Lukas Jenni

Lukas Jenni
Swiss Ornithological Institute

About

219
Publications
38,979
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9,926
Citations
Citations since 2016
41 Research Items
4195 Citations
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20162017201820192020202120220100200300400500600700
20162017201820192020202120220100200300400500600700

Publications

Publications (219)
Article
Full-text available
In many areas, domestic cats are the most abundant predators of small vertebrates. Due to the potential impact on prey populations by cats, there are calls to investigate the effectiveness of visual and acoustic cues as measures to reduce the cat's hunting efficiency. In this study, we complement previous studies on the efficacy of Birdsbesafe coll...
Article
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Space-based tracking technology using low-cost miniature tags is now delivering data on fine-scale animal movement at near-global scale. Linked with remotely sensed environmental data, this offers a biological lens on habitat integrity and connectivity for conservation and human health; a global network of animal sentinels of environmental change.
Article
Usually, some measurements are taken from birds caught for ringing, for example to differentiate between species, subspecies or sexes, or to obtain a measure of body size or energy stores. However, the ecomorphological interpretation of standard measures of the flight apparatus is often difficult, because flight models need parameters that are not...
Article
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Natal dispersal affects many processes such as population dynamics. So far, most studies have examined the intrinsic and extrinsic factors that determine the distance between the place of birth and of first breeding. In contrast, few researchers followed the first steps of dispersal soon after fledging. To study this gap, we radio-tracked 95 barn o...
Article
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The Brambling Fringilla montifringilla combines several special features of migration and wintering: differential migration according to age and sex groups, large differences in winter densities as a response to food availability, and flocking behaviour as a response to local mass fructification of the beech Fagus sp. resulting in roosts of several...
Article
Understanding how vulnerable species are to new stressors, such as anthropogenic changes, is crucial for mitigating their potential negative consequences. Many studies have investigated species sensitivity to human disturbance by focusing on single behavioral or physiological parameters, such as flight initiation distance and glucocorticoid levels....
Article
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Personalities, i.e. consistent individual differences in behaviour, have been found in many animal populations. However, the reasons why personalities emerge, how they persist and the consequences they have in a changing environment are poorly understood. Factors influencing personalities include genetic background, prenatal (e.g. hormonal) and pos...
Article
Animal reintroductions are important tools for conservation but often fail for reasons poorly understood. Biological and methodological factors can affect reintroduction success in complex manners. Investigating dispersal after release often relies on the use of biologging devices but individuals cope differently with these devices. They can detrim...
Article
Glucocorticoid hormones, such as corticosterone, are crucial in regulating daily life metabolism and energy expenditure, as well as promoting short-term physiological and behavioural responses to unpredictable environmental challenges. Therefore, glucocorticoids are considered to mediate trade-offs between survival and reproduction. Relatively litt...
Article
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During the periodic moult of the plumage of birds, a fast regrowth of feathers would shorten the time of reduced plumage functionality. However, it has long been known that feather growth-rate is limited and that long feathers take disproportionally longer to grow than small feathers, which has severe consequences on moult duration and the complete...
Article
Outdoor recreational activities are booming and most animals perceive humans as predators, which trigger behavioural and/or physiological reactions (e.g. heart rate increase, activation of the hypothalamic-pituitary-adrenal (HPA) axis). Physiological stress reactions have been shown to affect the immune system of an animal and therefore may also af...
Article
2014): Modulation of the stress response in birds and its meaning in nature conservation. Ornithol. Beob. 111: 107-120. During threatening situations birds react with the activation of the hypothala-mo-pituitary-adrenal axis (HPA-axis). Corticosterone, the main glucocorticoid in birds, is released from the adrenal cortex into the circulation in hig...
Article
Assessing and modelling abundance from animal count data is a very common task in ecology and management. Detection is arguably never perfect, but modern hierarchical models can incorporate detection probability and yield abundance estimates that are corrected for imperfect detection. Two variants of these models rely on counts of unmarked individu...
Article
Yolk hormones are substances which transmit non-genetic factors from the mother to the next generation. The systematic changes of yolk hormone concentrations within asynchronously hatching clutches have been interpreted as a means to adaptively shape the offspring's phenotype. However, in synchronously hatching clutches the role of yolk hormones is...
Article
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The hypothalamic–pituitary–adrenal (HPA) axis is responsible for the regulation of corticosterone, a hormone that is essential in the mediation of energy allocation and physiological stress. As a continuous source of challenge and stress for organisms, the environment has promoted the evolution of physiological adaptations and led to a great variat...
Article
1.Neonicotinoids are the most widely used class of insecticides globally. However, the link between farming practices and the extent of contamination of soils and crops by neonicotinoid insecticides, as well as and the extent of such contamination in organic fields and ecological focus areas (EFAs) are currently unclear. 2.We measured the concentra...
Preprint
Full-text available
In biparental species, reproductive success depends not only on the quality of the parents, the care they each provide and many environmental factors such as territory quality and food availability, but also on the ability of the parents to collaborate and divide reproductive tasks. Because hormones, such as corticosterone (CORT), modulate physiolo...
Preprint
Full-text available
Glucocorticoid hormones, such as corticosterone, are fundamental in the translation of external stimuli into physiological adjustments that promote the survival of an organism in face of changes in its environment. At baseline levels, corticosterone is crucial in regulating daily life metabolism and energy expenditure, whereas the acute corticoster...
Article
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Despite irrefutable evidence of its negative impact on animal behaviour and physiology, lethal and sublethal lead poisoning of wildlife is still persistent and widespread. For scavenging birds, ingestion of ammunition, or fragments thereof, is the major exposure route. In this study, we examined the occurrence of lead in four avian scavengers of Sw...
Article
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Outdoor recreational activities are increasing worldwide and occur at high frequency especially close to cities. Forests are a natural environment often used for such activities as jogging, hiking, dog walking, mountain biking, or horse riding. The mere presence of people in forests can disturb wildlife, which may perceive humans as potential preda...
Article
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Wildlife perceive humans as predators, and therefore normally flushes. Flight initiation distance (FID) is the distance a human can approach an animal at a steady pace until it flushes. Recently, several studies showed differences in within-species FID according to human presence by comparing urban and rural habitats, with urban birds showing reduc...
Data
Fig. S1. Vegetation measures (mean model estimates with 95% credible intervals) describing the three different forests where FID measures have been taken. Note that vegetation measures were taken within the framework of a different study and thus do not entirely coincide in season or exact locations within forest with the FID measures. Therefore we...
Article
Whether long‐distance animal migration facilitates or hampers pathogen transmission depends on how infections affect the routes and timing of migrating hosts. If an infection directly or indirectly impedes migratory flight capacity, infected individuals lag behind their uninfected conspecifics. Although such temporal segregation can limit parasite...
Article
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Methods to assess environmental pollution and stress responses in birds with scarcely invasive or non-invasive sampling are highly sought after in ecology and conservation. For several years now, feathers have been promoted as non-invasive tools to assess stress physiology and environmental pollution in birds. This has mainly been applied in whole...
Article
Large declines of farmland bird species have been observed in the lowlands of Western Europe, whereas important populations of some of these species have survived in parts of Eastern and Southern Europe and in small areas within Western Europe, e.g. in parts of the Alps. However, such extant hotspots of farmland biodiversity are at risk: The econom...
Article
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The worldwide increase in human outdoor activities raises concerns for wildlife. Human disturbances, even at low levels, are likely to impact species during sensitive periods of the annual cycle. However, experimental studies during the putative sensitive period of territory establishment of birds which not only investigate low disturbance levels,...
Article
Throughout Europe ground-nesting farmland bird species are rapidly declining and have become a conservation concern. Intensive agriculture and high nest predation rates are major factors causing the decline. Species conservation efforts often focus on habitat enhancement to increase the quantity and quality of available habitat structures (habitat...
Article
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Urban areas expand worldwide, transforming landscapes and creating new challenging habitats. Some bird species, mainly omnivorous feeding on human waste and cavity nesters, commonly breed in these habitats and are, therefore, regarded as urban-adapted. Although urban areas may provide new nesting sites and abundant human waste, the low breeding suc...
Article
Animals which spend subsequent seasons in different areas connect geographical regions. The connection between breeding and non-breeding grounds is defined as migratory connectivity. The quantification of such connectivity is important, because movements between different locations can have strong consequences for the moving animal as well as the e...
Article
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The solar day–night rhythm imposes a strict diel activity pattern on many organisms. Among birds, most species are generally either active during the day and rest during the night, or vice versa. However, many waterbird species can be active during both daylight and darkness. Hence, these species are much less limited by an external clock to alloca...
Article
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Endothermic animals vary in their physiological ability to maintain a constant body temperature. Since melanin-based coloration is related to thermoregulation and energy homeostasis, we predict that dark and pale melanic individuals adopt different behaviours to regulate their body temperature. Young animals are particularly sensitive to a decrease...
Article
Alpine species adapted to mountain climate are particularly vulnerable to environmental changes and have recently come under multiple environmental pressures, such as climate change associated with habitat loss (e.g. upward shift of the treeline) and unfavourable weather, as well as increasing human recreation activities. A prime example is the Alp...
Article
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Outdoor recreation is increasing in intensity and space. Areas previously inaccessible are now being visited by ever-growing numbers of people, which increases human-wildlife encounters across habitats. This has raised concern among researchers and conservationists as, even in non-aggressive encounters, animals often perceive humans as predators an...
Article
Full-text available
Several cases of acute lead poisoning of golden eagles Aquila chrysaetos have been documented in the Alps. The question, however, remains how often golden eagles take up lead (once, chronically or episodically) and whether this uptake is in fatal or sublethal amounts. We approached this question by examining the level and frequency distribution of...
Article
The Alpine Rock Ptarmigan Lagopus muta helvetica is considered to be particularly vulnerable to climate warming because it lives exclusively above the tree-line in alpine habitats and is adapted to cold climates. Its Swiss population index has decreased over the last two decades. A considerable shrinkage in distributional area is predicted with fur...
Article
Nine wintering Mallards were equipped with GPS tags with accelerometer. The location was registered every 30 min, and from the accelerometer data the duck was categorized as being active vs. inactive every two to five minutes. We observed large differences in the behaviour among individuals, e.g. in the local movements within the study perimeter of...
Article
Human activities can have a suite of positive and negative effects on animals and thus can affect various life history parameters. Human presence and agricultural practice can be perceived as stressors to which animals react with the secretion of glucocorticoids. The acute short-term secretion of glucocorticoids is considered beneficial and helps a...
Article
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The Alpine Rock Ptarmigan (Lagopus muta helvetica)—which is adapted to arctic and alpine environments—is suspected to be vulnerable to climate warming, but direct evidence is limited. Microclimates within a landscape may allow species to exist in regions where the general climate appears to be unsuitable for them. We therefore investigated the dive...
Article
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Fragments from lead ammunition pose a poisoning risk for predators like golden eagles that scavenge on non-retrieved carcasses or offal left behind by hunters. Three golden eagles were found in the Swiss Alps with an acute lead poisoning. To investigate whether the few cases of lead-poisoned golden eagles are exceptional events or whether a substan...
Article
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1. The concentration of the glucocorticoid hormone corticosterone (CORT) is increasingly used in ecology and conservation biology as an integrated measure of the historical record of an individual’s hypothalamo-pituitary-adrenal (HPA) activity during feather growth. However, where and how CORT is incorporated in feathers is incompletely known. 2. W...
Article
Glucocorticoid (GC) hormones, i.e. corticosterone (CORT) in birds, support physiological homeostasis and facilitate adaptations to stressful situations. However, maintaining high GC levels are energetically costly and interfere with other physiological processes. To keep the balance of costs and benefits of GC hormones, various mechanisms act to ad...
Article
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From 2007 to 2010, 4558 migrating and breeding birds of 71 species were caught and examined for ticks in Switzerland. A total of 1205 specimens were collected; all were Ixodes ricinus ticks except one Ixodes frontalis female, which was found on a common chaffinch (Fringilla coelebs) for the first time in Switzerland. Each tick was analysed individu...
Article
During translocations, stress, as measured by the increase of glucocorticoids, cannot be avoided, but has been suspected to exacerbate the vulnerability to many causes of mortality after release. Therefore, measures to reduce stress have been proposed, such as keeping animals in pens before release (soft release). In this study, we investigated two...
Article
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Migrating birds perform extraordinary endurance flights, up to 200 h non-stop, at a very high metabolic rate and while fasting. Such an intense and prolonged physical activity is normally associated with an increased production of reactive oxygen and nitrogen species (RONS) and thus increased risk of oxidative stress. However, up to now it was unkn...
Article
Climate warming and land use change represent a major challenge for both species and conservation managers. Temporally and spatially explicit projections of the future distribution of species have been extensively developed to support decision-making in conservation. The aim of this study was to move beyond the simple projections of likely impacts...
Article
Detailed knowledge about claw formation and growth rate is a prerequisite for the interpretation of avian claw stable isotopes, as is commonly done with feather stable isotopes to e.g. infer habitat use, dietary specialisations, and spatial occurrence. In this study, we provide basic information about claw formation and empirical evidence about the...
Article
Genetic background, prenatal and post-natal early-life conditions influence the development of interconnected physiological systems and thereby shape the phenotype. Certain combinations of genotypes and pre- and post-natal conditions may provide higher fitness in a specific environmental context. Here, we investigated how grey partridges Perdix per...