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In contrast to the main olfactory system that detects volatile chemicals in the nasal air, the vomeronasal system can detect nonvolatile chemicals as well as volatiles. In the vomeronasal system, chemicals are perceived by the vomeronasal... more
In contrast to the main olfactory system that detects volatile chemicals in the nasal air, the vomeronasal system can detect nonvolatile chemicals as well as volatiles. In the vomeronasal system, chemicals are perceived by the vomeronasal organ (VNO) projecting axons to the accessory olfactory bulb (AOB). Beavers (Castor spp.) are semiaquatic mammals that have developed chemical communication. It is possible that the beaver's anal gland secretions, nonvolatile and insoluble substances, may work as a messenger in the water and that beavers may detect the nonvolatile chemicals floating on the water surface via the VNO. The present study aimed to clarify the specificities of the beaver vomeronasal system by histologically and immunohistochemically analyzing the VNO and AOB of 12 Eurasian beavers (C. fiber). The VNO directly opened to the nasal cavity and was independent of a narrow nasopalatine duct connecting the oral and nasal cavities. The VNO comprised soft tissues including sensory and nonsensory epithelium, glands, a venous sinus, an artery, as well as cartilage inner, and bone outer enclosures. The AOB had distinct six layers, and anti‐G protein α‐i2 and α‐o subunits were, respectively, immunoreactive in rostral and caudal glomeruli layers indicating expressions of V1Rs and V2Rs. According to gene repertories analysis, the beavers had 23 and six intact V1R and V2R genes respectively. These findings suggested that beavers recognize volatile odorants and nonvolatile substances using the vomeronasal system. The beaver VNO was developed as well as in other rodents, and it had two specific morphological features, namely, disadvantaged contact with the oral cavity because of a tiny nasopalatine duct, and a double bone and cartilage envelope. Our results highlight the importance of the vomeronasal system in beaver chemical communication and support the possibility that beavers can detect chemicals floating on the water surface via the VNO.
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... Howard Parker 1 , Asbjørn Haugen 1 , Øystein Kristensen 1 , Erik Myrum 1 , Ronni Kolsing 1 ... Thesmall size of resulting impoundments on the study area may, in part, explain why beaver chose so frequently to establish colonies on... more
... Howard Parker 1 , Asbjørn Haugen 1 , Øystein Kristensen 1 , Erik Myrum 1 , Ronni Kolsing 1 ... Thesmall size of resulting impoundments on the study area may, in part, explain why beaver chose so frequently to establish colonies on existing bodies of water, as these would ...
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Research Interests: Zoology, Geography, Wildlife Biology, Biology, Ecology, and 3 moreInvasive Species, Beaver, and Alien
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Abstract: In Norway, Sweden and Finland hunting Eurasian beaver Castor fiber Linnaeus, 1758 with firearms is presently the main harvest form and most are shot in late April and early May. As beaver cannot be sexed from external... more
Abstract: In Norway, Sweden and Finland hunting Eurasian beaver Castor fiber Linnaeus, 1758 with firearms is presently the main harvest form and most are shot in late April and early May. As beaver cannot be sexed from external characteristics, and ageing by size is ...
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Redllced to 1200 animals in 8 small refllgia by the end of the 19 century, natura I spread and reintroductions have led to a powerflll recovery in Eurasian beaver (Castor fiber L. ] 758) range and populations. The minimum popu1ation is... more
Redllced to 1200 animals in 8 small refllgia by the end of the 19 century, natura I spread and reintroductions have led to a powerflll recovery in Eurasian beaver (Castor fiber L. ] 758) range and populations. The minimum popu1ation is now 592 000 animals, of which c.40% are found in Russia. In Europe, beaver are common and widespread in European Russia, Scandinavia, the Baltic states and Belarus; scattered populations are now established in al! other countries with the exception of the Caucasus, Iberia, Italy, the southern Balkans, and the British Isles. Further reintroductions are continuing. It seems clear that beaver will within a few decades once again be a tolerably common mammaI in suitable habitat over most of its former European range. Patterns of spread and population deve10pment indicate that populations should be managed at the watershed scale.
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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,... more
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 bio-loggers should function reliably for long periods of time. Here, we evaluated the retention of PIT tags, and of very high frequency (VHF) transmitters and bio-loggers that were either implanted subcutaneously or into the peritoneal cavity of Eurasian beavers (Castor fiber). Results Over a 21-year period, we implanted PIT tags in 456 individuals and failed to detect a PIT tag in 30 cases, consisting of 26 individuals (6% of individuals). In all instances, we were still able to identify the individual due to the presence of unique ear tag numbers and tail scars. Moreover, we implanted 6 VHFs, 36 body temperature loggers and 21 heart rat...
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Beavers tend not to be a commonly held captive species and there is little published material relating to their captive care. Beavers are kept in captivity for a variety of reasons, including entertainment, fur farming, habitat... more
Beavers tend not to be a commonly held captive species and there is little published material relating to their captive care. Beavers are kept in captivity for a variety of reasons, including entertainment, fur farming, habitat management, and conservation breeding. This chapter discusses captive care requirements, diet, best husbandry practices, and common captive behaviours and issues, with suggestions on how to improve captive welfare. This will range from health issues in captivity and common behavioural concerns to capture, handling, tagging, and sex determination, enclosure design, and animal management. Beavers may suffer from a perception that they have less behavioural requirements beyond their physical environment, potentially encouraged by their lack of visibility and rodent classification. However, as social mammals with complex chemical communication systems and as such an ability to modify their environments, studies of wild counterparts suggest their captive welfare requirements may actually be more sophisticated. Population monitoring can be achieved through various methods, including tagging individuals and using field signs to determine population distribution and size estimates. Many of these techniques have been developed or refined in the captive setting. The application and issues using various methods are discussed.
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This chapter introduces the long history of beaver and human interaction, discussing the folklore of First Nation peoples to whom the beaver was a sacred link to the Earth’s creation and the Catholic Church’s classification of them as... more
This chapter introduces the long history of beaver and human interaction, discussing the folklore of First Nation peoples to whom the beaver was a sacred link to the Earth’s creation and the Catholic Church’s classification of them as fish; fur wars over their luxuriant pelts in North America; and the cultural beliefs of the use of their castoreum as a medicinal product, including curing all kinds of fever, relief of toothache, prevention of insomnia, and treatment of stomach disorders. This chapter identifies the historic and current distribution range of both beaver species, each of which, after avoiding near extinction in historic times, in this more modern era been widely reintroduced. Numerous beaver restoration projects have focused on the rebooting of their critical role as ecosystem engineers. Eurasian beavers have recently been restored to more than 20 countries in Europe, with minimum estimates of 1.5 million individuals globally. In North America, populations returned from a low of several hundred thousand at the beginning of the nineteenth century to now approximately 6 million beavers.
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This chapter discusses the beaver’s role as a keystone species, wetland engineers and riparian restorers. Beavers can have a significant impact on the natural landscape, the geomorphology and hydrology of a system and biodiversity, as a... more
This chapter discusses the beaver’s role as a keystone species, wetland engineers and riparian restorers. Beavers can have a significant impact on the natural landscape, the geomorphology and hydrology of a system and biodiversity, as a result of their activities. Beaver-influenced environments, with a less dense or intermittent tree canopy, provide both a greater expanse and increased variety of living opportunities for a wide range of higher plant species, which in turn increases the feeding and breeding opportunities for insects. A greater abundance of standing and submerged dead wood habitat further enhances this process, and invertebrate densities can alter significantly in response. The presence of beavers thus tends to have a beneficial impact on fish populations through the creation of foraging and shelter habitats for a wide variety of species. Amphibian abundance in beaver-generated landscapes tends to be higher than in areas without beavers, and this has also generally been found to be true for reptiles and birds. Small mammals (such as water shrews and voles) adapt to utilize the variety of niche habitats and prey abundance provided by beaver-generated landscapes, while large herbivores such as deer exploit their greater grazing and browsing potential. Carnivores, particularly otter and mink but also potentially badger, red fox, stoat, and pine marten, may benefit through enhanced prey populations (such as fish, amphibians, and birds) and the presence of beaver lodges and burrows which they utilize for shelter and breeding.
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Beavers are highly territorial and actively defend a territory that includes nutritional resources, one or more rest sites, a family overwintering site, and a reproduction site. New territories are normally established during early autumn... more
Beavers are highly territorial and actively defend a territory that includes nutritional resources, one or more rest sites, a family overwintering site, and a reproduction site. New territories are normally established during early autumn when dispersing subadults settle down in a new area of their own, but this can vary considerably. Each family group scent marks its territories with castoreum and/or anal gland secretion. Territory size is generally measured as the length of shoreline but can also be expressed as a combination of terrestrial and aquatic patches used by the beavers in a two-dimensional space. The territorial size depends on many factors such as habitat quality and quantity, habitat type (stream, river, or pond), density of beavers, social factors (sex and age), time of year (season), and settlement pattern. Beavers patrol their territory to look out for intruders and potential predators and scent mark their territory with fluid from their castor sacs and/or secretions from their anal glands. Territorial defence can include direct fighting or even more unusual warning behaviours such as boundary stick displays. The duration of territory occupancy and its importance for the fitness of beavers are also discussed. Further, this chapter explores beaver communication using odours, sounds, tail slapping, poses, and other movements. Beavers predominantly communicate via odours, but the importance of all these modalities is explored. Lastly, population estimations, growth, fluctuations, and densities of beaver populations are discussed.
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Today, beavers are represented by two species, the Eurasian beaver and the North American beaver. Though these are the last remaining representatives of a once much larger consortium of animals, they have played a significant role in... more
Today, beavers are represented by two species, the Eurasian beaver and the North American beaver. Though these are the last remaining representatives of a once much larger consortium of animals, they have played a significant role in human history and dominated wetland ecology in the northern hemisphere. Their behaviour and ecology both fascinate and perhaps even infuriate, but seemingly they never fail to amaze. This comprehensive text serves to go beyond the natural history of these species, also describing their impacts on humans, conflict mitigation, animal husbandry, and conservation. This practical and accessible text incorporates some of the latest scientific findings, whilst setting the background of the broad depth of knowledge on beavers. The recovery and active restoration of both species has emerged following relentless persecution to the verge of extinction, a major conservation success story. Now can perhaps be described as the new dawn of the beaver, where more than ever its landscape-scale impacts, such as potential for water resource management, are being increasingly recognized.
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ABSTRACT The confirmed presence of alien North American beavers in some regions of Eurasia may compete with and hinder the successful recolonisation of the native Eurasian species back to its former range. Distinguishing the two species... more
ABSTRACT The confirmed presence of alien North American beavers in some regions of Eurasia may compete with and hinder the successful recolonisation of the native Eurasian species back to its former range. Distinguishing the two species in the field can be problematic, time consuming and expensive, thereby potentially limiting appropriate conservation actions. Here, a rapid and inexpensive genetic SNP assay is described that can separate the two species from either noninvasively collected samples or samples taken directly from restrained individuals. We applied these new genetic assays to free-living beavers of unknown origin sampled in Scotland.
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This chapter describes the beaver’s biology and physiology, including many unique specialized adaptations to enable them to cope with their semi-aquatic lifestyle, such as diving and digesting bark. The chapter begins with a general... more
This chapter describes the beaver’s biology and physiology, including many unique specialized adaptations to enable them to cope with their semi-aquatic lifestyle, such as diving and digesting bark. The chapter begins with a general description of the beaver body form and structure, including differences between the species. They possess a range of unique features and specialized organs that enable them to survive a semi-aquatic lifestyle, including thick waterproof fur, a cloaca, and various thermoregulation adaptations. Locomotion varies, on land, the beaver is a large, plodding animal that rarely waddles far from the water’s edge. In water they move quickly and dive efficiently and, while potentially not the most agile of swimming animals, spend large amounts of time in the water foraging and maintaining their territory. The beaver tail is quite unique, its form and function are discussed. The beaver’s digestive system is described, including specialized features, e.g. an enlarged caecum ‘fermentation chamber’ designed to accommodate large amounts of complex cellulose such as bark, which is aided by microorganisms in the beaver’s stomach that help in breaking down these substances. The physiology of scent production is also described as chemical communication is significant in these two species. This chapter highlights key features which enable beavers to spend long periods in water and underground especially in prolonged winters.
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This chapter discusses a range of biological and behavioural traits associated with beaver life history. First the chapter examines their typical daily activity patterns, including time budgets, sex and age-class differences, and activity... more
This chapter discusses a range of biological and behavioural traits associated with beaver life history. First the chapter examines their typical daily activity patterns, including time budgets, sex and age-class differences, and activity during winter. Beavers are crepuscular and nocturnal. The time budgets for adult males and females do not differ much for most activities. Beavers adapt to wintertime conditions by becoming less active and live off their pre-prepared food cache and accumulated body fat. It describes a typical beaver family that typically consists of the adult breeding pair with their offspring from the current breeding season and the previous year’s litter. They are living mostly a socially monogamous life, and usually mate for life. The key stages of a beaver’s life cycle are all described, i.e. mate choice and pair bonding, sexual maturity and mating, time of birth and litter sizes, factors affecting reproduction, kit development and life inside beaver lodges, dispersal, mate change, length of pair bonds, and loss of family members and longevity.
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This chapter introduces and describes the two extant species of beavers, the Eurasian Castor fiber and the North American Castor canadensis, including their classification from the order Rodentia, family Castoridae. The Castoridae family... more
This chapter introduces and describes the two extant species of beavers, the Eurasian Castor fiber and the North American Castor canadensis, including their classification from the order Rodentia, family Castoridae. The Castoridae family represents species that can produce, store, and distribute castoreum. This chapter describes the appearance of these two species in the fossil record and their evolution into two distinct species. Differences between the two species are discussed including chromosome number, appearance, behaviour, and ecology. Background information on extinct beaver species including Castoroides ohioensis—a giant beaver, the size of a bear—is provided. Also considered are the latest genetic findings on subspecies division of the Eurasian beaver which, as for its American counterpart, have been controversial and largely based on fur trade refugia populations. Similar species, which may be confused by some for beavers, are discussed and key differences noted.
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Like any wild mammal, beavers face a range of mortality risks including direct predation and infectious diseases. Their main predators are the wolf and bears. Beavers are also predated by alligators, coyotes, wolverines, cougars, lynx,... more
Like any wild mammal, beavers face a range of mortality risks including direct predation and infectious diseases. Their main predators are the wolf and bears. Beavers are also predated by alligators, coyotes, wolverines, cougars, lynx, bobcats, dogs, and foxes. Territorial fighting can have an indirect impact on beaver survival leading to injury and infection. Human-mitigated factors such as pollutants, hunting and trapping, and less documented causes of deaths such as road traffic and motorboat accidents, drowning, water regulations, floods, dental issues, harsh winters, droughts, tree felling are also discussed. This chapter discusses a range of pathogens that may be harboured by beavers and diseases caused by viruses (three rare ones in the North American beaver), bacteria (18), and internal (49) and external (65) parasites specific to beavers. The most common bacteria is the Tularemia and it occurs most often in the North American beaver. The most common endoparasites are the Giardia spp. (occurs mostly in the North American beaver), the roundworm Travassosius spp. and the beaver fluke. The most common ectoparasites are the beaver parasite beetle, and mites in the genus Schizocarpus spp.
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This chapter discusses the conflict between beavers and humans, techniques for effective management, and the role of beavers as a charismatic flagship species for restoration and conservation projects. As well as understanding the... more
This chapter discusses the conflict between beavers and humans, techniques for effective management, and the role of beavers as a charismatic flagship species for restoration and conservation projects. As well as understanding the benefits that beavers can bring, it is important to accept that their presence and reintroduction can sometimes generate conflict with human interests and impose a cost (including time and financial) in terms of resources, especially in intensively managed landscapes. Techniques for the effective mitigation of beaver impacts are now well developed across Europe and North America. Many of these techniques have been developed in response to both legal constraints and a wider social interest in non-lethal wildlife-management solutions. While this may reflect the conservation status of this species, it also offers a more practical solution, as the culling of problem individuals in a highly territorial species merely creates a vacuum to be filled by dispersers. When human–beaver conflicts are analysed in cultural landscapes, it is clear that the majority arise within a relatively slim strip of habitat adjacent to freshwater habitats. Beavers are also used for recreational hunting and as a fur resource in many countries. Interestingly, the two beaver species are now meeting at several fronts in parts of Europe, after introduction of North American beavers, provoking curiosity on which may have the competitive edge. The issues concerning the introduction, management and even eradication of the North American beaver in Europe are discussed.
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Many wild animals perceive humans as predators, and human disturbance, especially in the form of hunting, triggers antipredatory behavior among prey. Yet, knowledge of how game species react to different types of human disturbance and... more
Many wild animals perceive humans as predators, and human disturbance, especially in the form of hunting, triggers antipredatory behavior among prey. Yet, knowledge of how game species react to different types of human disturbance and adapt to repeated disturbances is limited. We investigated how disturbance in the form of a solitary human approacher (stalker) impacted behavior (flight response and short‐term habitat use) of 28 GPS‐collared red deer (Cervus elaphus) in two populations with contrasting population densities in Norway. We studied how the behavioral response differed: (1) with season (pre‐hunting vs. hunting); (2) by consecutive approaches within a day; (3) among replicated experiments within the same season; and (4) between two regions with contrasting densities of red deer. The average flight initiation distance (FID) increased by 15% during the hunting season, and consecutive approaches within the same day caused the red deer to move 49% longer distances. Flight init...
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The beaver is one of the world’s most unique animals in that it can fell and utilize whole mature trees as food and building resources; there are few plants they cannot digest; and their diet can include several plant species that are... more
The beaver is one of the world’s most unique animals in that it can fell and utilize whole mature trees as food and building resources; there are few plants they cannot digest; and their diet can include several plant species that are poisonous to humans and other animals. Beavers are opportunistic generalist herbivores that can eat bark, twigs, shoots, leaves of woody plants (mainly broad-leaved species), herbaceous and aquatic plants, fruits, and crops. There are over 300 plant species recorded in their diets. This chapter discusses typical foraging behaviours, central-place foraging, processing and felling of woody species, preferred species, diet variations, and seasonal variations in diets. Plant responses to beaver foraging and physiological defence of plants will also be central topics in this chapter.
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This chapter describes beaver habitat selection and modification activities. It discusses their unusual ability to modify environments to suit their needs, including lodge and dam construction, location selection for these structures, and... more
This chapter describes beaver habitat selection and modification activities. It discusses their unusual ability to modify environments to suit their needs, including lodge and dam construction, location selection for these structures, and alteration of vegetation. Historically beavers have been described as a forest species. Whilst beavers may preferentially select wooded freshwater habitats, particularly in more northern landscapes, they are capable of successfully establishing in widely varying terrain, including mountainous, brackish, tundra, cultivated, and urban landscapes. Beavers occupy a wide range of freshwater bodies (ponds, streams, rivers, marshes, and lakes) but will also travel through brackish and saltwater bodies during dispersal. Beavers prefer still or slow-moving water with stable water levels of at least 0.6–1.0 m in depth, but they are highly adaptable and can modify many types of natural, cultivated, and artificial habitats. When preferred habitats are unavaila...
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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... more
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 un...
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Several larger vertebrate species have recovered from dramatic bottlenecks caused by overhunting and habitat destruction. One of the most notable comebacks concerns the Eurasian beaver (Castor fiber L.), which has increased its range by... more
Several larger vertebrate species have recovered from dramatic bottlenecks caused by overhunting and habitat destruction. One of the most notable comebacks concerns the Eurasian beaver (Castor fiber L.), which has increased its range by natural dispersal from both relict populations and populations established through translocations. Genetic methods have recently been used to study beavers at several locations. However, owing to a lack of reference samples from relict populations and alternative names of mitochondrial DNA haplotypes, the ancestry of re-established beaver populations remains obscure. Here, we focus on the genetic characterization of several newly established populations. Unlike previous studies, we also used microsatellite genotypes of reference samples from all relict populations. Our analysis was fully capable of tracing the origin of the nuclear and mitochondrial genome to relict populations. Although we confirmed an extraordinarily low genetic diversity in relict...
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Data associated with the paper "Estimates for energy expenditure in free-living animals using acceleration proxies; a reappraisal", accepted for publication in the Journal of Animal Ecology in 2019.
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Information about population demography is crucial for developing and implementing conservation measures. The brown bear in the Gobi desert of southwestern Mongolia (referred to as the Gobi bear) is one of the smallest and most isolated... more
Information about population demography is crucial for developing and implementing conservation measures. The brown bear in the Gobi desert of southwestern Mongolia (referred to as the Gobi bear) is one of the smallest and most isolated brown bear populations in the world. We conducted genetic sampling (n = 2660 samples collected) using hair corrals around feeding sites at 13 water sources during 2009, 2013, and 2017 to evaluate population size, survival, and population trend. Bears were identified using 13 microsatellite loci and one sex marker. We detected 51 unique individuals (15F and 36M) from our targeted surveys in 2009, 2013, and 2017. Based on capture–mark–recapture robust design, population estimates were 23 (95% CI: 21–32) in 2009, 28 (95% CI: 25–35) in 2013, and 31 (95% CI: 29‐38) individuals in 2017. Spatial capture–recapture analysis suggested abundance was very low ( = 27; 95% CI: 22–35), and there was no significant change from 2009 to 2017. The population density wa...