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At least 145 records · Page 8Linked to original sources
USGS2022

Invasive plant hitchhikers: Appalachian Trail thru-hiker knowledge and attitudes of invasive plants and Leave No Trace practices

Hiking and backpacking on American National Scenic Trails has increased in popularity in recent years. To encourage responsible and sustainable outdoor recreation on these much-loved trails, direct and indirect management strategies must be employed by managerial agencies. The Leave No Trace (LNT) education program aims to protect natural resources by promoting minimum-impact behaviours that lessen environmental impacts. The accidental introduction and dispersal of non-native invasive flora by hikers is little studied but can have a detrimental environmental impact on protected areas. The purpose of our study was to understand whether Appalachian Trail thru-hikers are: 1) aware of this problem, 2) adhering to LNT principles to reduce this problem, and 3) willing to learn and adopt minimum-impact behaviours to address this problem. We found that thru-hiker knowledge of invasive plants was limited and that very few thru-hikers adopted low-impact practices to minimise plant introduction and spread. Promisingly, we found that most thru-hikers, once aware of the problems, were willing to learn and apply low-impact practices to minimise plant introduction and spread. We discuss the barriers to their adoption of these behaviours and present a comprehensive list of suggested LNT practices to limit invasive plant introduction and spread. We conclude that, whilst challenging, protected area managers can help deter the spread of invasive plants along trails by improving educational messaging, signage, personal communication, and providing supporting infrastructure that encourages visitors to adopt specific practices to minimise invasive plant introduction and spread within protected areas.

Virginia, West Virginia↗
USGS2019

Lava flow morphology at an erupting andesitic stratovolcano: A satellite perspective on El Reventador, Ecuador

Lava flows pose a significant hazard to infrastructure and property located close to volcanoes, and understanding how flows advance is necessary to manage volcanic hazard during eruptions. Compared to low-silica basaltic flows, flows of andesitic composition are infrequently erupted and so relatively few studies of their characteristics and behaviour exist. We use El Reventador, Ecuador as a target to investigate andesitic lava flow properties during a 4.5 year period of extrusive eruption between February 2012 and August 2016. We use satellite radar to map the dimensions of 43 lava flows and look at variations in their emplacement behaviour over time. We find that flows descended the north and south flanks of El Reventador, and were mostly emplaced over durations shorter than the satellite repeat interval of 24 days. Flows ranged in length from 0.3 to 1.7 km, and the length of flows generally decreased over the observation period. We measure a decrease in flow volume with time that is correlated with a long-term exponential decrease in effusion rate, and propose that this behaviour is caused by temporary magma storage in the conduit acting as magma capacitor between the magma reservoir and the surface. We use the dimensions of flow levées and widths to estimate the flow yield strengths. We observe that some flows were diverted by topographic obstacles, and compare measurements of decreased channel width and increased flow thickness at the obstacles with observations from laboratory experiments. Radar observations, such as those presented here, could be used to map and measure properties of evolving lava flow fields at other remote or difficult to monitor volcanoes.

El Reventador↗
USGS2015

The modelling and assessment of whale-watching impacts

In recent years there has been significant interest in modelling cumulative effects and the population consequences of individual changes in cetacean behaviour and physiology due to disturbance. One potential source of disturbance that has garnered particular interest is whale-watching. Though perceived as ‘green’ or eco-friendly tourism, there is evidence that whale-watching can result in statistically significant and biologically meaningful changes in cetacean behaviour, raising the question whether whale-watching is in fact a long term sustainable activity. However, an assessment of the impacts of whale-watching on cetaceans requires an understanding of the potential behavioural and physiological effects, data to effectively address the question and suitable modelling techniques. Here, we review the current state of knowledge on the viability of long-term whale-watching, as well as logistical limitations and potential opportunities. We conclude that an integrated, coordinated approach will be needed to further understanding of the possible effects of whale-watching on cetaceans.

Ocean and Coastal Management↗
USGS2016

Experience drives innovation of new migration patterns of whooping cranes in response to global change

Anthropogenic changes in climate and land use are driving changes in migration patterns of birds worldwide. Spatial changes in migration have been related to long-term temperature trends, but the intrinsic mechanisms by which migratory species adapt to environmental change remain largely unexplored. We show that, for a long-lived social species, older birds with more experience are critical for innovating new migration behaviours. Groups containing older, more experienced individuals establish new overwintering sites closer to the breeding grounds, leading to a rapid population-level shift in migration patterns. Furthermore, these new overwintering sites are in areas where changes in climate have increased temperatures and where food availability from agriculture is high, creating favourable conditions for overwintering. Our results reveal that the age structure of populations is critical for the behavioural mechanisms that allow species to adapt to global change, particularly for long-lived animals, where changes in behaviour can occur faster than evolution.

Nature Communications↗
USGS2019

Nutrient scarcity as a selective pressure for mast seeding

Mast seeding is one of the most intriguing reproductive traits in nature. Despite its potential drawbacks in terms of fitness, the widespread existence of this phenomenon suggests that it should have evolutionary advantages under certain circumstances. Using a global dataset of seed production time series for 219 plant species from all of the continents, we tested whether masting behaviour appears predominantly in species with low foliar nitrogen and phosphorus concentrations when controlling for local climate and productivity. Here, we show that masting intensity is higher in species with low foliar N and P concentrations, and especially in those with imbalanced N/P ratios, and that the evolutionary history of masting behaviour has been linked to that of nutrient economy. Our results support the hypothesis that masting is stronger in species growing under limiting conditions and suggest that this reproductive behaviour might have evolved as an adaptation to nutrient limitations and imbalances.

Nature Plants↗
USGS2020

Longer-lived tropical songbirds reduce breeding activity as they buffer impacts of drought

Droughts are expected to increase in frequency and severity with climate change. Population impacts of such harsh environmental events are theorized to vary with life history strategies among species. However, existing demographic models generally do not consider behavioural plasticity that may modify the impact of harsh events. Here we show that tropical songbirds in the New and Old Worlds reduced reproduction during drought, with greater reductions in species with higher average long-term survival. Large reductions in reproduction by longer-lived species were associated with higher survival during drought than predrought years in Malaysia, whereas shorter-lived species maintained reproduction and survival decreased. Behavioural strategies of longer-lived, but not shorter-lived, species mitigated the effect of increasing drought frequency on long-term population growth. Behavioural plasticity can buffer the impact of climate change on populations of some species and differences in plasticity among species related to their life histories are critical for predicting population trajectories.

Nature Climate Change↗
USGS2022

Industrial energy development decouples ungulate migration from the green wave

The ability to freely move across the landscape to track the emergence of nutritious spring green-up (termed ‘green-wave surfing’) is key to the foraging strategy of migratory ungulates. Across the vast landscapes traversed by many migratory herds, habitats are being altered by development with unknown consequences for surfing. Using a unique long-term tracking dataset, we found that when energy development occurs within mule deer ( Odocoileus hemionus ) migration corridors, migrating animals become decoupled from the green wave. During the early phases of a coalbed natural gas development, deer synchronized their movements with peak green-up. But faced with increasing disturbance as development expanded, deer altered their movements by holding up at the edge of the gas field and letting the green wave pass them by. Development often modified only a small portion of the migration corridor but had far-reaching effects on behaviour before and after migrating deer encountered it, thus reducing surfing along the entire route by 38.65% over the 14-year study period. Our study suggests that industrial development within migratory corridors can change the behaviour of migrating ungulates and diminish the benefits of migration. Such disruptions to migratory behaviour present a common mechanism whereby corridors become unprofitable and could ultimately be lost on highly developed landscapes.

Wyoming↗
USGS2024

Testing the effectiveness of interactive training on sexual harassment and assault in field science

Fieldwork is a critical tool for scientific research, particularly in applied disciplines. Yet fieldwork is often unsafe, especially for members of historically marginalized groups and people whose presence in scientific spaces threatens traditional hierarchies of power, authority, and legitimacy. Research is needed to identify interventions that prevent sexual harassment and assault from occurring in the first place. We conducted a quasi-experiment assessing the impacts of a 90-min interactive training on field-based staff in a United States state government agency. We hypothesized that the knowledge-based interventions, social modeling, and mastery experiences included in the training would increase participants’ sexual harassment and assault prevention knowledge, self-efficacy, behavioural intention, and behaviour after the training compared to a control group of their peers. Treatment–control and pre-post training survey data indicate that the training increased participants’ sexual harassment and assault prevention knowledge and prevention self-efficacy, and, to a lesser extent, behavioural intention. These increases persisted several months after the training for knowledge and self-efficacy. While we did not detect differences in the effect of the training for different groups, interestingly, post-hoc tests indicated that women and members of underrepresented racial groups generally scored lower compared to male and white respondents, suggesting that these groups self-assess their own capabilities differently. Finally, participants’ likelihood to report incidents increased after the training but institutional reports remained low, emphasizing the importance of efforts to transform reporting systems and develop better methods to measure bystander actions. These results support the utility of a peer-led interactive intervention for improving workplace culture and safety in scientific fieldwork settings.

Scientific Reports↗
USGS2015

Automated integration of lidar into the LANDFIRE product suite

Accurate information about three-dimensional canopy structure and wildland fuel across the landscape is necessary for fire behaviour modelling system predictions. Remotely sensed data are invaluable for assessing these canopy characteristics over large areas; lidar data, in particular, are uniquely suited for quantifying three-dimensional canopy structure. Although lidar data are increasingly available, they have rarely been applied to wildland fuels mapping efforts, mostly due to two issues. First, the Landscape Fire and Resource Planning Tools (LANDFIRE) program, which has become the default source of large-scale fire behaviour modelling inputs for the US, does not currently incorporate lidar data into the vegetation and fuel mapping process because spatially continuous lidar data are not available at the national scale. Second, while lidar data are available for many land management units across the US, these data are underutilized for fire behaviour applications. This is partly due to a lack of local personnel trained to process and analyse lidar data. This investigation addresses these issues by developing the Creating Hybrid Structure from LANDFIRE/lidar Combinations (CHISLIC) tool. CHISLIC allows individuals to automatically generate a suite of vegetation structure and wildland fuel parameters from lidar data and infuse them into existing LANDFIRE data sets. CHISLIC will become available for wider distribution to the public through a partnership with the U.S. Forest Service’s Wildland Fire Assessment System (WFAS) and may be incorporated into the Wildland Fire Decision Support System (WFDSS) with additional design and testing. WFAS and WFDSS are the primary systems used to support tactical and strategic wildland fire management decisions.

Remote Sensing Letters↗
USGS2015

Spatial-temporal variation of low-frequency earthquake bursts near Parkfield, California

Tectonic tremor (TT) and low-frequency earthquakes (LFEs) have been found in the deeper crust of various tectonic environments globally in the last decade. The spatial-temporal behaviour of LFEs provides insight into deep fault zone processes. In this study, we examine recurrence times from a 12-yr catalogue of 88 LFE families with ∼730 000 LFEs in the vicinity of the Parkfield section of the San Andreas Fault (SAF) in central California. We apply an automatic burst detection algorithm to the LFE recurrence times to identify the clustering behaviour of LFEs (LFE bursts) in each family. We find that the burst behaviours in the northern and southern LFE groups differ. Generally, the northern group has longer burst duration but fewer LFEs per burst, while the southern group has shorter burst duration but more LFEs per burst. The southern group LFE bursts are generally more correlated than the northern group, suggesting more coherent deep fault slip and relatively simpler deep fault structure beneath the locked section of SAF. We also found that the 2004 Parkfield earthquake clearly increased the number of LFEs per burst and average burst duration for both the northern and the southern groups, with a relatively larger effect on the northern group. This could be due to the weakness of northern part of the fault, or the northwesterly rupture direction of the Parkfield earthquake.

California↗
USGS2020

Spatial ecology of closely-related taxa: The case of the little shearwater complex in the North Atlantic Ocean

Seabirds inhabiting vast water masses provide numerous examples where opposing phenomena, such as natal and breeding philopatry vs. vagility have dug cryptic taxonomic boundaries among closely related taxa. The taxonomy of little shearwaters of the North Atlantic Ocean (Little–Audubon’s shearwater complex, Puffinus assimilis – lherminieri ) still remains unclear, and complementary information on non-breeding distributions and at-sea behaviour becomes essential to unravel divergent local adaptations to specific habitats. Using miniaturized light-level geolocators from seven study areas in the North Atlantic, we evaluate the spatial and habitat segregation, estimate the timing of their key life-cycle events and describe the at-sea behaviour of three taxa of these little shearwaters year-round to distinguish ecological patterns and specializations that could ultimately unravel potential lineage divergences. We also assess morphometric data from birds that were breeding at each study area to further discuss potential adaptations to specific habitats. Our results show that, while birds from different taxa segregated in space and habitats, they share ecological plasticity, similar annual phenology and diel foraging behaviour. These ecological inconsistencies, while defining the evolutionary stressors faced by these taxa, do not suggest the existence of three Evolutionary Significant Units. However, they confirm the recent evolutionary divergence among the three little shearwaters of the North Atlantic.

Zoological Journal of the Linnean Society↗
USGS2014

Retirement investment theory explains patterns in songbird nest-site choice

When opposing evolutionary selection pressures act on a behavioural trait, the result is often stabilizing selection for an intermediate optimal phenotype, with deviations from the predicted optimum attributed to tracking a moving target, development of behavioural syndromes or shifts in riskiness over an individual's lifetime. We investigated nest-site choice by female golden-winged warblers, and the selection pressures acting on that choice by two fitness components, nest success and fledgling survival. We observed strong and consistent opposing selection pressures on nest-site choice for maximizing these two fitness components, and an abrupt, within-season switch in the fitness component birds prioritize via nest-site choice, dependent on the time remaining for additional nesting attempts. We found that females consistently deviated from the predicted optimal behaviour when choosing nest sites because they can make multiple attempts at one fitness component, nest success, but only one attempt at the subsequent component, fledgling survival. Our results demonstrate a unique natural strategy for balancing opposing selection pressures to maximize total fitness. This time-dependent switch from high to low risk tolerance in nest-site choice maximizes songbird fitness in the same way a well-timed switch in human investor risk tolerance can maximize one's nest egg at retirement. Our results also provide strong evidence for the adaptive nature of songbird nest-site choice, which we suggest has been elusive primarily due to a lack of consideration for fledgling survival.

Manitoba, Minnesota↗
USGS2024

Greater plasticity in CTmax with increased climate variability among populations of tailed frogs

Temporally variable climates are expected to drive the evolution of thermal physiological traits that enable performance across a wider range of temperatures (i.e. climate variability hypothesis, CVH). Spatial thermal variability, however, may mediate this relationship by providing ectotherms with the opportunity to behaviourally select preferred temperatures (i.e. the Bogert effect). These antagonistic forces on thermal physiological traits may explain the mixed support for the CVH within species despite strong support among species at larger geographical scales. Here, we test the CVH as it relates to plasticity in physiological upper thermal limits (critical thermal maximum—CTmax) among populations of coastal tailed frogs ( Ascaphus truei ). We targeted populations that inhabit spatially homogeneous environments, reducing the potentially confounding effects of behavioural thermoregulation. We found that populations experiencing greater temporal thermal variability exhibited greater plasticity in CTmax, supporting the CVH. Interestingly, we identified only one site with spatial temperature variability and tadpoles from this site demonstrated greater plasticity than expected, suggesting the opportunity for behavioural thermoregulation can reduce support for the CVH. Overall, our results demonstrate one role of climate variability in shaping thermal plasticity among populations and provide a baseline understanding of the impact of the CVH in spatially homogeneous thermal landscapes.

Proceedings of the Royal Society B↗
USGS2021

Intraspecific variation in incubation behaviors along a latitudinal gradient is driven by nest microclimate and selection on neonate quality

The strategies by which animals allocate reproductive effort across their lifetimes vary, and the causes of variation in those strategies are actively debated. In birds, most research has focused heavily on variation in clutch size and fecundity, but incubation behaviour and other functionally related traits have received less attention. Variation in incubation period duration is notable because time-dependent sources of clutch mortality should impose strong directional selection to minimize the incubation period. However, life-history theory predicts multiple mechanisms by which inter- and intraspecific variation in incubation behaviours may be adaptive. We conducted one of the first studies of intraspecific latitudinal variation in avian incubation behaviours across a large portion of a single species’ range. We placed motion-activated nest cameras inside burrowing owl nests at five study sites to quantify variation in daily nest attentiveness, cumulative nest attendance and incubation period duration. We tested predictions of two alterative hypotheses that have been proposed to explain variation in incubation periods: the parental risk tolerance hypothesis and the neonate quality hypothesis . Daily nest attentiveness, cumulative nest attendance and incubation period duration in burrowing owls were all positively correlated with latitude. Burrowing owls reduced their daily nest attentiveness at low latitudes and on days when the average nest temperature was within the range that is optimal for embryo development. Further, longer incubation periods were most strongly associated with greater cumulative nest attendance instead of reduced daily nest attentiveness. These results support predictions of the neonate quality hypothesis: longer incubation periods result from stronger selection on neonate quality rather than selection to reduce reproductive effort in response to low extrinsic mortality risk. However, some owls facultatively reduced their daily nest attentiveness, and this result supports the general hypothesis that incubation decisions reflect a trade-off between reproduction and self-maintenance, and that the optimal solution to that trade-off varies systematically in response to latitudinal gradients in adult mortality.

California, Idaho, Nevada, Oregon, Utah↗
USGS2023

Why hibernate? Tests of four hypotheses to explain intraspecific variation in hibernation phenology

Hibernation is a remarkable behaviour deployed by a diverse array of endotherms within many clades that greatly reduces metabolic need, but also has somatic costs. Hibernation in modern endotherms is often assumed to be an adaptation allowing animals to avoid extreme thermal conditions or food shortages in seasonal environments. However, many animals hibernate when foraging conditions are energetically profitable, suggesting other causal factors influence hibernation behaviour. Understanding the selection pressures responsible for intraspecific variation in the timing and duration of hibernation can help elucidate the relative evolutionary influences of the ultimate ecological causes of hibernation. We tested four previously proposed mechanistic hypotheses to explain intraspecific variation in hibernation phenology in the federally threatened northern Idaho ground squirrel ( Urocitellus brunneus ): (1) thermal tolerance, (2) food limitation, (3) predation avoidance and (4) sexual selection. The predation avoidance and sexual selection hypotheses received the most support, although we also found some support for the thermal tolerance and food limitation hypotheses. Heavy squirrels increased hibernation duration regardless of environmental conditions, as predicted solely by the predation avoidance hypothesis. Reproductive males emerged from hibernation earlier in spring than other sex–age classes, a pattern predicted by the sexual selection hypothesis. Temperature and food availability explained a much smaller amount of the variation in hibernation behaviour, only partially supporting predictions of the thermal tolerance and food limitation hypotheses. Our results indicate that animals navigate life-history trade-offs between energetic allocation to survival and reproduction via state-dependent optimization of hibernation phenology. Consequently, any future environmental changes that influence body condition will have implications for population ecology and life-history evolution of hibernating animals due to stark differences in daily survival probability between hibernation and the active season.

Functional Ecology↗
USGS2016

Allometric and temporal scaling of movement characteristics in Galapagos tortoises

Understanding how individual movement scales with body size is of fundamental importance in predicting ecological relationships for diverse species. One-dimensional movement metrics scale consistently with body size yet vary over different temporal scales. Knowing how temporal scale influences the relationship between animal body size and movement would better inform hypotheses about the efficiency of foraging behaviour, the ontogeny of energy budgets, and numerous life-history trade-offs. We investigated how the temporal scaling of allometric patterns in movement varies over the course of a year, specifically during periods of motivated (directional and fast movement) and unmotivated (stationary and tortuous movement) behaviour. We focused on a recently diverged group of species that displays wide variation in movement behaviour – giant Galapagos tortoises ( Chelonoidis spp.) – to test how movement metrics estimated on a monthly basis scaled with body size. We used state-space modelling to estimate seven different movement metrics of Galapagos tortoises. We used log-log regression of the power law to evaluate allometric scaling for these movement metrics and contrasted relationships by species and sex. Allometric scaling of movement was more apparent during motivated periods of movement. During this period, allometry was revealed at multiple temporal intervals (hourly, daily and monthly), with values observed at daily and monthly intervals corresponding most closely to the expected one-fourth scaling coefficient, albeit with wide credible intervals. We further detected differences in the magnitude of scaling among taxa uncoupled from observed differences in the temporal structuring of their movement rates. Our results indicate that the definition of temporal scales is fundamental to the detection of allometry of movement and should be given more attention in movement studies. Our approach not only provides new conceptual insights into temporal attributes in one-dimensional scaling of movement, but also generates valuable insights into the movement ecology of iconic yet poorly understood Galapagos giant tortoises.

Journal of Animal Ecology↗
USGS2021

Group density, disease, and season shape territory size and overlap of social carnivores

1. The spatial organization of a population can influence the spread of information, behaviour, and pathogens. Territory size and territory overlap, components of spatial organization, provide key information as these metrics may be indicators of habitat quality, resource dispersion, contact rates, and environmental risk (e.g., indirectly transmitted pathogens). Furthermore, sociality and behaviour can also shape space use, and subsequently, how space use and habitat quality together impact demography. 2. Our study aims to identify factors shaping the spatial organization of wildlife populations and assess the impact of epizootics on space use. We also use network analysis to describe spatial organization and connectivity of social groups. 3. Here, we assessed the seasonal spatial organization of Serengeti lions and Yellowstone wolves at the group level. We examine the factors predicting mean territory size and mean territory overlap for each population using generalized additive models. We further explore the mechanisms by which disease perturbations could cause changes in spatial organization. 4. We demonstrate that lions and wolves were similar in that group-level factors, such as number of groups, shaped spatial organization more than population-level factors, such as population density. Factors shaping territory size were slightly different than factors shaping territory overlap; for example, wolf pack size was an important predictor of territory overlap, but not territory size. Lion spatial networks were more highly connected, while wolf spatial networks varied seasonally. We found that resource dispersion may be more important for driving territory size and overlap for wolves than for lions. Additionally, canine distemper epizootics may alter lion spatial organization, highlighting the importance of including behavioural and movement ecology in studies of pathogen transmission dynamics. 5. We provide insight about when we might expect to observe the impacts of resource dispersion, disease perturbations, and other ecological factors on spatial organization. Our work highlights the importance of monitoring and managing social carnivore populations at the group level. Future research should elucidate the complex relationships between demographics, social and spatial structure, abiotic and biotic conditions, and pathogen infections.

Journal of Animal Ecology↗
USGS2021

Drivers of site fidelity in ungulates

While the tendency to return to previously visited locations—termed ‘site fidelity’—is common in animals, the cause of this behaviour is not well understood. One hypothesis is that site fidelity is shaped by an animal's environment, such that animals living in landscapes with predictable resources have stronger site fidelity. Site fidelity may also be conditional on the success of animals’ recent visits to that location, and it may become stronger with age as the animal accumulates experience in their landscape. Finally, differences between species, such as the way memory shapes site attractiveness, may interact with environmental drivers to modulate the strength of site fidelity. We compared inter-year site fidelity in 669 individuals across eight ungulate species fitted with GPS collars and occupying a range of environmental conditions in North America and Africa. We used a distance-based index of site fidelity and tested hypothesized drivers of site fidelity using linear mixed effects models, while accounting for variation in annual range size. Mule deer Odocoileus hemionus and moose Alces alces exhibited relatively strong site fidelity, while wildebeest Connochaetes taurinus and barren-ground caribou Rangifer tarandus granti had relatively weak fidelity. Site fidelity was strongest in predictable landscapes where vegetative greening occurred at regular intervals over time (i.e. high temporal contingency). Species differed in their response to spatial heterogeneity in greenness (i.e. spatial constancy). Site fidelity varied seasonally in some species, but remained constant over time in others. Elk employed a ‘win-stay, lose-switch’ strategy, in which successful resource tracking in the springtime resulted in strong site fidelity the following spring. Site fidelity did not vary with age in any species tested. Our results provide support for the environmental hypothesis, particularly that regularity in vegetative phenology shapes the strength of site fidelity at the inter-annual scale. Large unexplained differences in site fidelity suggest that other factors, possibly species-specific differences in attraction to known sites, contribute to variation in the expression of this behaviour. Understanding drivers of variation in site fidelity across groups of organisms living in different environments provides important behavioural context for predicting how animals will respond to environmental change.

Journal of Animal Ecology↗