Marcel Eens

Corticosterone, inflammation, immune status and telomere length in frigatebird nestlings facing a severe herpesvirus infection.

Effects of testosterone on song, aggression, and nestling feeding behavior in male great tits, Parus major.

Context-dependent effects of castration and testosterone treatment on song in male European starlings.

Castration does not decrease nonreproductive aggression in yearling male European starlings (Sturnus vulgaris).

Effects of testosterone on Reelin expression in the brain of male European starlings.

Breeding performance of great tits (Parus major) along a gradient of heavy metal pollution.

Effect of age and testosterone on autumnal neurogenesis in male European starlings (Sturnus vulgaris).

Effects of heavy metal exposure on the condition and health of nestlings of the great tit (Parus major), a small songbird species.

Female presence affects male behavior and testosterone levels in the European starling (Sturnus vulgaris).

Seasonal fluctuations in plasma testosterone levels and diurnal song activity in free-living male great tits.

Urinary testosterone-metabolite levels and dominance rank in male and female bonobos (Pan paniscus).

Brain space for a learned task: strong intraspecific evidence for neural correlates of singing behavior in songbirds.

Differential effects of testosterone on neuronal populations and their connections in a sensorimotor brain nucleus controlling song production in songbirds: a manganese enhanced-magnetic resonance imaging study.

Urinary testosterone metabolite levels in captive bonobos: relationship with age.

The importance of exogenous contamination on heavy metal levels in bird feathers. A field experiment with free-living great tits, Parus major.

Heavy metal exposure affects the humoral immune response in a free-living small songbird, the great tit (Parus major).

Relationships between metal concentrations in great tit nestlings and their environment and food.

The combined effect of lead exposure and high or low dietary calcium on health and immunocompetence in the zebra finch (Taeniopygia guttata).

Sperm competition and sexually size dimorphic brains in birds.

Certain aspects of bonobo female sexual repertoire are related to urinary testosterone metabolite levels.

Feathers as a nondestructive biomonitor for persistent organic pollutants.

Brominated flame retardants and organochlorine pollutants in eggs of little owls (Athene noctua) from Belgium.

The reproductive success and quality of blue tits (Parus caeruleus) in a heavy metal pollution gradient.

Simultaneous treatment with an aromatase inhibitor and an anti-androgen decreases the likelihood of dawn song in free-living male great tits, Parus major.

Experimental removal of the male parent negatively affects growth and immunocompetence in nestling great tits.

Fish community responses to metal pollution.

Evaluation of biochemical effects related to perfluorooctane sulfonic acid exposure in organohalogen-contaminated great tit (Parus major) and blue tit (Parus caeruleus) nestlings.

Heavy metal pollution affects dawn singing behaviour in a small passerine bird.

Effects of heavy metal exposure on the condition and health of adult great tits (Parus major).

In vivo MR imaging of the seasonal volumetric and functional plasticity of song control nuclei in relation to song output in a female songbird.

Accumulation of organochlorines and brominated flame retardants in the eggs and nestlings of great tits, Parus major.

Can predatory bird feathers be used as a non-destructive biomonitoring tool of organic pollutants?

PFOS levels in the blood and liver of a small insectivorous songbird near a fluorochemical plant.

Variation, levels and profiles of organochlorines and brominated flame retardants in great tit (Parus major) eggs from different types of sampling locations in Flanders (Belgium).

Preen oil as the main source of external contamination with organic pollutants onto feathers of the common magpie (Pica pica).

Yolk testosterone, postnatal growth and song in male canaries.

Metallothioneins (MTs) and delta-aminolevulinic acid dehydratase (ALAd) as biomarkers of metal pollution in great tits (Parus major) along a pollution gradient.

Melanin- and carotenoid-dependent signals of great tits (Parus major) relate differently to metal pollution.

Predatory bird species show different patterns of hydroxylated polychlorinated biphenyls (HO-PCBs) and polychlorinated biphenyls (PCBs).

Birds reveal their personality when singing.

Maternal transfer of organochlorines and brominated flame retardants in blue tits (Cyanistes caeruleus).

Brominated flame retardants and organochlorines in the European environment using great tit eggs as a biomonitoring tool.

Interspecific differences in concentrations and congener profiles of chlorinated and brominated organic pollutants in three insectivorous bird species.

Elevated yolk androgen levels and the expression of multiple sexually selected male characters.

An exposure study with polybrominated diphenyl ethers (PBDEs) in female European starlings (Sturnus vulgaris): toxicokinetics and reproductive effects.

Concentrations in bird feathers reflect regional contamination with organic pollutants.

Does anthropogenic metal pollution affect carotenoid colouration, antioxidative capacity and physiological condition of great tits (Parus major)?

Effects of laying order and experimentally increased egg production on organic pollutants in eggs of a terrestrial songbird species, the great tit (Parus major).

Temperament in bullheads: do laboratory and field explorative behaviour variables correlate?

Historical metal pollution in natural gudgeon populations: Inferences from allozyme, microsatellite and condition factor analysis.

The relationship between perfluorinated chemical levels in the feathers and livers of birds from different trophic levels.

Complex modulation of singing behavior by testosterone in an open-ended learner, the European Starling.

Structural changes between seasons in the songbird auditory forebrain.

Haematological status of wintering great tits (Parus major) along a metal pollution gradient.

The use of blue tit eggs as a biomonitoring tool for organohalogenated pollutants in the European environment.

Acute stress induces a rapid increase of testosterone in a songbird: implications for plasma testosterone sampling.

A screening of persistent organohalogenated contaminants in hair of East Greenland polar bears.

Endocrine disrupting, haematological and biochemical effects of polybrominated diphenyl ethers in a terrestrial songbird, the European starling (Sturnus vulgaris).

Breeding experience and the heritability of female mate choice in collared flycatchers.

Songs differing in consistency elicit differential aggressive response in territorial birds.

A first evaluation of the usefulness of feathers of nestling predatory birds for non-destructive biomonitoring of persistent organic pollutants.

Difficulties when assessing birdsong learning programmes under field conditions: a re-evaluation of song repertoire flexibility in the great tit.

Carotenoid supplementation positively affects the expression of a non-visual sexual signal.

Yolk androgen deposition without an energetic cost for female rockhopper penguins: a compensatory strategy to accelerate brood reduction?

Organohalogenated contaminants in eggs of rockhopper penguins (Eudyptes chrysocome) and imperial shags (Phalacrocorax atriceps) from the Falkland Islands.

Body feathers as a potential new biomonitoring tool in raptors: a study on organohalogenated contaminants in different feather types and preen oil of West Greenland white-tailed eagles (Haliaeetus albicilla).

GnRH--a missing link between testosterone concentrations in yolk and plasma and its intergenerational effects.

Negative effects of yolk testosterone and ticks on growth in canaries.

A comparison of non-destructive sampling strategies to assess the exposure of white-tailed eagle nestlings (Haliaeetus albicilla) to persistent organic pollutants.

Intra-clutch ratio of yolk progesterone level changes with laying date in rockhopper penguins: a strategy to influence brood reduction?

Sources of variation in yolk hormone deposition: consistency, inheritance and developmental effects.

Food conditions affect yolk testosterone deposition but not incubation attendance.

Are low-frequency songs sexually selected, and do they lose their potency in male-female interactions under noisy conditions?

Testosterone stimulates the expression of male-typical socio-sexual and song behaviors in female budgerigars (Melopsittacus undulatus): An experimental study.

Non-breeding song rate reflects nutritional condition rather than body condition.

Migratory constraints on yolk precursors limit yolk androgen deposition and underlie a brood reduction strategy in rockhopper penguins.

Penguin chicks benefit from elevated yolk androgen levels under sibling competition.

Environmental effects shape the maternal transfer of carotenoids and vitamin E to the yolk.

Testosterone increases repertoire size in an open-ended learner: an experimental study using adult male European starlings (Sturnus vulgaris).

Can starling eggs be useful as a biomonitoring tool to study organohalogenated contaminants on a worldwide scale?

Perfluoroalkyl substances in soft tissues and tail feathers of Belgian barn owls (Tyto alba) using statistical methods for left-censored data to handle non-detects.

Ecological and spatial factors drive intra- and interspecific variation in exposure of subarctic predatory bird nestlings to persistent organic pollutants.

Coadaptation of offspring begging and parental provisioning--an evolutionary ecological perspective on avian family life.

Hot or not: the effects of exogenous testosterone on female attractiveness to male conspecifics in the budgerigar.

Females paired with new and heavy mates reduce intra-clutch differences in resource allocation.

Testosterone influences song behaviour and social dominance - but independent of prenatal yolk testosterone exposure.

Legacy and current-use brominated flame retardants in the Barn Owl.

Antiparasite treatments reduce humoral immunity and impact oxidative status in raptor nestlings.

Behavioural response of European starlings exposed to video playback of conspecific flocks: effect of social context and predator threat.

Bare-part color in female budgerigars changes from brown to structural blue following testosterone treatment but is not strongly masculinized.

Brominated and phosphorus flame retardants in White-tailed Eagle Haliaeetus albicilla nestlings: bioaccumulation and associations with dietary proxies (δ¹³C, δ¹⁵N and δ³⁴S).

The relationship between DRD4 polymorphisms and phenotypic correlations of behaviors in the collared flycatcher.

Does reproduction protect against oxidative stress?

Oxytocin and vasopressin receptor gene variation as a proximate base for inter- and intraspecific behavioral differences in bonobos and chimpanzees.

Variation in clutch size in relation to nest size in birds.

Sources of variation in innate immunity in great tit nestlings living along a metal pollution gradient: an individual-based approach.

Carotenoids, birdsong and oxidative status: administration of dietary lutein is associated with an increase in song rate and circulating antioxidants (albumin and cholesterol) and a decrease in oxidative damage.

Hatching asynchrony aggravates inbreeding depression in a songbird (Serinus canaria): an inbreeding-environment interaction.

Influence of mate preference and laying order on maternal allocation in a monogamous parrot species with extreme hatching asynchrony.

Individual consistency and phenotypic plasticity in rockhopper penguins: female but not male body mass links environmental conditions to reproductive investment.

Personality in Bonobos.

Chimpanzee sociability is associated with vasopressin (Avpr1a) but not oxytocin receptor gene (OXTR) variation.

Two eggs, two different constraints: a potential explanation for the puzzling intraclutch egg size dimorphism in Eudyptes penguins.

Light pollution disrupts sleep in free-living animals.

Mates but not sexes differ in migratory niche in a monogamous penguin species.

Sexually antagonistic selection during parental care is not generated by a testosterone-related intralocus sexual conflict-insights from full-sib comparisons.

Effects of breeding habitat (woodland versus urban) and metal pollution on the egg characteristics of great tits (Parus major).

Sex roles in nest keeping - how information asymmetry contributes to parent-offspring co-adaptation.

Vitally important - does early innate immunity predict recruitment and adult innate immunity?

When ambient noise impairs parent-offspring communication.

Effects of experimentally sustained elevated testosterone on incubation behaviour and reproductive success in female great tits (Parus major).

High levels of mercury and low levels of persistent organic pollutants in a tropical seabird in French Guiana, the Magnificent frigatebird, Fregata magnificens.

Artificial light at night disrupts sleep in female great tits (Parus major) during the nestling period, and is followed by a sleep rebound.

Structural (UV) and carotenoid-based plumage coloration - signals for parental investment?

Is individual consistency in body mass and reproductive decisions linked to individual specialization in foraging behavior in a long-lived seabird?

'Out of tune': consequences of inbreeding on bird song.

Early life exposure to artificial light at night affects the physiological condition: An experimental study on the ecophysiology of free-living nestling songbirds.

Transfer of hexabromocyclododecane flame retardant isomers from captive American kestrel eggs to feathers and their association with thyroid hormones and growth.

Artificial light at night affects body mass but not oxidative status in free-living nestling songbirds: an experimental study.

Positive effect of dietary lutein and cholesterol on the undirected song activity of an opportunistic breeder.

Coadaptation of offspring begging and parental provisioning: A role for prenatal maternal effects?

Bonobo personality traits are heritable and associated with vasopressin receptor gene 1a variation.

Extreme intra-clutch egg size dimorphism is not coupled with corresponding differences in antioxidant capacity and stable isotopes between eggs.

High levels of PFOS in eggs of three bird species in the neighbourhood of a fluoro-chemical plant.

Does baseline innate immunity change with age? A multi-year study in great tits.

Organohalogenated contaminants in plasma and eggs of rockhopper penguins: Does vitellogenin affect maternal transfer?

Trophic ecology drives contaminant concentrations within a tropical seabird community.

Oxidative stress biomarkers are associated with visible clinical signs of a disease in frigatebird nestlings.

Neither artificial light at night, anthropogenic noise nor distance from roads are associated with oxidative status of nestlings in an urban population of songbirds.

Perfluoroalkylated acids in the eggs of great tits (Parus major) near a fluorochemical plant in Flanders, Belgium.

Ambient anthropogenic noise but not light is associated with the ecophysiology of free-living songbird nestlings.

Rigorous field experiments are essential to understand the genuine severity of light pollution and to identify possible solutions.

Decreasing parental task specialization promotes conditional cooperation.

The Female Perspective of Personality in a Wild Songbird: Repeatable Aggressiveness Relates to Exploration Behaviour.

Disruptive effects of light pollution on sleep in free-living birds: Season and/or light intensity-dependent?

Artificial light at night affects sleep behaviour differently in two closely related songbird species.

Learning speed is affected by personality and reproductive investment in a songbird.

Experimental infection by microparasites affects the oxidative balance in their avian reservoir host the blackbird Turdus merula.

Artificial light at night causes an unexpected increase in oxalate in developing male songbirds.

Oxidative stress favours herpes virus infection in vertebrates: a meta-analysis.

Variation in personality traits across a metal pollution gradient in a free-living songbird.

Cavities shield birds from effects of artificial light at night on sleep.

Sex-specific effects of inbreeding on reproductive senescence.

An experimental study: Does inbreeding increase the motivation to mate?

Effects of interspecific coexistence on laying date and clutch size in two closely related species of hole-nesting birds.

Personality and artificial light at night in a semi-urban songbird population: No evidence for personality-dependent sampling bias, avoidance or disruptive effects on sleep behaviour.

Sex-specific effects of inbreeding and early life conditions on the adult oxidative balance.

Limited reproductive impairment in a passerine bird species exposed along a perfluoroalkyl acid (PFAA) pollution gradient.

How to quantify animal activity from radio-frequency identification (RFID) recordings.

Do concentrations of perfluoroalkylated acids (PFAAs) in isopods reflect concentrations in soil and songbirds? A study using a distance gradient from a fluorochemical plant.

Variation in PFAA concentrations and egg parameters throughout the egg-laying sequence in a free-living songbird (the great tit, Parus major): Implications for biomonitoring studies.

Perfluoroalkyl Acids (PFAAs) Concentrations and Oxidative Status in Two Generations of Great Tits Inhabiting a Contamination Hotspot.

Personality and plasticity in neophobia levels vary with anthropogenic disturbance but not toxic metal exposure in urban great tits: Urban disturbance, metal pollution and neophobia.

Artificial light at night does not affect telomere shortening in a developing free-living songbird: A field experiment: Artificial light at night and telomere dynamics.

Transgenerational endocrine disruption: Does elemental pollution affect egg or nestling thyroid hormone levels in a wild songbird?

Enduring rules of care within pairs - how blue tit parents resume provisioning behaviour after experimental disturbance.

Development and validation of an extraction method for the analysis of perfluoroalkyl substances (PFASs) in environmental and biotic matrices.

Progress on bringing together raptor collections in Europe for contaminant research and monitoring in relation to chemicals regulation.

Nest defence behavioural reaction norms: testing life-history and parental investment theory predictions.

Temporal trends of mercury differ across three northern white-tailed eagle (Haliaeetus albicilla) subpopulations.

High inter- and intraspecific niche overlap among three sympatrically breeding, closely related seabird species: Generalist foraging as an adaptation to a highly variable environment?

An Important Personality Trait Varies with Blood and Plumage Metal Concentrations in a Free-Living Songbird.

Correction to: Progress on bringing together raptor collections in Europe for contaminant research and monitoring in relation to chemicals regulation.

Influence of soil physicochemical properties on the depth profiles of perfluoroalkylated acids (PFAAs) in soil along a distance gradient from a fluorochemical plant and associations with soil microbial parameters.

White-Tailed Eagle () Body Feathers Document Spatiotemporal Trends of Perfluoroalkyl Substances in the Northern Environment.

Carotenoid- but not melanin-based plumage coloration is negatively related to metal exposure and proximity to the road in an urban songbird.

Bonobo personality predicts friendship.

Early-life exposure to artificial light at night elevates physiological stress in free-living songbirds.

Anthropogenic noise is associated with telomere length and carotenoid-based coloration in free-living nestling songbirds.

Temporal trends of legacy organochlorines in different white-tailed eagle (Haliaeetus albicilla) subpopulations: A retrospective investigation using archived feathers.

Impacts of selective logging on the oxidative status of tropical understorey birds.

Are Feathers of a Songbird Model Species (The Great Tit, ) Suitable for Monitoring Perfluoroalkyl Acids (PFAAs) in Blood Plasma?

Sources of individual variation in problem-solving performance in urban great tits (Parus major): Exploring effects of metal pollution, urban disturbance and personality.

Perfluoroalkyl acids and sulfonamides and dietary, biological and ecological associations in peregrine falcons from the Laurentian Great Lakes Basin, Canada.

Perfluoroalkyl acid (PFAA) profile and concentrations in two co-occurring tit species: distinct differences indicate non-generalizable results across passerines.

Connecting the data landscape of long-term ecological studies: The SPI-Birds data hub.

A risk assessment of the effects of mercury on Baltic Sea, Greater North Sea and North Atlantic wildlife, fish and bivalves.

Understanding PFAAs exposure in a generalist seabird species breeding in the vicinity of a fluorochemical plant: Influence of maternal transfer and diet.

Little parental response to anthropogenic noise in an urban songbird, but evidence for individual differences in sensitivity.

The Pan social brain: An evolutionary history of neurochemical receptor genes and their potential impact on sociocognitive differences.

A rapid method for the detection and quantification of legacy and emerging per- and polyfluoroalkyl substances (PFAS) in bird feathers using UPLC-MS/MS.

The serotonin transporter gene and female personality variation in a free-living passerine.

Variable and consistent traffic noise negatively affect the sleep behavior of a free-living songbird.

Perfluoroalkylated acids (PFAAs) accumulate in field-exposed snails (Cepaea sp.) and affect their oxidative status.

Impacts of selective logging on haemosporidian infection and physiological correlates in tropical birds.

Singing is not associated with social complexity across species.

Serotonin transporter (SERT) polymorphisms, personality and problem-solving in urban great tits.

Respiratory Disease Risk of Zoo-Housed Bonobos Is Associated with Sex and Betweenness Centrality in the Proximity Network.

Social and nonsocial stimuli alter the performance of bonobos during a pictorial emotional Stroop task.

Historical museum samples enable the examination of divergent and parallel evolution during invasion.