Foraging behaviour of Magellanic Penguins during the early chick‐rearing period at Isla de los Estados,Argentina

Studies of the at‐sea distribution and trophic ecology of penguins are essential to understand their role in the broader marine food web. Magellanic Penguins Spheniscus magellanicus have a wide distribution and their foraging behaviour varies across breeding sites and between sexes, among others. In this study, we characterized the at‐sea areas, the diving strategies and the relative trophic level of Magellanic Penguins breeding at Isla de los Estados, Argentina, during the early chick‐rearing period. In addition, we quantified the interannual, sexual and individual variability in those parameters during three breeding seasons (2011–2013) using devices recording position and dive depth, and obtained blood samples for stable isotope analysis. During the early chick‐rearing period, Magellanic Penguins showed small differences between the sexes in their foraging behaviour and large overlap in the at‐sea areas used, suggesting no intraspecific variation between sexes. Although there was interannual variability in the foraging behaviour and the trophic level of the penguins, most of the studied nests managed successfully to raise both chicks during the first stage of the breeding cycle (guard stage). The foraging ecology of Magellanic Penguins from this colony was comparable with results of past studies at other breeding colonies. This study contributes to the identification of important at‐sea areas for Magellanic Penguins at the southern edge of their distribution and also to the identification of possible threats in the study area such as interaction with fisheries.     

Winter distribution and behaviour of gentoo penguins<Emphasis Type="Italic"> Pygoscelis papua</Emphasis> at South Georgia

Knowledge of the spatial and temporal dynamics of foraging penguins is important to our understanding of the Southern Ocean marine ecosystem. We use satellite tracking to provide the first data on the distribution and behaviour of gentoo penguins (Pygoscelis papua) during the winter at South Georgia. Five penguins tracked from Bird Island remained close inshore, and although they did not return to the initial tagging site, they did appear to return to land each evening. They made diurnal trips to sea of similar distance from land as those during the breeding season, even though the constraints of chick rearing were absent. Despite potential greater flexibility in their responses to variations in prey availability in winter, the penguins still returned to land each night. This may reflect benefits from conserving energy by resting on land, possibly facilitating information exchange and avoiding predation. The distribution and behaviour of gentoo penguins during the winter enables efficient exploitation of a dynamic, patchy prey resource and may ultimately determine the timing of return to the colony, and onset of breeding in the following season.     

Adjustment of pre‐moult foraging strategies in Macaroni Penguins Eudyptes chrysolophus according to locality,sex and breeding status

The annual moult creates the highest physiological stress during a penguin's breeding‐cycle and is preceded by a period of hyperphagia at sea. Although crucial to individual survival, foraging strategies before moult have been little investigated in keystone marine consumers in the Southern Ocean. The Macaroni Penguin Eudyptes chrysolophus demonstrates how individuals may adjust their foraging strategies during this period in line with constraints such as potential intraspecific competition between localities, foraging ability between dimorphic sexes and timing at sea between breeding and non‐breeding population components. We recorded pre‐moult behaviour at sea for 22 Macaroni Penguins from Crozet and Kerguelen Islands (southern Indian Ocean) during 2009 and 2011, using light‐based geolocation and stable isotope analysis. Penguins were distributed in population‐specific oceanic areas with similar surface temperatures (3.5 °C) south of the archipelagos, where they foraged at comparable trophic levels based on stable isotopes of their blood. Bayesian ‘broken stick’ modelling with concurrent analysis of seawater temperature records from the animal‐borne devices showed that within each population, females remained 6 days longer than males in the colder waters before heading back towards their colonies. Finally, 17 other non‐breeding individuals that moulted earlier had a higher mean blood δ¹⁵N value than did post‐breeding birds, meaning that early moulters probably fed more on fish than did late moulters. Our findings of such adjustments in foraging strategies developed across locality, sex and breeding status help understanding of the species' contrasted pre‐moult biology across its range and its ecology in the non‐breeding period.     

Human-induced behaviour in Adélie penguins Pygoscelis adeliae

Summary Adélie penguins Pygoscelis adeliae appear to be little perturbed by man. We examined the incidence of nest desertion and duration of foraging trip in Adélie penguins when manipulated and fitted with devices of differing sizes. Birds with ca. 1 cm clipped from their tail feathers stayed at sea 50% longer than unmarked controls. The length of foraging trip and incidence of nest desertion increased with increasing device volume. Penguins fitted with devices did not reduce foraging trip length to that of unpackaged birds for at least 19 days. The susceptibility of Adélie penguins to disturbance should be carefully considered when activity patterns are being studied.     

Evolutionary and ecological aspects of some Antarctic and sub-Antarctic penguin distributions

Penguins probably originated in the core of Gondwanaland when South America, Africa, and Antarctica were just beginning to separate. As the continents drifted apart, the division filled with what became the southern ocean. One of the remaining land masses moved south and was caught at the pole by the Earth's rotation. It became incrusted with ice and is now known as East Antarctica. Linking it to South America was a series of submerged mountain ranges that formed a necklace of islands. The northern portion of the necklace, called the Scotia Arc, is now the "fertile crescent" of the Southern Ocean. The greatest numbers and biomass of penguins are found here as well as that of krill, the primary prey species of most penguins, and many other marine predators. Today penguins are found throughout the sub-Antarctic islands and around the entire Antarctic continent. Using satellite transmitters and time-depth recorders, while taking advantage of the parental dedication of breeding birds, numerous investigators have described foraging habits of several species of penguins. The information obtained is labor intensive and costly so that studies are restricted to certain species, areas and seasons. Here I review the patterns evident among six of the most abundant and completely studied of the penguins. The variation in behavior is considerable from those species that seldom dive deeper than 20 m in search of prey to those that will dive to depths >500 m to catch mesopelagic fish and squid. Foraging trips from breeding colonies vary among species and with the season. Often the birds travel no more than 30 km and at other times the trips may exceed 600 km. Sub-Antarctic species often reach more productive waters near or within the Antarctic Polar Front zone, where the mixing of Antarctic and sub-Antarctic waters provide rich resources for their prey. Antarctic species usually remain close to shore, along the continental slope, or near the sea ice edge. Less is known about penguins during the pelagic phase between breeding cycles. What we do know is surprising in regard to their dispersal, which ranges from hundreds to thousands of kilometers from the breeding colonies.     

Return to Robben Island of African Penguins that were rehabilitated,relocated or reared in captivity following the Treasure oil spill of 2000

Following an oil spill from the Treasure off the coast of South Africa in June 2000, about 19 000 oiled African Penguins Spheniscus demersus, including 14 825 from Robben Island, were caught for rehabilitation and subsequent release. A further 19 500 penguins that were not oiled — mostly birds in adult plumage, including 7 000 from Robben Island — were relocated some 700km to the east, to prevent them becoming oiled. Additionally, 3 350 orphaned chicks, including 2 643 from Robben Island — were collected for rearing in captivity and release to the wild. Some four years later — by the end of December 2004 — 70% of rehabilitated adults, 40% of relocated birds and 34% of captive-reared chicks had been seen back at Robben Island. Another 7% of birds relocated from Robben Island had been sighted at other localities. Rates of resighting rehabilitated birds were similar at Robben and Dassen Islands, but a greater proportion of relocated birds was seen at Dassen Island, where birds collected for relocation were mostly from breeding areas. The lower proportion of relocated birds seen at Robben Island is thought to result from this intervention causing some pre-breeding birds to move to other colonies. All three conservation interventions are considered to have been successful, but it is premature to assess their relative contributions to the conservation of the species. Three relocated birds tracked by satellite took 15–21 days to return to their home colonies. This rapid return may have resulted from breeding attempts being interrupted. After remaining at their home islands for 4–5 days, two of the tracked birds then left these islands for 19–36 days. We surmise that, after they had searched unsuccessfully for their mates, they abandoned breeding for the year 2000.     

Post-Fledging Dispersal of King Penguins (Aptenodytes patagonicus) from Two Breeding Sites in the South Atlantic

Most studies concerning the foraging ecology of marine vertebrates are limited to breeding adults, although other life history stages might comprise half the total population. For penguins, little is known about juvenile dispersal, a period when individuals may be susceptible to increased mortality given their naïve foraging behaviour. Therefore, we used satellite telemetry to study king penguin fledglings (n = 18) from two sites in the Southwest Atlantic in December 2007. The two sites differed with respect to climate and proximity to the Antarctic Polar Front (APF), a key oceanographic feature generally thought to be important for king penguin foraging success. Accordingly, birds from both sites foraged predominantly in the vicinity of the APF. Eight king penguins were tracked for periods greater than 120 days; seven of these (three from the Falkland Islands and four from South Georgia) migrated into the Pacific. Only one bird from the Falkland Islands moved into the Indian Ocean, visiting the northern limit of the winter pack-ice. Three others from the Falkland Islands migrated to the eastern coast of Tierra del Fuego before travelling south. Derived tracking parameters describing their migratory behaviour showed no significant differences between sites. Nevertheless, generalized linear habitat modelling revealed that juveniles from the Falkland Islands spent more time in comparatively shallow waters with low sea surface temperature, sea surface height and chlorophyll variability. Birds from South Georgia spent more time in deeper waters with low sea surface temperature and sea surface height, but high concentrations of chlorophyll. Our results indicate that inexperienced king penguins, irrespective of the location of their natal site in relation to the position of the APF, develop their foraging skills progressively over time, including specific adaptations to the environment around their prospective breeding site.     

Diving behaviour and energetics in breeding little penguins (Eudyptula minor)

We present data on the diving behaviour and the energetics of breeding little penguins in Tasmania, Australia. Using an 18 m long still water canal in conjunction with respirometry, we determined the energy requirements while diving. Using electronic devices measuring dive depth or swimming speed, we investigated the foraging behaviour at sea. Cost of Transport was calculated to be minimal at the speed the birds prefer at sea (1.8 m/s) and averaged 11.1 J/kg/m (power requirements at that speed: 20.0 W/kg). Metabolic rate of little penguins resting in water was found to be 8.5 W/kg. The externally-attached devices had no significant influence on the energy expenditure.
Foraging trips can be divided into four distinct phases with different diving behaviours. A mean of 500 dives was executed per foraging trip lasting about 18 hours with 60% of this time being spent swimming. The total distance travelled averaged 73 km per day, although foraging range was about 12km. Mean swimming speed of little penguins at sea was 1.8 m/s, maximum swimming speed was 3.3 m/s. More than 50% of all dives had maxima not exceeding 2 m. Maximum depth reached was 27 m. Mean dive duration was 21 s. There were inter-sex differences in diving behaviour as well as changes in foraging behaviour over the breeding period. Aerobic dive limits (ADL) in the wild were estimated between 42 and 50 s. From the swim canal experiments we derived an ADL of 44 s. Total oxygen stores were calculated to be 45 ml O₂/kg. Only 2% of all dives exceeded the ADL. FMRs at sea were calculated to be between 1280 and 1500 kJ/kg/d according to chick size. The yearly food requirements of a breeding little penguin amount to 114 kg.     

Satellite tracking of the winter migration of Magellanic Penguins Spheniscus magellanicus breeding in the Falkland Islands

Magellanic penguin populations in the Falkland Islands may have decreased over the past decade. The post-breeding migration may be the period in which the birds are most vulnerable. To investigate this we equipped ten Magellanic Penguins after their moult at Seal Bay (51̀38'S, 58̀03'W), East Falkland, with satellite transmitters. The movements of the penguins were tracked for between 15 and 99 days until transmission ceased. All birds initially migrated to the northwest. However, four birds entered Argentinean coastal waters, then headed northeast following the coastline, The other penguins remained offshore, but also changed to a northeasterly course. Two birds migrated beyond 36̀S with a maximum distance to the colony of more than 1800 km, while the minimum distance travelled was up to 2700 km. Initially, the birds migrated quickly but their speed was reduced and became more variable as time progressed. A high concentration of positional fixes, associated with low travelling speeds, indicated at least four different areas where birds were assumed to forage efficiently. The relevance of these areas is discussed with respect to the diet of Magellanic Penguins and possible interactions with human activities.     

Effects of attached data‐loggers on the activity budgets of captive Humboldt penguins

Although they can provide valuable information on at‐sea ecology, data‐loggers may adversely affect energetics, diving performance, and breeding success of equipped birds. With the aim of determining the effects of leg‐attached data‐loggers on the activity budgets of Humboldt penguins (Spheniscus humboldti) while on land, we equipped birds kept at the Landau Zoo, Landau, Germany, with such devices. We followed them during sample periods and recorded the occurrence and length of behaviors. Birds quickly habituated to the devices within 1 day of deployment, and mean rates of device‐pecking were low (0.7–1.7 pecks/hr), with device‐induced behaviors accounting for <1% of the mean daily activity budget. The method of device attachment appears behaviorally less stressful than the traditional tape‐based system in which devices are normally attached to the penguin's back. By facilitating the testing of newly developed data‐loggers on captive birds, or the development of methods for device attachment, zoos and aquaria may strengthen their role in animal conservation by helping research on free‐ranging animals. Zoo Biol 21:365–373, 2002. © 2002 Wiley‐Liss, Inc.     

Metal concentrations in the liver and kidney of aquatic mammals and penguins

We determined the hepatic and renal concentrations of Cd, Pb, Zn, Cu, and Fe in (1) marine mammals (three bottle-nosed dolphins, six California sea lions, and one sea otter), (2) freshwater and brackish-water mammals (one Oriental short-clawed otter and four European river otters), and (3) sea birds (three rock-hopper penguins, two king penguins, three Humboldt penguins, four Macaroni penguins, and four Magellanic penguins), all of which were kept in a zoo and an aquarium in Japan. We investigated the species-specificity of Cd accumulation in these aquatic animals. We also presented the basic data on metal concentrations. The concentrations of Cd in liver and kidney tended to be higher in marine mammals than in freshwater mammals. Many penguins, sea birds, showed high Cd concentrations. These results suggest that the habits of these animal species may be involved in accumulation of Cd. Pb concentrations were below the detection limit or low in both liver and kidney [not detected (ND)=0.132 μg/g and ND=0.183 μg/g, respectively]. The hepatic concentrations of Zn and Cu were high in young animals. In penguins, a positive correlation was found between the Zn and Cd concentrations in the liver and kidney and between the Cu and Cd concentrations in the liver. Individual variation was large in Fe concentration (48–3746 μg/g in the liver and 51–980 μg/g in the kidney).     

Odor-based recognition of familiar and related conspecifics: a first test conducted on captive Humboldt penguins (Spheniscus humboldti)

Studies of kin recognition in birds have largely focused on parent-offspring recognition using auditory or visual discrimination. Recent studies indicate that birds use odors during social and familial interactions and possibly for mate choice, suggesting olfactory cues may mediate kin recognition as well. Here, we show that Humboldt penguins (Spheniscus humboldti), a natally philopatric species with lifetime monogamy, discriminate between familiar and unfamiliar non-kin odors (using prior association) and between unfamiliar kin and non-kin odors (using phenotype matching). Penguins preferred familiar non-kin odors, which may be associated with the recognition of nest mates and colony mates and with locating burrows at night after foraging. In tests of kin recognition, penguins preferred unfamiliar non-kin odors. Penguins may have perceived non-kin odors as novel because they did not match the birds' recognition templates. Phenotype matching is likely the primary mechanism for kin recognition within the colony to avoid inbreeding. To our knowledge this is the first study to provide evidence of odor-based kin discrimination in a bird.     

Foraging movements of emperor penguins at Pointe Géologie, Antarctica

The foraging distributions of 20 breeding emperor penguins were investigated at Pointe Géologie, Terre Adélie, Antarctica by using satellite telemetry in 2005 and 2006 during early and late winter, as well as during late spring and summer, corresponding to incubation, early chick-brooding, late chick-rearing and the adult pre-moult period, respectively. Dive depth records of three post-egg-laying females, two post-incubating males and four late chick-rearing adults were examined, as well as the horizontal space use by these birds. Foraging ranges of chick-provisioning penguins extended over the Antarctic shelf and were constricted by winter pack-ice. During spring ice break-up, the foraging ranges rarely exceeded the shelf slope, although seawater access was apparently almost unlimited. Winter females appeared constrained in their access to open water but used fissures in the sea ice and expanded their prey search effort by expanding the horizontal search component underwater. Birds in spring however, showed higher area-restricted-search than did birds in winter. Despite different seasonal foraging strategies, chick-rearing penguins exploited similar areas as indicated by both a high ‘Area-Restricted-Search Index’ and high ‘Catch Per Unit Effort’. During pre-moult trips, emperor penguins ranged much farther offshore than breeding birds, which argues for particularly profitable oceanic feeding areas which can be exploited when the time constraints imposed by having to return to a central place to provision the chick no longer apply.     

Long-term fasting and re-feeding in penguins

Spontaneous fasting during reproduction (sometimes with a full stomach) and moult is a major characteristic of the annual cycle of penguins. Long-term fasting (up to four months in male emperor penguins) is anticipated by the accumulation of fat (incubation fast) and of fat and protein (moult fast). During most of the incubation fast, birds rely almost entirely on lipids as an energy source, body proteins being spared. However, below a critical (but non-total) fat store depletion, marked behavioural, metabolic, and endocrine changes occur. Spontaneous locomotor activity increases and the egg is transitorily left unincubated for increasingly long periods, until its definitive abandon and the bird departs to re-feed at sea. These changes are thought to be activated by an endogenous re-feeding signal triggered before lethal energy depletion. An increase in body protein catabolism in the face of a reduction in lipid availability and utilisation, and an increase in circulating corticosterone vs. a decrease in plasma prolactin, are likely to be major metabolic and hormonal components of this signal. The survival and rapid restoration of energy stores in birds having departed to re-feed at a stage of near total lipid depletion demonstrates the effectiveness of the re-feeding signal. Penguins, and possibly other seabirds, are therefore appropriate animal models for understanding the long-term interactions between body energy reserves and fasting, breeding and feeding physiology and behaviour.     

Adélie penguin parental activities and reproduction: effects of device size and timing of its attachment during chick rearing period

Summary Effects of device attachment on parental activities and body mass change in instrumented birds and their mates, and on chick growth and survival, were studied in Adélie Penguins Pygoscelis adeliae in Lützow-Holm Bay, Antarclica. Penguins on which small devices were fitted with rubber band harnesses exhibited increased foraging trip duration, and decreased body mass, food delivery rate, chick growth and chick survival. Their mates did not increase food delivery rate. Those on which small or large devices were fitted with epoxy glue did not change foraging trip duration, body mass, or chick survival. However, large devices decreased chick growth. These effects were more obvious; among penguins fitted with devices later in the chick rearing period, and suggest that: 1) parents fitted with devices give a priority to maintenance of their own energy reserve over guarding and food delivery for chicks; and, 2) parents' decreasing energy reserves later in the breeding season might intensify the effects of devices.     

Restoration of body mass in King Penguins after egg abandonment at a critical energy depletion stage: early vs late breeders

In fasting‐incubating seabirds, it has been proposed that egg abandonment and refeeding should be induced when a low body mass (BM) threshold is attained, thus ensuring adult survival at the expense of immediate breeding. In the context of life‐history trade‐offs in long‐lived birds, we have tested this hypothesis by comparing short‐term survival and restoration of BM in King Penguins Aptenodytes patagonicus that abandoned their egg to those that were relieved normally by their mate at the end of the first incubation shift. Since King Penguins have an extended laying period, the possible influence of seasonal factors was also examined by comparing early and late breeders. Forty incubating males were experimentally forced to fast until egg abandonment by preventing relief by the female. At egg abandonment of both early and late breeding males, BM was below the BM threshold, fasting duration was eight days (about 30%) longer than for relieved birds, and plasma uric acid level was elevated (signature of increased body protein catabolism, phase III of fasting). All abandoning birds survived and came back from sea at a BM similar to that of relieved penguins. The duration of the foraging trip of abandoning early breeders was the same as that of relieved birds, and some abandoning birds engaged in a new breeding attempt. Abandoning late breeders, however, made foraging trips twice as long as those of relieved males. This difference can be explained by time constraints rather than nutritional constraints, abandoning early breeders having enough time left in the breeding season to engage in a new breeding attempt in contrast to abandoning late breeders. These observations lend support to the suggestion that not only BM but also an internal clock intervene in the decision to engage in breeding or not. By preventing a lethal energy depletion ashore and by acting at a fasting stage where the capacity to restore BM at sea is unaffected, abandonment at a low body condition threshold plays a major role in the trade‐off between adult penguin survival and reproduction.     

Optimal conditions for breeding of captive humboldt penguins (Spheniscus humboldti): A survey of British zoos

We surveyed 16 British zoos and bird gardens to assess the optimal conditions for breeding of captive Humboldt penguins (Spheniscus humboldti). We obtained information on population, enclosure, and husbandry characteristics and related these variables to three measures of per capita breeding success, namely, per capita egg productivity, chick productivity, and hatching success (measured as the proportion of eggs laid that hatched). All three fitness measures increased with an increasing number of breeding pairs and total population size but were not related to population density. Once the effect of number of breeding pairs was removed statistically, chick productivity was found to be highest when nesting boxes were lined with sand and gravel instead of alternative substrata such as twigs or vegetation. Hatching success increased with increasing pool size and was highest in enclosures with concrete floors. Adult mortality in zoos was generally low and appeared related to the use of chlorine in freshwater pools and to the presence of other penguin species in Humboldt penguin displays. Several enclosure and husbandry parameters were not variable enough to assess their impact on reproduction of captive Humboldt penguins. Recommendations for optimising conditions for captive breeding of Humboldt penguins include keeping as large a population as possible in a concrete enclosure with a large pool area, while providing sand and gravel as nesting material. Bird density may be important but we did not detect detrimental effects on breeding for densities up to 0.25 birds m^–2. Adult mortality can be minimised by exhibiting Humboldt penguins in single‐species display and avoiding chlorination of pool water. An experimental approach is recommended to confirm the results of this correlational study. Zoo Biol 20:545–555, 2001. © 2002 Wiley‐Liss, Inc.     

Effects of long-term implanted data loggers on macaroni penguins Eudyptes chrysolophus

We tested the hypothesis that implanted data loggers have no effect on the survival, breeding success and behaviour of macaroni penguins Eudyptes chrysolophus . Seventy penguins were implanted with heart rate data loggers (DLs) for periods of up to 15 months. When compared to control groups, implanted penguins showed no significant difference in over-wintering survival rates, arrival date and mass at the beginning of the breeding season. Later in the breeding season, implanted penguins showed no significant difference in the duration of their incubation foraging trip, breeding success, fledging mass of their chicks, date of arrival to moult and mass at the beginning of the moult fast. We conclude that implanted devices had no effects on the behaviour, breeding success and survival of this species. We contrast these results to those from studies using externally attached devices, which commonly affect the behaviour of penguins. We suggest that implanted devices should be considered as an alternative to externally attached devices in order to obtain the most accurate representation of the free-ranging behaviour, ecology and physiology of penguins.     

Short-term responses of king penguins Aptenodytes patagonicus to helicopter disturbance at South Georgia

The short-term behavioural effects of helicopter overflights on breeding king penguins Aptenodytes patagonicus at South Georgia were examined. Seventeen helicopter overflights were made at altitudes between 230 and 1,768 m (750–5,800 ft) above ground level. Noise from the aircraft engines and helicopter blades increased sound levels in the colony from a background level of 65–69 dB(A) to a maximum mean peak level of 80 dB(A) during overflights. Penguin behaviour changed significantly during all overflights at all altitudes compared to the pre- and post-flight periods. Pre-overflight behaviour resumed within 15 min of the aircraft passing overhead and no chicks or eggs were observed to be taken by predators during overflights. Non-incubating birds showed an increased response with reduced overflight altitude, but this was not observed in incubating birds. Variability in overflight noise levels did not affect significantly the behaviour of incubating or non-incubating birds. Penguins exhibited a reduced response to overflights as the study progressed (despite later flights generally being flown at lower altitudes) suggesting some degree of habituation to aircraft. To minimise disturbance to king penguins we recommend a precautionary approach such that overflights are undertaken at the maximum altitude that is operationally practical, or preferably are avoided altogether.