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The article discusses the severe megadrought in the American West, U.S. and the impending threat of the Colorado River running dry. It highlights the role of the North American Beaver in restoring and revitalizing the landscape through the installation of beaver dam analogs and collaborative cohabitation with humans, offering a solution to the degraded lands and water scarcity in the region.

Abstract: Beaver damming creates and maintains riparian ecosystems in arid regions, which are often afflicted by seasonal and multi‐year droughts. We hypothesize that beaver ponds act as buffers against the effects of drought on nearby riparian vegetation via the following mechanism: Beaver ponds formed upstream of each dam retain water during wetter parts of the year, then during drier parts of the year, they gradually release that water into nearby soil where it is accessible to the roots of riparian vegetation. We calculated the evapotranspiration (ET) and normalized difference vegetation index (NDVI) of riparian vegetation on Susie and Maggie Creeks in north‐eastern Nevada from 2013 to 2016 and then compared the ET and NDVI to the location and intensity of beaver damming on the creeks. We found that the ET of riparian areas with beaver damming was 50–150% higher than the ET in riparian areas without beaver damming and that NDVI in dammed riparian areas was 6–88% higher than that in undammed areas. These differences peaked in mid‐summer when the landscape is at its hottest and driest state. There was no apparent loss of beaver pond drought buffering as a multi‐year drought (2013–2015) progressed. Our results indicate that riparian areas with beaver damming in arid landscapes are better able to maintain vegetation productivity than areas without beaver damming during both short and extended periods of drought. [ABSTRACT FROM AUTHOR]

Species distributions are shaped by numerous factors that vary in importance across spatiotemporal scale. Understanding drivers of the distribution of North American beavers (Castor canadensis Kuhl, 1820) is paramount given their profound influence on ecological communities. Our objectives were to evaluate the influence of habitat quality, risk of gray wolf (Canis lupus Linnaeus, 1758) predation, and anthropogenic disturbance on the occurrence of beaver colonies in northeast British Columbia (BC), Canada. We used mixed-effects multinomial logistic regression to model the occurrence of active and inactive colonies and t tests to compare landscape covariates associated with active versus inactive colonies. We determined that occurrence of beavers was driven by habitat quality. Occurrence increased in areas with higher vegetation-class richness and greater proportions of open water, nutrient-rich fen, and deciduous swamp. We also observed that active colonies were surrounded by greater amounts of deciduous swamps relative to inactive colonies. We found no evidence that predation risk or industrial activities decreased the occurrence of beavers in northeast BC, although numerical changes in abundance might occur without changes in distribution. This research illuminated drivers of beaver distribution while providing a means to predict the occurrence of a keystone species in the boreal ecosystem. [ABSTRACT FROM AUTHOR]

The article focuses on artificial beaver dams. Topics include the history of Scott Valley or Beaver Valley in Northern California's Klamath Mountains, the effort to re-beaver Beaver Valley with the collaborative beaver dam analog (BDA), and the conflict of some landowners and government agencies, including the U.S. Department of Agriculture which deems beavers a nuisance.

Animal habitat selection, among other ecological phenomena, is spatially scale dependent. Habitat selection by American beavers Castor canadensis (hereafter, beaver) has been studied at singular spatial scales, but to date no research addresses multi-scale selection. Our objectives were to determine if beaver habitat selection was specialized to semiaquatic habitats and if variables explaining habitat selection are consistent between landscape and fine spatial scales. We built maximum entropy (MaxEnt) models to relate landscape-scale presence-only data to landscape variables, and used generalized linear mixed models to evaluate fine spatial scale habitat selection using global positioning system (GPS) relocation data. Explanatory variables between the landscape and fine spatial scale were compared for consistency. Our findings suggested that beaver habitat selection at coarse (study area) and fine (within home range) scales was congruent, and was influenced by increasing amounts of woody wetland edge density and shrub edge density, and decreasing amounts of open water edge density. Habitat suitability at the landscape scale also increased with decreasing amounts of grass frequency. As territorial, central-place foragers, beavers likely trade-off open water edge density (i.e., smaller non-forested wetlands or lodges closer to banks) for defense and shorter distances to forage and obtain construction material. Woody plants along edges and expanses of open water for predator avoidance may limit beaver fitness and subsequently determine beaver habitat selection. [ABSTRACT FROM AUTHOR]

In an age of invasions, it is critical to design and test management strategies to more efficiently control foreign species. Spatially explicit individual based models (SEIBMs) are a powerful tool to explore different management scenarios to control invaders, but we rarely have enough data to parameterize these models, particularly for relatively long-lived species. Here we take advantage of our previous work estimating demographic rates of invasive beavers in Patagonia, and develop an SEIBM to model the spread of beavers in Patagonia. We used our SEIBM both to estimate dispersal distances by fitting their observed rate of spread and to test how placing a buffer zone (a longitudinal strip of land perpendicular to the direction of spread within which a fraction of beavers are culled) beyond the invasion front would work as a control strategy. Specifically, we explored six different scenarios with two different culling rates and two buffer zone widths. We found that beavers in Patagonia must disperse long distances on average to account for the observed rate of spread, and thus our model predicts that a 100 km buffer zone will be needed to slow (but likely not halt) the spread of beavers. Interestingly, culling a higher proportion of beavers within a 100 km buffer zone (90 vs. 60%) did not improve buffer zone performance. Our study shows that wide buffer zones can slow (but likely not halt) continental spread of beavers in Patagonia and potentially pave the way for beaver eradication. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This study was performed in the basin of the Tadenka River (Prioksko-Terrasny Nature Reserve) in the years 2007-2012. We investigated the spatial dynamics of beaver settlements and the stability of various elements of the biological signaling field (scent marks, lifetime of dams and dwellings). The data suggest that a high density of the biological signaling field is an additional sign of possible depletion of food resources. Beavers can rapidly occupy habitats with no elements of the signaling field, which contributed to the formation of their large range. [ABSTRACT FROM AUTHOR]

The present paper contains information on a new beaver colony discovered in the Chornyi mochar tract, which is located in the lowland part of Transcarpathia (= Zakarpattia Region). Th is rodent species disappeared from the territory of Transcarpathia most likely in the 18th century. Its fi rst reappearance was recorded in 2003. Since, the Eurasian beaver has demonstrated a rapid expansion, primarily along the main rivers. The discovered by us colony allows to suggest that the beaver is continuing its dispersal, entering far into the main river's tributaries and other shallower water bodies. Consequently, we are witnessing not only the expansion of the species' geographical range, but also the enlargement of the number of habitat types occupied by the animal. The possibilities and supposed consequences of the species' further expansion within the tract are shown as well. [ABSTRACT FROM AUTHOR]

The integrity of wetlands is of global concern. A common approach to evaluating ecological integrity involves bioassessment procedures that quantify the degree to which communities deviate from historical norms. While helpful, bioassessment provides little information about how altered conditions connect to community response. More detailed information is needed for conservation and restoration. We have illustrated an approach to addressing this challenge using structural equation modeling (SEM) and long-term monitoring data from Rocky Mountain National Park (RMNP). Wetlands in RMNP are threatened by a complex history of anthropogenic disturbance including direct alteration of hydrologic regimes; elimination of elk, wolves, and grizzly bears; reintroduction of elk (absent their primary predators); and the extirpation of beaver. More recently, nonnative moose were introduced to the region and have expanded into the park. Bioassessment suggests that up to half of the park's wetlands are not in reference condition. We developed and evaluated a general hypothesis about how human alterations influence wetland integrity and then develop a specific model using RMNP wetlands. Bioassessment revealed three bioindicators that appear to be highly sensitive to human disturbance (HD): (1) conservatism, (2) degree of invasion, and (3) cover of native forbs. SEM analyses suggest several ways human activities have impacted wetland integrity and the landscape of RMNP. First, degradation is highest where the combined effects of all types of direct HD have been the greatest (i.e., there is a general, overall effect). Second, specific HDs appear to create a "mixed-bag" of complex indirect effects, including reduced invasion and increased conservatism, but also reduced native forb cover. Some of these effects are associated with alterations to hydrologic regimes, while others are associated with altered shrub production. Third, landscape features created by historical beaver activity continue to influence wetland integrity years after beavers have abandoned sites via persistent landforms and reduced biomass of tall shrubs. Our model provides a system-level perspective on wetland integrity and provides a context for future evaluations and investigations. It also suggests scientifically supported natural resource management strategies that can assist in the National Park Service mission of maintaining or, when indicated, restoring ecological integrity "unimpaired for future generations." [ABSTRACT FROM AUTHOR]

In Scotland, UK, beavers became extinct about 400 years ago. Currently, two wild populations are present in Scotland on a trial basis, and the case for their full reintroduction is currently being considered by Scottish ministers. Beavers are widely considered 'ecosystem engineers'. Indeed, beavers have large impacts on the environment, fundamentally change ecosystems, and create unusual habitats, often considered unique. In this review, we investigate the mechanisms by which beavers act as ecosystem engineers, and then discuss the possible impacts of beavers on the biodiversity of Scotland., A meta-analysis of published studies on beavers' interactions with biodiversity was conducted, and the balance of positive and negative interactions with plants, invertebrates, amphibians, reptiles, birds, and mammals recorded., The meta-analysis showed that, overall, beavers have an overwhelmingly positive influence on biodiversity. Beavers' ability to modify the environment means that they fundamentally increase habitat heterogeneity. As beavers are central-place foragers that feed only in close proximity to watercourses, their herbivory is unevenly spread in the landscape. In addition, beaver ponds and their associated unique successional stages increase habitat heterogeneity both spatially and temporally. Beavers also influence the ecosystems through the creation of a variety of features such as dams and lodges, important habitat features such as standing dead wood (after inundation), an increase in woody debris, and a graded edge between terrestrial and aquatic habitats that is rich in structural complexity., In Scotland, a widespread positive influence on biodiversity is expected, if beavers are widely reintroduced. For instance, beaver activity should provide important habitat for the otter Lutra lutra, great crested newt Triturus cristatus and water vole Arvicola amphibious, all species of conservation importance., Beavers are most likely to have detrimental impacts on certain woodland habitats and species of conservation importance, such as the Atlantic hazelwood climax community and aspen Populus tremula woodland. A lack of woodland regeneration caused by high deer abundance could lead to habitat degradation or loss. These are also of particular importance due to the variety of associated dependent species of conservation interest, such as lichen communities in Atlantic hazelwoods. [ABSTRACT FROM AUTHOR]

One key assumption often inferred with using radio-equipped individuals is that the transmitter has no effect on the metric of interest. To evaluate this assumption, we used a known fate model to assess the effect of transmitter type (i.e. tail-mounted or peritoneal implant) on short-term (one year) survival and a joint live-dead recovery model and results from a mark-recapture study to compare long-term (eight years) survival and body condition of ear-tagged only American beavers Castor canadensis to those equipped with radio transmitters in Voyageurs National Park, Minnesota, USA. Short-term (1-year) survival was not influenced by transmitter type ( wi = 0.64). Over the 8-year study period, annual survival was similar between transmitter-equipped beavers (tail-mounted and implant transmitters combined; 0.76; 95% CI = 0.45-0.91) versus ear-tagged only (0.78; 95% CI = 0.45-0.93). Additionally, we found no difference in weight gain (t9 = 0.25, p = 0.80) or tail area ( t11 = 1.25, p = 0.24) from spring to summer between the two groups. In contrast, winter weight loss (t22 = - 2.03, p = 0.05) and tail area decrease ( t30 = - 3.04, p = 0.01) was greater for transmitterequipped (weight = - 3.09 kg, SE = 0.55; tail area = - 33.71 cm2, SE = 4.80) than ear-tagged only (weight = - 1.80 kg, SE = 0.33; tail area = - 12.38 cm2, SE = 5.13) beavers. Our results generally support the continued use of transmitters on beavers for estimating demographic parameters, although we recommend additional assessments of transmitter effects under different environmental conditions. [ABSTRACT FROM AUTHOR]

Beavers are known for their gnawing performance, e.g., felling trees. Even though this is well known, the biomechanics of it are not, and so this is the focus of this study. The lower incisors work as main cutting tools so that their technical parameters were studied. There are 3 angles (adding to 90°) of importance in cutting: 1) the wedge angle, the angle of the incisor tip; 2) the clearance angle between tooth and material (tree trunk); and 3) the chip angle between incisor tip and the perpendicular to the surface of the trunk. Cutting is usually oblique to the wood fibers. For technical wood cutting tools, an optimal wedge angle of 27° is known under certain conditions, and for the incisor of Castor fiber the wedge angle was determined using micro-Computed Tomography (µCT) scans to be 26.95°. Potential cutting forces of beavers were estimated for wood chips (2 mm in thickness) of 3 sample tree species. For plum trees hardness forces ranged from 246 to 328 N, and for maples from 190 to 254 N. Finite element analyses were performed to determine stresses in the incisor under different loads on the incisor tip. Three hypotheses concerning gnawing were posed and are supported by the data: 1) The shape of the cutting blade of the incisor determines the geometry of wood chips and ultimately the maximum wood hardness that can be cut. 2) Clearance angle and maximum gape determine the maximum diameter of a tree that can be cut (if rough bark is neglected). 3) Functionally most importantly the lower incisors are optimized in shape and supporting tissue for compression stress with all forces being transmitted along the locations of the center of gravity in theoretical cross sections within the tooth, so that only compression occurs under load. [ABSTRACT FROM AUTHOR]

Recent technological innovations have led to the development of miniature, accelerometer-containing electronic loggers which can be attached to free-living animals. Accelerometers provide information on both body posture and dynamism which can be used as descriptors to define behaviour. We deployed tri-axial accelerometer loggers on 12 free-ranging Eurasian beavers Castor fiber in the county of Telemark, Norway, and on four captive beavers (two Eurasian beavers and two North American beavers C. canadensis) to corroborate acceleration signals with observed behaviours. By using random forests for classifying behavioural patterns of beavers from accelerometry data, we were able to distinguish seven behaviours; standing, walking, swimming, feeding, grooming, diving and sleeping. We show how to apply the use of acceleration to determine behaviour, and emphasise the ease with which this non-invasive method can be implemented. Furthermore, we discuss the strengths and weaknesses of this, and the implementation of accelerometry on animals, illustrating limitations, suggestions and solutions. Ultimately, this approach may also serve as a template facilitating studies on other animals with similar locomotor modes and deliver new insights into hitherto unknown aspects of behavioural ecology. [ABSTRACT FROM AUTHOR]

Conspecific aggression may play an important role in partitioning resources and maintaining territories among beavers ( Castor canadensis), yet few studies have examined physical evidence of agonistic encounters. We trapped and examined pelts from 147 beavers harvested between 2006 and 2012 from the Sangamon River (n = 96) and tributary streams (n = 51) in central Illinois. We modeled the influence of sex, age class, season (predispersal or dispersal), and habitat (river or tributary stream) on the number of recent injuries caused by conspecifics. One-third (51/147) of beavers had ≥1 injury; of those, the median number of injuries was 2.0. Kits had fewer injuries than adults (β Kit = −2.24 ± 0.63), but yearlings and subadults did not (β yearling = 0.02 ± 0.38, β subadult = −0.22 ± 0.48). Beavers on small streams had only one-quarter of the injuries recorded for beavers on the river (β Stream = −1.34 ± 0.82). We failed to detect differences in injuries between the sexes. Our results suggest both sexes participate in territorial defense through physical confrontations and such encounters can be costly to both dispersing juveniles and resident adults. [ABSTRACT FROM AUTHOR]

As ecosystem engineers, North American beavers (Castor canadensis) change many environmental conditions in watersheds, felling trees, damming streams, and flooding riparian zones. In Tierra del Fuego, where beavers were introduced in 1946, these alterations have produced meadows that appear to be long-term alternate stable states, lacking signs of resilience and natural forest regeneration. The aim of this work was to determine the abiotic and biotic factors that affect native tree seedling success in abandoned beaver meadows in Nothofagus pumilio forests. Environmental conditions including light, soil moisture, herbaceous plant community composition, and reinvasion potential were measured in areas impacted by beavers and in unimpacted old-growth forests. Additionally, we monitored the survival and success of N. pumilio seedlings transplanted in plots where meadow vegetation was cleared. Tree seedlings showed little growth, and survival varied by type of beaver impact. While survival was high and similar to unimpacted sites in zones cut but not flooded by beavers, it was significantly lower in meadow zones that were previously flooded and cut, compared to old-growth forests. We found that the reinvasion of herbaceous plants into transplantation study plots was negatively related to tree seedling survival, and herbaceous (monocot) plant cover itself was related to beaver-created gradients in soil moisture and light availability. Overall, these abiotic changes modified the meadow's plant community and enhanced herbaceous vegetation cover, particularly monocots and exotics, thus hindering transplanted seedling survival. [ABSTRACT FROM AUTHOR]

Castor canadensis (Beaver) is a selective forager that can modify the species composition and structure of plant communities. However, no studies have examined the use of woody plants by Beaver in temperate forests that contain a dominant nonnative plant. We investigated foraging of woody plants by Beaver in a riparian shrub community that is dominated by both native and nonnative species, including the federally threatened shrub Spiraea virginiana (Virginia Spiraea). We established 48 random, 25-m transects along a 12-km reach of the Cheoah River in the Appalachian Mountains of North Carolina. We sampled woody plants every 5 m using a modified point-centered quarter method to estimate relative abundance and to quantify browsing by Beaver. We used a mixed linear model to determine Beaver forage selection on the 9 most abundant plant species and Virginia Spiraea. We recorded 984 plants of 58 woody species (55 native, 3 nonnative). Beaver browsed 24% of the woody species sampled and 8% of all stems. This finding suggests that the overall effects of browsing in this community were relatively low, likely because of the high gradient and turbulent nature of the Cheoah River. Relative stem abundance and location along the river did not differentially affect local levels of browsing. However, Beaver were selective foragers at both the species and individual-plant level. Of the 9 most abundant species, Carpinus carolinana (Musclewood), Liquidambar styraciflua (Sweetgum), and Alnus serrulata (Tag Alder) were selected most often; Lindera benzoin (Spicebush), Virginia Spiraea, Cornus amomum (Silky Dogwood), and Ligustrum sinense (Chinese Privet) were moderately selected. Least frequently selected species were Rhododendron maximum (Rosebay Rhododendron), Leucothoe fontanesiana (Doghobble), and Xanthorhiza simplicissima (Yellowroot). Browsing appeared to have a positive effect on both the invasive nonnative shrub, Chinese Privet, and the rare Virginia Spiraea by stimulating asexual reproduction and inducing plants to spread through suckering. This study demonstrates the importance of understanding the reproductive strategies of woody plants when gauging the community-wide effects of foraging by Beaver, particularly when an invasive plant species is present. [ABSTRACT FROM AUTHOR]

Physiological states and foraging behaviors may shape movement patterns of animals. Optimal foraging theory and what we term the deliberate movement hypothesis predict that, to reduce predation risk, central place foragers should move faster with smaller turning angles the further they are from their central place. The complementary bimodal foraging trip hypothesis predicts that the distribution of foraging distances exhibited by central place foragers should be bimodal due to a trade-off between provisioning offspring and self-feeding. We used radio-telemetry to test these hypotheses for American beavers (Castor canadensis) in northern Alabama, United States. American beavers moved faster with increasing distance from lodges in wetland land cover but not in terrestrial land covers, partially supporting the deliberate movement hypothesis. Hourly distances moved from lodges were distributed bimodally during the breeding season, which supports the bimodal foraging trip hypothesis. Therefore, central place foraging may be a determinant of movement characteristics of American beavers. [ABSTRACT FROM AUTHOR]

Ecosystem engineers are frequently observed to increase local biodiversity through their effects on resource flows. While promotion of successional processes and increased biodiversity may occur without direct interaction between ecosystem engineers and sympatric species, many cases exist where interactions are common. Under such conditions, it is unclear whether direct interactions serve to facilitate or inhibit coexistence of ecosystem engineers and the species attempting to use engineered habitats. We used remote videography within lodges of an ecosystem engineer, beavers (Castor canadensis), to quantify the taxonomic diversity of lodge use by non-beaver fauna and to characterize interactions between beavers and a second engineering species that commonly uses beaver-manipulated habitats, muskrats (Ondatra zibethicus). Beaver lodges were used by eleven types of vertebrates and invertebrates. Although no increased aggression was displayed by resident beavers towards intruding muskrats, the temporally partitioned patterns of muskrats' and beavers' entrances and exits to and from lodges, respectively, and altered behavior among both species during cohabitation, indicates that lodge use by muskrats represents an exploitative behavior as opposed to a mutualistic or even commensalistic relationship. We hypothesize that the ecological similarities between these species promotes competitive interactions, and the observed relationship highlights the tradeoffs faced by ecosystem engineers wherein constructed objects intended to exclude competitors are simultaneously associated with habitat modifications that promote the persistence of those same competitors. [ABSTRACT FROM AUTHOR]

ABSTRACT Two centuries of human activities in the Greater Yellowstone Ecosystem (GYE) have strongly influenced beaver activity on small streams, raising questions about the suitability of the historical (Euro-American) period for establishing stream reference conditions. We used beaver-pond deposits as proxy records of beaver occupation to compare historical beaver activity to that throughout the Holocene. Forty-nine carbon-14 (14C) ages on beaver-pond deposits from Grand Teton National Park indicate that beaver activity was episodic, where multi-century periods lacking dated beaver-pond deposits have similar timing to those previously documented in Yellowstone National Park. These gaps in the sequence of dated deposits coincide with episodes of severe, prolonged drought, e.g. within the Medieval Climatic Anomaly 1000-600 cal yr bp, when small streams likely became ephemeral. In contrast, many beaver-pond deposits date to 500-100 cal yr bp, corresponding to the colder, effectively wetter Little Ice Age. Abundant historical beaver activity in the early 1900s is coincident with a climate cooler and wetter than present and more abundant willow and aspen, but also regulation of beaver trapping and the removal of wolves (the beaver's main predator), all favorable for expanded beaver populations. Reduced beaver populations after the 1920s, particularly in the northern Yellowstone winter range, are in part a response to elk overbrowsing of willow and aspen that later stemmed from wolf extirpation. Beaver populations on small streams were also impacted by low streamflows during severe droughts in the 1930s and late 1980s to present. Thus, both abundant beaver in the 1920s and reduced beaver activity at present reflect the combined influence of management practices and climate, and underscore the limitations of the early historical period for defining reference conditions. The Holocene record of beaver activity prior to Euro-American activities provides a better indication of the natural range of variability in beaver-influenced small stream systems of the GYE. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Coastal marshes of eastern Georgian Bay contain unique water chemistry that reflects mixing between the relatively ion-rich waters of Georgian Bay and the relatively ion-poor water draining the Canadian Shield landscape. These unique chemical characteristics may be dramatically altered when wetlands become hydrologically disconnected from Georgian Bay through beaver activity. We sampled 35 coastal marshes in Georgian Bay, 17 of which had beaver impoundments built at the outlet of the coastal wetland. Impounded marshes had significantly higher total phosphorus (30.2 versus 15.3 μg·L−1, p = 0.0015), soluble reactive phosphorus, (13.33 versus 3.7 μg·L−1, p ≤ 0.0001), total suspended solids (15.5 versus 2.1 mg·L−1, p ≤ 0.0001), turbidity (5.4 versus 1.6, p = 0.0004), and chlorophyll (6.2 versus 1.9 μg·L−1, p = 0.0004), but significantly lower pH (5.57 versus 6.95, p ≤ 0.0001), nitrates (0.03 versus 0.04 mg·L−1, p = 0.0416), and conductivity (47 versus 134 μS·cm−1, p ≤ 0.0001), indicative of reduced mixing with Georgian Bay. The mosaic of chemical conditions and altered hydrological connectivity associated with beaver impoundments in coastal marshes of Georgian Bay may affect the distribution of other wetland biota, and further studies should be conducted to ascertain these impacts. [ABSTRACT FROM AUTHOR]

A field experiment was conducted with growing winter forage beans for grain, (fully) irrigated conditions, to determine its energy efficiency under the influence of six introduced varieties of various types of ecological origin. The experiment includes the following varieties: 1.Mearis Beaver (control-Ko); 2.Bulldog; 3.Burdon; 4.Mearis Beagle; 5.Webo; 6.Throws MS. The energy efficiency was calculated by applying a balance method (energy input/consumed and output/produced) by means of energy equivalents for all operations and biomass energy value as calculated through its chemical composition and digestibility. The energy efficiency of the winter forage beans depends on variety, varying in average from 8.84 for GE, 4.63 for ME and 2.66 for NE. The varieties Maeris Beaver and Throws MS show the most stable values of the parameters studied, regardless of the agro-meteorological conditions throughout the year. This variety contributes to the highest energy efficiency in the production of winter forage beans compared to other major factors of the agricultural technology applied, i.e. irrigation and fertilization. [ABSTRACT FROM AUTHOR]

Due to the beaver's former role as a ubiquitous keystone species, there are increasing efforts in the American West to assist beaver in recolonization. Many interested in reintroduction are using two methods to identify optimal habitat: habitat suitability indexes/models (HSI), and historic occupation. This study details some of the problems inherent in HSIs applied to beaver habitat. The paper then interrogates historical occupation as a relocation tool, and finds that while more logically consistent, this method of habitat identification is also problematic. Historic range does not integrate past or present causes of extirpation and absence. I argue that, specifically in the case of beaver relocation but potentially for other species as well, causes of mortality are as important as are environmental amenities in identifying appropriate habitat. [ABSTRACT FROM AUTHOR]

Abstract: Despite the ubiquity of denning as a natural history strategy among terrestrial vertebrates, little is known regarding basic patterns of within-den behavior, how such patterns are influenced by demographic and environmental parameters, or how within-den behavioral repertoires relate to activities performed in external environments. Den usage is believed to facilitate increased expression of behaviors that compromise fitness in external environments, though empirical data validating these assumptions are generally lacking. Relative isolation from external light cues within dens has been linked to temporal patterns of den use, yet few studies examine associations between photoperiod and rhythmicity strictly for within-den behavior. Also, for denning species with relatively equivalent parental investment, conclusions regarding sex-specific behavior have been equivocal, and no studies have examined potential segregation of parental activity within dens. We videorecorded 1506h of within-den activity from 23 beaver (Castor canadensis) colonies and characterized behavioral patterns based on sex and age over daily and monthly intervals. Within-den time-activity budgets were equivalent among male and female adult beavers, with feeding, sleeping, allogrooming, and individual grooming accounting for more than 95% of all recorded behaviors. Behavioral repertoires within dens exhibited distinct seasonality and were influenced by temporal variation in external conditions associated with food availability, indicating linkages between activities within and outside of dens. Lastly, beaver age classes varied considerably in their associations between diel activity patterns and photoperiod, with adults and kits exhibiting single and multiple sleep–wake cycles, respectively. [Copyright &y& Elsevier]

Riparian wildlife is as important as vegetation in maintaining watercourse ecological integrity, yet present riparian buffer guidelines often fail to maintain sufficient terrestrial habitat for a variety of riparian species in North America. This is of particular concern for the conservation of riparian obligate animals, defined as freshwater-dependent species for which the terrestrial habitat immediately adjacent to watercourses is indispensable to complete their life history. Terrestrial habitat requirements of riparian obligate species are reviewed in this paper using the North American beaver (Castor canadensis) as a focal species. As an ecosystem engineer, the beaver has a profound influence on the shape and function of riparian ecosystems and creates diverse habitat patches. Published data show that 95% of woody plants cut by beavers on land are obtained within 50 m of the water's edge. A review of riparian invertebrates, amphibians, reptiles, mammals, and birds indicates that a 50 m-wide riparian buffer (measured from the high water mark) in its natural state (intact native vegetation) is the minimum area for supporting the majority of riparian obligate species. Exceptions are moose and some amphibian species that also need habitat well beyond 50 m from the water's edge to complete their life history. To conserve these wide-ranging species it is recommended that riparian buffers be continuous and integrated in a connectivity plan including upland reserves. Such a watershed-wide plan will also ensure that riparian buffers can serve as travel and dispersal corridors for both riparian and upland wildlife. [ABSTRACT FROM AUTHOR]

In order to understand wabusk (polar bear, Ursus maritimus) behaviours and interactions with people in the Hudson Bay lowlands of northern Ontario we conducted this collaborative study of Cree kiskayndamowin/knowledge. Our findings reveal that Cree knowledge supports previously published information on polar bears, while adding further contextual findings: that male polar bears travel greater distances into the muskeg than previously recorded; that wabusk prey on amisk (beaver, Castor canadensis); that wabusk interact with muskwa (black bears, Ursus americanus); and that human-polar bear interactions occur in this region of northern Canada. Bearing in mind that Cree knowledge has been recognized in wildlife management strategies (i.e., for beaver, caribou and moose) elsewhere in Canada, this particular body of information is timely, especially since polar bears are considered threatened under the Ontario Endangered Species Act, and the province is developing a recovery strategy for the Southern Hudson Bay polar bear population. The federal government is also contemplating listing polar bears in Canada as a 'species of special concern' under the Species at Risk Act (SARA). While it is unclear as to how these decisions will impact the Cree-polar interactions, the listing of polar bears by both governments, but especially the provincial government of Ontario, must recognize treaty and Aboriginal rights, acknowledge its duties to consult and properly accommodate Aboriginal people's views, incorporate Cree kiskayndamowin/knowledge of wabusk, and re-examine the proposed Wabusk Co-Management Agreement draft developed by the Ontario Ministry of Natural Resources (OMNR) and Coastal Cree First Nations of Northern Ontario in 1994. The article provides recommendations that highlight how the Northern Cree First Nations, through the development of the Recovery Strategy for Polar Bear in Ontario, can become engaged in the management of wabusk in Ontario and throughout Canada. [ABSTRACT FROM AUTHOR]

Billions of dollars are being spent in the United States to restore rivers to a desired, yet often unknown, reference condition. In lieu of a known reference, practitioners typically assume the paradigm of a connected watercourse. Geological and ecological processes, however, create patchy and discontinuous fluvial systems. One of these processes, dam building by North American beavers (Castor canadensis), generated discontinuities throughout precolonial river systems of northern North America. Under modern conditions, beaver dams create dynamic sequences of ponds and wet meadows among free-flowing segments. One beaver impoundment alone can exceed 1000 meters along the river, flood the valley laterally, and fundamentally alter biogeochemical cycles and ecological structures. In this article, we use hierarchical patch dynamics to investigate beaver-mediated discontinuity across spatial and temporal scales. We then use this conceptual model to generate testable hypotheses addressing channel geomorphology, natural flow regime, water quality, and biota, given the importance of these factors in river restoration. [ABSTRACT FROM AUTHOR]

Predicting the effects of the loss of individual species on diversity represents one of the primary challenges facing community ecology. One pathway by which organisms of one species affect the distribution of species is ecosystem engineering. Changes in the dynamics of ecosystem engineers that lead to changes in the distribution of the patches of altered habitat are likely to lead to changes in diversity. I link data on the distribution of plant species found in the riparian zone of the Adirondacks (New York, USA) in patches modified by beaver and in unmodified forest patches to a model connecting the dynamics of ecosystem engineers to the dynamics of the patches that they create. These analyses demonstrate that changes in key parameters of the model, such as decreases in beaver colonization rates and rate of patch abandonment, lead to changes in species richness of up to 45% at the landscape scale, and that these changes are likely to occur over long time scales. This general approach of linking the population dynamics or behavior of a single species to changes in species richness at the landscape scale provides a means for both testing the importance of ecosystem engineering in different systems and developing scenarios to predict how changes in the dynamics of a single species are likely to affect species richness. [ABSTRACT FROM AUTHOR]

In Massachusetts, USA, both human and beaver (Castor canadensis) population levels are increasing, beaver damage complaints are escalating, and beaver management options are restricted by the 1996 Wildlife Protection Act. We looked at the public's norms toward beavers in Massachusetts. In 2002 we sent a mail-back questionnaire to a random sample of 5,563 residents in 3 geographic regions in Massachusetts and to residents who submitted a beaver complaint to Massachusetts Division of Fisheries and Wildlife (MassWildlife) in 1999- 2000 (47.3% overall response rate). Respondents supported some form of beaver management. As severity of beaver damage was perceived to increase, respondents were more willing to accept lethal management and control of beavers. These results emphasize the importance of how tolerance and acceptability of wildlife are influenced by the type of activity the animal is engaged in, the type of management action that is proposed, the positive or negative perception of a species in the eye of the public, and the public's preference for future population levels. A full understanding of these 4 points will help tailor management accordingly, because this knowledge can define a threshold of acceptance by the public for anticipated management actions. Restoration of full beaver management authority to the cognizant wildlife management agency would facilitate application of normative information to determine appropriate management response for minimizing conflicts between humans and beavers. [ABSTRACT FROM AUTHOR]

Beaver impoundments flood forested areas and may be important production sites for methylmercury (MeHg) because of the resulting enhanced microbial activity and oxygen depletion. The influence of 17 beaver impoundments on streamwater chemistry [total mercury (THg), MeHg, nutrients, cations, and anions)] was investigated by sampling sites located along vegetation and pond-age gradients in southwestern Quebec (Canada). Recently inundated beaver ponds (<10 years old) and those located in coniferous watersheds had the highest MeHg concentrations (range, 0.10-4.53 ng L-1) and greatest methylation efficiencies (%THg as MeHg; range, 10-74%). High heterotrophic activity likely occurred in the beaver ponds as suggested by depletions of dissolved oxygen, sulfate and nitrite—nitrate concentrations, and increases in nutrients (e.g., dissolved organic carbon, total phosphorus, and total nitrogen) in outlets compared to inlets. Acidic waters at coniferous sites may have stimulated more MeHg production than in mixed woodland regions. Lower methylation efficiencies in older ponds (>20 years old) may be due to the degradation of less labile organic matter as ponds age. Beavers actively alter watersheds by building impoundments, and our findings indicate that this landscape disturbance may be a significant source of MeHg to downstream water bodies. [ABSTRACT FROM AUTHOR]

We developed a remote videography system for monitoring behavior and demography of beavers (Castor canadensis) inside lodges and bank dens. Videography systems taped 6 beaver colonies for 1,080 hours and recorded 300 hours of beaver activity. Upon viewing videotape, we could characterize 86% of beaver activity into 1 of 12 behavioral categories. Of 26 individually marked beavers, we observed 8 (31%) on videotape and obtained a complete count of kits in 4 of 5 colonies. The remote videography system was generally useful and can provide wildlife biologists with demographic and behavioral information to support population modeling and management programs for beavers. [ABSTRACT FROM AUTHOR]

Beaver–willow (Castor-Salix) communities are a unique and vital component of healthy wetlands throughout the Holarctic region. Beaver selectively forage willow to provide fresh food, stored winter food, and construction material. The effects of this complex foraging behavior on the structure and function of willow communities is poorly understood. Simulation modeling may help ecologists understand these complex interactions. In this study, a modified version of the SAVANNA ecosystem model was developed to better understand how beaver foraging affects the structure and function of a willow community in a simulated riparian ecosystem in Rocky Mountain National Park, Colorado (RMNP). The model represents willow in terms of plant and stem dynamics and beaver foraging in terms of the quantity and quality of stems cut to meet the energetic and life history requirements of beaver. Given a site where all stems were equally available, the model suggested a simulated beaver family of 2 adults, 2 yearlings, and 2 kits required a minimum of 4ha of willow (containing about10stemsm−2) to persist in a steady-state condition. Beaver created a willow community where the annual net primary productivity (ANPP) was 2 times higher and plant architecture was more diverse than the willow community without beaver. Beaver foraging created a plant architecture dominated by medium size willow plants, which likely explains how beaver can increase ANPP. Long-term simulations suggested that woody biomass stabilized at similar values even though availability differed greatly at initial condition. Simulations also suggested that willow ANPP increased across a range of beaver densities until beaver became food limited. Thus, selective foraging by beaver increased productivity, decreased biomass, and increased structural heterogeneity in a simulated willow community. [Copyright &y& Elsevier]

The article presents a study of the relationships between beaver and elk herbivores. It highlights their potential in minimizing willows' standing crop in a competitive environment. It also outlines their compensatory growth and interaction at the Rocky Mountain National Park in Colorado which is considered a benefit for plants.

Suggests a kind of utopian society, expressed poetically and metaphorically in terms of the community of beavers. Talents of beavers and their similarity to humans; Instances in the book `Rusticatio Mexicana' in which there is a reference to the humanization of beavers; Precision in the way beavers construct their houses; Division of labor and communal spirit among beavers.

Presents a study of the effects of beaver activities on the biogeochemical cycles and the accumulation and distribution of chemical elements over time and space in boreal forest drainage networks. Elemental concentrations in soils and pore water; Anaerobic conditions due to saturation of soil by water as a control over alterations of biogeochemical pathways.

Examines the effects of changing sapling availability on foraging selectivity and cutting rates by beavers in large experimental closures. Correlation of mean size of saplings cut with distance from lodge; Correlation of species selectivity with sapling selectivity; Preferred species; Comparison with trials using a single species of saplings of variable sizes and trials using three species of saplings of variable sizes.

Studies the creation of aquatic patches by beaver (Castor canadensis) in the boreal forest of northern Minnesota to determine how the population dynamics of a disturbance-causing animal are linked to rates of patch formation and growth over a period of population expansion and stabilization.

Investigates how information about relatedness is coded in the anal gland secretion (AGS) of the beaver. Use of gas chromatography; Individual secretion profiles; Variation in the AGS profile within an individual and between individuals; Features shared by related individuals in the AGS profile.

Presents information on a study which focused on the use of scent marks by beavers (Castor canadensis) to mark their territory. How territory-owning beavers respond to a recurrent alien scent; Examination of two hypothesis used to determine the functions of scent marking; Examination of the study; Findings of the study.

We investigated how information about family membership is coded by the individually specific anal gland secretion (AGS) in the beaver, Castor canadensis. Because beavers live in strict family units and relatives share more features in the AGS profile than non-relatives, family members share more AGS features than non-family members. Therefore, family recognition seems to be a natural consequence of the more specific kin recognition. Multivariate statistical analyses revealed two possibilities in coding for family membership using the multi-component AGS: either two (female) to three (male) AGS compounds or many compounds were used, but we were not able to determine which possibility is more likely. Compounds were not equally important in coding family membership information, and the interactions among compounds were complex. We attempted to reconstruct a lineage tree for the relationship among different families using two–three or many compounds. We found there was no significant difference for trees constructed by using few or many compounds in either males or females. However, the trees derived from male compounds and female compounds lacked good congruence. [ABSTRACT FROM AUTHOR]