Movement Ecology最新文献

Background: An abundance of white-tailed deer (Odocoileus virginianus) in suburban communities can lead to problems such as increased deer-vehicle collisions (DVCs), tick-borne illnesses, and forest degradation. Deer populations can be managed using traditional lethal methods; however, these methods are often impractical, ineffective, or socially unacceptable, prompting interest in management alternatives, including fertility control. Some fertility control methods (such as vasectomy, tubal ligation, and porcine zona pellucida-based vaccines) cause unsuccessfully bred females to experience multiple estrous cycles, potentially altering their movement behavior and fine-scale activity. Such changes could increase the risk of DVCs and negatively affect the physical condition of the animals. However, the effects of such treatments on animal behavior remain poorly understood, specifically in terms of breeding-related movements and energetics. This study aimed to evaluate the behavioral impacts of a large-scale vasectomy program on white-tailed deer.

Methods: We conducted a 2-year study using a treatment/control design and analyzed biologging data of white-tailed deer at two sites near New York City, USA. We used a moving-window approach to assess the effects of a large-scale vasectomy program on the seasonal changes in movement behavior (home-range size, distance traveled, diffusion, and excursivity) and fine-scale activity (time spent in low-activity states and the daily number of state transitions).

Results: There were no biologically significant differences in movement behavior or activity trends in either sex between the treatment and control groups. Females in both groups exhibited similar trends in all movement metrics, but females at the treatment site tended to switch between activity states more often in winter. Males at the treatment site expanded their space use less than control males during peak breeding season but otherwise exhibited similar movement behavior trends. Mortality rates and causes were similar at both sites.

Conclusions: The vasectomy program, despite causing extra estrus periods in unsuccessfully bred females, is unlikely to cause appreciable behavioral changes that could exacerbate management-related issues at the time scales investigated. Fertility control methods inducing extra estrus periods could be implemented alone or alongside other strategies to reduce abundant deer populations with minimal impact on behavior.

Background: Climate change is impacting the distribution and movement of mobile marine organisms globally. Statistical species distribution models are commonly used to explain past patterns and anticipate future shifts. However, purely correlative models can fail under novel environmental conditions, or omit key mechanistic processes driving species habitat use.

Methods: Here, we used a unique combination of laboratory measurements, field observations, and environmental predictors to investigate spatial variability in energetic seascapes for juvenile North Pacific albacore tuna (Thunnus alalunga). This species undertakes some of the longest migrations of any finfish, but their susceptibility to climate-driven habitat changes is poorly understood. We first built a framework based on Generalized Additive Models to understand mechanisms of energy gain and loss in albacore, and how these are linked to ocean conditions. We then applied the framework to projections from an ensemble of earth system models to quantify changes in thermal and foraging habitats between historical (1971-2000) and future (2071-2100) time periods.

Results: We show how albacore move seasonally between feeding grounds in the California Current System and the offshore North Pacific, foraging most successfully in spring and summer. The thermal corridors used for migration largely coincide with minimum metabolic costs of movement. Future warming may result in loss of favorable thermal habitat in the sub-tropics and a reduction in total habitat area, but allow increased access to productive and energetically favorable sub-arctic ecosystems. Importantly, while thermal considerations suggest a loss in habitat area, forage considerations suggest that these losses may be offset by more energetically favorable conditions in the habitat that remains. In addition, the energetic favorability of coastal foraging areas may increase in future, with decreasing suitability of offshore foraging grounds. Our results clearly show the importance of moving beyond temperature when considering climate change impacts on marine species and their movement ecology.

Conclusions: Considering energetic seascapes adds essential mechanistic underpinning to projections of habitat gain and loss, particularly for highly migratory animals. Overall, improved understanding of mechanisms driving migration behavior, physiological constraints, and behavioral plasticity is required to better anticipate how climate change will impact pelagic marine ecosystems.

Juvenile passerines are expected to have lower migration performance than adults due to their inexperience with long-distance flights and morphological limitations, such as shorter wing length. From 2016 to 2019 we radio-tagged nestling and adult Wood Thrushes (Hylocichla mustelina) at a breeding site in southwestern Ontario and used the automated Motus Wildlife Tracking System to test if age class predicts timing of the onset of fall migration (date, time of night), flight speed during the initial migration flight across Lake Erie, and overall pace of migration southward through the eastern United States. We detected 60/117 (51%) adults and 82/119 (69%) juveniles departing the breeding area as they initiated fall migration. Compared with adults, juveniles departed at an earlier date in fall and later time in the evening. When crossing Lake Erie on their first migratory flight juveniles travelled about 25% slower than adults but this was due primarily to adults making better use of tailwinds. When travelling south through the eastern U.S. juveniles had a slower overall migration pace (47.3 ± 5.1km/day) than adults (71.6 ± 4.7km/day). Although we found evidence that juvenile Wood Thrushes have an earlier and slower fall migration than adults, identifying the proximate and ultimate mechanisms remains a challenge. There is no evidence that juvenile Wood Thrushes are inefficient in migration flight or refueling at stopovers, and it is unlikely that the fall migration pace in this species affects their ability to compete for wintering food resources. More tracking studies from breeding sites are needed to understand the ecological factors favouring and biological significance of, age-related differences in migration performance.

Background: Foraging rates directly influence animals' energetic intake and expenditure and are thus linked to body condition and the ability to survive and reproduce. Further, understanding the underlying processes driving a species' behaviour and habitat use is important as changes in behaviour could result from changes in environmental conditions.

Methods: In this study, the dives of Saimaa ringed seals (Pusa hispida saimensis) were classified for the first time using hidden Markov models and telemetry data collected on individual dives, and the behavioural states of the diving seals were estimated. In addition, we used generalized additive mixed models on the foraging probability of the seals to identify environmental and temporal drivers of foraging behaviour.

Results: We inferred three (in winter) or four (in summer) different dive types: sleeping/resting dives, shallow inactive dives, transiting dives and foraging dives, based on differences in dive metrics logged by or derived from data from telemetry tags. Long and relatively deep sleeping/resting dives were missing entirely in the winter, compensated by an increased proportion of time used for haul-out. We found profound differences in the behaviour of Saimaa ringed seals during the open water season compared to the ice-covered winter, with the greatest proportion of time allocated to foraging during the summer months (36%) and the lowest proportion in the winter (21%). The seals' foraging probability peaked in summer (July) and was highest during the daytime during both summer and winter months. Moreover, foraging probability was highest at lake depths of 7-30 m in the winter and at depths > 15 m in the summer. We also found some evidence of sex-specific foraging strategies that are adapted seasonally, with females preferring more sheltered water areas during winter.

Conclusions: We suggest that the foraging behaviour of Saimaa ringed seals is largely influenced by diel vertical movements and availability of fish, and that the seals optimize their energy acquisition while conserving energy, especially during the cold winter months. Further, the seals display some flexibility in foraging strategies, a feature that may help this endangered subspecies to cope with the ongoing climate change.

Background: Animals with key ecological roles, such as seed-dispersing fruit bats, rely to varying degrees on habitat structure to indicate the locations of resources and risks.

Methods: To understand how variation in vegetation structure influences fruit bat habitat selection, we related movement steps of hammer-headed bats (Hypsignathus monstrosus) to attributes of canopy height, vertical and horizontal vegetation structure, and habitat type in a mature rainforest of southern Cameroon. Vegetation structural metrics were measured with UAV-LiDAR at 10 m resolution for a 25 km² study area. Because bats frequently moved outside the study area, we also characterized vegetation height and horizontal complexity over the full extent of bat movement trajectories by upscaling UAV-LiDAR measurements using primarily GEDI LiDAR data.

Results: At the site level, hammer-headed bats preferred areas of intermediate canopy height (13.9-32.0 m) close to large canopy gaps (≥ 500 m²). Individual bats varied in selection for vertical vegetation complexity, distance to smaller canopy gaps (≥ 50 m²) and plant volume density of intermediate vegetation strata (10-20 m). Over the full extent of movement trajectories, hammer-headed bats consistently preferred intermediate canopy height, and areas closer to canopy gaps. At both spatial extents, bats moved the shortest distances in swamp habitats dominated by Raphia palms. These behaviors indicate the use of forest types that vary structurally, with a preference for open airspace during foraging or moving among resources, and for dense swamp vegetation during roosting and resting periods. In addition, most bats regularly made long flights of up to 17.7 km shortly after sunset and before sunrise and limited their movements to three or fewer destinations throughout the tracking period.

Conclusions: These results highlight the importance of structurally diverse landscapes for the nightly movements of hammer-headed bats. Our results show how remote sensing methods and animal tracking data can be integrated to understand habitat selection and movement behavior in tropical ecosystems.

Background: Beaked whale response to Navy sonars is a global concern due to past stranding events coinciding with training activity. Often, controlled exposure experiments involve tagging cetaceans with short-term, high-resolution tags and exposing them to relatively short, single bouts of mid-frequency active sonar (MFAS). In contrast, longer-duration satellite-transmitting tags deployed around Navy ranges enables behavioral response studies of animals exposed to realistic Navy training activities over extended periods and spatial scales, with multiple exposures to different sources.

Methods: To study their behavior relative to extended periods of realistic Navy training, satellite-transmitting tags were deployed on four Blainville's beaked whales (Mesoplodon densirostris) on the Pacific Missile Range Facility (PMRF) off Kaua'i. Tags were deployed in 3 years, ahead of Submarine Command Courses (SCCs) with multiple sources of MFAS. Dive behavior of two tagged together were compared to acoustically detected group vocal periods (GVPs) on the range. Pre-exposure dive behavior metrics were compared to those during exposures. Horizontal movement behavior metrics were analyzed using Kruskal-Wallis non-parametric and Tukey-Kramer multiple comparison tests.

Results: Two whales remained together and highly synchronized in their dive and movement behavior until the onset of MFAS, at which time they appeared to separate. Twenty-three deep foraging dives were matched to GVPs, including three during MFAS. Of the dive behavior metrics, only the depth of one intermediate dive during an exposure was outside the 95th percentile of baseline behavior. Three of the four movement behavior metrics (75%) were atypical relative to baseline for at least one whale across SCC phases, but response varied by individual. However, throughout the SCCs, the whales remained within tens of kilometers of PMRF, near areas used before and after SCCs.

Conclusions: These data demonstrate some apparent short-term changes to dive behavior and horizontal movement in response to MFAS. However, these beaked whales did not demonstrate sustained avoidance responses, remaining in the area west of the range during MFAS and in two cases returning to the range after the SCC. Additional tagging and photo-identification studies are critical to understand Blainville's beaked whale habitat use and residency and to assess the potential impact of repeated exposures to MFAS.

Understanding species-habitat associations is fundamental to ecological sciences and for species conservation. Consequently, various statistical approaches have been designed to infer species-habitat associations. Due to their conceptual and mathematical differences, these methods can yield contrasting results. In this paper, we describe and compare commonly used statistical models that relate animal movement data to environmental data. Specifically, we examined selection functions which include resource selection function (RSF) and step-selection function (SSF), as well as hidden Markov models (HMMs) and related methods such as state-space models. We demonstrate differences in assumptions while highlighting advantages and limitations of each method. Additionally, we provide guidance on selecting the most appropriate statistical method based on the scale of the data and intended inference. To illustrate the varying ecological insights derived from each statistical model, we apply them to the movement track of a single ringed seal (Pusa hispida) in a case study. Through our case study, we demonstrate that each model yields varying ecological insights. For example, while the selection coefficient values from RSFs appear to show a stronger positive relationship with prey diversity than those of the SSFs, when we accounted for the autocorrelation in the data none of these relationships with prey diversity were statistically significant. Furthermore, the HMM reveals variable associations with prey diversity across different behaviors, for example, a positive relationship between prey diversity and a slow-movement behaviour. Notably, the three models identified different "important" areas. This case study highlights the critical significance of selecting the appropriate model as an essential step in the process of identifying species-habitat relationships and specific areas of importance. Our comprehensive review provides the foundational information required for making informed decisions when choosing the most suitable statistical methods to address specific questions, such as identifying expansive corridors or protected zones, understanding movement patterns, or studying behaviours. In addition, this study informs researchers with the necessary tools to apply these methods effectively.

Background: Understanding the abiotic and biotic drivers of species distribution is critical for climate-informed ecosystem management. We aimed to understand habitat selection of northern fur seals in the eastern Bering Sea, a declining population that is also a key predator of walleye pollock, the target species for the largest U.S. commercial fishery.

Methods: We developed species distribution models using random forest models by combining satellite telemetry data from lactating female fur seals tagged at different rookery complexes on the Pribilof Islands in the eastern Bering Sea with regional ocean model simulations. We explored how data aggregation at two spatial scales (Pribilof-wide and complex-specific) impacted model performance and predicted distributions. Spatial predictions under hindcasted (1992-2018) and projected (2050-2059) physical and biological conditions were used to identify areas of core habitat, overlap with commercial fishery catches, and potential changes in future habitat suitability.

Results: The most important environmental predictor variables across all models were bathymetry, bottom temperature, and surface temperature. The Pribilof-wide model both under- and overrepresented the importance of specific areas, while complex-specific models exhibited considerable variability in transferability performance. The majority of core habitat occurred on the continental shelf in areas that overlapped with commercial catches of walleye pollock during the "B" season (June - October), with an average of 76% of the total percentage of the catch occurring in core fur seal habitat within the foraging range of lactating females. Projections revealed that considerable changes in fur seal habitat suitability may occur in the coming decades, with complex-specific variation in the magnitude and direction of changes.

Conclusions: Our results illustrate the need to sample multiple sites whenever possible and consider spatial scale when extrapolating species distribution model output for central-place foragers, even when terrestrial sites are < 10 km apart. The high overlap between suitable fur seal habitat and commercial fishery catches of pollock, coupled with projected changes in habitat suitability, underscore the need for targeted studies investigating fisheries impacts on this declining population.

Background: Limited information exists on the active role of females during mate searching. Theory primarily focuses on male reproductive behaviours, suggesting male distribution follows that of females, while female distribution is influenced by food resources and habitat. This approach might underestimate the females' role in shaping mating strategies. Incorporating a female perspective into mating studies can enhance our understanding of evolutionary factors.

Methods: Using GPS data from brown bears Ursus arctos across Finland, Romania and Slovakia, we explored female movement behaviour during the mating period. First, we estimated movement speed, total distance and net distance at a daily scale. Then, we quantitatively described when the movement peaks occur by estimating two critical points of the functions described by each of the aforementioned movement parameters: (1) the point in time when the rate of change in brown bear movement behaviour is the highest; and (2) the point in time when each aspect of brown bear movement is most pronounced. We quantified temporal variations in male and female movements throughout the year using generalized additive mixed models, while we used linear mixed models to assess the relationship between peak movement parameters, bear sex and population.

Results: Our findings identified two overlooked behaviours: (1) male and female movement parameters showed the highest rate of change during the mating season, challenging the notion of male roaming as the primary mating strategy; and (2) females travelled the longest distances during the mating season, potentially seeking high-quality mates. This behaviour aligns with the strategy of engaging in copulations with multiple males to avoid infanticide.

Conclusions: Our study reveals novel insights into the active role of female brown bears in mating strategies, challenging traditional male-centric views. These results support the need for detailed investigations into female behaviours across mammalian taxa, which offer potential to advance our understanding of mammalian social and mating systems. Local differences also underscore the importance of social and ecological conditions to explain variation in the female role in mating strategies.