Marine ecology and conservation of the Galápagos penguin, Spheniscus mendiculus

The presented thesis outlines several aspects of the marine ecology and conservation of the Galápagos penguin (Spheniscus mendiculus). This project was realised between July 2003 and September 2005 in the Galápagos islands as a collaborative project between the Charles Darwin Foundation, the Galápagos National Park Service and the University of Kiel in Germany. In two concurrent years, 2004 and 2005, breeding activities of the Galápagos penguin were investigated. The majority of all the breeding sites was found on Isabela Island, the largest island in the archipelago, with the highest aggregations of active nests concentrated in the southwest of the island. The study showed that the distribution of the breeding sites is strongly related to nutrient-rich upwelling areas within the archipelago, caused by the Equatorial Undercurrent (EUC; also known as the Cromwell Current). Considering penguin breeding sites in light of the Galápagos Marine Reserve (GMR) zoning system however, raises interesting concerns. While only a few nests (25.2 %) are afforded the highest protection level, the large majority of nests (74.8 %) were found in areas designated for extractive uses (e.g., fisheries). The implications for penguin conservation may be significant. Even though nesting penguins may not feed in this adjacent coastal area, they need to pass through this zone on their way to their foraging sites. Although active nests could be discovered virtually throughout the year, the results showed generally two well-defined breeding peaks within the year: March to May, and from July to September. The region in the western part of the archipelago undergoes (except in El Niño years) a seasonal increase in phytoplankton biomass in the second part of the year (from June to December) which coincides well with the second period of egg-laying. The first egg-laying peak corresponds with the strengthening and shoaling of the EUC in April. An inter-annual and regional comparison in breeding patterns indicated that egg-laying was variable on both a temporal and spatial scale. Thus, the breeding biology of the Galápagos penguin seems to be well adapted to the highly variable oceanographic environment surrounding the Galápagos islands. Between May 2004 and May 2005, the horizontal and vertical movements of foraging Galápagos penguins was studied during their breeding season to examine space use at sea and to compare the volume of water exploited by this penguin to those of other penguin species. Twenty-three adult penguins (11 males and 12 females) brooding chicks were equipped with Global Positioning System-temperature depth data logger at the three main nesting sites on south-western Isabela Island. Birds moved between 1.1 and 23.5 km (mean = 5.2 ± 4.9 km) from the nest, concentrating foraging in a strip of sea within 1.0 km of the shore. Foraging trips lasted a mean of 8.4 ± 2.0 hours. Although the deepest dive was 52.1 m, birds spent, on average, 90 % of their time underwater at depths less than 6 m. Both foraging ranges and dive depths were below those predicted from allometric regressions derived from other penguin species. Applying the maximum values for movement to calculate space use, the Galápagos penguin exploits a maximum volume of water of < 1.4 km3, which is almost 90 times less than that predicted for its mass, and thus utilises only a small portion of the total potentially available upwelling area within the Galápagos archipelago. This work was complemented by analysis of non-breeding penguin diet using the combined approach of stable-isotope analysis and conventional dietary sampling of stomach samples. The resulting data set revealed that diet was mainly composed of neritic, pelagic species typical of upwelling systems, dominanted by Engraulidae (here represented by Pacific anchoveta (Cetengraulis mysticetus)). However, while other Spheniscus penguins are known to feed on adult schooling fish, this study provided strong evidence that Galápagos penguins’ feeding preferences were young fish or even larvae (≤ 30 mm). Since larvae and juvenile phases of these fish species inhabit the surface inshore waters, and migrate offshore when adult. The use of coastal habitat by device-equipped breeding Galápagos penguins corresponds well with the results obtained from the stomach samples of non-breeding penguins. The stable-isotope analysis provides estimates of diet changes on a temporal and spatial scale. There was no differences in diet composition detectable in our study animals. These results provided critical information on the penguins’ use of the GMR and will be applied to appropriately design the layout and protection levels of the zonation system. This data represents a strong argument for improved fisheries management to avoid undue competition between man and penguins. Since the principal threat to seabirds breeding in the Galápagos islands past and present is that of introduced alien mammals, the predatory impact of cats (Felis catus) on the endangered Galápagos penguin population was studied at the penguins’ main breeding site. Here, two methods were used to assess penguin mortality rate: 1) direct counts of penguin carcasses and 2) an energetic approach. The results of these two independent mortality assessments suggested that a single cat was responsible for an increase in adult mortality of 49 % year-1 at this site. Although the annual penguin census shows a relative stable and even slightly increasing population trend over the last years, the vulnerability of this population to even small changes in mortality rates is well known and these results even reveal that the situation of the Galápagos penguin is more fragile than previously assumed. Greater attention should be paid to the impact of introduced species that are increasingly affecting this species.Die vorliegende Arbeit untersucht verschiedene Aspekte der marinen Ökologie und des Artenschutzes des Galápagos Pinguins (Spheniscus mendiculus). Dieses Projekt wurde zwischen Juli 2003 und September 2005 in Kollaboration mit der Charles Darwin Foundation, dem Galápagos Nationalparkamt und der Universität Kiel durchgeführt. Die Brutaktivität des Galápagos Pinguins wurde in zwei aufeinanderfolgenden Jahren, 2004 und 2005, untersucht. Die Mehrheit der Nistplätze befand sich auf Isabela, der größten Insel des Archipels, wobei die höchste Dichte an aktiven Nestern im Südwesten der Insel beobachtet werden konnte. Die Untersuchung ließ einen deutlichen Zusammenhang zwischen der Verteilung der Brutgebiete und den nährstoffreichen Auftriebsgebieten innerhalb des Archipels, die durch den Äquatorialen Unterstrom (auch bekannt als Cromwellstrom) hervorgerufen werden, erkennen. Betrachtet man die Standorte der Brutplätze der Pinguine in Hinblick auf das Zonierungssystem der Galápagos Marine Reserve (GMR), so ist zu erkennen, dass nur wenigen Nestern (25.2%) der höchste Schutzstatus gewährt wird und die Mehrheit der Nester (74.8%) in Gebieten liegt, in denen Fischerei erlaubt ist. Dies kann unmittelbare Folgen für den Schutz der Pinguine haben. Selbst wenn die nistenden Pinguine nicht in den angrenzenden Küstengebieten auf Nahrungssuche gehen, so müssen sie diese auf dem Weg zu ihren Nahrungsgebiete durchqueren. Die Pinguine wiesen eine ganzjährige Brutaktivität auf, jedoch konnten zwei Hauptbrutperioden zwischen März und Mai und Juli und September beobachtet werden. Der Westen des Archipels unterliegt, zumindest in nicht El Niño Jahren, in der zweiten Jahreshälfte (Juni bis Dezember) einem saisonalen Anstieg an Phytoplanktonbiomasse, welcher zeitlich mit der zweiten Brutperiode übereinstimmt. Die erste Brutperiode wiederum steht in einem klaren zeitlichen Zusammenhang mit einem verstärkten Auftrieb der kalten nährstoffreichen Wassermassen des EUCs im April. Ein Vergleich der Brutaktivitäten zwischen den Jahren deutet darauf hin, dass die Eiablage sowohl zeitlich als auch räumlich variabel ist. Die Brutbiologie des Galápagos Pinguins ist demnach sehr gut an das marine Habitat mit sich schnell ändernden ozeanographischen Bedingungen angepasst. Zwischen Mai 2004 und Mai 2005 wurden horizontale und vertikale Bewegungen nahrungssuchender Galápagos Pinguine während der Brutsaison aufgezeichnet, um die Habitatnutzung zu untersuchen und das genutzte Wasservolumen mit dem anderer Pinguinarten zu vergleichen. An den drei Hauptbrutplätzen im Südwesten der Insel Isabela wurden 23 adulte Pinguine (11 Männchen und 12 Weibchen) während der Kükenaufzucht mit GPS (Global Positioning System)-Temperatur-Tiefenrekordern ausgerüstet. Die Tiere entfernten sich zwischen 1.1 und 23.5 km (im Mittel 5.2 ± 4.9 km) von ihrem Nistplatz, wobei sie sich zur Nahrungssuche in einem parallel zur Küste verlaufenden, maximal 1.0 km breiten Streifen aufhielten. Die Beutezüge dauerten im Durchschnitt 8.4 ± 2.0 Stunden. Obwohl die maximale Tauchtiefe bei 52.1 m lag, verbrachten die Vögel durchschnittlich 90% ihrer Zeit in Wassertiefen geringer als 6 m. Sowohl das zur Nahrungssuche genutzte Gebiet als auch die Tauchtiefe lagen unterhalb der durch allometrische Regressionen vorhergesagten Werte. Berechnet man den von den Galápagos Pinguinen genutzten marinen Raum mit Hilfe der maximalen Tauchtiefe und Distanzen zum Nest, ergibt sich ein maximales Wasservolumens von < 1.4 km3. Dieser Wert ist 90 mal geringer als angenommen, demnach wird nur ein kleiner Teil des potentiell verfügbaren Auftriebsgebietes innerhalb des Galápagos Archipels genutzt. Desweiteren wurde mittels konventioneller Mageninhaltsuntersuchung und Stable-Isotope-Analyse die Nahrungszusammensetzung nicht-brütender Pinguine untersucht. Das Nahrungsspektrum bestand hauptsächlich aus für Auftriebsgebiete typischen pelagischen Arten, dominiert von Engraulidae (hier Pacific anchoveta (Cetengraulis mysticetus)). Während andere Spheniscus Pinguinarten sich vorwiegend von adulten Schwarmfischen ernähren, zeigt diese Studie, dass die Nahrung der hier untersuchten Galápagos Pinguine aus Jungfischen oder sogar Larven bestand. Die Larven und juvenilen Stadien dieser Fischarten halten sich im küstennahen Gewässer auf und wandern erst als Adulttiere in tiefere Gewässer ab. Die Nutzung küstennaher Gebiete brütender Pinguine stimmt daher mit den Ergebnisse der Mageninhalts-Analyse nicht-brütender Pinguine überein. Die Stable-Isotope Analyse ermöglicht unter anderem zeitliche und räumliche Veränderungen in der Nahrungszusammensetzung zu erkennen. Bei den von mir untersuchten Tieren konnten keine Unterschiede bezüglich der Nahrungswahl beobachtet werden. Die Ergebnisse dieser Arbeit über die Habitatwahl und der Ernährungsweise des Galápagos Pinguins liefern entscheidende Informationen über dessen Nutzung der GMR. Sie werden bei der Gestaltung und der Festlegung des Zonierungssystems zur Anwendung kommen und helfen, durch ein verbessertes Fischereimanagement eine potentielle Konkurrenz zwischen Mensch und Pinguin zu vermeiden. Eine der Hauptbedrohungen für die auf den Galápagos Inseln brütenden Seevögeln stellen eingeführte Säugetiere da. Aufgrund des gefährdeten Status des Galápagos Pinguins wurde daher der Einfluss von Katzen (Felis catus) auf dessen Population in seinem Hauptbrutgebiet untersucht. Hierzu wurden zwei Methoden zur Abschätzung der Mortalitätsrate der Pinguine angewandt 1) direkte Zählung von tot aufgefundenden Pinguinen und 2) energetische Berechnungen. Die Ergebnisse dieser beiden unabhängigen Mortalitätsabschätzungen führten zu der Erkenntnis, dass eine einzelne Katze einen Anstieg der Mortalität adulter Pinguine um 49% pro Jahr an diesem Brutplatz verursachen kann. Obwohl die jährlich stattfindenden Pinguinzählungen eine in den letzten Jahren relativ stabile und sogar leicht zunehmende Population anzeigt, kann bereits ein geringer Anstieg der Mortalitätsrate bedeutende Auswirkungen auf die Populationsentwicklung haben. Mit dieser Studie konnte gezeigt werden, dass eingeführte Arten eine ernstzunehmende Bedrohung für bereits gefährdete Tierarten darstellt

Lip-reading in remote subjects: An attempt to quantify and separate ingestion, breathing and vocalisation in free-living animals

A new mandibular sensor is presented here based on the use of a Hall sensor, attached to one mandible, opposite a magnet, attached to the other mandible. Changes in sensor voltage, proportional to magnetic field strength, and thus inter-mandibular angle, are recorded in a logger. This system was tested on seven captive Adélie penguins (Pygoscelis adeliae) and three gentoo penguins (Pygoscelis papua) during: (1) feeding trials on land, where birds were given known quantities and types of food; and (2) trials in water where birds were allowed to swim and dive freely. In addition, six free-living Magellanic penguins (Spheniscus magellanicus) were equipped with the system for single foraging trips. Angular signatures were looked for in instances when both captive and free-living birds might open their beaks, and it was discovered that five major behaviours could be identified: ingestion, breathing, calling, head shaking and preening. Captive feeding trials showed that prey mass could be determined with reasonable accuracy (r 2=0.92), and there was some indication that prey type could be resolved if recording frequency were high enough. Vocalisations in Adélie penguins (arc calls) took <0.7 s for mean maximum beak angles of 4.2° (SD 1.3), and were distinguished by their relatively gradual change in beak angle and by their high degree of symmetry. Beak shakings were distinguishable by their short duration (multiple peaks of <0.5 s) and minimal maximum angle (<0.5°). Preening behaviour was apparent due to multiple decreasing peaks (angles <8°). Breathing could be subdivided into that during porpoising, where a characteristic double peak in beak angle was recorded, and that during normal surface rests between dives. During porpoising, only the primary peak (mean maximum beak angle 25.1°, SD 4.7) occurred when the bird was out of the water (mean maximum for second peak 5.9°, SD 4.1). During normal surface rests in free-living birds, breaths could be distinguished as a series of beak openings and closures, showing variation in amplitude and frequency according to an apparent recovery from the previous dive and preparation for the subsequent dive to come. The mandibular measuring system presented shows considerable promise for elucidating many hitherto intractable aspects of the behaviour of free-living animals

Patterns of respiration in diving penguins: Is the last gasp based on an inspired tactic?

Humboldt penguins Spheniscus humboldti in captivity and free-living Magellanic penguins S. magellanicus were fitted with loggers to determine beak angles during breathing. The Humboldt penguins were also fitted with masks for determining rates of air flow during breathing. During periods of higher gas exchange requirement, Humboldt penguins opened their beaks during inspiration, where tidal volume was linearly correlated with both change in beak angle and maximum beak angle, closed them slightly during the final stages of inspiration and finally closed them during expiration. Substantial differences were apparent between individuals. Contrary to the condition proposed for most birds, our data suggest that expiration is passive during periods of high respiratory tidal volumes, and that the increased resistance of the respiratory pathway serves to slow air flow so as to maximize gas exchange in the lungs. During foraging, Magellanic penguins at the surface between dives showed similar breathing patterns but maximum beak angles were much higher and breath cycle time shorter, as would be expected for animals attempting to maximize gas exchange. Both maximum beak angle per breath and breath frequency changed systematically over the surface pause; both were initially high, then decreased to a low before rising again to a maximum just before diving. Based on known changes in tidal volume with beak angle derived from Humboldt penguins, a simple model is proposed to examine rates of gas exchange over the surface pause. This indicates that the observed patterns do not maximize the rate of transfer of oxygen over the whole of the surface pause but are rather concerned with an initial rapid accumulation of oxygen in the tissues followed by effective carbon dioxide release.Articl

Bayesian inference reveals positive but subtle effects of experimental fishery closures on marine predator demographics

Global forage-fish landings are increasing, with potentially grave consequences for marine ecosystems. Predators of forage fish may be influenced by this harvest, but the nature of these effects is contentious. Experimental fishery manipulations offer the best solution to quantify population-level impacts, but are rare. We used Bayesian inference to examine changes in chick survival, body condition and population growth rate of endangered African penguins Spheniscus demersus in response to 8 years of alternating time-area closures around two pairs of colonies. Our results demonstrate that fishing closures improved chick survival and condition, after controlling for changing prey availability. However, this effect was inconsistent across sites and years, highlighting the difficultly of assessing management interventions in marine ecosystems. Nevertheless, modelled increases in population growth rates exceeded 1% at one colony; i.e. the threshold considered biologically meaningful by fisheries management in South Africa. Fishing closures evidently can improve the population trend of a forage-fish-dependent predator-we therefore recommend they continue in South Africa and support their application elsewhere. However, detecting demographic gains for mobile marine predators from small no-take zones requires experimental time frames and scales that will often exceed those desired by decision makers

Plan d’action en faveur du gorfou sauteur du Nord Eudyptes moseleyi 2017-2027

International audienceLa planification stratégique pour la protection des espèces est l’un des trois éléments du cycle évaluation-planification-action soutenu par la Commission de la survie des espèces (CSE) de l’UICN. Les Plans d’action en faveur des espèces constituent des cadres mondiaux élaborés par différentes parties prenantes en vue de promouvoir la coopération, de recenser les actions prioritaires et d’éclairer les décisions en matière d’allocation de ressources humaines et financières limitées. Les stratégies et plans d’action en faveur des espèces contribuent notamment à atteindre l’objectif 12 d’Aichi de la Convention sur la diversité biologique, lequel consiste à améliorer l’état de conservation des espèces menacées.Le plan stratégique de la CSE pour la période quadriennale 2017-2020 fixe un objectif quant au nombre de plans à élaborer. Aussi le présent Plan d’action en faveur du gorfou sauteur du Nord contribue-t-il de manière précieuse à la poursuite de cet objectif. Les manchots jouent le rôle de sentinelles à la fois pour les milieux terrestres et aquatiques. Les îles reculées de l’océan Atlantique sud et de l’océan Indien, où ces oiseaux se reproduisent, sont d’une importance majeure, pas seulement pour les colonies d’oiseaux marins qu’elles abritent, mais aussi en raison des espèces endémiques de flore et de faune qui s’y trouvent. Certaines des îles habitées par ces manchots figurent en effet parmi les environnements les plus préservés qu’il reste sur la planète. Le plan d’action pour le gorfou sauteur du Nord est le fruit des efforts conjugués de plus de 15 parties prenantes clés, agences de recherches gouvernementales, administrations locales et ONG internationales, qui consacrent depuis de nombreuses années un temps et un travail considérables à la conservation de cette espèce.Au nom du Groupe de spécialistes des manchots CSE UICN, nous félicitons tous nos partenaires pour leur contribution à la préparation et à l’élaboration de ce plan d’action. Nous exhortons toutes les parties prenantes, y compris les États, à poursuivre les buts et les objectifs de ce plan et à mettre en œuvre les actions qu’il prévoit

Foraging plasticity of breeding Northern Rockhopper Penguins, Eudyptes moseleyi, in response to changing energy requirements

During the breeding season, seabirds must balance the changing demands of self- and off-spring provisioning with the constraints imposed by central-place foraging. Recently, it was shown that Northern Rockhopper Penguins at Tristan da Cunha in the South Atlantic Ocean switch diet from lower to higher trophic level prey throughout their breeding cycle. Here, we investigated if this switch is reflected in their foraging behaviour, using time-depth recorders to study the diving behaviour of 27 guard and 10 crèche birds during the breeding season 2010 at Tristan da Cunha and obtaining complementary stomach contents of 20 birds. While no significant effects of breeding stage were detected on any foraging trip or dive parameters, stage/prey had a significant effect on feeding dive parameters, with dive duration, bottom time, and maximum depth explaining the majority of the dissimilarity amongst categories. We verified the previously shown dietary shift from zooplankton and cephalopods during the guard stage to a higher-energy fish-based diet during the crèche stage, which was reflected in a change in dive behaviour from shorter, shallower to longer, deeper dives. This prey switching behaviour may reflect preferential selection to account for the increased physiological needs of chicks or simply mirror changes in local prey abundance. Nonetheless, we show that Northern Rockhopper Penguins demonstrate behavioural plasticity as a response to their changing energy requirements, which is a critical trait when living in a spatio-temporally heterogeneous environment. This ability is likely to be particularly important under extrinsic constraints such as long-term environmental change

Dives_Processed

African penguin diving data, processed using MTDiv

RawDiveFiles

Unprocessed data file