial" compared to hatchlings of other Galliformes. In this paper, we examine patterns of growth and inquire about evolutionary processes that led to different degrees of precocity at hatching in Galliformes. The postnatal development of body mass and that of seven morphometric parameters of wing and leg of Brush Turkey Alectura lathami , Peacock Pavo cristatus , Pheasant Phasianus colchicus and Japanese Quail Coturnix japonica was characterized by the ratio of exponential growth rate ( EGR ) to relative size (ln  ( W / A) ; W =size at a given age; A =asymptote) at a given age. From that relationship, we derived developmental trajectories as the slopes of a least squares regression of EGR on relative size. The slopes of the developmental trajectories are indicative of the degree of precocity of development. We found that Brush Turkey, Peacock, and Pheasant follow the same developmental trajectory. However, the Brush Turkey hatches heterochronically delayed on that trajectory and consequently, its hatchlings are superprecocial. The Quail follows a significantly steeper developmental trajectory and hatches with a high degree of embryonic function ( EGR ). From a comparative phylogenetic analysis we reconstruct the ancestral galliform developmental trajectory and infer that hypermorphosis of Brush Turkey embryos led to the superprecocial hatchlings. The steeper developmental trajectory of Quail is evolutionary derived from ancestral patterns of growth by somatic paedomorphosis. Using a multivariate approach we show that development of different parts of the body is coherent, i.e., that patterns of development of wing and leg do not vary independently of each other. Consequently, selection for changed development of any part of the wing or the leg will cause the other parts to change too.     

Influence of body composition on the metabolic rate of nestling European shags (Phalacrocorax aristotelis)

During the early development of avian nestlings, their mass-specific resting metabolic rate (RMR) changes in a biphasic pattern with the peak value often being much higher than that expected for an adult bird of similar body mass. In the present study we examined the possible influence of variations in the size of internal organs in “setting” the high RMR and peak metabolic rate (PMR) during development in a large altricial species, the European shag (Phalacrocorax aristotelis). Thermoneutral RMR and cold-exposure induced PMR were measured in nestlings 15 days old, the age at which the highest RMR occurred during development. Body mass averaged 414 g. Mean values of RMR and PMR were 5.75 W and 9.08 W, respectively; the RMR value corresponds to approximately 250% of the expected value for an adult non-passerine bird of similar body mass. The masses of all the organs measured (breast and leg muscles, heart, liver, intestine, and kidney) varied isometrically with total body mass. However, large chicks had a significantly lower fractional water content than small chicks, suggesting that the former had achieved a higher level of functional maturity. In contrast to what has been suggested for adult birds in general, the heart and kidney masses of shag nestlings were not significantly correlated with the metabolic rates. The intestine length, in contrast, was highly and positively correlated with both the RMR and the PMR, i.e. intestine length was a better predictor of RMR and PMR than was total body mass. In addition, liver mass was positively correlated with RMR. The results of the present study suggest that the liver in particular may play a key role in establishing the high, mass-specific RMR which is attained during development in bird chicks. Our results also support previous suggestions that early in their development, altricial chicks mainly allocate energy to the growth of `energy-processing' organs (such as the intestine and liver) rather than to `energy-consuming' organs. Accepted: 3 March 1999     

Post-hatching growth and development of the pectoral and pelvic limbs in the black noddy, Anous minutus

The black tern (Anous minutus) uses a semi-precocial growth strategy. Terrestrial locomotor capacity occurs soon after hatching, but pectoral limb development is delayed and flight is not possible until about post-hatching day 50. A growth series (hatchlings to fledglings) was used to explore how limb musculoskeletal development varied with body mass. In the pelvic limb, bone lengths scaled isometrically or with negative allometry. Gastrocnemius muscle mass and the failure load and stiffness of the tibiotarsus scaled isometrically. In the pectoral limb, pectoralis and supracoracoideus muscle masses increased with strong positive allometry that was mirrored by increases in wing bone strength and stiffness. Bending strength (sigma(ult)) and modulus (E) remained fairly constant throughout development to fledging for all limb bones. The moment of inertia (I) scaled with negative allometry for the tibiotarsus and with strong positive allometry in the wing bones. Differences in sigma(ult) and E of the tibiotarsus between pre-fledged chicks and adults was due, primarily, to increases in bone density rather than increases in the moment of inertia of the skeletal elements, whereas sigma(ult) of wing bones was a function of increases in both bone density and I. Early development of functional pelvic limbs in tree-nesting birds is relatively unusual, and presumably reflects a familial trait that does not appear to compromise breeding success in this species.     

Energy requirements of migrating Great White Pelicans Pelecanus onocrotalus

The Great White Pelican Pelecanus anocrotalus is the largest migrating bird in Israel and is an endangered species. The Palearctic populations of the Great White Pelican breed in eastern Europe and Asia and most of them pass through the ‘bottleneck’ of Israel to wintering grounds in Africa. Natural feeding sites for pelicans have diminished during recent decades due to human activities, and sites of extensive aquaculture have become the favourite feeding places for wintering and migrating Great White Pelicans. The fish industry has reported a significant impact on fish yield and the conflict between pelicans and fishermen has escalated so that hundreds of pelicans have died in recent years from shooting or accidental electrocution. We approached this management problem by studying the energy requirements of the Great White Pelican during migration and while wintering in Israel, under different feeding regimes (fish or chicks) and in different seasons, in captivity. The results show that a captive bird consumes 1.1 kg of fish per day. The basal metabolic rate and apparent metabolized energy of the Great White Pelican are both higher than predicted from allometric equations. Energetic demands were quite stable on both diets (fish and chicks) and during both seasons (winter and summer). The fat deposits of migrating pelicans averaged 313.5 g compared with 480 g in wintering birds (3.4% and 5.4% of body mass, respectively). Based on these fat contents and on the measured daily energy consumption, we calculated that birds that do not feed in Israel can fly only up to 1620 km from Israel southward and could not cover the distance to their likely wintering grounds in the Sudd area in southern Sudan. However, birds that replenish their fuel reserves could fly up to 2460 km and hence could reach this area. Therefore, we conclude that Great White Pelicans must feed in Israel during the autumn migration in order to complete their journey to Africa. One solution to the conflict between pelicans and fishermen could be to combine deterrents preventing pelicans from feeding in fish‐ponds with the provision of attractive alternative reservoirs, to ensure regular food supplies during autumn.     

Post-hatching growth and development of the pectoral and pelvic limbs in the black noddy, Anous minutus.

The black tern (Anous minutus) uses a semi-precocial growth strategy. Terrestrial locomotor capacity occurs soon after hatching, but pectoral limb development is delayed and flight is not possible until about post-hatching day 50. A growth series (hatchlings to fledglings) was used to explore how limb musculoskeletal development varied with body mass. In the pelvic limb, bone lengths scaled isometrically or with negative allometry. Gastrocnemius muscle mass and the failure load and stiffness of the tibiotarsus scaled isometrically. In the pectoral limb, pectoralis and supracoracoideus muscle masses increased with strong positive allometry that was mirrored by increases in wing bone strength and stiffness. Bending strength (sigma(ult)) and modulus (E) remained fairly constant throughout development to fledging for all limb bones. The moment of inertia (I) scaled with negative allometry for the tibiotarsus and with strong positive allometry in the wing bones. Differences in sigma(ult) and E of the tibiotarsus between pre-fledged chicks and adults was due, primarily, to increases in bone density rather than increases in the moment of inertia of the skeletal elements, whereas sigma(ult) of wing bones was a function of increases in both bone density and I. Early development of functional pelvic limbs in tree-nesting birds is relatively unusual, and presumably reflects a familial trait that does not appear to compromise breeding success in this species.     

An allometric study of pulmonary morphometric parameters in birds, with mammalian comparisons

Comprehensive pulmonary morphometric data from 42 species of birds representing ten orders were compared with those of other vertebrates, especially mammals, relating the comparisons to the varying biological needs of these avian taxa. The total lung volume was strongly correlated with body mass. The volume density of the exchange tissue was lowest in the charadriiform and anseriform species and highest in the piciform, cuculiform and passeriform species. The surface area of the blood-gas (tissue) barrier, the volume of the pulmonary capillary blood and the total morphometric pulmonary diffusing capacity were all strongly correlated with body mass. The harmonic mean thickness of both the blood-gas (tissue) barrier and the plasma layer were weakly correlated with body mass. The mass-specific surface area of the blood-gas (tissue) barrier (surface area per gram body mass) and the surface density of the blood-gas (tissue) barrier (i.e. its surface area per unit volume of exchange tissue) were inversely correlated (though weakly) with body mass. The passeriform species exhibited outstanding pulmonary morphometric adaptations leading to a high specific total diffusing capacity per gram body mass, consistent with the comparatively small size and energetic mode of life which typify passeriform birds. The relatively inactive, ground-dwelling domestic fowl (Gallus gallus) had the lowest pulmonary diffusing capacity per gram body mass. The specific total lung volume is about 27% smaller in birds than in mammals but the specific surface area of the blood-gas (tissue) barrier is about 15% greater in birds. The ratio of the surface area of the tissue barrier to the volume of the exchange tissue was also much greater in the birds (170-305%). The harmonic mean thickness of the tissue barrier was 56-67% less in the birds, but that of the plasma layer was about 66% greater in the birds. The pulmonary capillary blood volume was also greater (22%) in the birds. Except for the thickness of the plasma layer, these morphometric parameters all favour the gas exchange capacity of birds. Consequently, the total specific mean morphometric pulmonary diffusing capacity for oxygen was estimated to be about 22% greater in birds than in mammals of similar body mass. This estimate was obtained by employing oxygen permeation constants for mammalian tissue, plasma and erythrocytes, as avian constants were not then available.(ABSTRACT TRUNCATED AT 400 WORDS)     

The energetic demand of the Great White Pelican during migration in Israel and its implication to the conflict between fish industry and pelicans

Shmueli, M., Arad, Z., Izhaki, I. & Crivelli, A. 2000. The energetic demand of the Great White Pelican during migration in Israel and its implication to the conflict between fish industry and pelicans. Ostrich 71 (1 & 2): 1.

The Great White Pelican Pelecanus onocrotalus is a migrating bird, which is an endangered species. The majority of the western Palaearctic populations stopover in Israel during their autumn migration (71 421 ± 127 individuals per year). Although most of these birds are transient over Israel, an increasing number of individuals (1 142 ± 882, between 1990–1994) stay and winter in the northern part of Israel. The natural feeding sites for pelicans diminished during recent decades due to human activities, and the aquaculture sites of intensive fishery became their favourite feeding places either during migration or during winter. The fish industry reports huge damages to fish yield. This study tried to assess ecophysiological needs of the White pelicans during migration and wintering in Israel, and to evaluate the necessity for pelicans to feed in Israel on their route to east-central Africa. The study combines laboratory measurements of energy consumption of captive pelicans, and field observations of migrant and wintering pelicans, and satellite tracking of migrating pelicans. The mean mass-specific metabolic rate (BMR) of the pelican was 236 kJ/(kg*day), without significant differences between sexes or diets (fish or chicks) and seasons: digestible energy intake (DEI) was 490–730 kJ/(kg*day) also without significant differences between sexes and diets. Wet food consumption (WFC) was greater on the fish diet (1.120 kg/day per bird) than on the chick diet (0.970 kg/day). Digestive efficiency was higher on the fish than on the chick diet (86% and 77%, respectively). Fat deposition in dead migrant pelicans during autumn, was 290 g (3.4% + 2.6% of body mass, n = 81). Fat deposition in wintering pelicans was significantly higher (5.4% ± 3.4% of body mass, n = 21). From these data, the average flight range of transient pelicans was estimated as 1 120 km without refueling. Although satellite records gave us information on the northward migration routes of pelicans from Israel, we need further information about the precise area of the pelicans in Africa. Nevertheless it is concluded that pelicans need to feed during their stopover in Israel, or at some unknown feeding sites along their southward migratory route, to complete their journey to their wintering grounds in east-central Africa. The results of this research should contribute to the establishment of new management policies, to the solution of conflict with the fish industry and to the conservation of pelicans in Israel.     

Thermoregulatory abilities in chicks of the Antarctic Petrel (Thalassoica antarctica)

Summary We studied the thermoregulatory capacity of Antarctic Petrel chicks, Thalassoica antarctica, breeding in a large colony in Queen Maud Land (71°53S,5°10E) on the Antarctic continent. Compared to newly hatched chicks of other birds, those of the Antarctic Petrel are characterized by a relatively high standard metabolic rate (SMR) and thermal conductance. Their metabolic scope is limited, however, being only 1.6 times the SMR, and they consequently depend on parental brooding to maintain T_b. At an age of 11 days the chicks become thermally independent and are left alone in the nest. The chicks keep a relatively high body temperature (>36°C) throughout their early development and we found no indication that they normally experience hypothermia. A significant positive relationship between latitude of breeding and SMR of the hatchlings is shown to exist for procellariiform birds. It is suggested that the high SMR found in Antarctic Petrel hatchlings could be a prerequisite for achieving a high growth rate, rather than being of any thermoregulatory significance.Publication no. 105 from the Norwegian Antarctic Research Expeditions (1984/1985)     

Life history of Rhamphorhynchus inferred from bone histology and the diversity of pterosaurian growth strategies

Background

Rhamphorhynchus from the Solnhofen Limestones is the most prevalent long tailed pterosaur with a debated life history. Whereas morphological studies suggested a slow crocodile-like growth strategy and superprecocial volant hatchlings, the only histological study hitherto conducted on Rhamphorhynchus concluded a relatively high growth rate for the genus. These controversial conclusions can be tested by a bone histological survey of an ontogenetic series of Rhamphorhynchus.

Methodology/Principal Findings

Our results suggest that Bennett''s second size category does not reflect real ontogenetic stage. Significant body size differences of histologically as well as morphologically adult specimens suggest developmental plasticity. Contrasting the ‘superprecocial hatchling’ hypothesis, the dominance of fibrolamellar bone in early juveniles implies that hatchlings sustained high growth rate, however only up to the attainment of 30–50% and 7–20% of adult wingspan and body mass, respectively. The early fast growth phase was followed by a prolonged, slow-growth phase indicated by parallel-fibred bone deposition and lines of arrested growth in the cortex, a transition which has also been observed in Pterodaustro. An external fundamental system is absent in all investigated specimens, but due to the restricted sample size, neither determinate nor indeterminate growth could be confirmed in Rhamphorhynchus.

Conclusions/Significance

The initial rapid growth phase early in Rhamphorhynchus ontogeny supports the non-volant nature of its hatchlings, and refutes the widely accepted ‘superprecocial hatchling’ hypothesis. We suggest the onset of powered flight, and not of reproduction as the cause of the transition from the fast growth phase to a prolonged slower growth phase. Rapidly growing early juveniles may have been attended by their parents, or could have been independent precocial, but non-volant arboreal creatures until attaining a certain somatic maturity to get airborne. This study adds to the understanding on the diversity of pterosaurian growth strategies.     

Weather,microclimate, and energy costs of thermoregulation for breeding Adélie Penguins

Summary We measured meteorological conditions and estimated the energy costs of thermoregulation for young and adult Adélie Penguins (Pygoscelis adeliae) at a breeding colony near the Antarctic Peninsula. Air temperatures averaged < 5°C and strong winds were frequent. Operative temperatures (T_e) for adults ranged from –8 to 28°C, averaging 5–6°C, for the period from courtship to fledging of chicks. The average energy cost of thermoregulation (C_th) for adult penguins was equivalent to 10–16% of basal metabolism. C_th comprised about 15% of the estimated daily energy budget (DEB) of incubating adults, but only about 1% of the DEB of adults feeding chicks. The T_e's for chicks older than 14 days ranged from 0 to 31°C, averaging 8.0 C. The C_th for downy chicks ranged from about 31% of minimal metabolic rate (MMR) in 1 kg chicks to about 10% of MMR in 3 kg chicks. Between initial thermal independence (age 12–14 days) and the cessation of parental feeding (age 35–40 days), chicks use about 10–11% of assimilated energy for thermoregulation. C_th is equivalent to about 17% of the MMR of fledglings during their 2–3 week fast. We observed no indication of thermal stress (i.e., conditions in which birds cannot maintain stable T_b) in adults and no indication of cold stress in any age class. However, on clear, calm days when air temperature exceeds 7–10°C for several hours, downy chicks are vulnerable to lethal hyperthermia.     

Aufzucht von Chilemeerespelikane (Pelecanus occidentalis thagus) im Vogelpark Walsrode mit Vergleichen zu anderen publizierten Erfahrungen mit Pelikanen

The probable world first captive breeding success in Chilean Brown Pelican (Pelecanus occidentalis thagus) in captivity is reported. Two chicks were hand reared at Walsrode Birdpark, Germany in 2006. Parents were imported in October 2005 and were wild birds that had been injured and subsequently rescued. All 10 adult birds demonstrated detrimental and chronically handicaps. First eggs were laid in January 2006. Eggs were incubated artificially at 37.1 °C and 56% rel. humididty. Two chicks hatched after 33 days of incubation. First feeding was made one day after hatching in the morning. Food was given 5 times a day. Until the 8th day after hatching, exclusively cut naked baby rats were fed. For stimulating the digestion and providing a good intestinal flora Lactobacillus powder was used and food was warmed up before application. After 8 days the diet was changed to fish. For development see figures. Worth to mention is the black-purple colour of the freshly hatched chicks which became successively paler with age. Also the development of the feather areas is characteristic for this (sub)-species. Taxonomy is discussed with some morphological arguments that are typical for subspecies. Nevertheless, some indications of possible breeding barriers between subspecies could support the suggestions for species status. Hatching and rearing data are compared with dates from other zoos and species of pelicans. The good development of the Walsrode birds based on the data and methods described leaves this article useful as a reference guideline for hand rearing pelicans.     

Aufzucht von Chilemeerespelikane (Pelecanus occidentalis thagus) im Vogelpark Walsrode mit Vergleichen zu anderen publizierten Erfahrungen mit Pelikanen

The probable world first captive breeding success in Chilean Brown Pelican (Pelecanus occidentalis thagus) in captivity is reported. Two chicks were hand reared at Walsrode Birdpark, Germany in 2006. Parents were imported in October 2005 and were wild birds that had been injured and subsequently rescued. All 10 adult birds demonstrated detrimental and chronically handicaps. First eggs were laid in January 2006. Eggs were incubated artificially at 37.1 °C and 56% rel. humididty. Two chicks hatched after 33 days of incubation. First feeding was made one day after hatching in the morning. Food was given 5 times a day. Until the 8th day after hatching, exclusively cut naked baby rats were fed. For stimulating the digestion and providing a good intestinal flora Lactobacillus powder was used and food was warmed up before application. After 8 days the diet was changed to fish. For development see figures. Worth to mention is the black-purple colour of the freshly hatched chicks which became successively paler with age. Also the development of the feather areas is characteristic for this (sub)-species. Taxonomy is discussed with some morphological arguments that are typical for subspecies. Nevertheless, some indications of possible breeding barriers between subspecies could support the suggestions for species status. Hatching and rearing data are compared with dates from other zoos and species of pelicans. The good development of the Walsrode birds based on the data and methods described leaves this article useful as a reference guideline for hand rearing pelicans.     

Energy metabolism and thermoregulation in hand-reared chukars (Alectoris chukar)

Metabolic rate and colonic temperature were measured in chukars between 1st and 108th day of life (divided into six age groups: 1-3-days old, 1, 2, 3, and 4-weeks old and 3.5-months old) in ambient temperatures set separately for each group and ranging from -12 to 41 degrees C. The Gompertz growth constant for growing chukars (0.042) was close to the value obtained in earlier study for the grey partridge. Similarly as in other species of Galliformes, newly hatched chukar chicks had lower T(b) at TNZ (39.5 degrees C) than that found in older birds (41.3 degrees C in 4-weeks old). The body temperatures taken at TNZ in 2-weeks old chicks and older fitted neatly within allometrically predicted limits of body temperatures for adult birds. The values of RMR at TNZ followed closely a biphasic pattern, with the second phase correlating strongly with the body mass. The value of metabolic scope (the level of metabolic efficiency) for the youngest group was high (3.2) and exceeded the values obtained in earlier studies for other gallinaceous species, including the grey partridge. The obtained values of minimum wet thermal conductance for growing chukar chicks exceeded the predicted values by approximately 40% but the slopes of both lines were very similar. In chukars, the key stage in the expression of fully developed thermoregulatory capacities comes immediately after the first week of life (maintaining somewhat constant body temperature, evident drop in the value of RMR at TNZ and minimal thermal conductance). The model of gradual development of thermoregulation which could be derived from the experiments on chukar chicks was characteristic for typical precocial birds.     

Anthelminthic treatment negatively affects chick survival in the Eurasian Oystercatcher Haematopus ostralegus

Eurasian Oystercatchers Haematopus ostralegus are infested with a wide range of gut parasites, but experimental evidence of their effects on host fitness is scant. We investigated prevalence of parasites, and experimentally tested the effects of gut parasites on chick survival and growth. One hundred and fifty-nine hatchlings from 66 nests were treated with a single dose anthelminthic medicine (0.5 mL Spectril + 0.0025 mL Ivomec) and compared with a sham-treated control group of 163 hatchlings from 66 nests. Unexpectedly, chicks treated with the anthelminthic drug survived less well than control chicks. Fledglings from the treated group were significantly less infected with gut parasites than untreated fledglings, although they were of similar body mass. One possible explanation for these findings is that the treatment interferes with the development of the immune system in the hatchlings. This might have caused mass mortality of treated hatchlings after the drug ceased to work and the treated chicks became susceptible to infections for the first time. Furthermore, all chicks and adults from both saltmarsh and adjacent freshwater habitat appeared free from blood parasites. Thus, in the Eurasian Oystercatcher, we found no support for the hypothesis, based on between-species comparisons, that the presence of blood parasites is related to the saltiness of the environment.     

Age and hunting success in the brown pelican: influences of skill and patch choice on foraging efficiency

Summary Age-related differences in the foraging efficiency of piscivorous birds may be the results of differences in foraging skill, patch usage, or both. Brown pelicans were observed while foraging around a small Caribbean island. Areas where the birds fed were subdivided into small, homogeneous subunits (patches), and the bird's foraging success and patch use were noted and analyzed using multivariate techniques. Adult birds were found to be better at capturing prey under all conditions than were juveniles, but the differences were small in some patches. The density of prey and the birds' foraging success influenced the foraging efforts of adult and juvenile pelicans to similar degrees. Both age groups utilized local enhancement in their foraging, but such behavior augmented the foraging success only of juvenile birds. Both age groups often fed in patches where their foraging success was quite low. Such behaviour was much more costly for juvenile than for adult pelicans.     

Does basal metabolic rate contain a useful signal? Mammalian BMR allometry and correlations with a selection of physiological, ecological, and life-history variables

Basal metabolic rate (BMR, mL O2 h(-1)) is a useful measurement only if standard conditions are realised. We present an analysis of the relationship between mammalian body mass (M, g) and BMR that accounts for variation associated with body temperature, digestive state, and phylogeny. In contrast to the established paradigm that BMR proportional to M3/4, data from 619 species, representing 19 mammalian orders and encompassing five orders of magnitude variation in M, show that BMR proportional to M2/3. If variation associated with body temperature and digestive state are removed, the BMRs of eutherians, marsupials, and birds do not differ, and no significant allometric exponent heterogeneity remains between orders. The usefulness of BMR as a general measurement is supported by the observation that after the removal of body mass effects, the residuals of BMR are significantly correlated with the residuals for a variety of physiological and ecological variables, including maximum metabolic rate, field metabolic rate, resting heart rate, life span, litter size, and population density.     

Population ecology of the southern cassowary Casuarius casuarius johnsonii , Mission Beach north Queensland

Little is known of the ecology and population dynamics of the world’s largest avian frugivore. This study investigated the population of endangered southern cassowary at Mission Beach, northeast Australia, and examined the problems associated with determining population size and density of this keystone species. Using the results of an intensive field survey aimed at estimating absolute numbers of individual cassowaries, the appropriate sampling methodology for rare and elusive species was explored. Approximately 102 km² of rainforest was surveyed using 346 km of search transects. Of a total of 110 cassowaries, there were 49 adults (28 male, 19 female, 2 unknown), 28 subadults, 31 chicks, and 2 independent birds of unknown status. This is approximately 35% of the adult population previously estimated for the Mission Beach area. Overall adult cassowary density was 0.48 adults/km²; the density of independent birds, i.e. adults and subadults, was 0.78 birds/km². Mean indicative home range (IHR) for adult females and males was 2.13 and 2.06 km², respectively. Mean IHR of subadults was smaller at 0.95 km². It was concluded that the previous practice of surveying small areas at Mission Beach (<4 km²) has led to consistent overestimation of cassowary population density, up to six times its real number. It is shown that a sample plot between 5 and 15 km² is necessary to approximate true cassowary density. These findings have significant application to the conservation of cassowaries in New Guinea and in the Wet Tropics World Heritage Area of Australia.     

Intraspecific correlations of basal and maximal metabolic rates in birds and the aerobic capacity model for the evolution of endothermy

The underlying assumption of the aerobic capacity model for the evolution of endothermy is that basal (BMR) and maximal aerobic metabolic rates are phenotypically linked. However, because BMR is largely a function of central organs whereas maximal metabolic output is largely a function of skeletal muscles, the mechanistic underpinnings for their linkage are not obvious. Interspecific studies in birds generally support a phenotypic correlation between BMR and maximal metabolic output. If the aerobic capacity model is valid, these phenotypic correlations should also extend to intraspecific comparisons. We measured BMR, M(sum) (maximum thermoregulatory metabolic rate) and MMR (maximum exercise metabolic rate in a hop-flutter chamber) in winter for dark-eyed juncos (Junco hyemalis), American goldfinches (Carduelis tristis; M(sum) and MMR only), and black-capped chickadees (Poecile atricapillus; BMR and M(sum) only) and examined correlations among these variables. We also measured BMR and M(sum) in individual house sparrows (Passer domesticus) in both summer, winter and spring. For both raw metabolic rates and residuals from allometric regressions, BMR was not significantly correlated with either M(sum) or MMR in juncos. Moreover, no significant correlation between M(sum) and MMR or their mass-independent residuals occurred for juncos or goldfinches. Raw BMR and M(sum) were significantly positively correlated for black-capped chickadees and house sparrows, but mass-independent residuals of BMR and M(sum) were not. These data suggest that central organ and exercise organ metabolic levels are not inextricably linked and that muscular capacities for exercise and shivering do not necessarily vary in tandem in individual birds. Why intraspecific and interspecific avian studies show differing results and the significance of these differences to the aerobic capacity model are unknown, and resolution of these questions will require additional studies of potential mechanistic links between minimal and maximal metabolic output.     

Energy requirements of a Great white pelican (Pelecanus onocrotalus) population and its impact on fish stocks

The Great white pelican Pelecanus onocrotalus is a major predator of some freshwater fish stocks in much of Africa. Detailed population time-activity budgets allowed us to estimate that the south-western Cape Province population consumed 184 tonnes offish annually. Of this, 69% was required for adult existence, 17% for chicks and 14% for flight. Per capita consumption averaged 840 g per day, or 8–8% of body weight; very much less than the figure of 17–6% used in some energy budget calculations. Our integrative bioenergetics approach lends some support for the use of 10% of body weight as the amount of food consumed per day by large piscivorous birds for initial estimates of their impact on stocks.
Predation by Great white pelicans may account for some 10–25% offish production, a shortage of reliable data on fish production in African freshwater ecosystems makes a more precise estimate impossible. Food supplies and shoreline length may both be important factors for pelican populations.