Southern rockhopper penguin Eudyptes chrysocome chrysocome foraging at Possession Island

The foraging ecology of rockhopper penguins was studied at Possession Island, southern Indian Ocean, by counting the number of birds departing from and arriving at colonies over the course of the day and by equipping three birds with time/depth loggers, one of which was recovered having recorded a total of 12 days foraging activity. Both the counts and the results from the diving behaviour showed that the birds foraged exclusively diurnally. Maximum dive depth was 66 m although most time was spent between 10 and 25 m, depths that did not accord with the published distribution of their principal prey as detected by nets and acoustics. Received: 29 March 1996/Accepted: 10 June 1996     

The primary structure of the hemoglobin of the Rock-Hopper penguin (Eudyptes crestatus, Sphenisciformes)

The blood of the Rock-Hopper Penguin contains only one hemoglobin component, corresponding to the Hb A of other birds. The primary structures of the alpha- and beta-chains are presented. The chains were separated by high-performance liquid chromatography and cleaved either enzymatically (alpha) or both enzymatically and chemically (beta). Both the native chains and their peptides were sequenced using liquid and gas phase sequenators. The peptides were aligned using their homology to the sequence of human hemoglobin and other bird hemoglobins. As compared to human hemoglobin, 44 amino-acid replacements are found in the alpha-chains (68% homology) and 47 in the beta-chains (67.8% homology). These exchanges involve seven alpha 1/beta 1 and one alpha 1/beta 2 contact in the alpha-chains, whereas in the beta-chains eight alpha 1/beta 1, one alpha 1/beta 2 and one hem contact are substituted. The influence of these replacements on the structure-function relationships in hemoglobin, as well as their importance for the diving ability of penguins, are discussed.     

The diet of the Southern rockhopper penguin Eudyptes chrysocome chrysocome at Beauchene Island, Falkland Islands

The diet of the Southern rockhopper penguin at Beauchene Island, Falkland Islands, was studied in the early chick-rearing period by quantitative analysis of adult stomach contents. Juvenile squid (Teuthowenia sp.) comprised on average 21% by numbers (c. 1000 per sample) and 53% by weight; crustaceans contributed 79% by numbers (c. 4000 per sample) but only 45% by weight, and fish 2% by weight. Of the crustaceans only the euphausids Euphausia lucens (66% by numbers), E. vallentini (19%) and Thysanoessa gregaria (15%) were present in significant quantities, and all are swarming species characteristic of the Patagonian shelf epipelagic zooplankton. Comparison is made with the limited dietary data available from other studies, and rockhopper penguins are suggested typically to feed opportunistically on swarming or shoaling zooplankton (particularly euphausids and young squid) and small fish. Whereas the average weight of the stomach contents was 220 g, the biomass of the individuals originally ingested was estimated to total 800 g; the c. 3000 kj this represents is consistent with the likely energy requirements of adults making daily foraging trips to rear small chicks.     

A stable isotopic investigation into the causes of decline in a sub-Antarctic predator, the rockhopper penguin Eudyptes chrysocome

The rockhopper penguin (Eudyptes chrysocome) is a conspicuous apex marine predator that has experienced marked population declines throughout most of its circumpolar breeding distribution. The cause(s) for the declines remain elusive, but the relatively large spatio‐temporal scale over which population decreases have occurred implies that ecosystem‐scale, at‐sea factors are likely to be involved. We employ stable isotope analyses of carbon (¹³C/¹²C, expressed as δ¹³C) and nitrogen (¹⁵N/¹⁴N, δ¹⁵N) in time‐series of rockhopper penguin feather samples, dating back to 1861, in order to reconstruct the species' ecological history. Specifically, we examine whether rockhopper penguin population decline has been associated with a shift towards lower primary productivity in the ecosystem in which they feed, or with a shift to a diet of lower trophic status and lower quality, and we use long‐term temperature records to evaluate whether shifts in isotope ratios are associated with annual variations in sea surface temperature. Having controlled temporally for the Suess Effect and for increases in CO₂ concentrations in seawater, we found that overall, δ¹³C signatures decreased significantly over time in rockhopper penguins from seven breeding sites, supporting the hypothesis that decreases in primary productivity, and hence, carrying capacity, for which δ¹³C signature is a proxy, have been associated with the decline of penguin populations. There was some evidence of a long‐term decline in δ¹⁵N at some sites, and strong evidence that δ¹⁵N signatures were negatively related to sea surface temperatures across sites, indicative of a shift in diet to prey of lower trophic status over time and in warm years. However, a site‐by‐site analysis revealed divergent isotopic trends among sites: five of seven sites exhibited significant temporal or temperature‐related trends in isotope signatures. This study highlights the utility of stable isotope analyses when applied over relatively long timescales to apex predators.     

Inter-annual variation in the diet of female southern rockhopper penguin (Eudyptes chrysocome chrysocome) at Tierra del Fuego

Inter-annual variation in the diet of female southern rockhopper penguins (Eudyptes chrysocome chrysocome) at Staten Island was studied during the early chick-rearing period to investigate the components of the diet and highlight some points of the possible food web in the study area. Gregarious crustaceans, small juveniles of squid and octopus, fish larvae and juvenile fish dominated the diet. There was a high degree of variability in the relative contribution of the different prey taxa during the three seasons studied. Overall, crustaceans were by far the most abundant in terms of number. Cephalopods contributed less to numbers, while fish was the least represented of the prey item in 2 years. Inter-annual variation in the proportion of prey items consumed was apparent only for some prey species: Thysanoessa gregaria, Gonatus antarcticus, Themisto gaudichaudii, Harpagifer bispinis and Salilota australis. These data suggest variability in the prey resources at sea during the study period and a subsequent opportunism of this penguin species to exploit what is differentially available. In terms of the food web in the area, we suggest an apparent relationship in the availability between T. gaudichaudii and G. antarcticus, and between T. gaudichaudii and H bispinnis. These relationships emphasise the importance of understanding food web interactions, especially those involving multiple trophic levels, when determining the role of upper-trophic level predators in marine systems.     

Genetic isolation and divergence in sexual traits: evidence for the northern rockhopper penguin Eudyptes moseleyi being a sibling species

The taxonomic status of populations of rockhopper penguins (Eudyptes chrysocome) is still enigmatic. Northern populations differ from southern ones in breeding phenology, song characteristics and head ornaments used as mating signals. We conducted a molecular analysis using mitochondrial DNA sequencing to test if there is a gene flow barrier between northern (subtropical) populations and southern (subantarctic) populations in relation to the Subtropical Convergence, a major ecological boundary for marine organisms. Sequences of the control region and the ND2 gene were analysed in rockhopper penguins and in the macaroni penguin (Eudyptes chrysolophus), a closely related species. Genetic distances and phylogenetic analyses showed a clear split into three clades, two rockhopper clades and the macaroni penguin. Moreover, Theta(ST) and gene flow estimates also suggested genetic structuring within the northern rockhoppers. Our results add further support to the notion that the two rockhopper penguin taxa, often considered as two subspecies, can be recognized as two species E. chrysocome and E. moseleyi. The divergence in mating signals found between these two taxa seems to have occurred recently and relatively rapidly. Thus, the behavioural changes may have been enough to isolate these taxa without the need for morphological differentiation. The findings have important conservational implications, since E. moseleyi is far less abundant than E. chrysocome, but more populations may warrant an uplisting to endangered status if full species status should be recognized for more subpopulations.     

Genetic evidence for three species of rockhopper penguins, Eudyptes chrysocome

The taxonomy of rockhopper penguins, Eudyptes chrysocome (Forster 1781), is contentious. Some authorities recognise three subspecies based on morphological differences and geographical separation of breeding populations while others suggest that morphological differences support classifying rockhopper penguins as two distinct species. The taxonomy of rockhopper penguins is of more than academic interest as breeding colonies worldwide have declined markedly in size since the 1930s and rockhopper penguins are currently listed as vulnerable by the IUCN. We compared the genetic distances between three mitochondrial gene regions from the three putative rockhopper penguin subspecies with the distances between various penguin sister species to clarify the taxonomy and systematics of rockhopper penguins. Genetic distances between the rockhopper penguin taxa, relative to other closely related penguin species, support reclassifying the three rockhopper penguin subspecies as species. Reclassification of rockhopper penguins as three species could result in their conservation status being upgraded from vulnerable to endangered.     

A northern rockhopper penguin unveils dispersion pathways in the Southern Ocean

We report the first record of a northern rockhopper penguin Eudyptes moseleyi on the Kerguelen Islands, Southern Indian Ocean. The penguin must have crossed the subtropical convergence to reach the island. This species was recently proved to be genetically different from the subantarctic eastern rockhopper penguin E. filholi that normally breeds on the Kerguelen Islands. The sequencing of a part of the mitochondrial control region shows that this bird may come from the population of Gough Island, 6,000 km away, in the south Atlantic Ocean. This finding confirms that the genetic isolation between these two penguin species is complete, although some individuals may sporadically disperse between the breeding sites. This first direct observation of a disperser from the Atlantic to the Indian Ocean also adds further support to a biogeographic dispersion pattern already suggested by phylogeographic patterns in other species from the Southern Ocean.     

Spatial and temporal variation in the provisioning behaviour of female rockhopper penguins Eudyptes chrysocome filholi

As seabirds are central place foragers during breeding, their provisioning behaviour and their ability to face variable energy demand from the chicks is expected to vary with environmental conditions. The provisioning behaviour of female rockhopper penguins Eudyptes chrysocome filholi was recorded over the chick‐rearing period at Kerguelen (KER) and Crozet (CRO) archipelagoes (two very distinct marine environments), using time‐depth recorders, or VHF transmitters coupled with an automatic recording station. No influences of the method have been found on the average foraging trip durations. Some previously undescribed short and multiple trips within a day were recorded using the automatic recording system. These multiple trips (6.8 h) were mostly performed with <5 days old chicks, a period during which feeding rates were the highest (1.1 meals per day), at both sites. During the brooding period, both KER and CRO females mainly performed daily trips of increasing duration (2 h longer at CRO) and at decreasing frequency. During the crèche compared to the brooding period, females from KER performed slightly fewer daily trips (0.6 per day) and more (<3 days) overnight trips, while females from CRO performed very few daily trips (0.1 per day) and more overnight trips, some of them being long trips lasting 5 to 29 days, mostly initiated during the transition between the brooding and the crèche periods. The result fit the hypothesis that long trips permit females to restore and/or maintain their body condition at more distant foraging places. It seemed that chick developement during the brooding period and environmental factors during the crèche period conditioned trip duration of females. Due to more long trips at CRO, the female feeding frequency was twice as high at KER than at CRO during the crèche period, while males participated in the feeding duties. Based on differences in female behaviour, we hypothesize that the male's contribution is likely to differ strongly from one site to another, and may buffer the possible decrease in female feeding frequency by feeding the chicks if food is less abundant.     

Pasteurella multocida infections in rockhopper penguins (Eudyptes chrysocome) from Campbell Island, New Zealand

During an investigation into the population decline of rockhopper penguins (Eudyptes chrysocome) on Campbell Island, New Zealand, avian cholera (Pasteurella multocida) was found in dead adults and chicks. An RNA enveloped virus was isolated from Ixodes uriae, a tick which commonly parasitizes rockhopper penguins on the island. It is not known whether this virus is virulent for penguins. No evidence was obtained to suggest that avian cholera was the principal cause for the decline in the rockhopper penguin population.     

Satellite tracking of male rockhopper penguins Eudyptes chrysocome during the incubation period at the Falkland Islands

The foraging patterns of ten male rockhopper penguins Eudyptes chrysocome from the Falkland Islands were recorded during the incubation period by using satellite telemetry. Irrespective of study site and year, two different foraging areas could be identified. Three foraging trips were directed towards the slope of the Patagonian Shelf c. 140 km to the northeast of the breeding colony and these trips had a duration of 11–15 days. The seven other rockhopper penguins travelled c. 400 km towards the edge of the Falkland Islands' waters; all these foraging trips followed an anti-clockwise direction and lasted 16–27 days. The calculated mean daily travelling speed, based on the time spent underwater and the distance covered between two positions, was significantly higher in birds travelling to the edge of the Falkland Islands' waters compared with those foraging at the shelf slope (4.4±1.6 km/h vs. 3.4±2.0 km/h, respectively). The consistent foraging patterns exhibited during the long trips may be linked to the Falklands current, allowing the penguins to reach remote areas while reducing their energy expenditure. Potential interactions between commercial fisheries and hydrocarbon exploration are discussed.     

A new high-latitude record for the macaroni penguin (Eudyptes chrysolophus) at Avian Island, Antarctica

On 20 and 22 January 2007, we observed macaroni penguins (Eudyptes chrysolophus) on Avian Island, Antarctica, approximately 1° south of the Antarctic Circle along the Western Antarctic Peninsula (WAP) near Adelaide Island, a new high-latitude observational record for the species within this region of the continent. Additionally, we report several extra-limital sightings of macaroni penguins over the last decade at relatively lower latitudes along the WAP near Anvers Island, including observations of breeding attempts. Although vagrancy cannot be ruled out as a possible causal factor in our observations, we hypothesize that a climate-induced shift in the species’ bio-geographic range may be in progress. In this context, our observations are similar to the well-documented range shifts and eventual establishment of breeding populations by other sub-Antarctic penguin species along the WAP, over the last three decades, in response to regional climate warming. We highlight that the few observations reported here do not provide conclusive evidence for any putative causal mechanism explaining the presence of macaroni penguins at locations outside their natural geographic range. However, our observations are important for developing a better understanding of the natural history of the species along the WAP.     

The effect of investigators on the breeding success of royal,Eudyptes schlegeli,and rockhopper penguins,E. chrysocome,at Macquarie Island

The impact on reproductive success of investigators studying the breeding biology of royal and rockhopper penguins was assessed. Control and experimental transects were established in a colony of each species and the number of active nests, from egg laying to creche stage, were compared. Experimental nests were those used in breeding biology work, where birds were measured and banded, and nest checks were carried out at least once per week. Control nests were in equivalent locations but birds were not handled, and no contact was made with the nests once breeding had begun. There were no significant differences in the number of active nests between the control and experimental transects (and, therefore, breeding success) in either species. It is concluded that, provided care is taken when working with these species, no impacts on the short-term (up to creche stage, in one breeding season) breeding success of these populations will occur.     

Maximum diving depths of northern rockhopper penguins (Eudyptes chrysocome moseleyi) at Amsterdam Island

 The mean maximum dive depth from 49 foraging bouts by northern rockhopper penguins, measured using capillary-tube depth gauges, was 66±4 m (12–168 m). There were no differences in the maximum dive depths between male and female penguins. Northern rockhopper penguins dived deeper in early than in late creche stages (83±7 vs 57±4 m), and this was associated with probable dietary changes, squid dominating the diet by mass (44%) in November, and fish (64%) in December 1994 at Amsterdam Island. Received: 10 January 1996/Accepted: 31 March 1996     

Isolation and characterization of macaroni penguin (Eudyptes chrysolophus) microsatellite loci and their utility in other penguin species (Spheniscidae, AVES)

We report the characterization of 25 microsatellite loci isolated from the macaroni penguin (Eudyptes chrysolophus). Thirteen loci were arranged into four multiplex sets for future genetic studies of macaroni penguin populations. All 25 loci were tested separately in each of four other penguin species [Adélie penguin (Pygoscelis adeliae), chinstrap penguin (Pygoscelis antarctica), gentoo penguin (Pygoscelis papua) and king penguin (Aptenodytes patagonicus)]. Between eight and 12 loci were polymorphic per species. These loci are expected to be useful for studies of population genetic structure in a range of penguin species.     

Lipids in the Harder's gland of certain rodents. III: Glycolipids

Following the study of total lipid and phospholipid contents of Harderian gland, we carried out analysis of glycolipid fractions. The data showed that most of the pigment is bound to mono-hexose ceramides, while only a minor fraction of it is bound to ceramides and/or to phospholipids. Histochemical studies confirmed the lipid and glycolipid nature of the Harder's gland secretion. The presence of mono-hexose ceramides linked to the characteristic fluorescent porphyrin was shown.     

Lipids in the Harder's gland of certain rodents. II: Phospholipids

The phospholipid components of Harder's glands of rats and mice were investigated. The content of phosphatidylcholine and of sphyngomyelin is notably less in the rat than in the mouse difference among the other components, being negligible. In the male rat the total phospholipid content is larger than in the female, while in mice the opposite is true. The presence of a large red fluorescent spot, which is not phospholipid, has been shown.