Martin Mayer

• PhD
• Associate Professor at University of Inland Norway

Large carnivore populations have increased in many areas of Europe, resulting in socio-political conflicts, especially in areas with extensive outfield grazing systems. In Norway, the occurrence of large carnivores, especially brown bears (Ursus arctos) and grey wolves (Canis lupus), are largely separated from outfield grazing areas via carnivore m...

We present an overview of wildlife-vehicle collision (WVC) liability covering 36 European countries. We reviewed approaches to WVC liability which are currently in effect across Europe and their potential consequences for WVC reporting. To obtain relevant information, we conducted a survey, including a web-based questionnaire. We retrieved answers...

Knowledge concerning seasonal changes of species richness and abundance across different habitats is an important step to understand crucial landscape features for the conservation of declining species. This is especially the case in highly human-dominated agricultural landscapes, which have undergone massive changes in land use structure and inten...

Understanding intraspecific variation in habitat selection by polytypic species, where distinct variants occur in separate populations, can improve our knowledge of population-specific selective pressures and inform conservation measures. Here, we investigated differences in habitat selection across six populations of the dyeing poison frog (Dendro...

Aim: Colour polymorphism within ectothermic species and populations is shaped by multiple selection pressures that can vary geographically. Here, we tested different hypotheses to better understand this variation in colour polymorphism. The thermal melanism hypothesis predicts that darker colouration is beneficial in colder regions, due to enhanced...

Roadkill is widely recognized as one of the primary negative effects of roads on many wildlife species and also has socioeconomic impacts when they result in accidents. A comprehensive dataset of roadkill locations is essential to evaluate the factors contributing to roadkill risk and to enhance our comprehension of its impact on wildlife populatio...

Roadkill is widely recognized as one of the primary negative effects of roads on many wildlife species and also has socioeconomic impacts when they result in accidents. A comprehensive dataset of roadkill locations is essential to evaluate the factors contributing to roadkill risk and to enhance our comprehension of its impact on wildlife populatio...

Fenced areas are commonly used for conservation purposes or to prevent human-wildlife conflicts. However, their use is controversial since they create barriers blocking the movements of terrestrial species, thereby potentially impeding their biological needs and ecological functions. Using >440,000 GPS positions of 37 female red deer (Cervus elaphu...

Population indices, such as transect counts of animals, can provide important information concerning population changes over time. Moreover, data concerning the home range size and habitat selection of individuals can provide valuable insight into spatial requirements of animals and how they can adapt to variable environments. Here, we describe the...

Globally, collisions with vehicles result in millions of animal deaths every year, representing a major issue for wildlife conservation and management. Consequently, and importantly, much research has focused on understanding patterns of animal–vehicle collisions with the aim to reduce roadkill of wildlife. However, existing data on animal–vehicle...

Efficient wildlife management requires precise monitoring methods, for example to estimate population density, reproductive success, and survival. Here, we compared the efficiency of drone (equipped with a RGB camera) and ground approaches to detect and observe GPS‐collared female moose Alces alces and their calves. We also quantified how drone (n...

Intraspecific variation in body size, both among populations and between sexes, is an important factor influencing life-history strategies. This variation might be the response to different environmental conditions, as well as natural and sexual selection, and can result in differences in behavior and reproductive strategies among populations. Here...

Artisanal and small-scale gold mining (ASGM) has become a major threat for Neotropical forests. This technique for obtaining gold is a substantial driver of small-scale deforestation and the largest contributor of Hg emissions to both the atmosphere and freshwater systems globally. Previous studies have demonstrated the impacts of Hg accumulation o...

Efficient wildlife management requires precise monitoring methods, e.g., to estimate population density, reproductive success, and survival. Here, we compared the efficiency of drone and ground approaches to detect and monitor GPS-collared female moose (Alces alces) and their calves. Moreover, we quantified how drone (n = 42) and ground (n = 41) ap...

Intraspecific variation in body size, both among populations and between sexes, is an important factor influencing life-history strategies. This variation might be the response to different environmental conditions, as well as natural and sexual selection, and can result in differences in behavior and reproductive strategies among populations. Here...

Wetlands are particularly vulnerable to degradation in urban environments, partially due to the introduction of non-native plants. Invasive weeds in wetlands can replace native plants leading to alterations in habitat composition and vegetation, in turn, animal movements and ultimately population dynamics might be affected. Here we investigate how...

I rapporten analyseres bestandsdata for rådyr baseret på vildtudbyttestatistikken (1955-2020) og påkørsler i trafikken (2003-2010, 2017-2019) med henblik på at beskrive bestandens sammensætning og status samt variation i tid og rum. Analyserne har særlig fokus på at tilvejebringe viden, som kan forklare nedgangen i det nationale vildtudbytte siden...

Assessing the underlying mechanisms of species co-occurrence patterns can be challenging as biotic and abiotic factors are hard to disentangle. To date, few studies have investigated co-occurrence patterns of mammals within urban areas. As urban areas are increasingly used as habitat by wildlife, there is a need for a better understanding of urban...

Beavers can change habitat composition by cutting down trees, digging, and damming activities, thereby affecting species richness and abundance. Although there is large body of literature regarding the effects of beaver activity on a wide range of taxonomic groups, relatively little is known about how space use by ungulates is affected by beavers i...

Context Roads are ubiquitous in human inhabited landscapes, and can impact animal movement and population dynamics, due to barrier effects, road mortality, but also by providing resources at road verges. Thus, we need a better understanding of how roads, in interaction with seasonal changes in habitat structure, affect space use and habitat selecti...

Farmland biodiversity is declining at an alarming rate and various conservation measures have been implemented to reverse this negative trend. Farmsteads within agricultural landscapes were recently identified as farmland bird hotspots, so we ask whether the modernization of farmsteads has substantially reduced their conservation potential for farm...

Beavers can change habitat composition by cutting down trees, digging, and damming activities, thereby affecting species richness and abundance. Although there is large body of literature regarding the effects of beaver activity on a wide range of taxonomic groups, relatively little is known about how space use by ungulates is affected by beavers i...

Abstract Coevolutionary host–parasite “arms races” can be disrupted by new evolutionary forces imposed by biological invasions, affecting both host and parasite densities, as well as their traits. The spread of cane toads (Rhinella marina) and their parasitic lungworm (Rhabdias pseudosphaerocephala) across tropical Australia provides an ideal oppor...

Antipredator behaviors allow prey to mitigate the impacts of their predators. We investigated antipredator responses of two herbivore species, roe deer and European hare, and one mesopredator, red fox, toward predation risk imposed by lynx and wolf. We collected data (using camera traps) on visitation frequency and vigilance behavior to olfactory p...

Translocations, “the deliberate movement of organisms from one site for release in another”, are increasingly being used for wildlife conservation and management. However, their success rate is still relatively low. Failures of translocation projects have often been attributed to the extensive movements made by newly-released individuals or their i...

Background Passive integrated transponder devices (PIT tags) are a valuable tool for individual identification of animals. Similarly, the surgical implantation of transmitters and bio-loggers can provide useful data on animal location, physiology and behavior. However, to avoid unnecessary recapture and related stress of study animals, PIT tags and...

The zip-file ” Mammal responses to predator scents across multiple study areas_data, scripts and outputs.zip” contains raw data, scripts and outputs (with explanations) for the paper: P. Sunde, F. Böcker, G-R. Rauset, P. Kjellander, M. Chrenkova, T. M. Skovdal, S. van Beeck Calkoen, M. Mayer & M. Heurich (2022). Mammal responses to predator scents...

Assessing the underlying mechanisms of co-occurrence patterns can be challenging as biotic and abiotic causations are hard to disentangle. To date, few studies have investigated co-occurrence patterns within urban areas that constitute novel habitat to numerous wildlife species. Moreover, as urban areas expand and are increasingly used as habitat b...

ContextRoads are ubiquitous in human inhabited landscapes, and can impact animal movement and population dynamics, due to barrier effects, road mortality, but also by providing resources at road verges. Thus, we need a better understanding of how roads, in interaction with seasonal changes in habitat structure, affect space use and habitat selectio...

Attacks by large predators on livestock are an important driver of conflicts. Consequently, knowledge about where predators occur, where livestock depredation takes place and what factors influence it will aid the mitigation of stakeholder conflicts. Following legal protection, wolves (Canis lupus) in Central Europe are recently spreading to areas...

Background Passive integrated transponder devices (PIT tags) are a valuable tool for individual identification of animals. Similarly, the surgical implantation of transmitters and bio-loggers can provide useful data on animal location, physiology and behavior. However, to avoid unnecessary recapture and related stress of study animals, PIT tags and...

Attacks by large predators on livestock are an important driver of conflicts. Consequently, knowledge about where predators occur, where livestock depredation takes place and what factors influence it will aid the mitigation of stakeholder conflicts. Following legal protection, wolves (Canis lupus) in Central Europe are recently spreading to areas...

Bio-logging is a common method to collect ecological data on wild animals, but might also induce stress, reduce body condition, and alter behavior. Eurasian beavers (Castor fiber) are a semi-aquatic and nocturnal species that are challenging to observe in the wild. Bio-loggers are hence useful tools to study their behaviour and movements, but this...

Advances in bio-logging technology for wildlife monitoring have expanded our ability to study space use and behavior of many animal species at increasingly detailed scales. However, such data can be challenging to analyze due to autocorrelation of GPS positions. As a case study, we investigated spatiotemporal movements and habitat selection in the...

Capture and handling of wildlife is an important component of wildlife studies, and hunting can be a central tool for wildlife management. However, human-caused disturbance of animals can cause various negative effects on individuals. Thus, an increased understanding of different disturbances on animals will allow improved mitigation of human stres...

Amphibian skin secretions (substances produced by the amphibian plus microbiota) plausibly act as a first line of defense against parasite/pathogen attack, but may also provide chemical cues for pathogens. To clarify the role of skin secretions in host–parasite interactions, we conducted experiments using cane toads (Rhinella marina) and their lung...

Vehicles collide with hundreds of thousands of deer on European roads each year. This leads to animal deaths and suffering, economic damage and risks for human safety, making the reduction of road mortality a major field in conservation biology. In order to successfully reduce roadkill, we need improved knowledge regarding spatio-temporal patterns...

With less than 15 known remaining breeding pairs, the Little Owl Athene noctua is on the verge of extinction as a Danish breeding bird, due to inadequate juvenile production, caused by lack of natural food during the breeding season. This report presents results of a study to identify the requirements for maintaining a natural, self-supporting popu...

Det biologiske levegrundlag for kirkeugler i Danmark. In Danish with English Summary: Habitat and prey requirements for the Little Owl in Denmark, and Deutsche Zusammenfassung: Lebensraum- und Beuteanforderungen für den Steinkauz in Dänemark Sammendrag Med under 15 kendte, tilbageværende ynglepar er kirkeuglen på randen til at uddø som dansk yng...

Eurasian beaver familiarity mate change mate choice pair replacement reproductive success territoriality Territory acquisition and pair compatibility are determining factors for the fitness of territorial animals. Although these aspects are often studied separately, for territorial monogamous species acquiring a territory and obtaining a mate are n...

Amphibian skin secretions (substances produced by the amphibian plus microbiota) plausibly act as a first line of defense against pathogen attack, but may also provide chemical cues for pathogens. To clarify the role of skin secretions in host-parasite interactions, we conducted experiments using cane toads (Rhinella marina) and their lungworms (Rh...

By perturbing co-evolved interactions, biological invasions provide an opportunity to study the evolution of interactions between hosts and their parasites on ecological timescales. We studied the interaction between the cane toad (Rhinella marina) and its direct-lifecycle lungworm (Rhabdias pseudosphaerocephala) that was brought from South America...

In our paper, using distance sampling, we estimated the population density of hares in Aarhus city to 6.8 hares/km2.

Intraspecific competition plays an important role for territory acquisition and occupancy, in turn affecting individual fitness. Thus, understanding the drivers of intraspecific aggression can increase our understanding of population dynamics. Here, we investigated intraspecific aggression in Eurasian (Castor fiber) and North American (Castor canad...

Food storage (caching, hoarding), which is observed in many species of animals, increases food availability during times of food insecurity. Both species of beaver (Eurasian beaver, Castor fiber, and the North American beaver, C. canadensis) living at northern latitudes where food may be scarce during winter are larder-hoarders, constructing a food...

Social interactions among individuals play a central role in behavioural ecology and studying cohesion of monogamous pairs is important to understand their social relationships. Here, we tested five hypotheses to investigate patterns of pair cohesion in an obligate monogamous mammal, the Eurasian beaver, Castor fiber. We hypothesized that pair cohe...

Animal carcasses provide an ephemeral pulse of nutrients for scavengers that use them. Carcass sites can increase species interactions and/or ephemeral, localized landscapes of fear for prey within the vicinity. Few studies have applied the landscape of fear to carcasses. Here, we use a mass die-off of reindeer caused by lightning in Norway to test...

Animal behaviour can affect individual fitness and is influenced by exogenous and endogenous factors. Here, we investigated how light (daylight length and moonlight), weather (precipitation and temperature), age, sex and social status affected activity and movement of a semiaquatic mammal, the Eurasian beaver (Castor fiber), using GPS relocation da...

Predator presence can create a “landscape of fear,” which is defined as the spatially explicit distribution of perceived predation risk as seen by prey. Prey species can alter their behavior and space use as a response to increased predation risk, which might be traded off with energetic requirements. Thus, whether or not an anti‐predator behavior...

Despite the accelerating global urbanization and its associated implications for wildlife and humans, we know little about the biology of urban ecosystems. Here, we investigated colonization and habitat selection of the European hare (Lepus europaeus), a declining farmland species, in urban areas in Denmark, using a combination of citizen science d...

Although risk assessments for pesticides involve quantifying exposure routes for animals, little empirical evidence exists on how individuals use areas where pesticides were used. Further, the European Food Safety Authority guidelines for the risk assessment of birds and mammals currently only include direct dietary uptake from exposed plants as im...

Context Human land use intensified over the last century and simultaneously, extreme weather events have become more frequent. However, little is known about the interplay between habitat structure, direct short-term weather effects and indirect seasonal effects on animal space use and behavior. Objectives We used the European hare (Lepus europaeu...

Territoriality is an important process shaping population dynamics, and the defence of a territory is crucial for individuals to increase the duration of territory occupancy and, consequently, reproductive success. However, little is known about how the frequency of territory intrusions and subsequent territorial behaviours and aggression by territ...

Human encroachment on nature grows constantly, increasing human-wildlife interactions. Flight initiation distance (FID, the distance at which animals flee from an approaching threat) is often used to measure antipredator behaviour and establish buffer zones to reduce human impact on wildlife. In this study, we approached 10 waterbird species on lar...

Global Positioning System (GPS) technology is widely used in wildlife research to study animal movement and habitat use. In order to evaluate the quality and reliability of GPS data, the factors influencing the performance of these devices must be known, especially for semiaquatic species, because terrestrial and aquatic habitat might affect GPS pe...

Agricultural land-use practices have intensified over the last decades, leading to population declines of various farmland species, including the European hare (Lepus eu-ropaeus). In many European countries, arable fields dominate agricultural landscapes. Compared to pastures, arable land is highly variable, resulting in a large spatial variation o...

Chemical communication by scent‐marking is widespread among mammals and can serve different purposes, such as territory demarcation, mate attraction and self‐advertisement. In this study, we examined scent‐marking behavior by subordinate Eurasian beavers (Castor fiber) in a population in southeast Norway. We conducted scent experiments in 18 family...

Front Cover: A GPS-collared European hare (Lepus europaeus) in a barley field. During the last decades, hare populations have declined due to agricultural intensification. Vegetation height and agricultural field size are important factors affecting habitat selection by hares in arable landscapes. Thus, increasing landscape heterogeneity can increa...

Territorial animals carry out extraterritorial movements (forays) to obtain pre-dispersal information or to increase reproductive success via extra-pair copulation. However, little is known about other purposes and spatial movement patterns of forays. In this study, we GPS-tagged 54 Eurasian beavers (Castor fiber), a year-round territorial, monogam...

We studied life history strategies in the Eurasian beaver (Castor fiber), a territorial, monogamous, long-lived mammal, to increase our understanding of the mechanisms and trade-offs affecting the onset of natal dispersal, mate change, spatial movement patterns, and the duration of territory occupancy. The mean age at dispersal in our study area wa...

Many invasive species exploit anthropogenically disturbed habitats, but most of those taxa evolved long before humans. Presumably, then, an ability to use natural (non-anthropogenic) disturbances pre-adapted invaders to a world later degraded by people. Studies on invasive species in naturally disturbed habitats thus can clarify the ancestral niche...

In territorial, socially monogamous species, the establishment and defense of a territory are an important strategy to maximize individual fitness, but the factors responsible for the duration of territory occupancy are rarely studied, especially in long-lived mammals. A long-term monitoring program in southeast Norway spanning over 18 years allowe...

Mate change in socially monogamous species can be explained by adaptive and non-adaptive hypotheses. Adaptive hypotheses describe a mate change as a strategy to correct for initial mate choice and to improve reproductive success: the ‘incompatibility’ hypothesis states that mate change is initiated by both mates, whereas in the ‘better option’ hypo...

As dispersal is a dangerous part of an individual's life, its timing is important to increase the chances of survival and successful establishment of a territory. We investigated factors affecting the timing of natal dispersal in the Eurasian beaver, Castor fiber, a territorial, monogamous, long-lived mammal, using data from an 18-year individual-b...

In tropical Australian rainforests, predators and scavengers aggregate beneath emergent trees that house large colonies of metallic starlings (Aplonis metallica), feeding in the nutrient-rich open areas below. Analysis of camera-trap records shows that the presence of feral pigs (Sus scrofa) is associated with an absence of birds (cockatoos and bru...

Territoriality is only profitable when the benefits gained from territory exploitation exceed the costs of defence, and territory sizes are usually optimized by time constraints related to resource defence (e.g. patrolling) and exploitation. In this study, we equipped 25 dominant Eurasian beavers (Castor fiber) with GPS units to study spatial movem...

An animal’s susceptibility to risk may be partly dependent on its body size. But are larger individuals bolder? We assessed this question by measuring time to emerge from a shelter in repeated trials on hatchling keelback snakes (Tropidonophis mairii). Estimates of repeatability of emergence times suggested they measure some underlying personality...

The ecological impacts of introduced species can reveal mechanisms underlying habitat selection and behaviour. We investigated the habitat use of native frog species and the invasive cane toads ( Rhinella marina ) in tropical northern Australia to measure overlap in habitat use, and to test if the presence of the cane toad influences frog behaviour...

We investigated patterns of prevalence and intensity of gastrointestinal nematode infections in a tropical natricine snake, the keelback (Tropidonophis mairii). Ninety-eight per cent of keelbacks were infected with Tanqua anomala (Gnathostomidae), with infection intensities of up to 243 worms per snake. Infection with T. anomala caused severe infla...

Two species of green frogs exist in the state of Bavaria (Germany), the Marsh Frog (Pelophylax ridibundus) and the Pool Frog (Pelophylax lessonae). The Edible Frog (Pelophylax esculentus) is a hybridogenetic hybrid originally resulting from Marsh Frogs mating with Pool Frogs and therefore sometimes not considered a true species. Its distribution co...