Pitfalls and advances in morphometric sexing: insights from the Adélie penguin Pygoscelis adeliae

Polar Biology ◽

10.1007/s00300-021-02893-6 ◽

2021 ◽

Author(s):

Niccolò Fattorini ◽

Silvia Olmastroni

Keyword(s):

Discriminant Analysis ◽

Sample Size ◽

Body Mass ◽

Ross Sea ◽

Analytical Techniques ◽

Sex Discrimination ◽

Large Sample Size ◽

Polar Regions ◽

Pygoscelis Adeliae ◽

Adélie Penguins

AbstractSexing weakly/criptically dimorphic birds requires invasive techniques or molecular analysis. Alternatively, sexing can be based upon morphometric analysis, which remains invaluable in remote field conditions such as Polar regions. Nevertheless, discriminatory power may be affected by methodological issues hampering comparison between/within studies, e.g. considering alternative analytical techniques or measurements taken by different researchers. We investigated the sexing potential of bill length, bill depth and body mass in adult Adélie penguins Pygoscelis adeliae of known sex. We performed discriminant analysis on a large dataset of measurements (237 males; 264 females) taken from penguins marked between 1994 and 2001, at Edmonson Point (Ross Sea, Antarctica). In a second step, we accounted for measurements collected by different researchers through permuted discriminant analysis. We found moderate support for sex discrimination through bill measurements (77%). Considering body mass did not improve classification power substantially (78.2%), possibly because of confounding inter/intra-annual oscillations in body condition. Discriminant rate decreased when controlling the researcher effect (72.7% and 71.4%, respectively). Results were also confirmed by logistic (mixed) models. Simulations showed that reduction in sample size markedly increased uncertainty in classification power. Differences with previous studies achieving a slightly greater classification power for sexing Adélie penguins through morphometrics could be related to (i) our higher sample size and/or (ii) geographical, population-specific differences, e.g. lower degree of sexual dimorphism. Our work emphasises key-factors influencing performance of morphometric sexing in avian species, advocating population-specific validation with large sample size as well as the necessity to account for the researcher effect prior to apply morphometric sexing.

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Seabirds of human settlements in Antarctica: A case study of the Mirny Station

Czech Polar Reports ◽

10.5817/cpr2021-1-8 ◽

2021 ◽

Vol 11 (1) ◽

pp. 98-113

Author(s):

Sergey Golubev

Keyword(s):

Bird Species ◽

Weather Conditions ◽

Polar Regions ◽

Pygoscelis Adeliae ◽

Human Settlements ◽

Breeding Bird ◽

Bird Population ◽

Catharacta Maccormicki ◽

South Polar ◽

Adélie Penguins

Antarctica is free of urbanisation, however, 40 year-round and 32 seasonal Antarctic stations operate there. The effects of such human settlements on Antarctic wildlife are insufficiently studied. The main aim of this study was to determine the organization of the bird population of the Mirny Station. The birds were observed on the coast of the Davis Sea in the Mirny (East Antarctica) from January 8, 2012 to January 7, 2013 and from January 9, 2015 to January 9, 2016. The observations were carried out mainly on the Radio and Komsomolsky nunataks (an area of about 0.5 km). The duration of observations varied from 1 to 8 hours per day. From 1956 to 2016, 13 non-breeding bird species (orders Sphenisciformes, Procellariiformes, Charadriiformes) were recorded in the Mirny. The South polar skuas (Catharacta maccormicki) and Adélie penguins (Pygoscelis adeliae) form the basis of the bird population. South polar skuas are most frequently recorded at the station. Less common are Brown skuas (Catharacta antarctica lonnbergi) and Adélie penguins. Adélie penguins, Wilson's storm petrels (Oceanites oceanicus), South polar and Brown skuas are seasonal residents, the other species are visitors. Adélie penguins, Emperor (Aptenodytes forsteri), Macaroni (Eudyptes chrysolophus) and Chinstrap penguins (Pygoscelis antarctica), Wilson's storm petrels, South polar and Brown skuas interacted with the station environment, using it for comfortable behavior, feeding, molting, shelter from bad weather conditions, and possible breeding. South polar and Brown skuas tend to be attracted to the station, while other Antarctic bird species are indifferent to humans. Birds spend part of the annual cycle at the station or visit it with different frequency, but they cannot meet their ecological needs there all year round. The study improves our understanding of the regularities of the phenomenon of urbanization of the avifauna in the polar regions of the planet Earth.

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Effects of Flipper Bands on Foraging Behavior and Survival of Adélie Penguins (Pygoscelis Adeliae)

The Auk ◽

10.1093/auk/123.3.858 ◽

2006 ◽

Vol 123 (3) ◽

pp. 858-869 ◽

Cited By ~ 4

Author(s):

Katie M. Dugger ◽

Grant Ballard ◽

David G. Ainley ◽

Kerry J. Barton

Keyword(s):

Foraging Behavior ◽

Radio Frequency Identification ◽

Ross Sea ◽

High Survival ◽

Negative Consequences ◽

Negative Effects ◽

Pygoscelis Adeliae ◽

Variable Effect ◽

Breeding Seasons ◽

Adélie Penguins

Abstract Since the 1950s, flipper bands have been used widely to mark penguins (Spheniscidae), but not without concerns regarding possible negative effects on survival and fitness. As part of a demographic study of Adélie Penguins (Pygoscelis adeliae) in the western Ross Sea, Antarctica, we investigated effects of flipper bands on foraging-trip duration and food loads, as well as apparent survival, during four breeding seasons (2000-2003), using mark-recapture and radio-frequency identification (RFID) technology. Foraging-trip durations were ∼8% (3.5 h) longer, on average, for banded compared with unbanded birds, but the effect varied among years. Food loads did not differ between banded and unbanded birds, but males carried heavier food loads than females. Flipper bands decreased apparent annual survival by 11–13% during 2000-2003, but over a longer time period (1996-2003) we observed high annual variability, including years of high survival for banded birds. Males had slightly higher survival than females in both banded and unbanded birds. Mechanisms resulting in band effects on foraging behavior and survival, the variable effect of bands by season, and the potential ameliorating effect of age or experience on the effects of bands need further investigation in Adélie and other penguin species. We recognize a need to understand and balance the negative consequences of flipper bands for penguins against the beneficial gains in information associated with their use. Effets du Baguage à l'Aileron sur le Comportement de Recherche Alimentaire et la Survie de Pygoscelis adeliae

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Status and trends of Adélie penguin populations in the Ross Sea region

Polar Record ◽

10.1017/s0032247400011803 ◽

1990 ◽

Vol 26 (159) ◽

pp. 293-304 ◽

Cited By ~ 38

Author(s):

R. H. Taylor ◽

P. R. Wilson ◽

B. W. Thomas

Keyword(s):

Climatic Change ◽

Seasonal Variations ◽

Ross Sea ◽

Weather Conditions ◽

World Population ◽

Pygoscelis Adeliae ◽

The World ◽

Status And Trends ◽

Aerial Reconnaissance ◽

Adélie Penguins

AbstractAerial reconnaissance and photography were used in the Ross Sea sector of Antarctica to determine the breeding locations of Adelie penguinsPygoscelis adeliae, and to count the numbers of nests occupied during the early incubation period. From 1981 to 1987, all islands and sea coasts between 158°E and 175°E were searched, and 11 previously unreported breeding rookeries were discovered. Thirty-eight Adé1ie rookeries are now known from the region, with a total of about 1,082,000 breeding pairs — almost half the world population. Some rookeries were photographed in all, or most, of the seven seasons to study the pattern of natural fluctuations in Adelie populations, and comparisons have been made with earlier counts. Populations at nearly all rookeries have increased in size over the last 10–20 years. Possible reasons for this, and for annual fluctuations in numbers breeding, include seasonal variations in. sea ice and weather conditions, and longer-term climatic change.

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Corticosterone in relation to body mass in Adelie penguins (Pygoscelis adeliae) affected by unusual sea ice conditions at Ross Island, Antarctica

General and Comparative Endocrinology ◽

10.1016/j.ygcen.2006.06.002 ◽

2006 ◽

Vol 149 (3) ◽

pp. 244-252 ◽

Cited By ~ 47

Author(s):

J.F. Cockrem ◽

M.A. Potter ◽

E.J. Candy

Keyword(s):

Sea Ice ◽

Body Mass ◽

Pygoscelis Adeliae ◽

Ice Conditions ◽

Adélie Penguins

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Relational discriminant analysis and its large sample size problem

Proceedings. Fourteenth International Conference on Pattern Recognition (Cat. No.98EX170) ◽

10.1109/icpr.1998.711176 ◽

2002 ◽

Cited By ~ 2

Author(s):

R.P.W. Duin

Keyword(s):

Discriminant Analysis ◽

Sample Size ◽

Large Sample Size ◽

Large Sample ◽

Size Problem

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Air census of two colonies of Adelie Penguins (Pygoscelis adeliae)in Ross Dependency, Antarctica

Polar Record ◽

10.1017/s0032247400064494 ◽

1969 ◽

Vol 14 (91) ◽

pp. 471-475 ◽

Cited By ~ 8

Author(s):

Bernard Stonehouse

Keyword(s):

Ross Sea ◽

Breeding Population ◽

Breeding Cycle ◽

Pygoscelis Adeliae ◽

Breeding Colony ◽

Black And White ◽

Biological Survey ◽

Victoria Land ◽

Using Data ◽

Adélie Penguins

Air photographs taken on biological survey flights between 1962 and 1965 have yielded counts of Adelie Penguin breeding colonies at Beaufort Island in the southwestern Ross Sea and Inexpressible Island on the Victoria Land coast (Fig 1). These colonies are remote from expedition bases, seldom visited, and too large for accurate assessment from the ground. Earlier estimates of their size are summarised by Taylor (1964). Methods of estimating colony size are discussed by Caughley (1960) and Taylor (1962). This survey is based on serial black and white photographs taken at optimal times of the breeding cycle; counts are converted to estimates of breeding population size using data from a ground study at the Cape Royds (Fig 1) breeding colony and from known patterns of breeding at other colonies (Sladen, 1958; SapinJaloustre, 1960; Taylor. 1962; Stonehouse. 1963; Reid. 1964).

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Ancient Adélie penguin colony revealed by snowmelt at Cape Irizar, Ross Sea, Antarctica

Geology ◽

10.1130/g48230.1 ◽

2020 ◽

Cited By ~ 1

Author(s):

Steven D. Emslie

Keyword(s):

Ross Sea ◽

Bone Collagen ◽

Adélie Penguin ◽

Pygoscelis Adeliae ◽

Adelie Penguin ◽

Terra Nova Bay ◽

Penguin Colony ◽

Marine Productivity ◽

First Time ◽

Adélie Penguins

The Ross Sea (Antarctica) is one of the most productive marine ecosystems in the Southern Ocean and supports nearly one million breeding pairs of Adélie penguins (Pygoscelis adeliae) annually. There also is a well-preserved record of abandoned penguin colonies that date from before the Last Glacial Maximum (>45,000 14C yr B.P.) through the Holocene. Cape Irizar is a rocky cape located just south of the Drygalski Ice Tongue on the Scott Coast. In January 2016, several abandoned Adélie penguin sites and abundant surface remains of penguin bones, feathers, and carcasses that appeared to be fresh were being exposed by melting snow and were sampled for radiocarbon analysis. The results indicate the “fresh” remains are actually ancient and that three periods of occupation by Adélie penguins are represented beginning ca. 5000 calibrated calendar (cal.) yr B.P., with the last occupation ending by ca. 800 cal. yr B.P. The presence of fresh-appearing remains on the surface that are actually ancient in age suggests that only recently has snowmelt exposed previously frozen carcasses and other remains for the first time in ~800 yr, allowing them to decay and appear fresh. Recent warming trends and historical satellite imagery (Landsat) showing decreasing snow cover on the cape since 2013 support this hypothesis. Increased δ13C values of penguin bone collagen further indicate a period of enhanced marine productivity during the penguin “optimum”, a warm period at 4000–2000 cal. yr B.P., perhaps related to an expansion of the Terra Nova Bay polynya with calving events of the Drygalski Ice Tongue.

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Spatial and Temporal Variation of Diet Within a Presumed Metapopulation Of Adélie Penguins

The Condor ◽

10.1093/condor/105.1.95 ◽

2003 ◽

Vol 105 (1) ◽

pp. 95-106 ◽

Cited By ~ 10

Author(s):

David G. Ainley ◽

Grant Ballard ◽

Kerry J. Barton ◽

Brian J. Karl ◽

Greg H. Rau ◽

...

Keyword(s):

Stable Isotopes ◽

Sea Ice ◽

Population Growth ◽

Diet Composition ◽

Ross Sea ◽

Isotope Analysis ◽

Spatial And Temporal Variation ◽

Large Area ◽

Pygoscelis Adeliae ◽

Adélie Penguins

Abstract We investigated temporal and spatial variability in the diet of chick-provisioning Adélie Penguins (Pygoscelis adeliae) breeding at all colonies within one isolated cluster in the southwestern Ross Sea, Antarctica, 1994–2000. We wished to determine if prey quality explained different population growth and emigration rates among colonies. Diet composition was described both by conventional means (stomach samples) and by analysis of stable isotopes in chick tissues (toenails of individuals killed by skuas [Stercorarius maccormicki]). Diets were similar among the four study colonies compared to the disparity apparent among 14 widely spaced sites around the continent. Calorimetry indicated that fish are more energetically valuable than krill, implying that if diet varied by colony, diet quality could attract recruits and help to explain differential rates of colony growth. However, a multiple-regression analysis indicated that diet varied as a function of year, time within the year, and percent of foraging area covered by sea ice, but not by colony location. Stable isotopes revealed similarity of diet at one colony where conventional sampling was not possible. We confirmed that sea ice importantly affects diet composition of this species in neritic waters, and found that (1) quality of summer diet cannot explain different population growth rates among colonies, and (2) stable isotope analysis of chick tissues (toenails) is a useful tool to synoptically describe diet in this species over a large area. Variación Espacial y Temporal de la Dieta en una Supuesta Metapoblación de Pygoscelis adeliae Resumen. Investigamos la variabilidad temporal y espacial en la dieta de Pygoscelis adeliae que se encontraban aprovisionando a sus polluelos en todas las colonias dentro de un grupo aislado en el mar de Ross sud-occidental, Antártica, entre 1994 y 2000. Deseábamos determinar si la calidad de la presa explicaba las diferentes tasas de crecimiento poblacional y emigración entre colonias. La composición de la dieta fue descrita por medios convencionales (muestras estomacales) y por el análisis de isótopos estables en tejidos de los polluelos (uñas de las patas de los individuos matados por Stercorarius maccormicki). Las dietas fueron similares entre las 4 colonias estudiadas en relación a la disparidad de la dieta evidente entre 14 sitios dispersos a través del continente. Las análisis de calorimetría indicaron que los peces tienen un mayor valor energético que el krill, sugiriendo que si la dieta varía entre colonias, la calidad de la dieta podría atraer a reclutas y ayudaría a explicar los diferentes índices de crecimiento entre colonias. Sin embargo, un análisis de regresión múltiple indicó que la dieta varió en función del año, de la época dentro de un año, y del porcentaje de área de forrajeo cubierta por el hielo del mar, pero no en función de la localización de la colonia. Los isótopos estables revelaron la semejanza de la dieta en una colonia en que no era posible el muestreo convencional. Confirmamos que el hielo en el mar afecta de manera importante la composición de la dieta de esta especie en aguas neríticas, y encontramos que (1) la calidad de la dieta de verano no puede explicar las diferentes tasas de crecimiento poblacional entre colonias, y que (2) el análisis de isótopos estables de los tejidos de polluelos (uñas de las patas) es una herramienta útil para describir, sinópticamente, la dieta en esta especie a través de un área extensa.

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