King Penguin Chicks Research Articles

Modeling the Marine Resources Consumed in Raising a King Penguin Chick: An Energetics Approach

Accurate estimates of penguin energetics would represent an important contribution to our understanding of the trophodynamics of the Southern Ocean ecosystem and our ability to predict effects of environmental change on these species. We used the heart rate-rate of oxygen consumption technique to estimate rate of energy expenditure in adult king penguins raising a chick, in combination with data from the literature on changes in adult mass, chick energy requirements, and prey energy density. Our model estimated a variety of energetic costs and quantities of prey consumption related to raising a king penguin chick during the austral summer. The total energy requirements of a king penguin chick at the Crozet Archipelago from hatching until reaching a mass of 8 kg 90 d later is 271 MJ, representing the consumption of 38.4 kg of myctophid fish. A successfully breeding male requires 0.78 kg d(-1) of fish during the entirety of the incubation period and 1.14 kg d(-1) during the subsequent 90 d of chick rearing. Assuming the same energy requirements for females, the estimated 580,000 pairs of king penguins that breed successfully at Crozet each year, together with their chicks, consume a total of around 190,000 tons of fish during the incubation and summer rearing periods combined. If, due to depletion of fish stocks, the diet of breeders and chicks during the summer becomes identical to the typical diet of adults during the austral winter, the mass of prey required by both adults and chicks combined (where the chick still reaches 8 kg after 90 d) would increase by more than 25%.

Is fledging in king penguin chicks related to changes in metabolic or endocrinal status?

This study examines the possibility that metabolic or endocrinal factors initiate fledging in the king penguin, a semi-altricial seabird species breeding a single chick on the ground. Chick fledging (departure to sea) occurred 5 d after completion of the molt. It was preceded by a 16 d fasting period and by a 7-fold increase in locomotor activity. From the measurement of the plasma concentration of metabolites and of glucagon and insulin, pre-fledging king penguin chicks were found to adapt to fasting in a classical way, i.e. by sparing body protein and mobilizing fat stores. At fledging, chicks were in phase II of fasting and their departure to sea was not stimulated by reaching critical energy depletion (phase III), in contrast to that which has been reported in breeding-fasting adults. The plasma level of corticosterone remained unchanged throughout the whole pre-fledging period, providing no support for a role of this stress-hormone in the facilitation of fledging. Thus, king penguin fledglings did not appear to be environmentally or nutritionally stressed. The plasma levels of thyroid hormones were elevated during the pre-fledging molt, in accordance with their key role in molt control in adult penguins. These levels declined by the time of the molt end, the plasma level of T 4 thereafter being directly related to the time left before fledging. These results do not support the view that chronically elevated levels of thyroid hormones are required for the energy-demanding transition between being ashore and in cold water, but they suggest that the maintenance of high T 4 levels may delay fledging.

Long–term effects of flipper bands on penguins

Changes in seabird populations, and particularly of penguins, offer a unique opportunity for investigating the impact of fisheries and climatic variations on marine resources. Such investigations often require large-scale banding to identify individual birds, but the significance of the data relies on the assumption that no bias is introduced in this type of long-term monitoring. After 5 years of using an automated system of identification of king penguins implanted with electronic tags (100 adult king penguins were implanted with a transponder tag, 50 of which were also flipper banded), we can report that banding results in later arrival at the colony for courtship in some years, lower breeding probability and lower chick production. We also found that the survival rate of unbanded, electronically tagged king penguin chicks after 2-3 years is approximately twice as large as that reported in the literature for banded chicks.

Plasma thyroid hormone pattern in king penguin chicks: a semi-altricial bird with an extended posthatching developmental period

Plasma concentrations of thyroid hormones (TH) were investigated during the extended posthatching developmental period (∼11 months) of a semi-altricial bird species, the king penguin ( Aptenodytes patagonicus). The first period of growth in summer was marked by a progressive rise in plasma T 4 concentration that paralleled rapid increases in body mass and in structural and down growth. By contrast, plasma T 3 concentration had already reached adult levels in newly hatched chicks and did not change thereafter. Circulating TH of king penguin chicks thus follow an original pattern when comparing to altricial and precocial species. During the austral winter, the long period of undernutrition of king penguin chicks was characterized by a decrease in circulating TH that can be related to a seasonal stop in growth and energy saving mechanisms. Plasma TH concentrations increased again during the second growth phase in spring, and they reached their highest levels at the end of the fledging period, slightly before juveniles initiated their first foraging trip at sea. As expected, plasma T 4 levels were elevated when chicks moulted, developing a true-adult type waterproof plumage. The data also suggest that T 4 plays a major role in skeletal development and pectoral muscle maturation in anticipation of marine life. Plasma T 3 was at its highest during the period when juveniles improved resistance to cold waters by going back and forth to the sea, suggesting a role for circulating T 3 in cold acclimatization occurring at that time.

Assessing a relationship between bone microstructure and growth rate: a fluorescent labelling study in the king penguin chick (Aptenodytes patagonicus)

Microstructure-function relationships remain poorly understood in primary bone tissues. The relationship between bone growth rate and bone tissue type, although documented in some species by previous works, remains somewhat unclear and controversial. We assessed this relationship in a species with extreme adaptations, the king penguin (Aptenodytes patagonicus). These birds have a peculiar growth, interrupted 3 months after hatching by the austral winter. Before this interruption, chicks undergo extremely rapid statural and ponderal growth. We recorded experimentally (by means of fluorescent labelling) the growth rate of bone tissue in four long bones (humerus, radius, femur and tibiotarsus) of four king penguin chicks during their fastest phase of growth (3-5 weeks after hatching) and identified the associated bone tissue types ('laminar', 'longitudinal', 'reticular' or 'radial' fibro-lamellar bone tissue). We found the highest bone tissue growth rate known to date, up to 171 microm day(-1) (mean 55 microm day(-1)). There was a highly significant relationship between bone tissue type and growth rate (P<10(-6)). Highest rates were obtained with the radial microarchitecture of fibro-lamellar bone, where cavities in the woven network are aligned radially. This result supports the heuristic value of a relationship between growth rate and bone primary microstructure. However, we also found that growth rates of bone tissue types vary according to the long bone considered (P<10(-5)) (e.g. growth rates were 38% lower in the radius than in the other long bones), a result that puts some restriction on the applicability of absolute growth rate values (e.g. to fossil species). The biomechanical disadvantages of accelerated bone growth are discussed in relation to the locomotor behaviour of the chicks during their first month of life.

Nocturnal predation of king penguins by giant petrels on the Crozet Islands

Dietary segregation of sympatric seabirds in the Southern Ocean is partly linked to differences in their foraging techniques. We have investigated the activity of giant petrels (Macronectes spp.) in a king penguin (Aptenodytes patagonicus) colony day and night during the austral winter of 2001 on the Crozet Islands. Using an automatic identification system and an infrared video camera, we followed 15 petrels tagged with micro transponders. Our data show that giant petrels predate king penguin chicks during the night. The activity of giant petrels is even slightly higher during nighttime than during the day. In addition, our data show a higher nocturnal activity by northern giant petrels (M. halli) than by southern giant petrels (M. giganteus). These unexpected results raise questions concerning visual adaptations to nocturnal foraging in giant petrels and their potential impact on the sleep, vigilance and creching behavior of penguin chicks.

Changes in tissue fatty acid composition during the first month of growth of the king penguin chick.

The switch from yolk to food (myctophid fishes) as the nutrient source for the newly hatched chick of the king penguin ( Aptenodytes patagonicus) results in a profound change in the pattern of fatty acid provision. This is characterized by major increases in the proportionate intake of n-3 polyunsaturates (20:5n-3 and 22:6n-3) and long chain (C(20-24)) monounsaturates, accompanied by relatively lower levels of n-6 polyunsaturates (18:2n-6 and 20:4n-6). The effects of this change on the fatty acid composition of tissue lipids during the first month of growth, a period of tissue maturation leading to thermal emancipation, were determined. The composition of adipose tissue triacylglycerol responded rapidly to the switch in nutrient source, the proportion of long chain monounsaturates (mainly 20:1n-9 and 22:1n-11) increasing five-fold between hatch and emancipation while the relative levels of 20:5n-3 and 22:6n-3 also increased significantly, by 3- and 1.2-fold, respectively. At emancipation, the fatty acid profile of adipose tissue triacylglycerol was essentially identical to that of the diet. At hatch, the main polyunsaturates of muscle phospholipid were 20:4n-6, 20:5n-3, and 22:6n-3, respectively, forming (w/w of fatty acids) 13.2%, 5.0%, and 12.0%. By emancipation, 20:4n-6 had decreased to 4.8%, 20:5n-3 increased to 10.9%, and 22:6n-3 at 11.4% showed little change. The main polyunsaturate in brain phospholipid at hatch was 22:6n-3 (19.3%): this remained almost constant until day 15 but then increased significantly to 23.6% by emancipation. Significant but minor changes in the proportions of 20:4n-6 (from 5.2% at hatch to 3.5% at emancipation) and 20:5n-3 (from 3.0% to 3.9%) were also observed in brain phospholipid. The data do not allow us to completely distinguish changes that are solely diet driven from those which are a consequence of tissue differentiation. Nevertheless, it is evident that, whereas the fatty acid composition of adipose tissue responds faithfully to the change in nutrient source, the phospholipids of muscle and, especially, of brain are much more refractory to the effects of diet during this period of tissue maturation.

Status and Numerical Trends of King, Gentoo, and Rockhopper Penguins Breeding in the Falkland Islands

Abstract During the austral summer of 2000/01 a census of breeding King Penguins (Aptenodytes patagonicus), Gentoo Penguins (Pygoscelis papua) and Rockhopper Penguins (Eudyptes chrysocome) was carried out in the Falkland Islands. Results from this census were compared with those from the previous census of 1995/96. The number of King Penguin chicks decreased by 19% from 339 to 275, which is probably a reflection of variable breeding success, rather than a decline in breeding pairs. The number of Gentoo Penguins increased by 79%, from 64,426 breeding pairs in 1995/96 to 115,327 breeding pairs in 2000/01. The Rockhopper Penguin numbers appeared to be stable, with 286,964 breeding pairs in 2000/01 compared to 263,590 breeding pairs in 1995/96 (the difference being within the error margin).

Ontogeny of thermoregulatory mechanisms in king penguin chicks ( Aptenodytes patagonicus)

The rapid maturation of thermoregulatory mechanisms may be of critical importance for optimising chick growth and survival and parental energy investment under harsh climatic conditions. The ontogeny of thermoregulatory mechanisms was studied in growing king penguin chicks from hatching to the full emancipation observed at 1 month of age in the sub-Antarctic area (Crozet Archipelago). Newly hatched chicks showed small, but significant regulatory thermogenesis (21% rise in heat production assessed by indirect calorimetry), but rapidly became hypothermic. Within a few days, both resting (+32%) and peak (+52%) metabolic rates increased. The first week of life was characterised by a two-fold rise in thermogenic capacity in the cold, while thermal insulation was not improved. During the second and third weeks of age, thermal insulation markedly rose (two-fold drop in thermal conductance) in relation to down growth, while resting heat production was slightly reduced (−13%). Shivering (assessed by electromyography) was visible right after hatching, although its efficiency was limited. Thermogenic efficiency of shivering increased five-fold with age during the first weeks of life, but there was no sign of non-shivering thermogenesis. We conclude that thermal emancipation of king penguin chicks may be primarily determined by improvement of thermal insulation after thermogenic processes have become sufficiently matured. Both insulative and metabolic adaptations are required for the rapid ontogeny of thermoregulation and thermal emancipation in growing king penguin chicks.

Fatty acid evidence for the importance of myctophid fishes in the diet of king penguins, Aptenodytes patagonicus

We tested the usefulness of the fatty acid signature-method in investigating the diet of seabirds in conjunction with the conventional technique of stomach-content analysis. We compared the fatty acid composition of subcutaneous white adipose tissue (SWAT) of king penguin chicks (Aptenodytes patagonicus) during fattening periods to that of total lipids from their food. In both spring and autumn, the fatty acid composition of chick SWAT was identical to that of the dietary lipids. Because the diet of adult king penguins feeding for self-maintenance (i.e. not for their chicks) was essentially unknown, we subsequently analysed their SWAT fatty acid patterns after premolting and prebreeding foraging trips (during which they build up large energy reserves). The fatty acid composition of SWAT from adults was identical to that of chick adipose tissue and food. King penguin diet and SWAT were characterized by high levels of very long-chain mono-unsaturated fatty acids (20 to 24 carbon atoms, 16 to 23% by mass) and (n-3) poly-unsaturated fatty acids (19 to 27%); these consisted mainly of 20:1n-9 (5 to 8%) and 22:1n-11 (5 to 8%), and 22:6n-3 (10 to 13%) and 20:5n-3 (3 to 9%), respectively. Prey items identified from chick stomach contents indicated that the bulk of the food was oceanic myctophid fishes, mainly Electrona carlbergi, Krefftichthys anderssoni and Protomyctophum tenisoni. The fatty acid composition of four other species of myctophid fishes was similar to that of penguin diet and SWAT, but markedly different from that measured for a squid species and that reported for crustaceans. These findings indicate that adult king penguins prey on myctophid fish not only to feed their chicks but also for their own nutrition. The fatty acid signature-technique is therefore a reliable method to gain information on the food and feeding ecology of seabirds when more conventional techniques are of limited value. Such information is important to the understanding of trophic relationships between key species of the ecosystems, and also to provide insight into the nature of avian adaptations to the marine environment.

Pick out a penguin

King penguin chicks are fed by a parent who goes off to sea to forage. Colonies of these birds can be huge and noisy, meaning that there is potentially a problem for the chick in identifying the calls of the returning parent. Experiments involving playback of calls show that the chicks have remarkable abilities to pick out those of their parent against the background din.

Food requirements of breeding king penguins at Heard Island and potential overlap with commercial fisheries

The diet composition of king penguins (Aptenodytes patagonicus) at Heard Island (53°05′S; 73°30′E) was determined from stomach contents of 98 adults captured as they returned to the island throughout 1992. During the two growth seasons, the diet was dominated by the myctophid fish Krefftichthys anderssoni (94% by number, 48% by mass). The paralepidid fish Magnisudis prionosa contributed <1% by numbers but 17% by mass. Mackerel icefish (Champsocephalus gunnari) accounted for 17% by mass of chick diet in late winter, when chicks were malnourished and prone to starvation, although its annual contribution to the penguins' diet was only 3%. Squid was consumed only between April and August; Martialia hyadesi was the commonest squid taken, comprising 40–48% of the winter diet. The remainder of the diet consisted of the squid Moroteuthis ingens and fish other than K. anderssoni. The energy content of the diet mix fed to the chicks varied seasonally being highest during the growth seasons (7.83 ± 0.25 kJ g−1) and lowest in winter (6.58 ± 0.19 kJ g−1). From energetic experiments we estimated that an adult penguin consumed 300 kg of food each, of which its chick received 55 kg during the 1992 season. The chicks received large meals at the beginning of winter (1.2 ± 0.3 kg) and during the middle of the second growth season (1.2 ± 0.3 kg), and their smallest meals in late winter (0.4 ± 0.1 kg). The gross energy required to rear a king penguin chick was estimated to be 724 MJ. The potential impact of commercial fisheries on the breeding activities of king penguins is discussed.

Effects of food availability on fledging condition and post-fledging survival in king penguin chicks

Effects of summer food shortage on king penguin Aptenodytes patagonicus chicks were studied at South Georgia. Two cohorts were compared, fledging in the austral summers of 1992 (n = 32) and 1994 (n = 33) when availability of food was judged good and poor, respectively. The former cohort had a higher pre-fledging mean mass (12.78 kg vs ≤ 10.03 kg), fledged earlier (median 5 January vs 21 January), and a higher proportion was re-sighted within 2 years of fledging (28% vs 0%). Within 4 years, 47% of the former cohort had been re-sighted (i.e. post-fledge survival); in addition, one was observed at the Falkland Islands, and 22% had bred (i.e. recruitment) in their colony of origin. The re-sighted chicks of the 1992 cohort fledged earlier than those not re-sighted (median 24 December vs 10 January), but it remain unclear if they were heavier at fledging. All chicks in this study (n = 65) were marked with both transponders (subcutaneously implanted) and flipper bands (on one flipper), and no losses of any markings were found (controlled up to 4 years afterwards). Therefore, data on chick post-fledging survival and recruitment were not adjusted for losses of markings, as has been done in other studies.

Fish and squid in the diet of king penguin chicks, Aptenodytes patagonicus, during winter at sub-antarctic Crozet Islands

The diet of king penguins, Aptenodytes patagonicus, rearing chicks was studied during three consecutive austral winters (1990, 1991 and 1992) at Crozet Islands. The mean stomach content mass of the 47 samples was 503 g. Percentages of wet and reconstituted masses showed that both fishes (66 and 36%, respectively) and squid (34 and 64%) are important components of the winter diet. Juveniles of the demersal onychoteuthid squid Moroteuthis ingens form the bulk of the cephalopod diet, and this was the main prey by reconstituted mass (57%). Myctophid fish (lantern-fishes) accounted for most of the fish diet, constituting together 32% by mass. The three main species of myctophids eaten in summer by king penguins were either very rare in winter (Electrona carlsbergi) or accounted for a smaller proportion of the diet (Krefftichthys anderssoni = 1.5% by mass and Protomyctophum tenisoni = 4.6%). Five other myctophids, which are rarely consumed in summer, contributed 24% of the diet by mass in winter (Gymnoscopelus piabilis = 18.1%, Lampichthys procerus = 2.4%, G. nicholsi = 1.3%, and Metelectrona ventralis and Electrona subaspera = 1.0%). The greater diversity of prey in winter suggests a more opportunistic feeding behaviour at a time probably marked by a change in prey availability. Both the known ecology of the fish and squid prey and the barely digested state of some items suggest that in winter breeding adults forage in the outer shelf, upper slope and oceanic areas in the close vicinity of the Crozet Islands to feed their chicks. Finally, using king penguins as biological samplers, the present work provides novel data on the previously unstudied mesopelagic/epibenthic marine community in waters surrounding the Crozet Islands. Seventeen myctophid fish have been identified to species level. These include several poorly known species in the southern Indian Ocean. The occurrence of small, nearly intact, cephalopods in the diet of king penguins suggests that spawning grounds of four squid species may be located near the Crozet Archipelago.

Seasonal importance of oceanic myctophids in king penguin diet at Crozet Islands

Commercial fisheries of lanternfishes (Myctophidae: Osteichthyes) began a few years ago in the Atlantic sector of the Southern Ocean and exploitable stocks of myctophids probably also occur in the Indian and Pacific sectors. The Scientific Committe for the Conservation of Antarctic Marine Living Ressources (CCAMLR 1991) recommended to collect informations on potential competition between these fisheries and populations of predators. The king penguin (Aptenodytes patagonicus) is the most specialized subantarctic seabird preying upon mesopelagic rnyctophids (Adams and Klages 1987; Hindell 1988; Klages et al. 1990; Ridoux 1992), and more than 50% of the bird's world population is located in Crozet Archipelago (Jouventin et al. 1984). Since only limited king penguin diet data from Crozet Islands are available (Cherel and Ridoux 1992; Ridoux 1992), we investigated the food of king penguin chicks during their extended fledging period (about 11 months; Stonehouse 1960), to test for seasonal variation and the significance of their main prey in relation to the bird's breeding cycle.

Comparative fuel metabolism in Gentoo and King Penguins: adaptation to brief versus prolonged fasting

To compare fuel utilization in large birds adapted to brief or prolonged fasting, protein and lipid utilization were quantified in the Gentoo Penguin (Pygoscelis papua) and the King Penguin (Aptenodytes patagonica). The inshore feeder Gentoo Penguin fasts for only a few days in its colony, while King Penguin chicks starve for several months in the subantarctic winter and male King Penguins starve for 5–6 weeks at the beginning of their breeding cycle. After an initial decrease in both daily body mass loss and nitrogen excretion during the first days of food deprivation, these two parameters thereafter stabilized at low values. At that time, protein utilization accounted for 15% of total energy expenditure in Gentoo Penguins and only 6% in King Penguin chicks during winter, the remainder (85% and 94%, respectively) being provided by fat oxidation. Similar percentages in fuel metabolism as seen in chicks during winter were reached in fasting adult King Penguins and spring chicks. However, a seasonal adaptation occurs in fasting chicks because energy expenditure is lower during winter. As previously described in starved mammals, the effectiveness in protein sparing could be related to the initial adiposity of the birds: the larger the fat stores (about 9% and 30% in Gentoo Penguins and winter chicks of King Penguins, respectively), the longer the fast duration and the better the level of protein conservation.

Differential Growth of King Penguin Chicks in Relation to Date of Hatching

Differential Growth of King Penguin Chicks in Relation to Date of Hatching

Nonshivering thermogenesis in king penguin chicks. II. Effect of fasting.

The effect of fasting on the energy metabolism of skeletal muscle and liver was investigated in cold-acclimatized short-term fasting (STF) (3 wk) and naturally long-term fasting (LTF) (4-5 mo) king penguin chicks, both groups exhibiting nonshivering thermogenesis (NST). A comparison was made with nourished cold-acclimatized controls. In these chicks, no brown adipose tissue deposits could be found on electron-microscopic observations of fat deposits. Protein content and cytochrome oxidase (CO) activity of tissue homogenates were measured in liver and pectoralis and gastrocnemius muscles, as were protein content, CO activity, and respiration rates of mitochondria isolated from these organs. Fasting-induced protein loss affected the pectoralis more than the gastrocnemius muscle, thus preserving locomotor function. In STF chicks, specific mitochondrial protein content and specific tissue CO activity were preserved but total organ CO capacity was reduced by half in pectoralis and liver following the fall in organ mass. In LTF chicks, both specific and total CO activity were drastically reduced in muscles, whereas specific CO activity was preserved in liver. In these LTF chicks, muscle mitochondria showed an energized configuration associated with an increased area of inner membrane in gastrocnemius. A reduction of respiratory control ratio (RCR) was observed in subsarcolemmal muscle mitochondria of STF chicks, whereas intermyofibrillar and liver mitochondria kept high RCR values.(ABSTRACT TRUNCATED AT 250 WORDS)

Nonshivering thermogenesis in king penguin chicks. I. Role of skeletal muscle.

In cold-acclimatized (CA) king penguin chicks exhibiting nonshivering thermogenesis (NST), protein content and cytochrome oxidase (CO) activity of tissue homogenates were measured together with protein content, CO, and respiration rates of isolated mitochondria from skeletal muscle (gastrocnemius and pectoralis) and liver. The comparison was made with chicks reared at thermoneutrality (TN) for at least 3 wk. In CA chicks showing a NST despite the lack of brown adipose tissue, an increase in thermogenic capacity was observed in skeletal muscle in which the oxidative capacity rose (+28% and +50% in gastrocnemius and pectoralis muscles, respectively), whereas no change occurred in the liver. Oxidative capacity of skeletal muscle increased together with the development of mitochondrial inner membrane plus cristae in muscles of CA chicks contrary to their TN littermates (+30 to +50%). Subsarcolemmal mitochondria of CA chicks had a higher protein content (+65% in gastrocnemius muscle) and higher oxidative capacities than in controls. The lower respiratory control ratio of these mitochondria might result from a low ADP phosphorylation rate. No change occurred in the intermyofibrillar fraction nor in liver mitochondria. These findings together with earlier results obtained in cold-acclimated ducklings indicate the marked and suited adaptation of skeletal muscle and in particular of subsarcolemmal mitochondria allowing them to play a role in NST.

The impact of avian predator‐scavengers on King Penguin Aptenodytes patagonicus chicks at Marion Island

While ashore King Penguins Aptenodytes patagonicus are fed upon by a guild of five predator‐scavenger seabirds. During the winter (April‐October) male Southern Giant Petrels Macronectes giganteus killed an estimated 6430 (11.2%) of Marion Island's King Penguin chicks, although most birds only scavenged in the colonies. The rate of predation varied, with peaks in April‐May and in September. The proportion of successful attacks was 22.7%. There was a strong correlation between colony size and the rate of accumulation of chick corpses. Kelp Gulls Larus dominicanus and Lesser Sheathbills Chionis minor also scavenged penguin corpses but Northern Giant Petrels M. halli and female Southern Giant Petrels rarely entered the colonies. During the summer predation was mainly by Sub‐Antarctic Skuas Catharacta lonnbergi which took eggs and small chicks.