Movement Ecology最新文献

Background: The Chinese mitten crab (Eriocheir sinensis) is a widespread species that is both threatened and commercially valuable in its native range, but considered invasive in various other parts of the world. Being catadromous, their downstream spawning migration to the sea marks the crucial final step in their life. Yet, little is known about their behaviour during this migration.

Methods: In this study we investigated the migration of mitten crabs from non-tidal freshwater rivers to the tidal estuarine mouth over a distance of 125 km using acoustic telemetry. During a three-year period, a total of 34 adult mitten crabs were equipped with acoustic tags. Six were equipped with tags that also had an accelerometer and pressure sensor to record the activity and depth of the crabs.

Results: All mitten crabs migrated downstream, primarily residing within the deeper parts of the rivers. They were detected until the border between the mesohaline and polyhaline zone of the estuary, suggesting that this area serves as their spawning habitat. Migration speeds were significantly higher in non-tidal freshwater rivers (on average 4.65 ± 3.51 km day^-1, range: 0.06-15.37 km day^-1) compared to the tidal estuary (on average 1.29 ± 1.22 km day^-1, range: 0.05-8.19 km day^-1). Mitten crabs migrated primarily during the darker hours of the day, however this pattern diminished in the estuary. In tidal rivers migratory activity was largely driven by the tidal cycle, with crabs selectively moving downstream during the ebb tide. No behavioural differences between male and female crabs were observed.

Conclusions: During their spawning migration, adult mitten crabs reveal movement behaviour that maximises their fitness. In shallow non-tidal rivers, migrating at night likely reduces predation risk. In tidal rivers, this behaviour largely disappears, which could be linked to increased depth and turbidity, or the prevalence of the tidal migration cue. Based on detection and acceleration data, this study provides the first evidence that adult mitten crabs use selective tidal stream transport during their migration. As a slow-moving species, this behaviour helps to preserve energy for spawning during the challenging final phase of their life cycle.

Sharing biologging data can facilitate collaborative research and biological conservation by providing maps showing animals' distribution and movements. It is a critical social mission to preserve not only horizontal position data, but also behavioral data such as diving depth, flight altitude, speed, and acceleration, as well as physiological data such as body temperature, along with related metadata, ensuring their preservation for future generation. Moreover, although biologging was initially developed in the field of biology, it now contributes to diverse fields such as meteorology and oceanography, leading to expanded opportunities for secondary data utilization. In light of social and academic requirements, we developed "Biologging intelligent Platform (BiP)", which adheres to internationally recognized standards for sensor data and metadata storage. As a result, BiP not only stores sensor data along with metadata but also standardizes this information to facilitate secondary data analysis, facilitating broader applications of biologging data across various disciplines. By visiting the website ( https://www.bip-earth.com ) and completing the user registration, data owners can interactively upload sensor data, input metadata associated with individual animals, devices, and deployments, standardize data formats, and choose between open and private settings for sharing data. Anyone interested in utilizing the data can access metadata and visualized route maps, irrespective of the data's open or private status. Users can freely download open datasets that are available under the CC BY 4.0 license, which permits copying, redistribution, and modification while adhering to the metadata's credit requirements. To use private datasets, users can contact the data owner to request permission. A unique feature of BiP is the Online Analytical Processing (OLAP) tools that calculate environmental parameters, such as surface currents, ocean winds, and waves from data collected by animals. Algorithms published in some previous studies are integrated into the OLAP which can estimate the environmental and behavioral parameters. To enhance data accessibility, BiP allows users to search for datasets using the DOI of the paper in which the data was used. We believe that linking with other databases for data exchange and multi-repository storage could enhance the sustainability of the data itself.

Background: Since the 1980s, Pacific Black Brant (Branta bernicla nigricans, hereafter brant) have shifted their winter distribution northward from Mexico to Alaska (approximately 4500 km) with changes in climate. Alongside this shift, the primary breeding population of brant has declined. To understand the population-level implications of the changing migration strategy of brant, it is important to connect movement and demographic data. Our objectives were to calculate migratory connectivity, a measure of spatial and temporal overlap during the non-breeding period, for Arctic and subarctic breeding populations of brant, and to determine if variation in migration strategies affected nesting phenology and nest survival.

Methods: We derived a migratory network using light-level geolocator migration tracks from an Arctic site (Colville River Delta) and a subarctic site (Tutakoke River) in Alaska. Using this network, we quantified the migratory connectivity of the two populations during the winter. We also compared nest success rates among brant that used different combinations of winter sites and breeding sites.

Results: The two breeding populations were well mixed during the winter, as indicated by a migratory connectivity score close to 0 (- 0.06) at the primary wintering sites of Izembek Lagoon, Alaska (n = 11 brant) and Baja California, Mexico (n = 48). However, Arctic birds were more likely to migrate the shorter distance to Izembek (transition probability = 0.24) compared to subarctic birds (transition probability = 0.09). Nest survival for both breeding populations was relatively high (0.88-0.92), and we did not detect an effect of wintering site on nest success the following year.

Conclusions: Nest survival of brant did not differ among brant that used wintering sites despite a 4500 km difference in migration distances. Our results also suggested that the growing Arctic breeding population is unlikely to compensate for declines in the larger breeding population of brant in the subarctic. However, this study took place in 2011-2014 and wintering at Izembek Lagoon may have greater implications for reproductive success under future climate conditions.

Background: The ability to navigate is crucial to the survival of many flying animals. Though relatively much less is known about the navigational abilities of bats versus birds, recent progress has been made in understanding the navigational abilities of cave roosting bats, but little is known about those of arboreal roosting flying-foxes, despite their extreme mobility.

Methods: We use extremely high spatiotemporal resolution GPS tracking to examine the flight behaviour of 11 grey-headed flying-foxes (Pteropus poliocephalus) displaced 16.8 km from their roost. We examined flight metrics of the resulting high-resolution traces to understand whether the displaced animals were aware their location with respect to the roost of capture. We use 7 grey-headed flying-foxes tracked from the roost of capture-as part of a separate, concurrent study-to aid in this comparison.

Results: Ten of 11 displaced individuals were detected at the roost of capture within four days of release, but all displaced individuals roosted for at least one night away from the roost of capture. Six individuals returned 'home' the next day, and four roosted away from 'home' for ≥ one further night. Prior to their return 'home', displaced individuals on average flew 2.7 times further and stopped 1.7 more times than reference individuals or displaced animals that had already returned 'home'. This indicates that displaced individuals expended more effort each night than non-displaced individuals. This suggests that these individuals were attempting to return 'home', rather than choosing not to return due to a lack of motivation to home. Flight segments of displaced individuals were higher, less straight, and less likely to be oriented. Flight segments that ended in a point that an individual had previously visited were faster, higher, and straighter than those not known to end in a point previously visited.

Conclusions: Our findings suggest that approximately half of the displaced animals were aware of where they were with respect to 'home' the night after release, whereas other individuals took at least a further night to orient themselves. While our results are consistent with previous work suggesting that non-echolocating bats may use a large-scale navigational map based on vision, sensory manipulations would be needed to confirm this.

Background: From megafauna to amoebas, the amount of space heterotrophic organisms use is thought to be tightly linked to the availability of resources within their habitats, such that organisms living in productive habitats generally require less space than those in resource-poor habitats. This hypothesis has widespread empirical support, but existing studies have focused primarily on responses to spatiotemporal changes in mean resources, while responses to unpredictable changes in resources (i.e., variance in resources or resource stochasticity) are still largely unknown. Since organisms adjust to variable environmental conditions, failing to consider the effects of resource unpredictability can result in an insufficient understanding of an organism's range size.

Methods: We leverage the available literature to provide a unifying framework and hypothesis for the effects of resource abundance and stochasticity on organisms' range sizes. We then use simulated movement data to demonstrate how the combined effects of resource abundance and stochasticity interact to shape predictable patterns in range size. Finally, we test the hypothesis using real-world tracking data on a lowland tapir (Tapirus terrestris) from the Brazilian Cerrado.

Results: Organisms' range sizes decrease nonlinearly with resource abundance and increase nonlinearly with resource stochasticity, and the effects of resource stochasticity depend strongly on resource abundance. Additionally, the distribution and predictability of resources can exacerbate the effects of other drivers of movement, such as resource depletion, competition, and predation.

Conclusions: Accounting for resource abundance and stochasticity is crucial for understanding the movement behavior of free-ranging organisms. Failing to account for resource stochasticity can lead to an incomplete and incorrect understanding of how and why organisms move, particularly during periods of rapid change.

Background: An animal's movement reflects behavioral decisions made to address ecological needs; specifically, that movement will become less directional in regions with high prey availability, indicating foraging behavior. In the marine realm, animal behavior occurs below the sea surface and is difficult to observe. We used an extensive satellite tagging dataset to explore how physical and biological habitat characteristics influence blue (Balaenoptera musculus) and fin (B. physalus) whale movement and foraging behavior in the California Current Ecosystem across four known bioregions.

Methods: We fitted movement models to 14 years of blue whale satellite tracking data and 13 years of fin whale data to characterize their movement persistence, with higher move persistence values representing more directional movement and lower move persistence values representing less directional movement. Models were evaluated against a range of physical and biological environmental predictors to identify significant correlates of low move persistence (i.e., presumed intensified foraging behavior). We then used data from a subset of sensor-equipped tags that monitored vertical behavior (e.g., dive and feeding), in addition to movement, to test the relationship between vertical behavior and movement persistence.

Results: Low move persistence was strongly correlated with shallower water depth and sea surface height for both species, with additional effects of chlorophyll-a concentration, vorticity and marine nekton biomass for blue whales. Data from sensor-equipped tags additionally showed that low move persistence occurred when whales made more numerous feeding dives. Temporal patterns of bioregion occupancy coincided with seasonal peaks in productivity. Most blue whale low-move-persistence movements occurred in the northern, nearshore bioregion with a late-season peak in productivity and were evenly distributed across all bioregions for fin whales.

Conclusions: We demonstrated that low move persistence is indicative of increased feeding behavior for both blue and fin whales. The environmental drivers of low move persistence were similar to those previously identified for survey-based species distribution models, linking environmental metrics to subsurface behavior. Occupancy and movement behavior patterns across bioregions indicate both species moved to exploit seasonal and spatial variability in productivity, with blue whales especially focusing on the bioregion of highest productivity during late summer and fall.

Variation in somatic growth plays a critical role in determining an individual's body size and the expression of its life history. Understanding the environmental drivers of growth variation in mobile organisms such as fishes can be challenging because an individual's growth expression integrates processes operating at different spatial and temporal scales. Traditionally, otolith (ear stone) based growth analyses have focussed on temporal environmental variation by assuming an individual spends its whole life at its capture location. This approach ignores the movement potential of individuals and thus the role of spatio-temporal variation in conditions experienced. Here, we develop a modelling framework that incorporates individual movement information reconstructed via the analysis of chemical tracers in otoliths. We assess whether consideration of movement histories is important to estimating growth of a mobile freshwater fish, golden perch (Macquaria ambigua) at three spatial resolutions: basin-scale, reach-scale (movement-exclusive), and reach-scale (movement-inclusive). The predictive capacity of annual growth models slightly improved from the basin to the reach spatial scales (inclusive or exclusive of movement histories). Contrary to expectations, incorporating individual movement information, did not improve our ability to describe growth patterns. Golden perch growth was linked to the magnitude of and variation in spring, summer, and previous-year (antecedent) discharge, and spring temperature. The direction and magnitude of these effects was, however, dependent on life stage. Adults benefitted strongly from any increase in discharge or temperature, whereas juveniles benefitted only from increased summer discharge and grew slower in years characterised by wetter and warmer springs. We suggest that, for highly mobile fish like golden perch and in the absence of fine, 'within reach' scale biological data, coarser 'reach-scale' environmental variation may adequately describe individual growth trajectories.

In a chemosensing system, the local olfactory environment experienced by a foraging organism is defined as an odorscape. Using the nocturnal pink bollworm moth (Pectinophora gossypiella), we tested the combined effect of three biophysical aspects in its immediate odorscape to shed light on the coupling effects of biotic and abiotic factors on navigation performances of a nocturnal forager: i) the quality of the pheromone source, ii) the pheromone availability, and iii) the airflow characteristics. The navigation performance of the males was investigated using a wind tunnel assay equipped with 3D infrared high-speed cameras. The navigation performance of the males was analyzed using ethological and biomechanical parameters.The results of this work indicate that: (1) the biophysical factors have combined effects on the navigation performance of mate-searching males; (2) Natural and sexual selection play an important role in shaping the pheromone-mediated sensory performance of nocturnal male moths; herein, the role of natural selection overrides that of sexual selection; (3) During odor-mediated mate-finding navigation, the male moth applies a tradeoff decision-making process based on weighted information from the biological and physical characteristics of the odorscape. This decision-making process includes weighting the tradeoff between the cost involved in flying under different flow conditions, the availability of different odor sources, and their quality.

Avian navigation has fascinated researchers for many years. Yet, despite a vast amount of literature on the topic it remains a mystery how birds are able to find their way across long distances while relying only on cues available locally and reacting to those cues on the fly. Navigation is multi-modal, in that birds may use different cues at different times as a response to environmental conditions they find themselves in. It also operates at different spatial and temporal scales, where different strategies may be used at different parts of the journey. This multi-modal and multi-scale nature of navigation has however been challenging to study, since it would require long-term tracking data along with contemporaneous and co-located information on environmental cues. In this paper we propose a new alternative data-driven paradigm to the study of avian navigation. That is, instead of taking a traditional theory-based approach based on posing a research question and then collecting data to study navigation, we propose a data-driven approach, where large amounts of data, not purposedly collected for a specific question, are analysed to identify as-yet-unknown patterns in behaviour. Current technological developments have led to large data collections of both animal tracking data and environmental data, which are openly available to scientists. These open data, combined with a data-driven exploratory approach using data mining, machine learning and artificial intelligence methods, can support identification of unexpected patterns during migration, and lead to a better understanding of multi-modal navigational decision-making across different spatial and temporal scales.

Background: Freshwater megafishes are among some of the most commercially and ecologically important aquatic organisms yet are disproportionately threatened with range and population reduction. Anthropogenic alterations of rivers influencing migrations are among the most significant causes for these declines. However, migratory fishes do not always respond similarly to movement barriers and thus it is necessary to develop models to predict movements of freshwater migratory fishes in the face of anthropogenic alteration. Predicting movement of freshwater fishes is often investigated using statistical packages. However, empirical studies assessing these packages have led to mixed results, questioning its applicability to all taxa. We argue that spatial, temporal, and environmental attributes are more influential for movement of a migratory megafish, the Alligator Gar (Atractosteus spatula), than the current parameters explored in a globally relevant fish movement model.

Methods: This study explored two independent mobile telemetry datasets investigating Alligator Gar movement on the Brazos and Trinity rivers. Environmental associations were investigated to predict Alligator Gar displacement and dispersal using generalized additive models, generalized linear models, and model selection. Leptokurtosis of Alligator Gar populations was also assessed. Predictability of the movement model was tested by comparing observed to model derived stationary and mobile components making up a leptokurtic movement distribution.

Results: Our study suggests that current and antecedent measures of discharge and water temperature are positively correlated with Alligator Gar displacement and dispersal. However, these patterns are only detectable when monthly relocation intervals are explored rather than seasonal scales. Leptokurtosis was observed in both Alligator Gar populations. However, movement was normally distributed (i.e., mesokurtic) under tracking events following high flood pulses. Additionally, predicted Alligator Gar movement was significantly farther under modeled values compared to observed values, in part because the species undergoes cyclical migrations for reproduction that are sensitive to water temperature and discharge.

Discussion: In conclusion, this study provides an alternative framework to assess the movement patterns of migratory fishes, which could be tested on additional freshwater fishes, and suggests that assessing spatial, environmental, and temporal processes simultaneously are necessary to capture the complexities of fish movement which currently are unavailable for the movement model we investigated.