Sensor:
Radio Transmitter

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Radio Transmitter
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radio-transmitter
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Start date: 2012 × End date: 2019 ×

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Now showing 1 - 10 of 14
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    Data from: Modelling landscape connectivity for greater horseshoe bat using an empirical quantification of resistance
    (2018-07-09) Pinaud, David; Claireau, Fabien; Leuchtmann, Maxime; Kerbiriou, Christian
    (1) Habitat fragmentation and isolation as a result of human activities have been recognized as great threats to population viability. Evaluating landscape connectivity in order to identify and protect linkages has therefore become a key challenge in applied ecology and conservation. (2) One useful approach to evaluate connectivity is Least‐Cost Path (LCP) analysis. However, several studies have highlighted importance of parameterization with empirical, biologically‐relevant proxies of factors affecting movements, as well as the need to validate the LCP model with an independent dataset. (3) We used LCP analysis incorporating quantitative, empirical data about behaviour of the greater horseshoe bat Rhinolophus ferrumequinum to build up a model of functional connectivity in relation to landscape connecting features. We then validated the accumulated costs surface from the LCP model with two independent datasets; one at an individual level with radio tracking data and one at a population level with acoustic data. (4) When defining resistance, we found that the probability of bat presence in a hedgerow is higher when the distance between hedgerows is below 38 m, and decrease rapidly when gaps are larger than 50 m. The LCP model was validated by both datasets: the independent acoustic data showed that the probability of bat presence was significantly higher in areas with lower accumulated costs, and the radio tracking data showed that foraging was more likely in areas where accumulated costs were significantly lower. (5) Synthesis and applications. Through our modelling approach, we recommend a maximum of 38m (and no more than 50m) between connecting features around colonies of greater horseshoe bats. Our quantitative study highlights the value of this framework for conservation: results are directly applicable in the field and the framework can be applied to other species sensitive to habitat loss, including other bats. Provided that it is parameterized with empirical, biologically‐relevant data, this modelling approach can be used for restoring and evaluating green networks in agri‐environmental schemes and management plans.
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    Data from: Summer precipitation predicts spatial distributions of semiaquatic mammals
    (2015-09-24) Ahlers, Adam A.; Cotner, Lisa A.; Wolff, Patrick J.; Mitchell, Mark A.; Heske, Edward J.; Schooley, Robert L.
    Climate change is predicted to increase the frequency of droughts and intensity of seasonal precipitation in many regions. Semiaquatic mammals should be vulnerable to this increased variability in precipitation, especially in human-modified landscapes where dispersal to suitable habitat or temporary refugia may be limited. Using six years of presence-absence data (2007–2012) spanning years of record-breaking drought and flood conditions, we evaluated regional occupancy dynamics of American mink (Neovison vison) and muskrats (Ondatra zibethicus) in a highly altered agroecosystem in Illinois, USA. We used noninvasive sign surveys and a multiseason occupancy modeling approach to estimate annual occupancy rates for both species and related these rates to summer precipitation. We also tracked radiomarked individuals to assess mortality risk for both species when moving in terrestrial areas. Annual model-averaged estimates of occupancy for mink and muskrat were correlated positively to summer precipitation. Mink and muskrats were widespread during a year (2008) with above-average precipitation. However, estimates of site occupancy declined substantially for mink (0.56) and especially muskrats (0.09) during the severe drought of 2012. Mink are generalist predators that probably use terrestrial habitat during droughts. However, mink had substantially greater risk of mortality away from streams. In comparison, muskrats are more restricted to aquatic habitats and likely suffered high mortality during the drought. Our patterns are striking, but a more mechanistic understanding is needed of how semiaquatic species in human-modified ecosystems will respond ecologically in situ to extreme weather events predicted by climate-change models.
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    Data from: Automated telemetry reveals age specific differences in flight duration and speed are driven by wind conditions in a migratory songbird
    (2015-09-24) Mitchell, Greg W.; Woodworth, Bradley K.; Taylor, Philip D.; Norris, D. Ryan
    Background: Given that winds encountered on migration could theoretically double or half the energy expenditure of aerial migrants, there should be strong selection on behaviour in relation to wind conditions aloft. However, evidence suggests that juvenile songbirds are less choosey about wind conditions at departure relative to adults, potentially increasing energy expenditure during flight. To date, there has yet to be a direct comparison of flight efficiency between free-living adult and juveniles songbirds during migration in relation to wind conditions aloft, likely because of the challenges of following known aged individual songbirds during flight. We used an automated digital telemetry array to compare the flight efficiency of adult and juvenile Savannah sparrows (Passerculus sandwichensis) as they flew nearly 100 km during two successive stages of their fall migration; a departure flight from their breeding grounds out over the ocean and then a migratory flight along a coast. Using a multilevel path modelling framework, we evaluated the effects of age, flight stage, tailwind component, and crosswind component on flight duration and groundspeed. Results: We found that juveniles departed under wind conditions that were less supportive relative to adults and that this resulted in juveniles taking 1.4 times longer to complete the same flight trajectories as adults. We did not find an effect of age on flight duration or groundspeed after controlling for wind conditions aloft, suggesting that both age groups were flying at similar airspeeds. We also found that groundspeeds were 1.7 times faster along the coast than over the ocean given more favourable tailwinds along the coast and because birds appeared to be climbing in altitude over the ocean, diverting some energy from horizontal to vertical movement. Conclusions: Our results provide the first direct evidence that adult songbirds have considerably more efficient migratory flights than juveniles, and that this efficiency is driven by the selection of more supportive tailwind conditions aloft. Given the importance of wind for efficient flight, we suggest this behaviour could be adaptive in juveniles, if for example, the benefits of a more flexible departure schedule outweigh the costs of flying with less supportive winds.
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    Data from: Fat, weather, and date affect migratory songbirds’ departure decisions, routes, and time it takes to cross the Gulf of Mexico
    (2016-09-08) Deppe, Jill L.; Ward, Michael P.; Bolus, Rachel T.; Diehl, Robert H.; Celis-Murillo, Antonio; Zenzal, Theodore J. Jr.; Moore, Frank R.; Benson, Thomas J.; Smolinsky, Jaclyn A.; Schofield, Lynn N.; Enstrom, David A.; Paxton, Eben H.; Bohrer, Gil; Beveroth, Tara A.; Raim, Arlo; Obringer, Renee L.; Delaney, David; Cochran, William W.
    Approximately two thirds of migratory songbirds in eastern North America negotiate the Gulf of Mexico (GOM), where inclement weather coupled with no refueling or resting opportunities can be lethal. However, decisions made when navigating such features and their consequences remain largely unknown due to technological limitations of tracking small animals over large areas. We used automated radio telemetry to track three songbird species (Red-eyed Vireo, Swainson’s Thrush, Wood Thrush) from coastal Alabama to the northern Yucatan Peninsula (YP) during fall migration. Detecting songbirds after crossing ∼1,000 km of open water allowed us to examine intrinsic (age, wing length, fat) and extrinsic (weather, date) variables shaping departure decisions, arrival at the YP, and crossing times. Large fat reserves and low humidity, indicative of beneficial synoptic weather patterns, favored southward departure across the Gulf. Individuals detected in the YP departed with large fat reserves and later in the fall with profitable winds, and flight durations (mean = 22.4 h) were positively related to wind profit. Age was not related to departure behavior, arrival, or travel time. However, vireos negotiated the GOM differently than thrushes, including different departure decisions, lower probability of detection in the YP, and longer crossing times. Defense of winter territories by thrushes but not vireos and species-specific foraging habits may explain the divergent migratory behaviors. Fat reserves appear extremely important to departure decisions and arrival in the YP. As habitat along the GOM is degraded, birds may be limited in their ability to acquire fat to cross the Gulf.
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    Data from: Ecological opportunity leads to the emergence of an alternative behavioural phenotype in a tropical bird
    (2015-03-13) Touchton, Janeene M
    1. Loss of a dominant competitor can open ecological opportunities. Ecological opportunities are considered prerequisites for adaptive radiations. Nonetheless, initiation of diversification in response to ecological opportunity is seldom observed, so we know little about the stages by which behavioural variation either increases or coalesces into distinct phenotypes. 2. Here, a natural experiment showed that in a tropical island’s guild of army-ant following birds, a new behavioural phenotype emerged in subordinate spotted antbirds (Hylophylax naevioides) after the socially dominant ocellated antbird (Phaenostictus mcleannani) died out. 3. Individuals with this behavioural phenotype are less territorial; instead, they roam in search of ant swarms where they feed in locations from which dominant competitors formerly excluded them. Roaming individuals fledge more young than territorial individuals. 4. We conclude that ecological opportunity arising from species loss may enhance the success of alternative behavioural phenotypes and can favour further intraspecific diversification in life-history traits in surviving species.
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    Data from: Foraging and roosting behaviour of the fringe-lipped bat, Trachops cirrhosus, on Barro Colorado Island, Panamá
    (2017-12-18) Hämsch, Frank; O'Mara, M. Teague; Jones, Patricia L.
    The Neotropical fringe-lipped bat, Trachops cirrhosus, is a generalist predator that hunts frogs and insects by homing in on their mating calls. Although research has examined cognition and prey preferences of bats in captivity, little is known of the foraging or roosting behaviour of this species in the wild. We radio tracked six T. cirrhosus individuals on Barro Colorado Island, Panamá. Bat day roosts were all in hollow cashew trees, Anacardium excelsum, in mixed sex groups of three to five T. cirrhosus individuals, with frequent roost switching. Radio tracked individuals flew an average of 218 ± 227 m from their day roosts to 12.0 ± 10.17 ha foraging areas (50% utilization distribution [UD] kernels = area where bats spent 50% of their time as estimated from a probability distribution). These 50% UD kernels were less than 10% of their average total range use, but larger than previously reported for T. cirrhosus. Radio tracked individuals overlapped in 50% UD kernel foraging areas by only 2.1 ± 5.9 % on average. Foraging behaviour consisted predominantly of short sally flights of less than one minute, indicating bats were likely perch hunting. Bats were more frequently in flight, and had longer flight durations, at the beginning of the night and just before dawn than throughout the rest of the night. These data provide insight into the foraging behaviour of T. cirrhosus in the wild that is a species fast becoming a model system of cognition in captivity.
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    Data from: Spatial ecology of the water opossum Chironectes minimus in Atlantic Forest streams
    (2016-06-13) Leite, Melina de Souza; Galliez, Maron; Queiroz, Thiago Lopes; Pinto de Mendonça, Patrícia; Fernandez, Fernando A.S.
    The water opossum Chironectes minimus is the world’s only semi-aquatic marsupial. It is considered rare, and it is reported on several regional conservation lists of species as either endangered or data deficient. Given its uniqueness and the poor knowledge of its ecology, we aimed to investigate home range size and overlap and habitat selection of the water opossum in Atlantic Forest streams in southeastern Brazil. We radio tracked water opossums and collected information about their habitats and behaviour from October 2004 to April 2010. We combined common home range estimators for animals living in linear habitats with the synoptic model of home range and habitat selection. For the 10 individuals monitored, the home ranges varied between 0.80 and 9.66 km of watercourses; none of them had exclusive home ranges. The home range size for males was, on average, three times larger than for females. The overlap data showed that, on average, one male could encompass the home ranges of up to five females simultaneously, but more than one male could have access to the same female. For habitat selection at the individual level, we could not find any strong influence of habitat features on water opossum preferences because individuals selected different sets of habitat variables. However, at the population level, we found a negative relationship between home range size and river size. The water opossum seems to prefer shallow and narrow watercourses to establish its home ranges. Here, we present valuable information to advance our knowledge of the water opossum and its ecology, which is urgent for conservation purposes.
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    Data from: Defensive fruit metabolites obstruct seed dispersal by altering bat behavior and physiology at multiple temporal scales
    (2019-11-25) Baldwin, Justin W.; Dechmann, Dina K.N.; Thies, Wibke; Whitehead, Susan R.
    The paradoxical presence of toxic chemical compounds in ripe fruits represents a balance between plant enemies and allies: chemical traits can defend seeds against antagonistic herbivores, seed predators or fungal pathogens, but also can impose costs by repelling mutualistic seed dispersers, although the costs are often difficult to quantify. Seeds gain fitness benefits from travelling far from the parent plant, as they can escape from parental competition and elude specialized herbivores as well as pathogens that accumulate on adult plants. However, seeds are difficult to follow from their parent plant to their final destination. Thus, little is known about the factors that determine seed dispersal distance. We investigated this potential cost of fruit secondary compounds – reduced seed dispersal distance ‐ by combining two datasets from previous work on a Neotropical bat‐plant dispersal system (bats in the genus Carollia and plants in the genus Piper). We used data from captive behavioral experiments, which show how amides in ripe fruits of Piper decrease the retention time of seeds and alter food choices. With new analyses, we show that these defensive secondary compounds also delay the time of fruit removal. Next, with a behaviorally annotated bat telemetry dataset, we quantified post‐feeding movements (i.e. seed dispersal distances). Using generalized additive mixed models we found that seed dispersal distances varied nonlinearly with gut retention times as well as with the time of fruit removal. By interrogating the model predictions, we identified two novel mechanisms by which fruit secondary compounds can impose costs in terms of decreased seed dispersal distances: 1) small scale reductions in gut retention time and 2) causing fruits to forgo advantageous bat activity peaks that confer high seed dispersal distances.
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    Data from: A multi-scale test of the forage maturation hypothesis in a partially migratory ungulate population
    (2016-01-29) Hebblewhite, Mark; Merrill, Evelyn
    The forage maturation hypothesis (FMH) proposes that ungulate migration is driven by selection for high forage quality. Because quality declines with plant maturation, but intake declines at low biomass, ungulates are predicted to select for intermediate forage biomass to maximize energy intake by following phenological gradients during the growing season. We tested the FMH in the Canadian Rocky Mountains by comparing forage availability and selection by both migrant and nonmigratory resident elk (Cervus elaphus) during three growing seasons from 2002–2004. First, we confirmed that the expected trade-off between forage quality and quantity occurred across vegetation communities. Next, we modeled forage biomass and phenology during the growing season by combining ground and remote-sensing approaches. The growing season started 2.2 days earlier every 1 km east of the continental divide, was delayed by 50 days for every 1000-m increase in elevation, and occurred 8 days earlier on south aspects. Migrant and resident selection for forage biomass was then compared across three spatial scales (across the study area, within summer home ranges, and along movement paths) using VHF and GPS telemetry locations from 119 female elk. Migrant home ranges occurred closer to the continental divide in areas of higher topographical diversity, resulting in migrants consistently selecting for intermediate biomass at the two largest scales, but not at the finest scale along movement paths. In contrast, residents selected maximum forage biomass across all spatial scales. To evaluate the consequences of selection, we compared exposure at telemetry locations of migrant and resident elk to expected forage biomass and digestibility. The expected digestibility for migrant elk in summer was 6.5% higher than for residents, which was corroborated with higher fecal nitrogen levels for migrants. The observed differences in digestibility should increase migrant elk body mass, pregnancy rates, and adult and calf survival rates. Whether bottom-up effects of improved forage quality are realized will ultimately depend on trade-offs between forage and predation. Nevertheless, this study provides comprehensive evidence that montane ungulate migration leads to greater access to higher-quality forage relative to nonmigratory congeners, as predicted by the forage maturation hypothesis, resulting primarily from large-scale selection patterns.
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    Data from: Science update for the South Peace Northern Caribou (Rangifer tarandus caribou pop. 15) in British Columbia
    (2019-08-27) Seip, Dale R.; Price, Elena
    All caribou in British Columbia belong to the woodland subspecies (Rangifer tarandus caribou) and are further classified into three ecotypes based on differences in habitat use, behaviour and migration patterns. Approximately 17,000 northern ecotype Woodland Caribou reside in the province. This document focuses on seven herds belonging to this population found in the southern Peace region of BC (South Peace Northern Caribou, SPNC). These herds are referred to as the Graham, Moberly, Scott, Burnt Pine, Kennedy Siding, Quintette and Narraway. There are approximately 1,000 SPNC in BC The following summarizes the designations that apply to SPNC, which are designated as Threatened by the Committee on the Status of Endangered Wildlife in Canada. They are listed as Threatened in Canada on Schedule 1 of the Species at Risk Act. In BC, the SPNC are ranked S3 (special concern, vulnerable to extirpation or extinction) by the Conservation Data Centre and are on the provincial Blue list. The BC Conservation Framework ranks the SPNC as a priority 2 under goal 2 (prevent species and ecosystems from becoming at risk). They are protected from capture and killing, under the BC Wildlife Act. Caribou are also listed as a “Category of Ungulate Species” for which an Ungulate Winter Range (UWR) may be legally established under Section 11(3) of the Government Actions Regulation of the Forest and Range Practices Act (FRPA). UWRs contain habitat necessary to meet the winter habitat requirements of an ungulate species. Caribou are also listed as a "Category of Species at Risk" for which a Wildlife Habitat Area (WHA) may be legally established under Section 11(1) of the Government Actions Regulation. WHAs for caribou may be established to protect habitat required for calving, rutting, matrix/connectivity and mineral licks. UWRs and WHAs established under FRPA are also recognized under the Oil and Gas Activities Act. Recovery is considered to be biologically and technically feasible. The seasonal habitat use patterns of SPNC vary among herds, but generally in winter, they will select low-elevation forests (low-elevation winter habitat) and/or windswept alpine ridges (high-elevation winter habitat). In summer, certain herds use and select alpine and subalpine habitat, while other herds may use low-elevation boreal forest habitat. Use of high-elevation habitat provides some spatial separation between SPNC and predators such as grey wolves (Canis lupus) because these wolves primarily use low-elevation forest where the density of other ungulate species is higher. The primary cause of known adult mortality of SPNC is predation, primarily wolf predation. Other species including bears, wolverines (Gulo gulo) and eagles can be significant predators, particularly on calves. Any habitat change that compromises the spatial separation between caribou and their predators can compound this threat by increasing the risk of predation. Forestry-related activities have impacted SPNC and their habitat and are expected to do so into the future. Present-day energy production and mining are the most imminent industry-related threats to SPNC and their habitat. Impacts associated with forestry activities and energy and mining development include habitat loss, alteration and fragmentation and displacement of caribou from preferred habitats. Alteration of habitat may include the reduction of the availability of forage and/or the facilitation of habitat into early-seral forest, which supports more abundant early-seral ungulates (e.g., moose) and their predators. Most linear corridors such as access roads, seismic lines, pipelines and all- weather roads associated with energy production into the alpine increase SPNC risk to predation and have the potential to displace caribou from preferred habitats. Effluents and pollutants associated with energy production may also pose a risk to SPNC. The overall calculated and assigned threat impact that is observed, inferred, or suspected to be directly or indirectly effecting the ecology of SPNC over the next 10 years is very high (75% population declines).