Publications

maternal deposition of yolk corticosterone in clutches of southern rockhopper penguins (eudyptes chrysocome chrysocome).	high corticosterone levels can have deleterious effects in developing avian embryos and chicks. therefore, it may be adaptive for avian mothers to reduce corticosterone transfer to their eggs. however, until now, data about the active or/and passive role of mothers in corticosterone transfer to eggs are inconclusive. here, we study maternal investment into a- and b-eggs of southern rockhopper penguins (eudyptes chrysocome chrysocome). this species exhibits reversed hatching asynchrony and provid ...	2009	19232349
differences in the stable isotope signatures of seabird egg membrane and albumen--implications for non-invasive studies.	in many bird species, egg membranes can be obtained non-invasively after the chicks have hatched, and stable isotope analysis of egg membranes can be used to study the diet and foraging distribution of these birds during egg formation. it has been suggested that the enrichment factors of albumen and egg membranes differ for 13c, but are similar for 15n. in this study, we compared carbon and nitrogen stable isotopes of the membranes and albumen of individual eggs of three wild seabird species, th ...	2009	19890954
reversed hatching order, body condition and corticosterone levels in chicks of southern rockhopper penguins (eudyptes chrysocome chrysocome).	in altricial and semi-altricial species, asynchronous hatching gives the first chicks to hatch an initial advantage over other siblings and often leads to the elimination of the smallest chicks. both baseline corticosterone and acute stress-induced corticosterone levels have been shown to be higher in food deprived chicks than in chicks fed ad libitum. however, first-hatched chicks have also been shown to exhibit higher corticosterone levels than last-hatched chicks, suggesting an influence of t ...	2010	20850443
leucocyte profiles and corticosterone in chicks of southern rockhopper penguins.	the immune system is essential for health and survival of vertebrates, yet still little is known about the ontogeny of the immune system in wild birds. the southern rockhopper penguin (eudyptes chrysocome chrysocome) is a semi-altricial seabird with a long developmental period and reversed hatching asynchrony, favouring the survival of b-chicks. we compared leucocyte counts and baseline corticosterone levels of southern rockhopper penguin chicks under different preconditions such as sex and orig ...	2011	20721561
measuring corticosterone in seabird egg yolk and the presence of high yolk gestagen concentrations.	large inter-species differences have been found in yolk corticosterone amounts in avian eggs. while some studies have failed to detect significant amounts of corticosterone, in other species high amounts have been recorded, such as in a recent study of southern rockhopper penguins eudyptes chrysocome chrysocome. however, attention has been drawn recently to the fact that many antibodies for corticosterone measurement cross-react with other steroids present in the yolk. in particular, progesteron ...	2011	21640119
yolk androgen deposition in rockhopper penguins, a species with reversed hatching asynchrony.	to maximize fitness, females should invest optimally in the siblings within a litter or brood and adapt this investment to environmental conditions. chick mass and yolk androgens have been shown to influence the outcome of sibling competition. in birds, asynchronous hatching plays a major role in this process and often leads to brood reduction. we studied maternal deposition of yolk androgens in eggs of southern rockhopper penguins (eudyptes chrysocome chrysocome). contrary to other avian models ...	2011	21130090
evaluating the impact of handling and logger attachment on foraging parameters and physiology in southern rockhopper penguins.	logger technology has revolutionised our knowledge of the behaviour and physiology of free-living animals but handling and logger attachments may have negative effects on the behaviour of the animals and their welfare. we studied southern rockhopper penguin (eudyptes chrysocome) females during the guard stage in three consecutive breeding seasons (2008/09-2010/11) to evaluate the effects of handling and logger attachment on foraging trip duration, dive behaviour and physiological parameters. sma ...	2012	23185623
penguin chicks benefit from elevated yolk androgen levels under sibling competition.	crested penguins (genus eudyptes) have a peculiar hatching pattern, with the first-laid egg (a-egg) hatching after the second-laid egg (b-egg) and chicks from a-eggs typically having a much lower survival probability. maternal yolk androgens have been suggested to contribute to the competitive superiority of the b-chick in southern rockhopper penguins eudyptes chrysocome, given their important role in mediating sibling competition in other species. we therefore increased the yolk androgen levels ...	2012	22860073
coexistence of oceanic predators on wintering areas explained by population-scale foraging segregation in space or time.	ecological niche theory predicts segregation mechanisms that mitigate potential competition between closely related organisms. however, little is known outside the breeding season, when central-place foraging animals may move on larger scales. this study tested for segregation mechanisms within the same 2007 inter-breeding period on three neighboring populations of avian predators from the southern indian ocean: eastern rockhopper penguins eudyptes filholi from crozet and kerguelen and northern ...	2012	22486093
good days, bad days: wind as a driver of foraging success in a flightless seabird, the southern rockhopper penguin.	due to their restricted foraging range, flightless seabirds are ideal models to study the short-term variability in foraging success in response to environmentally driven food availability. wind can be a driver of upwelling and food abundance in marine ecosystems such as the southern ocean, where wind regime changes due to global warming may have important ecological consequences. southern rockhopper penguins (eudyptes chrysocome) have undergone a dramatic population decline in the past decades, ...	2013	24236139
females paired with new and heavy mates reduce intra-clutch differences in resource allocation.	reproductive investment affects both offspring and parental fitness and influences the evolution of life histories. females may vary their overall primary reproductive effort in relation to the phenotypic characteristics of their mate. however, the effects of male quality on differential resource allocation within clutches have been largely neglected despite the potential implications for mate choice and population dynamics, especially in species exhibiting biparental care and brood reduction. f ...	2013	23967280
penguins as bioindicators of mercury contamination in the southern ocean: birds from the kerguelen islands as a case study.	seabirds have been used extensively as bioindicators of mercury (hg) contamination in the marine environment, although information on flightless species like penguins remains limited. in order to assess the use of penguins as bioindicators of hg contamination in subantarctic and antarctic marine ecosystems, hg concentrations were evaluated in the feathers of the four species that breed on the kerguelen islands in the southern indian ocean. compared to other seabirds, adult kerguelen penguins had ...	2013	23542487
love thy neighbour or opposites attract? patterns of spatial segregation and association among crested penguin populations during winter.	competition for food among populations of closely related species and conspecifics that occur in both sympatry and parapatry can be reduced by interspecific and intraspecific spatial segregation. according to predictions of niche partitioning, segregation is expected to occur at habitat boundaries among congeners and within habitats among conspecifics, while negative relationships in the density of species or populations will occur in areas of overlap. we tested these predictions by modelling th ...	2014	25505357
ocular findings and reference values for selected ophthalmic diagnostic tests in the macaroni penguin (eudyptes chrysolophus) and southern rockhopper penguin (eudyptes chrysocome).	to describe ophthalmic examination findings and standard diagnostic test results in 2 penguin species.	2015	24238103
mates but not sexes differ in migratory niche in a monogamous penguin species.	strong pair bonds generally increase fitness in monogamous organisms, but may also underlie the risk of hampering it when re-pairing fails after the winter season. we investigated whether partners would either maintain contact or offset this risk by exploiting sex-specific favourable niches during winter in a migratory monogamous seabird, the southern rockhopper penguin eudyptes chrysocome. using light-based geolocation, we show that although the spatial distribution of both sexes largely overla ...	2015	26562934
individual consistency and phenotypic plasticity in rockhopper penguins: female but not male body mass links environmental conditions to reproductive investment.	in marine habitats, increasing ocean temperatures due to global climate change may distinctly reduce nutrient and consequently food availability for seabirds. food availability is a known driver of body mass and reproductive investment in birds, but these traits may also depend on individual effects. penguins show extreme intra-annual body mass variation and rely on accumulated body reserves for successful breeding. however, no study so far has tested individual consistency and phenotypic respon ...	2015	26030824
is individual consistency in body mass and reproductive decisions linked to individual specialization in foraging behavior in a long-lived seabird?	individual specialization in diet or foraging behavior within apparently generalist populations has been described for many species, especially in polar and temperate marine environments, where resource distribution is relatively predictable. it is unclear, however, whether and how increased environmental variability - and thus reduced predictability of resources - due to global climate change will affect individual specialization. we determined the within- and among-individual components of the ...	2016	27386091
intraocular pressure in southern rockhopper (eudyptes chrysocome) and macaroni penguins (eudyptes chrysolophus): evaluation of influencing factors.	ophthalmic examinations were performed on 160 macaroni penguins (eudyptes chrysolophus) and 90 southern rockhopper penguins (eudyptes chrysocome) at eight north american zoos and aquaria. intraocular pressure (iop) was measured using rebound tonometry while penguins were held in two different body positions. correlations between iop and factors including age, body position, eye pathology, and housing parameters were evaluated. normal macaroni penguins had a mean iop of 42.0 ± 9.7 mm hg. normal r ...	2016	27010282
organohalogenated contaminants in plasma and eggs of rockhopper penguins: does vitellogenin affect maternal transfer?	although many studies have investigated organohalogenated contaminants (ohcs) in yolk, little is known about the mechanisms and timing of transfer of ohcs from the female to the egg. vitellogenin, a yolk precursor, has been suggested to play a role in this transport. we here report for the first time the temporal changes in ohc and an index of vitellogenin concentrations in female plasma from the pre-laying period to clutch completion in free-living birds: the southern rockhopper penguin (eudypt ...	2017	28392239
extreme intra-clutch egg size dimorphism is not coupled with corresponding differences in antioxidant capacity and stable isotopes between eggs.	oviparous females need to allocate resources optimally to their eggs in order to maximize their fitness. among these resources, dietary antioxidants, acquired by females and transferred to the eggs during egg formation, can greatly affect the development and survival of the embryo and chick. in crested penguins, incubation starts after the second and last egg is laid and, as opposed to many other bird species, this egg hatches first, thereby enhancing the survival of the chick. here, we assessed ...	2017	28062221
phylogeography, population structure, and species delimitation in rockhopper penguins (eudyptes chrysocome and eudyptes moseleyi).	rockhopper penguins are delimited as 2 species, the northern rockhopper (eudyptes moseleyi) and the southern rockhopper (eudyptes chrysocome), with the latter comprising 2 subspecies, the western rockhopper (eudyptes chrysocome chrysocome) and the eastern rockhopper (eudyptes chrysocome filholi). we conducted a phylogeographic study using multilocus data from 114 individuals sampled across 12 colonies from the entire range of the northern/southern rockhopper complex to assess potential populatio ...	2019	31737899
fatal sarcocystis falcatula infection in three penguins.	sarcocystis falcatula is a well-known cause of fatal pneumonia in some birds, particularly old world psittacines. here we describe fatal sarcosystosis due to s. falcatula in 3 penguins (family spheniscidae) under managed care, including one african penguin (spheniscus demersus), and two southern rockhopper penguins (eudyptes chrysocome). randomly distributed foci of necrosis, inflammatory cell infiltrates, edema, and variable numbers of round to elongated protozoal schizonts were observed in sec ...	2019	31649941
training penguins to interact with enrichment devices for lasting effects.	the modern zoo has brought about two major advances in the behavioral welfare of their exhibited animals: (a) the use of environmental enrichment to promote naturalistic behaviors and (b) the use of training to improve voluntary husbandry care. whereas training itself has been talked about as an effective enrichment strategy, little has been done to combine training procedures with enrichment. typically, enrichment is treated as a trial and error process, where potential enrichment items or proc ...	2019	31355481
temporal and interspecific variation in feather mercury in four penguin species from macquarie island, australia.	we measured mercury (hg) concentrations in feathers from four penguin species collected on macquarie island, southern ocean, to 1) establish baseline hg concentrations; and 2) compare hg from samples collected in 2002 ("modern") and from museum specimens collected between 1937 and 1976 ("historic"). inter-specific differences in feather hg reflected known differences in habitats and diversity of diets: benthic-foraging gentoo penguins and rockhopper penguins that foraged both inshore and offshor ...	2019	31232305
diet-tissue discrimination factors (δ15 n and δ13 c values) for blood components in magellanic (spheniscus magellanicus) and southern rockhopper (eudyptes chrysocome) penguins.	analysis of the stable isotope ratios of carbon and nitrogen (δ13 c and δ15 n values) is increasingly being used to gain insight into predator trophic ecology, which requires accurate diet-tissue discrimination factors (dtdfs), or the isotopic difference between prey and predator. accurate dtdfs must be calculated from predators consuming an isotopically constant diet over time in controlled feeding experiments, but these studies have received little attention to date, especially among seabird s ...	2020	31657501
mycobacterial airsacculitis caused by mycobacterium fortuitum in a southern rockhopper penguin (eudyptes chrysocome).	a 21-year-old male southern rockhopper penguin (eudyptes chrysocome) was presented with a chronic history of intermittently decreased appetite, lethargy, and regurgitation. on the external physical examination, the bird was determined to be in fair-to-thin body condition with the complete blood count and plasma chemistry panel being largely unremarkable. full-body radiographic images were considered normal, and gastroscopy showed only mild gastritis and duodenitis. the penguin was euthanatized s ...	2020	33099984
compound-specific stable isotope analyses in falkland islands seabirds reveal seasonal changes in trophic positions.	while nitrogen and carbon stable isotope values can reflect ecological segregation, prey choice and spatial distribution in seabirds, the interpretation of bulk stable isotope values is frequently hampered by a lack of isotopic baseline data. in this study, we used compound-specific isotope analyses of amino acids (csia-aa) to overcome this constraint and to study interspecific differences, seasonal and historical changes in trophic positions of five seabird species, three penguins and two petre ...	2020	32293412
metapopulation dynamics and foraging plasticity in a highly vagile seabird, the southern rockhopper penguin.	population connectivity is driven by individual dispersal potential and modulated by natal philopatry. in seabirds, high vagility facilitates dispersal yet philopatry is also common, with foraging area overlap often correlated with population connectivity. we assess the interplay between these processes by studying past and current connectivity and foraging niche overlap among southern rockhopper penguin colonies of the coast of southern south america using genomic and stable isotope analyses. w ...	2020	32273992