Martin Mayer

• Mayer, Martin; Furuhovde, Erlend; Nordli, Kristoffer; Ausilio, Giorgia; Wabakken, Petter & Eriksen, Ane [Vis alle 9 forfattere av denne artikkelen] (2024). Monitoring GPS-collared moose by ground versus drone approaches: efficiency and disturbance effects. Wildlife Biology. ISSN 0909-6396. doi: 10.1002/wlb3.01213.
• Schlippe-Justicia, Lia; Lemaire, Jérémy; Dittrich, Carolin; Mayer, Martin; Bustamante, Paco & Rojas, Bibiana (2023). Poison in the nursery: Mercury contamination in the tadpole-rearing sites of an Amazonian frog. Science of the Total Environment. ISSN 0048-9697. 912. doi: 10.1016/j.scitotenv.2023.169450.
• Schlippe Justicia, Lia; Mayer, Martin; Lorioux-Chevalier, Ugo; Dittrich, Carolin; Rojas, Bibiana & Chouteau, Mathieu (2023). Intraspecific divergence of sexual size dimorphism and reproductive strategies in a polytypic poison frog. Evolutionary Ecology. ISSN 0269-7653. doi: 10.1007/s10682-023-10280-2. Fulltekst i vitenarkiv
• Svanholm Pejstrup, Malene; Andersen, Jonas & Mayer, Martin (2023). Beaver foraging patterns in a human-dominated landscape: Effects on woody vegetation and mammals. Forest Ecology and Management. ISSN 0378-1127. 528. doi: 10.1016/j.foreco.2022.120645. Fulltekst i vitenarkiv
• Bach, Henriette; Escoubet, Hannah & Mayer, Martin (2023). Co-occurrence patterns and habitat selection of the mountain hare, European hare, and European rabbit in urban areas of Sweden. Mammalian Biology. ISSN 1616-5047. 103, s. 187–203. doi: 10.1007/s42991-022-00339-y. Fulltekst i vitenarkiv
• Mayer, Martin; Fischer, Christina; Blaum, Niels; Sunde, Peter & Ullmann, Wiebke (2022). Influence of roads on space use by European hares in different landscapes. Landscape Ecology. ISSN 0921-2973. doi: 10.1007/s10980-022-01552-3. Fulltekst i vitenarkiv Vis sammendrag

  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 selection of the animals that persist in these landscapes. Objectives Here, we used the European hare (Lepus europaeus) as model species to investigate how human-induced changes in landscape composition—measured as road density, land cover type, and field size—affect home range location, seasonal habitat selection and road crossings, which are likely to correlate with wildlife-vehicle collision risk. Methods We collected > 240,000 GPS positions of 90 hares from three populations (one in Denmark and two in Germany) that differed regarding agricultural intensification and road density. Using this data, we analyzed home range location and habitat selection (using step-selection functions) in relation to roads, habitat composition, and seasonality, and quantified how these factors affected road crossings by hares. Results In comparatively more heterogeneous landscapes, hares established home ranges in areas with lower road densities compared to the surrounding area, but not in more simple landscapes. Moreover, hares generally avoided main roads and selected for minor roads during the vegetation growth seasons, especially in areas with comparatively less heterogeneous habitat structure. Hares crossed more main roads when moving greater distances, with movement distances being comparatively larger in simpler landscapes. Conclusions Our findings emphasize that it is important to distinguish between road types, as different roads can have different impacts on animals (e.g., small roads providing foraging opportunities via roadside vegetation and large roads being avoided). Moreover, animals in comparatively more heterogeneous landscapes are better able to adjust their habitat selection to avoid main roads than animals inhabiting simpler landscapes. More generally, homogenous landscapes increase the space use requirements of animals, leading to increased probability of road crossings, which in turn might affect population dynamics via increased road mortality risk.

• Šálek, Martin & Mayer, Martin (2022). Farmstead modernization adversely affects farmland birds. Journal of Applied Ecology. ISSN 0021-8901. 60(1), s. 101–110. doi: 10.1111/1365-2664.14314. Vis sammendrag

  1. 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 farmland birds. 2.We assessed the effect of farmstead modernization on 29 farmland bird species in rural landscapes on 97 dairy farms across the Czech Republic, investigating differences in farmland bird abundance and species richness, as well as nest abundance of declining farmland species breeding in buildings, by comparing new/modernized with old and mixed farmsteads. Additionally, we investigated how farmstead size and environmental variables influenced avian assemblages on farmsteads. 3.Farmland bird abundance was almost 3-fold lower in new/modernized farmsteads compared to mixed and old farmsteads (this difference was mostly driven by building-nesters and noncrop-nesters). Similarly, species richness was higher in old and mixed farmsteads compared to new farmsteads. Old cow sheds hosted more nests (both old and new nests; by a factor of 1.6–21) of house sparrows Passer domesticus, barn swallows Hirundo rustica and house martins Delichon urbicum compared to new cow sheds. 4.Importantly, effects of environmental variables were negligible or smaller compared to the farmstead type, suggesting that bird abundance and species richness on farmsteads was primarily driven by farmstead modernization rather than the structure of surrounding farmland. 5.Synthesis and applications. Farmstead modernization may have strong adverse effects on farmland bird populations due to reducing the availability of critical high-quality nesting and foraging opportunities. Modernization is largely financed from existing EU funds, which directly conflicts with EU biodiversity strategies aiming at halting biodiversity loss. We therefore recommend (i) including compensatory measures to increase nesting and foraging opportunities for birds during farmstead construction/modernization, (ii) increasing awareness of these problems among critical stakeholders and (iii) increasing support to small-sized traditional farms to retain and improve habitat conditions for declining farmland species.

• Sunde, Peter; Böcker, Felix; Rauset, Geir Rune; Kjellander, Petter; Chrenkova, Monika & Skovdal, Trine Munck [Vis alle 9 forfattere av denne artikkelen] (2022). Mammal responses to predator scents across multiple study areas. Ecosphere. ISSN 2150-8925. 13(8). doi: 10.1002/ecs2.4215. Fulltekst i vitenarkiv Vis sammendrag

  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 fre quency and vigilance behavior to olfactory predator stimuli during 158 stan dardized scent trials in five areas across Europe, where lynx and wolves either occurred or had been absent for centuries. After a period without scent, trial sites were either marked with lynx or wolf urine, or butyric acid (unspecific scent used to contrast species-specific scent responses). We expected the two herbivores to respond aversively (reduced visitation frequency, and increased vigilance) to predator urine, while red foxes (scavengers) might adopt a risk-sensitive exploration strategy by increasing vigilance near predator urine without reducing visitation frequency. For all species, we expected stronger responses toward the ambush predator lynx than to the pursue predator wolf (cryptic predator hypothesis). If prey responds more strongly to predator stim uli when coexisting with the predator, we expected stronger reactions to preda tor urine in areas where predators occurred (naïve prey hypothesis). Roe deer significantly avoided lynx urine and butyric acid, but not wolf urine. However, roe deer visitation frequency did not differ between scent treatment with largecarnivore urine and butyric acid (suggesting that roe deer generally avoid areas with unfamiliar scent), or between areas where large carnivores were present and absent. Hares did not significantly avoid predator urine. Red foxes were attracted to lynx urine in sympatry, but not in allopatry with large carnivores. They increased vigilance rates in the presence of lynx urine independent of sympatry/ allopatry with large carnivores. These findings generally confirm our expectations of predator avoidance by herbivores, and attraction combined with increased vigi lance of mesopredators. In all species, lynx urine elicited stronger responses than wolf urine (although not significantly different), which to some extent conforms to the cryptic predator hypothesis. We found no support for the naïve prey hypothesis. However, higher attraction of red foxes to lynx urine in sympatric situ ations might indicate that positive responses by scavengers are learning based. antipredator behavior, avoidance, Canis lupus, Capreolus capreolus, intra-guild predation, landscapes of fear, Lepus europaeus, Lynx lynx, odor, risk-sensitive foraging, vigilance, Vulpes vulpes

• Mayer, Martin; Lian, Marianne; Fuchs, Boris; Robstad, Christian; Evans, Alina & Perrin, Kathryn [Vis alle 10 forfattere av denne artikkelen] (2022). Retention and loss of PIT tags and surgically implanted devices in the Eurasian beaver. BMC Veterinary Research. ISSN 1746-6148. 18(1). doi: 10.1186/s12917-022-03333-1. Fulltekst i vitenarkiv
• Mayer, Martin; Schlippe Justicia, Lia; Shine, Richard & Brown, Gregory P. (2021). Host defense or parasite cue: Skin secretions mediate interactions between amphibians and their parasites. Ecology Letters. ISSN 1461-023X.
• Mayer, Martin; Shine, Richard & Brown, Gregory P. (2021). Rapid divergence of parasite infectivity and host resistance during a biological invasion. Biological Journal of the Linnean Society. ISSN 0024-4066.
• Mayer, Martin; Haugaard, Lars & Sunde, Peter (2021). Scared as a hare: Effects of capture and experimental disturbance on survival and movement behavior of European hares. Wildlife Biology. ISSN 0909-6396. Fulltekst i vitenarkiv
• Mayer, Martin; Coleman Nielsen, Jakob; Elmeros, Morten & Sunde, Peter (2021). Understanding spatio-temporal patterns of deer-vehicle collisions to improve roadkill mitigation. Journal of Environmental Management. ISSN 0301-4797.
• Nimje, Priyank Sharad; Mayer, Martin; Zedrosser, Andreas; Sæbø, Mona & Rosell, Frank Narve (2021). Territory acquisition and mate choice in a monogamous mammal, the Eurasian beaver. Animal Behaviour. ISSN 0003-3472. 178, s. 165–173. doi: 10.1016/j.anbehav.2021.06.015. Vis sammendrag

  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 not mutually exclusive. In this study, we investigated territory acquisition and mate choice characteristics in a saturated population of the Eurasian beaver, Castor fiber, by comparing individuals that successfully acquired territories with ones that were available in the study area (potential competitors). We used body mass and familiarity with an area as proxies for competitive ability, and genetic measures of inbreeding and relatedness, as well as age difference between pair members as proxies for mate compatibility. Comparatively older individuals and ones familiar with an area had a higher probability of territory acquisition, indicating that competitive ability was important for territory acquisition, whereas mate compatibility characteristics generally were not. However, in pairs that had a large age difference (between pair members), annual reproductive success decreased in more inbred pairs. These findings indicate that there might be a trade-off between territory acquisition and pair compatibility in saturated populations, that is, individuals accept being paired with a suboptimal mate when acquiring a territory, owing to intense competition. Our study emphasizes the importance of incorporating both factors related to competitive ability and mate compatibility when investigating territory acquisition in animals.

• Robstad, Christian; Lodberg-Holm, Hanna Kavli; Mayer, Martin & Rosell, Frank Narve (2021). The impact of bio-logging on body weight change of the Eurasian beaver. PLOS ONE. ISSN 1932-6203. 16(12). doi: 10.1371/journal.pone.0261453. Fulltekst i vitenarkiv Vis sammendrag

  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 raises concerns of potential negative impacts of tagging. To investigate the potential negative impacts of glue-on tags, we compared body weight change for tagged and untagged Eurasian beavers. We hypothesized that tagged beavers would gain less body weight compared to untagged beavers, and that weight change might be affected by tagging length, tag weight, water temperature and the season of tagging. Daily percentage body weight change in relation to initial body weight during the first capture was compared during 57 tagging periods (18±7 days) and 32 controls periods (64±47 days). Body weight change varied between the two groups, with untagged beavers on average gaining daily weight whilst tagged beavers on average lost weight daily, indicating a negative effect of tagging. The average reduction in percentage body weight change per day for tagged beavers was small (0.1 ± 0.3%), and with large individual variation. Neither tag weight, number of tagging days, nor season were important in explaining body weight change of tagged animals. In other words, we found that tagging reduced daily body weight during the tagging period but were unable to determine the mechanism(s) responsible for this decline. Detrimental effects of tagging have important implications for animal welfare and can introduce bias in data that are collected. This calls for careful consideration in the use of tags. We conclude that studies investigating the effects of tagging should consider individual variation in the effects of tagging and, where possible, compare tagged animals with a control group.

• Mayer, Martin; Fog Bjerre, Dagmar & Sunde, Peter (2020). Better safe than sorry: The response to a simulated predator and unfamiliar scent by the European hare. Ethology. ISSN 0179-1613.
• Mayer, Martin & Sunde, Peter (2020). Colonization and habitat selection of a declining farmland species in urban areas. Urban Ecosystems. ISSN 1083-8155.
• Mayer, Martin & Sunde, Peter (2020). The role of maize cultivation on European hare abundance. Agriculture, Ecosystems & Environment. ISSN 0167-8809.
• Mayer, Martin; Duan, Xiaodong; Sunde, Peter & Topping, Chris J. (2020). European hares do not avoid newly pesticide-sprayed fields: Overspray as unnoticed pathway of pesticide exposure. Science of the Total Environment. ISSN 0048-9697.
• Mayer, Martin; Aparicio, Claudia; Windels, Steve K. & Rosell, Frank Narve (2020). Landscape structure and population density affect intraspecific aggression in beavers. Ecology and Evolution. ISSN 2045-7758. 10(24), s. 13883–13894. doi: 10.1002/ece3.6980. Vis sammendrag

  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 canadensis) beavers that are both monogamous, territorial mammals. Combined, we examined tail scars from >1,000 beavers (>2,000 capture events) as part of two long‐term studies in Norway and the USA. We investigated the influence of landscape structure, population density, sex, age, and (for Eurasian beavers only) social status and group size on the number of tail scars caused by conspecifics. The number of tail scars was affected by population density in well‐connected landscape types (large lakes and rivers), but not in more isolated areas (ponds), where individuals generally had fewer tail scars. Further, the relationship of population density was not linear. In the North American beaver population occurring in large lakes, intraspecific aggression increased with population density. Conversely, in the saturated Eurasian beaver population, intraspecific aggression was in a negative relationship with population density (except at the highest densities), likely due to inverse density‐dependent intruder pressure via dispersers. Our findings emphasize that population density can affect intraspecific aggression depending on landscape structure, which might have important consequences for local patterns of dispersal, mate change, and territory occupancy, all of which can affect population dynamics.

• Busher, Peter E.; Mayer, Martin; Ulevicius, Alius; Samus, Arunas; Hartman, Göran & Rosell, Frank Narve (2020). Food caching behavior of the Eurasian beaver in northern Europe. Wildlife Biology. ISSN 0909-6396. 2020(3). doi: 10.2981/wlb.00734. Vis sammendrag

  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 cache of branches of woody species during autumn. We studied the food caching behavior of the Eurasian beaver in three northern European countries (Sweden, Norway, Lithuania) to provide additional insight into this important behavior. Thirty-seven of forty-seven (79%) active family groups had food caches by mid-November and 41 of 47 (87%) had caches by December. Water depth of caches ranged from 1 to 2.3 m and depths at caches in Sweden were significantly deeper than in either Norway or Lithuania. Construction of caches began as early as late September (week 39/40) in Sweden and Lithuania and by mid-October (week 42) in Norway. We observed plasticity in timing of cache initiation but the majority of active sites in all areas had food caches by the beginning of November (week 45). Declining air temperature and mean minimum temperatures of 0°C or below were associated with cache initiation. Caches in Lithuania were larger than in Sweden and Norway, which may be associated with colder winter temperatures. We did not find any relationship between family size or length of territory occupancy and cache size at our Norway sites where population demographics were available. Our results are generally consistent with other studies of food caching behavior in both species and suggest general similarities as well as behavioral plasticity in this important evolutionary strategy.

• Bartra Cabré, Laura; Mayer, Martin; Steyaert, Sam & Rosell, Frank Narve (2020). Beaver (Castor fiber) activity and spatial movement in response to light and weather conditions. Mammalian Biology. ISSN 1616-5047. 100, s. 261–271. doi: 10.1007/s42991-020-00029-7. Fulltekst i vitenarkiv Vis sammendrag

  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 data from 47 individuals in south-eastern Norway. Independent of daylight length, beavers had a mean daily activity time of 9:42 h and reduced their activity periods when they were older, most likely due to senescence. In line with this, older individuals also spent less time in water and moved shorter distances. Furthermore, beavers reduced their activity periods in drier weather conditions and spent less time on land during brighter nights and drier conditions, indicating a predation risk avoidance strategy. Individuals spent less time in the water during the colder parts of the year and moved shorter distances with decreasing temperature, suggesting thermal constraints. Our study adds to the increasing amount of evidence that animal behaviour is modulated by various endogenous and exogenous factors, and that weather conditions can affect their behaviour. It remains to be tested, however, how climate variability together with hunting and predation pressure affect space use and demography in species such as the Eurasian beaver.

• Frank, Shane; Blaalid, Rakel; Mayer, Martin; Zedrosser, Andreas & Steyaert, Sam (2020). Fear the reaper: ungulate carcasses may generate an ephemeral landscape of fear for rodents: Rodents fear scavengers at mass die-off. Royal Society Open Science. ISSN 2054-5703. 7(6), s. 1–11. doi: 10.1098/rsos.191644. Fulltekst i vitenarkiv Vis sammendrag

  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 whether rodents avoided larger scavengers (e.g. corvids and fox). We used the presence and abundance of faeces as a proxy for carcass use over the course of 2 years and found that rodents showed the strongest avoidance towards changes in raven abundance (β = −0.469, s.e. = 0.231, p-value = 0.0429), but not fox, presumably due to greater predation risk imposed by large droves of raven. Moreover, the emergence of rodent occurrence within the carcass area corresponded well with the disappearance of raven during the second year of the study. We suggest that carcasses have the potential to shape the landscape of fear for prey, but that the overall effects of carcasses on individual fitness and populations of species ultimately depend on the carcass regime, e.g. carcass size, count, and areal extent, frequency and the scavenger guild. We discuss conservation implications and how carcass provisioning and landscapes of fear could be potentially used to manage populations and ecosystems, but that there is a gap in understanding that must first be bridged.

• McClanahan, Kari; Rosell, Frank Narve & Mayer, Martin (2020). Minding your own business: low pair cohesion in a territorial, monogamous mammal. Animal Behaviour. ISSN 0003-3472. 166, s. 119–128. doi: 10.1016/j.anbehav.2020.05.008. Vis sammendrag

  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 cohesion is related to the spatial structure of the territory, territory defence, resource competition, offspring provisioning and the age difference between pair members. We analysed GPS data of 14 beaver pairs and calculated the distance between pair members, and the proportion of territory and core area overlap. While overall territory size was similar between partners and overlap was high, the distance between pair members was large, averaging 500 m, and increased with increasing territory size. Moreover, the proportion of core area overlap was comparatively low and decreased with territory size, also indicating low pair cohesion. Pair members were closest at the beginning and end of their nightly activity periods, suggesting that variation in pair cohesion was caused by the spatial structure of territories with the lodge serving as a central place. We found no support for the other hypotheses, but the overall low pair cohesion might nevertheless serve to increase territory defensibility and reduce intrapair competition for resources. Ultimately, low pair cohesion might be caused by the obligate monogamous mating system of beavers, leading to the defence of spatially structured territories rather than the defence of a partner.

• Mayer, Martin; Ullmann, Wiebke; Heinrich, Rebecca; Fischer, Christina; Blaum, Niels & Sunde, Peter (2019). Seasonal effects of habitat structure and weather on the habitat selection and home range size of a mammal in agricultural landscapes. Landscape Ecology. ISSN 0921-2973.
• Mayer, Martin; Frank, Shane; Zedrosser, Andreas & Rosell, Frank Narve (2019). Causes and consequences of inverse density-dependent territorial behaviour and aggression in a monogamous mammal. Journal of Animal Ecology. ISSN 0021-8790. doi: 10.1111/1365-2656.13100. Vis sammendrag

  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 territory owners are affected by external factors, such as population density. This is important because it can affect mate change (the replacement of one pair member) and dispersal, a key ecological process. The aim of this study was to investigate the behavioural and spatial response of territory owners to intruder pressure as a function of population density in a territorial, monogamous mammal, the Eurasian beaver (Castor fiber). Using a combination of GPS technology, scent experiments, camera trap data and tail scar observations from an individual‐based long‐term study, we investigated the factors influencing spatial movement patterns by territory owners in response to a simulated intruder and the factors affecting territory intrusions. We found consistent inverse density‐dependent patterns in territorial behaviours and evidence of conspecific aggression. At lower densities, territory owners detected more simulated intrusions, showed more territorial reactions and experienced increased conspecific aggression as indicated by tail scars, suggesting increased intruder pressure. Inverse density‐dependent territorial behaviour and aggression suggest a potential mechanistic link between inverse density‐dependent natal dispersal and mate change. At low population densities, increased dispersal amplifies intruder pressure, leading to the observed increases in territorial behaviours, conspecific aggression and previously observed mate turnover, which in turn might increase natal dispersal. Our study demonstrates how population density can affect the behaviour and space use of individuals, which is important for territory occupancy and fitness.

• Mayer, Martin; Natusch, Daniel J D & Frank, Shane (2019). Water body type and group size affect the flight initiation distance of European waterbirds. PLOS ONE. ISSN 1932-6203. 14(7). doi: 10.1371/journal.pone.0219845. Fulltekst i vitenarkiv Vis sammendrag

  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 larger lakes and narrower rivers using a motorboat. We investigated whether water body type, season (winter/spring), approach starting distance, species body mass, and group size influenced bird FID. Average bird FID was 145 ± 92 m and differed between species. In general, FID of all species was larger on lakes than rivers and increased with increasing group size and approach starting distance. When analysed separately for the two most common species, common goldeneyes (Bucephala clangula) and mallards (Anas platyrhynchos), FID increased with increasing starting distance on rivers, but not lakes, likely because birds on lakes have enough time to evaluate the approaching object and take flight at great distance. Additionally, birds might perform different activities on lakes versus rivers, leading to varying energetic trade-offs between the two habitat types, which may affect the decision when to take flight. Finally, mallards aggregated in larger groups on lakes, which affected FID, likely due to enhanced visibility (i.e., earlier detection of the approaching boat) and detection probability (via increased group size) on lakes. Our results emphasize the importance of accounting for habitat characteristics, such as water body type, when studying waterbird FID, because they can affect the visibility of stimuli, group size and potentially animal behaviour, factors which should be taken into account when planning buffer zones for waterbirds in conservation areas.

• Mayer, Martin; Ullmann, Wiebke; Sunde, Peter; Fischer, Christina & Blaum, Niels (2018). Habitat selection by the European hare in arable landscapes: The importance of small-scale habitat structure for conservation. Ecology and Evolution. ISSN 2045-7758.
• Mayer, Martin; Lyons, Jessica A; Shine, Richard & Natusch, Daniel J. D. (2018). Air-pressure waves generated by vehicles do not imperil road-crossing amphibians. Salamandra (Frankfurt). ISSN 0036-3375. 54(1), s. 80–82.
• Schlippe Justicia, Lia; Rosell, Frank Narve & Mayer, Martin (2018). Performance of GPS units for deployment on semiaquatic animals. PLOS ONE. ISSN 1932-6203. doi: 10.1371/journal.pone.0207938. Fulltekst i vitenarkiv Vis sammendrag

  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 performance differently. We evaluated the location error and fix success rate of three GPS receiver models in stationary tests and on a semi-aquatic mammal, the Eurasian beaver (Castor fiber). The location error during stationary tests was on average 15.7 m, and increased with increasing canopy closure, slope, and horizontal dilution of precision, potentially leading to the erroneous classification of GPS positions when studying habitat use in animals. In addition, the position of the GPS antenna (flat versus 90˚ tilted) affected the location error, suggesting that animal behavior affects GPS performance. The fix success rate was significantly higher during stationary tests compared to when GPS units were deployed on beavers (94% versus 86%). Further, GPS receivers did not obtain any positions underwater and underground, the latter potentially allowing the estimation of activity periods in animals that use lodges or burrows as shelter. We discuss the possibilities for data screening, the use of buffer zones along the shoreline, and combination with other data loggers to avoid the erroneous classification of GPS positions when studying habitat use.

• Hohwieler, Katrin; Rosell, Frank Narve & Mayer, Martin (2018). Scent-marking behavior by subordinate Eurasian beavers. Ethology. ISSN 0179-1613. 124(8), s. 591–599. doi: 10.1111/eth.12762.
• Lettoof, Damian C.; Lyons, Jessica A; Shine, Richard; Maniel, Grégoire; Mayer, Martin & Natusch, Daniel J D (2017). Cane toads beneath bird rookeries: utilization of a natural disturbance by an invasive species. Current Zoology. ISSN 1674-5507. 64(4), s. 433–439. doi: 10.1093/cz/zox041. Fulltekst i vitenarkiv Vis sammendrag

  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 of invaders. In the Australian tropics, metallic starlings Aplonis metallica nest communally in emergent rainforest trees during the wet-season, and invasive cane toads Rhinella marina join other predators (mammals, birds, reptiles, and other anurans) to exploit the food resources beneath those trees. Compared to conspecifics found along nearby roads through the forest, cane toads beneath bird-nesting trees occur at higher densities, and are smaller in body size. The sex ratio is female-biased, and recapture records suggest that fe- males may be philopatric at these sites (whereas recaptures were rare for both sexes found along the roads). Some toads were found under the same trees in successive wet-seasons. Spooling showed that distances moved per night were similar along the road versus under the trees, but toads under trees showed lower net displacements. Diets also differed (based upon scat analysis), with tree toads feeding more on beetles and less on ants. These nutrient-rich hotspots are ex- ploited primarily by adult females and juvenile toads, whereas adult males congregate at breeding sites. By magnifying pre-existing intraspecific divergences in habitat use, bird rookeries may en- hance population viability of cane toads by enabling critical age and sex classes to exploit food- rich patches that are rarely used by adult males

• Natusch, Daniel J D; Mayer, Martin; Lyons, Jessica A & Shine, Richard (2017). Interspecific interactions between feral pigs and native birds reveal both positive and negative effects. Austral ecology (Print). ISSN 1442-9985. 42(4), s. 479–485. doi: 10.1111/aec.12465. Vis sammendrag

  In tropical Australian rainforests, predators and scavengers aggregate beneath emergent trees that houselarge colonies of metallic starlings (Aplonis metallica), feeding in the nutrient-rich open areas below. Analysis of cam-era-trap records shows that the presence of feral pigs (Sus scrofa) is associated with an absence of birds (cockatoosand brush turkeys), presumably reflecting behavioural avoidance (pigs pose a direct danger to birds). However, birdnumbers increase as soon as pigs depart, then fall if pigs are absent for long periods. Feral pigs thus displace nativebirds from these resource hotspots; but by turning over the soil and enhancing the birds’ access to food, the pigs alsohave a positive impact on food availability for the avifauna. Thus, although invasive species have caused irreparableenvironmental damages worldwide, they may also provide positive benefits for certain species. The net benefitofsuch interspecific interactions will depend on the outcome of both positive and negative effects.

• Mayer, Martin; Zedrosser, Andreas & Rosell, Frank Narve (2017). Couch potatoes do better: Delayed dispersal and territory size affect the duration of territory occupancy in a monogamous mammal. Ecology and Evolution. ISSN 2045-7758. 7(12), s. 4347–4356. doi: 10.1002/ece3.2988. Fulltekst i vitenarkiv Vis sammendrag

  In territorial, socially monogamous species, the establishment and defense of a terri - tory are an important strategy to maximize individual fitness, but the factors responsi - ble 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 allowed us to follow the individual life histories of Eurasian beavers ( Castor fiber ) from adolescence in their natal family group to dispersal and territory establish - ment until the end of territory occupancy. We investigated whether territory size, re - source availability, population density, and dispersal age could explain the duration of territory occupancy, which ranged from 1 to 11 years. The duration of territory occu - pancy was positively related to dispersal age, suggesting that individuals that delayed dispersal had a competitive advantage due to a larger body mass. This is in support with the maturation hypothesis, which states that an animal should await its physical and behavioral maturation before the acquisition of a territory. Further, we found that individuals that established in medium- sized territories occupied them longer as com - pared to individuals in small or large territories. This suggests that large territories are more costly to defend due to an increased patrolling effort, and small territories might not have sufficient resources. The lifetime reproductive success ranged from zero to six kits and generally increased with an increasing duration of territory occupancy. Our findings show the importance of holding a territory and demonstrate that dispersal decisions and territory selection have important consequences for the fitness of an individual.

• Mayer, Martin; Zedrosser, Andreas & Rosell, Frank Narve (2017). Extra-territorial movements differ between territory holders and subordinates in a large, monogamous rodent. Scientific Reports. ISSN 2045-2322. 7(1). doi: 10.1038/s41598-017-15540-0. Fulltekst i vitenarkiv Vis sammendrag

  Territorial animals carry out extra-territorial 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 fber), a year-round territorial, monogamous mammal, during the non-mating season. We investigated forays in territory-holding breeders (dominants) and non-breeding (subordinate) family members. Twenty of 46 dominant individuals (44%), and 6 of 10 subordinates (60%) conducted forays. Generally, beavers spent between 0 and 11% of their active time on forays, travelled faster and spend more time in water when on forays compared to intra-territorial movements, suggesting that forays are energetically costly. Further, beavers in smaller territories conducted more forays. Possibly, smaller territories might not have sufcient resources and thus dominant individuals might conduct forays to assess possibilities for territory expansion, and potentially for foraging. Generally, besides territory advertisement (e.g. via scent-marking), forays might serve as an additional mechanism for territory owners to assess neighbours. Subordinates spent more time on forays, moved greater distances and intruded into more territories than dominant individuals did, suggesting that they prospected to gain information on the population density and available mates before dispersal.

• Mayer, Martin; Künzel, Fabian; Zedrosser, Andreas & Rosell, Frank Narve (2017). The 7-year itch: non-adaptive mate change in the Eurasian beaver. Behavioral Ecology and Sociobiology. ISSN 0340-5443. 71:32(2), s. 1–9. doi: 10.1007/s00265-016-2259-z. Vis sammendrag

  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 thatmate change is initiated by both mates, whereas in the ‘better option’ hypothesis, one partner initiates the mate change. In contrast, non-adaptive hypotheses predictmate change to be independent from previous reproduction: the ‘forced divorce’ hypothesis suggests that mate change is initiated by an incoming individual and the ‘obligate mate change’ hypothesis states that the mate change occurs after the accidental death of a partner.We investigated these hypotheses in the socially monogamous Eurasian beaver (Castor fiber), using data from a long-term study in southeast Norway between 1998 and 2014. Generally, the mate change occurred in the seventh year of a partnership and the staying individual repaired with a younger, incoming individual. The fate of the replaced individual was mostly unknown. Resident individuals had a decreased reproductive success with increasing age but gained no benefits from a mate change in terms of reproduction. Thus, we reject the adaptive hypotheses as cause of mate change. Our results support non-adaptive mate change hypotheses, most likely the ‘forced divorce’ hypothesis and to a lower degree the ‘obligate mate change’ hypothesis. Significance statement

• Mayer, Martin; Zedrosser, Andreas & Rosell, Frank Narve (2017). When to leave: the timing of natal dispersal in a large, monogamous rodent, the Eurasian beaver. Animal Behaviour. ISSN 0003-3472. 123(January), s. 375–382. doi: 10.1016/j.anbehav.2016.11.020. Vis sammendrag

  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-based study (1998–2015). We tested hypotheses about the causes of dispersal onset, namely competitive ability, kin competition (sibling competition and offspring–parent competition), population density and intolerance by an incoming, unrelated dominant individual. Only 9% of individuals remained philopatric and became dominant after both of their parents disappeared. Average age at dispersal was 3.5 years, with some individuals delaying dispersal up to age 7 years. Beavers dispersed more frequently with increasing age (i.e. with increasing competitive ability and possibly experience) and when population density was lower. Further, both females and males delayed dispersal with increasing same-sex parental age. Older parents were either more tolerant towards philopatric subordinates, or subordinates awaited the disappearance of their senescing parents to take over the natal territory. From comparisons with other populations, we conclude that the high population density in our area was possibly the ultimate driver of dispersal with individuals delaying dispersal to increase their competitive ability.

• Graf, Patricia Maria; Mayer, Martin; Zedrosser, Andreas; Hackländer, Klaus & Rosell, Frank Narve (2016). Territory size and age explain movement patterns in the Eurasian beaver. Mammalian Biology. ISSN 1616-5047. 81(6), s. 587–594. doi: 10.1016/j.mambio.2016.07.046. Vis sammendrag

  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 movement patterns both on land and in water in relation to territory size, resource availability, the number of neighbours, season, and the beavers’ age. We show a territory size-dependent trade-off between territorial behaviours and foraging distances: Beavers in larger territories moved greater distances each night, thereby spending more time patrolling, and stayed closer to the shoreline when being on land (i.e. when foraging). Inversely, in smaller territories beavers patrolled less and foraged further away from the shoreline. These results suggest that individuals trade-off the costs of patrolling larger territories against the benefits of foraging closer towards the shoreline. Smaller territories might be more prone to resource depletion, thus, making foraging further from the shoreline a strategy to ensure sustainable resource use. Further, older beavers spent more time on land and close to territory borders compared to younger ones, suggesting a behavioural change with age possibly due to increased experience and boldness.

• Mayer, Martin; Shine, Richard & Brown, Gregory P. (2016). Bigger babies are bolder: Effects of body size on personality of hatchling snakes. Behaviour. ISSN 0005-7959. 153(3), s. 313–323. doi: 10.1163/1568539X-00003343. Vis sammendrag

  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 dimension related to boldness. Larger hatchlings emerged from shelter sooner than small ones. Hatchling mass of keelbacks is substantially influenced both by maternal phenotype and by incubation conditions. Given the environmental basis of much of the variation in offspring size, the size-boldness association may reflect a facultative ability to adjust behavioural tactics to body size, as well as innate differences in personality traits between large versus small hatchlings. The link between size and boldness suggests that the survival advantage of larger offspring size in this population may be driven by snake behaviour as well as morphology.

• Mayer, Martin; Brown, Gregory P.; Zimmermann, Barbara; Greenlees, Matthew J. & Shine, Richard (2015). Habitat use of the introduced cane toad (Rhinella marina) and native frog species in tropical Australia. Journal of Tropical Ecology. ISSN 0266-4674. 31(6), s. 531–540. doi: 10.1017/S0266467415000474. Vis sammendrag

  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. Native frog species and the cane toad both preferred habitats close to water and unvegetated holes. However, native frogs were found further from water (on average 19.4 m) than were toads (on average 12.6 m), and preferred areas with higher vegetation (8–50 cm) than did toads,which were more abundant in vegetation lower than 8 cm. For both types of anuran, the next neighbour was more often of the same type (89% in frogs, 52% in toads) than expected by chance (observed ratio: 75% frogs vs 25% toads), reflecting these differences in habitat use. Our Counts of frog abundance increased on average 14.5% in areas from which we removed cane toads temporarily. This result suggests that cane toads inhibit the activity of native anurans either by inducing avoidance, or by reducing activity. By modifying the behaviour and spatial distribution of native taxa, invasive cane toads may curtail activities such as feeding and breeding.

• Mayer, Martin; Brown, Gregory P.; Zimmermann, Barbara & Shine, Richard (2015). High infection intensities, but negligible fitness costs, suggest tolerance of gastrointestinal nematodes in a tropical snake. Austral ecology (Print). ISSN 1442-9985. 40(6), s. 683–692. doi: 10.1111/aec.12235. Vis sammendrag

  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 inflammation of stomach mucosa and submucosa at the sites of parasite attachment and encystment. Nonetheless, we did not detect detrimental effects of nematode infection on measures of fitness among wild or captive snakes. Snakes with heavier nematode infections had higher body condition scores than less-infected individuals. Deworming captive snakes had no measurable effect on their growth rate, body condition or locomotor performance. In combination with an earlier study on blood-dwelling hepatozoons, our work suggests that keelbacks have a high tolerance to parasites. The ‘fast-pace’ life history and short lifespan of these snakes may make it beneficial for them to tolerate infection, rather than expend energy on resisting parasite attack.

• Mayer, Martin; Hawlitschek, Oliver; Zahn, Andreas & Glaw, Frank (2013). Composition of twenty green frog populations (Pelophylax) across Bavaria, Germany. Salamandra (Frankfurt). ISSN 0036-3375.

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• Mayer, Martin (2023). Patterns of cattle depredation by large carnivores in Norway.
• Mayer, Martin; Furuhovde, Erlend; Nordli, Kristoffer; Ausilio, Giorgia; Eriksen, Ane & Evans, Alina [Vis alle 8 forfattere av denne artikkelen] (2023). Efficiency and disturbance effects of drone versus ground approaches to monitor moose.
• Mayer, Martin (2022). Predation on a Hooded Oriole Icterus cucullatus by the Green Vine Snake Oxybelis fulgidus in Mexico. Herpetology Notes. ISSN 2071-5773.
• Mayer, Martin; Olsen, Kent; Schulz, Bjorn; Matzen, Jens; Novak, Carsten & Thomsen, Phillip Francis [Vis alle 9 forfattere av denne artikkelen] (2022). Occurrence and livestock depredation patterns by wolves in highly cultivated landscapes. Frontiers in Ecology and Evolution. ISSN 2296-701X. doi: 10.3389/fevo.2022.783027.
• Justicia, Lia Schlippe; Mayer, Martin; Shine, Richard; Shilton, Cathy & Brown, Gregory P. (2022). Host-parasite interactions diverge during a biological invasion - cane toads and lungworms in Australia. Ecology and Evolution. ISSN 2045-7758. doi: 10.1002/ece3.9220.
• Mayer, Martin; Lyons, Jessica A; Shine, Richard & Natusch, Daniel J D (2018). Air-pressure waves generated by vehicles do not imperil road-crossing amphibians. Salamandra (Frankfurt). ISSN 0036-3375. 54(1), s. 80–82.
• Mayer, Martin; Robstad, Christian; Pi Serra, E.; Hohwieler, K.; Fuchs, B & Evans, A. L. [Vis alle 9 forfattere av denne artikkelen] (2017). Exposure of the Eurasian beaver (Castor fiber) towards hunters during the spring hunt. Universitetet i Sørøst-Norge/Universitetet i Søraust-Noreg.

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