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Abstract

Recent increases in human disturbance pose significant threats to migratory species using collective movement strategies. Key threats to migrants may differ depending on behavioural traits (e.g. collective navigation), taxonomy and the environmental system (i.e. freshwater, marine or terrestrial) associated with migration. We quantitatively assess how collective navigation, taxonomic membership and environmental system impact species' vulnerability by (i) evaluating population change in migratory and non-migratory bird, mammal and fish species using the Living Planet Database (LPD), (ii) analysing the role of collective navigation and environmental system on migrant extinction risk using International Union for Conservation of Nature (IUCN) classifications and (iii) compiling literature on geographical range change of migratory species. Likelihood of population decrease differed by taxonomic group: migratory birds were more likely to experience annual declines than non-migrants, while mammals displayed the opposite pattern. Within migratory species in IUCN, we observed that collective navigation and environmental system were important predictors of extinction risk for fishes and birds, but not for mammals, which had overall higher extinction risk than other taxa. We found high phylogenetic relatedness among collectively navigating species, which could have obscured its importance in determining extinction risk. Overall, outputs from these analyses can help guide strategic interventions to conserve the most vulnerable migrations. This article is part of the theme issue ‘Collective movement ecology'.

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... This predicted collapse is due to an Allee effect, whereby positive feedback between reduced population size and reduced benefits from collective navigation (regardless of mechanism) leads to further reductions in the population size. Indeed, sudden population collapse has been observed in many group migrating species [100]. Further, migratory distance in wildebeest may be linked to population size [101,102] and in the case of caribou, migrations have stopped altogether when population sizes became low, only to recover when the number of animals increased [103]. ...
... Empirical tests of these predictions (e.g. [100]) could yield important insights for conservation and management. How will collective navigation shape adaptation (or not) to the Anthropocene? ...
... For example, sudden population collapse and hysteresis are predicted by ( phenomenological) models in which migration success is dependent on social learning [50,51], leadership [29] and many wrongs or emergent sensing [99]. Such predictions are consistent with empirical data suggesting that population size and migratory status are linked [145] and population collapse is associated with group travel in birds and fishes [100]. On the other hand, collective navigation could lead to density-dependent dispersal [17], and models predict that this density dependence should increase the robustness of metapopulations [146]. ...
Article
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Animals often travel in groups, and their navigational decisions can be influenced by social interactions. Both theory and empirical observations suggest that such collective navigation can result in individuals improving their ability to find their way and could be one of the key benefits of sociality for these species. Here, we provide an overview of the potential mechanisms underlying collective navigation, review the known, and supposed, empirical evidence for such behaviour and highlight interesting directions for future research. We further explore how both social and collective learning during group navigation could lead to the accumulation of knowledge at the population level, resulting in the emergence of migratory culture. This article is part of the theme issue ‘Collective movement ecology’.
... This predicted collapse is due to an Allee effect, whereby positive feedback between reduced population size and reduced benefits from collective navigation (regardless of mechanism) leads to further reductions in the population size. Indeed, sudden population collapse has been observed in many group migrating species [100]. Further, migratory distance in wildebeest may be linked to population size [101,102] and in the case of caribou, migrations have stopped altogether when population sizes became low, only to recover when the number of animals increased [103]. ...
... Empirical tests of these predictions (e.g. [100]) could yield important insights for conservation and management. How will collective navigation shape adaptation (or not) to the Anthropocene? ...
... For example, sudden population collapse and hysteresis are predicted by ( phenomenological) models in which migration success is dependent on social learning [50,51], leadership [29] and many wrongs or emergent sensing [99]. Such predictions are consistent with empirical data suggesting that population size and migratory status are linked [145] and population collapse is associated with group travel in birds and fishes [100]. On the other hand, collective navigation could lead to density-dependent dispersal [17], and models predict that this density dependence should increase the robustness of metapopulations [146]. ...
Preprint
Animals often travel in groups, and their navigational decisions can be influenced by social interactions. Both theory and empirical observations suggest that such collective navigation can result in individuals improving their ability to find their way and could be one of the key benefits of sociality for these species. Here we provide an overview of the potential mechanisms underlying collective navigation and review the known, and supposed, empirical evidence for such behaviour, and highlight interesting directions for future research. We further explore how both social and collective learning during group navigation could lead to the accumulation of knowledge at the population level, resulting in the emergence of migratory culture.
... The increase of human footprint is causing a reduction in animal vagility globally (Tucker et al. 2018), and species having large spatial requirements, such as large carnivores or migrating species, can be especially vulnerable to such threat (Hardesty-Moore et al. 2018). One of the most serious consequences of human expansion is the fragmentation of natural habitats, whose outcomes can have degrading effects on entire ecosystems and ecological processes (Haddad et al. 2015), including animal movement (Fahrig 2003;Crooks and Sanjayan 2006;Hardesty-Moore et al. 2018). ...
... The increase of human footprint is causing a reduction in animal vagility globally (Tucker et al. 2018), and species having large spatial requirements, such as large carnivores or migrating species, can be especially vulnerable to such threat (Hardesty-Moore et al. 2018). One of the most serious consequences of human expansion is the fragmentation of natural habitats, whose outcomes can have degrading effects on entire ecosystems and ecological processes (Haddad et al. 2015), including animal movement (Fahrig 2003;Crooks and Sanjayan 2006;Hardesty-Moore et al. 2018). At the scale of animal populations, fragmentation can be one of the major causes of loss of genetic diversity (Fahrig 2003). ...
Thesis
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Space is one of the most disputed resources between humans and other wildlife species in modern human-dominated landscapes. Successful wildlife management and conservation requires a deep understanding of the interactions between a species and the space where it lives, including direct and indirect effects of both natural and human-related factors of fundamental ecological processes. The high spatio-temporal resolution of Global Positioning System (GPS) tracking data turns tagged animals into in situ sensors of the environment, and allows investigating how environmental changes affect species’ distribution and ecological function. Large carnivores, in particular, with their wide movement ranges and large spatial requirements are highly susceptible to disturbance from infrastructure development; as such, they can represent an ideal case study to investigate the effects of expansion of human activities on species’ spatial ecology at multiple levels, spanning from patch to landscape scales. In this thesis, I investigated space-use patterns of a south-eastern European population of brown bears (Ursus arctos), whose distribution is shared among more than five countries, from Slovenia to Northern Greece, with its core between Slovenia and Croatia. Despite being the third largest brown bear population in Europe, only few studies have focussed on the spatial ecology of the Dinaric-Pindos bear population. I investigated how environmental factors and proxies of human activities (e.g., roads, human settlements, hunting sites) influenced patterns of bear space use, movements and habitat selection. I used this knowledge to develop a movement-based modelling approach, aimed at mapping patch connectivity for seasonal movements of bears within the study area. In addition to enhancing our knowledge of bear ecology at broader scale across Europe, the results from this thesis are also of practical value, as they inform current and future management and conservation scenarios in the light of ongoing development projects throughout the countries inhabited by the study population.
... Migratory populations that return to breeding sites for reproduction can be linked to each other by some proportion of the population that disperses into the 'wrong' site. Recently, the role of social interactions to lead to collective navigation has been hypothesized as a mechanism shaping the success of philopatric migrations [21][22][23]. The collective navigation hypothesis posits that the rate at which individuals disperse may be linked to individual-level error, which is diminished by migrating in groups and pooling individual choices [21,23,24]. ...
... Generally, increasing the strength of collective behaviour mitigates the potentially negative impacts of so-called migrational meltdown [12]. Thus, preserving the biological processes that facilitate collective behaviour of migratory species may be an important conservation target in its own right, echoing the sentiments of Hardesty-Moore et al. [22]. We suggest that an increased understanding of the proximate and ultimate factors governing dispersal among local populations within metapopulations, across heterogeneous environments, in tandem with the mosaic of selective forces acting on those environments, may be key to promoting persistence in the wild [81]. ...
Article
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The spatial dispersal of individuals plays an important role in the dynamics of populations, and is central to metapopulation theory. Dispersal provides connections within metapopulations, promoting demographic and evolutionary rescue, but may also introduce maladapted individuals, potentially lowering the fitness of recipient populations through introgression of heritable traits. To explore this dual nature of dispersal, we modify a well-established eco-evolutionary model of two locally adapted populations and their associated mean trait values, to examine recruiting salmon populations that are connected by density-dependent dispersal, consistent with collective migratory behaviour that promotes navigation. When the strength of collective behaviour is weak such that straying is effectively constant, we show that a low level of straying is associated with the highest gains in metapopulation robustness and that high straying serves to erode robustness. Moreover, we find that as the strength of collective behaviour increases, metapopulation robustness is enhanced, but this relationship depends on the rate at which individuals stray. Specifically, strong collective behaviour increases the presence of hidden low-density basins of attraction, which may serve to trap disturbed populations, and this is exacerbated by increased habitat heterogeneity. Taken as a whole, our findings suggest that density-dependent straying and collective migratory behaviour may help metapopulations, such as in salmon, thrive in dynamic landscapes. Given the pervasive eco-evolutionary impacts of dispersal on metapopulations, these findings have important ramifications for the conservation of salmon metapopulations facing both natural and anthropogenic contemporary disturbances. This article is part of the theme issue ‘Collective movement ecology’.
... In this way, they maintain WEF such as disease spread control and carrion removal (Table 1). At the global scale, aerial migrants compensate for the loss of the ecological functions provided by migratory mammals due to reduction in their terrestrial ranges over the last decades (Hardesty-Moore et al., 2018;Harris et al., 2009;Kauffman et al., 2021). In this way, aerial migrants maintain gene and species flow (Lin et al., 2021) preserving connectivity among distant resident species communities (i.e. ...
... GlobalRanges of migratory mammals have been strongly reduced(Hardesty-Moore et al., 2018;Harris et al., 2009;Kauffman et al., 2021).Bauer and Hoye, 2014) which could trigger negative cascading effects worldwide, with detrimental effects to humankind (e.g., increasing emergent infectious diseases)(Doughty et al., 2020). ...
Article
Land use change alters wildlife critical animal behaviours such as movement, becoming the main driver threatening wildlife ecological functions (WEF) and nature’s contribution to people (NCP) provided by terrestrial species. Despite the negative impacts of current rates of terrestrial fragmentation on WEF, many ecological processes can be still occurring through aerial habitats. Here, we propose and discuss that the movement capabilities of aerial species, as well their functional redundancy with non-flying wildlife, are the mechanisms by which some ecological processes can be still occurring. We show examples of how the movements of aerial wildlife may be masking the loss of important functions and contributions by compensating for the lost ecosystem functions previously provided by terrestrial wildlife. We also highlight the implications of losing aerial wildlife in areas where that functional redundancy was already lost due to the impacts of land use change on terrestrial wildlife. We suggest to consider flying wildlife as a biological insurance against the loss of WEF and NCP due to terrestrial fragmentation and proposed some aeroconservation measures.
... For ocean-run sockeye salmon, to use our focal example, adaptation could be possible, since the species has repeatedly evolved a landlocked form (kokanee; Wood et al. 2008), and a small proportion of Fraser River sockeye already use a less salmon farm-exposed southern migration route (Tucker et al. 2009;Morton and Routledge 2016). Many other species might not be so lucky (Hardesty-Moore et al. 2018). For those species that evolved migration strategies in response to disease pressure, migration barriersdisease-induced or otherwise imposedcould even trap populations in the same maladaptive scenarios they originally evolved to evade (Satterfield et al. 2015). ...
Article
Full-text available
Juvenile sockeye salmon (Oncorhynchus nerka) in British Columbia migrate past numerous Atlantic salmon (Salmo salar) farms from which they may acquire infectious agents. We analyse patterns of molecular detection in juvenile sockeye for the bacterium Tenacibaculum maritimum, known to cause disease in fish globally and to cause mouthrot disease in farmed Atlantic salmon in British Columbia. Our data show a clear peak in T. maritimum detections in the Discovery Islands region of British Columbia, where sockeye migrate close to salmon farms. Using well-established differential equation models to describe sockeye migration and bacterial infection, fit to detection data, we assessed support for multiple hypotheses describing farm- and background-origin infection. Our best models (with 99.8% empirical support) describe constant background infection pressure, except around Discovery Islands salmon farms, where farm-origin infection pressure peaked at 12.7 (approximate 95% CI: 4.5 to 31) times background levels. Given the severity of associated disease in related species and the imperilled nature of Fraser River sockeye, our results suggest the need for a more precautionary approach to managing farm–wild interactions in sockeye salmon.
... Many migratory species of conservation concern are declining worldwide (Hardesty- Moore et al. 2018). Comprehensive conservation strategies for these species must take into account breeding, migratory stopover, and overwintering sites. ...
Article
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Context Identifying core migratory pathways and associated threats is important for developing conservation priorities for declining migratory species, such as eastern monarch butterflies (Danaus plexippus L.). Objectives Characterization of monarch fall migration core pathways and annual variability was compared using kernel density estimation models (KDEMs) and MaxEnt ecological niche models. Potential anthropogenic hazards were identified across migratory pathways and related to conservation strategies. Methods Journey North citizen scientist monarch overnight roost data from 2002 to 2016 were used to model the fall migration at 10 km spatial resolution with MaxEnt and KDEMs. Potential anthropogenic threats to the fall migration were spatially identified along core migratory routes. Results The KDEM migratory pathways best represented patterns of monarch movement towards overwintering locations. Migratory routes varied as much as 200 km from east to west in the southern Central Flyway, which was also the only area identified with monarch roadkill hotspots. Potential threats from mosquito adulticide ultra-low volume (ULV) spraying were concentrated along Eastern Flyway coastal areas. Potential nectar resource loss or contamination from high usage of glyphosate herbicide and neonicotinoid insecticides was greatest in the Midwest, within the core route of the Central Flyway. Conclusions MaxEnt and KDEM were complementary in modeling monarch migratory pathways. Monarch roadkill estimation and mitigation strategies are most needed in the southern core migratory pathways through Texas and Mexico. High quality nectar resource enhancement could help to mitigate potential threats from mosquito ULV spraying and nectar resource loss or contamination in coastal areas and the Midwest, respectively.
... In the Central American region, migratory freshwater fishes are known mainly within the families Mugilidae, Eleotridae and Gobiidae (Matamoros et al., 2009;Lorion, Kennedy, & Braatne, 2011;Angulo et al., 2013;McMahan et al., 2013), and there are some efforts to understand the migratory behavior, aspects of distribution, diet and reproduction of some them, mainly species as Joturus pichardi and Dajaus monticola (Mugilidae) and some species of the genus Sicydium (Gobiidae) (Bussing & López, 1977;Cruz, 1987;Cruz, 1989;Bussing, 2002;Lyons, 2005;Ribeiro & Villalobos, 2010;Eslava & Díaz, 2011;Lorion et al., 2011;Barboza & Villalobos, 2018;González-Murcia & Álvarez, 2018), however, there are still gaps in information. In addition to this, there are currently conservation difficulties for this group due to development of hydroelectric plants (Anderson, Freeman, & Pringle, 2006;Liermann, Nilsson, Robertson, & Ng, 2012), fragmentation and alteration of habitat, and different environmental problems that threatens the conservation of freshwater ecosystems and fish populations (McDowall, 1992(McDowall, , 1999Hardesty-Moore et al., 2018). ...
Article
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Introduction: Joturus pichardi is an important migratory species that inhabits the rivers of the Atlantic zone of Costa Rica and has been little studied. Objective: To describe the diet and reproduction of J. pichardi and its relationship with environmental factors in the Pacuare River basin. Methods: Sixteen sampling sites were selected along the main channel or Pacuare River. The samplings were performed from October 2015 to October 2016. The gonads, stomach, and intestines of seven individuals of J. pichardi were analyzed. The relationship of J. pichardi between the physicochemical variables of the water and the structure of the habitat was analyzed. Results: Twenty individuals were collected at an elevation of 225-235masl. The occurrence of J. pichardi was related to sites with higher river velocity, high values of dissolved oxygen, rock substrate and forest land use. All the individuals analyzed had visceral fat and endoparasites in the stomach. Bryophytes, ferns, macroinvertebrates, and detritus were identified as part of the diet of J. pichardi. According to the analysis of gonads in adults, the individuals were identified in the gonadal state types I, II and V. Conclusions: Our results suggest J. pichardi is an omnivorous species associated with sites with rocks, rapids, well-oxygenated waters , and forest land use. Also, the analysis of gonads coincides with the known reproduction period of the species. Finally, individuals of Neoechinorhynchus spp. are recorded for the first time in stomachs of J. pichardi in Costa Rica.
... As mobile organisms that can move freely between habitats with a diverse suite of body size, feeding, and behavioral traits, bird community structure and composition can quickly change in response to environmental perturbations on short-time scales (Thorn et al. 2018). As long-lived vertebrates that may or may not adapt to changing conditions, population responses of individual species may not be consistent over longer time scales (Hardesty-Moore et al. 2018). Birds also perform a wide range of important ecosystem processes including pollination (Zanata et al. 2017), seed dispersal (Sekercioglu et al. 2004), and can also be important topdown controls on lower trophic levels (Gruner 2004). ...
Article
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Land‐use transformation is one of the most important and pervasive ecological changes occurring across the Earth, but its long‐term effects are poorly understood. Here, we analyze the effects of urban and agriculture development on bird biodiversity and community structure over a 16‐yr study period. We found that long‐term effects of land‐use change are dependent on spatial scale and land‐use type. At the regional scale, we found that gamma diversity (total number of species observed) declined by ~10% over time. At the landscape spatial scale, we found that beta diversity (uniqueness of bird communities) increased by ~16% over time. Additionally, the average contributions of urban riparian bird communities to beta diversity were generally the highest but declined by ~26% over the study period. Contributions of urban communities to beta diversity were generally the lowest but increased by ~10% over time. At the local scale, we observed different responses for different measures of alpha diversity. For bird species richness, temporal changes varied by land use. Species richness declined 16% at sites in desert riparian areas but increased by 21% and 12% at sites in urban and agricultural areas, respectively. Species evenness declined across all land uses, with some land uses experiencing more rapid declines than others. Our analysis of species groups that shared certain traits suggests that these community‐level changes were driven by species that are small, breed onsite, and feed on insects, grains, and nectar. Collectively, our results suggest that biodiversity declines associated with land‐use change predominate at the regional and local spatial scale, and that these effects can strengthen or weaken over time. However, these changes counterintuitively led to increases in biodiversity at the landscape scale, as bird communities became more unique. This has implications for conservation and management as it shows that the effects of land‐use modification on biodiversity may be positive or negative depending on the spatial scale considered.
... Although migratory species are less threatened overall than sedentary species, this trend is driven by the larger breeding range size of migratory species and, having accounted for this, we found the migratory behaviour promotes extinction risk. This is expected because migrants are sensitive to human pressures not only in their breeding distribution but also along their migratory routes and in their wintering range [54]. We also show that this effect of migration interacts with body size to determine threat. ...
Article
Insights into animal behaviour play an increasingly central role in species-focused conservation practice. However, progress towards incorporating behaviour into regional or global conservation strategies has been more limited, not least because standardized datasets of behavioural traits are generally lacking at wider taxonomic or spatial scales. Here we make use of the recent expansion of global datasets for birds to assess the prospects for including behavioural traits in systematic conservation priority-setting and monitoring programmes. Using International Union for Conservation of Nature Red List classifications for more than 9500 bird species, we show that the incidence of threat can vary substantially across different behavioural categories, and that some types of behaviour—including particular foraging, mating and migration strategies—are significantly more threatened than others. The link between behavioural traits and extinction risk is partly driven by correlations with well-established geographical and ecological factors (e.g. range size, body mass, human population pressure), but our models also reveal that behaviour modifies the effect of these factors, helping to explain broad-scale patterns of extinction risk. Overall, these results suggest that a multi-species approach at the scale of communities, continents and ecosystems can be used to identify and monitor threatened behaviours, and to flag up cases of latent extinction risk, where threatened status may currently be underestimated. Our findings also highlight the importance of comprehensive standardized descriptive data for ecological and behavioural traits, and point the way towards deeper integration of behaviour into quantitative conservation assessments. This article is part of the theme issue ‘Linking behaviour to dynamics of populations and communities: application of novel approaches in behavioural ecology to conservation’.
... Although migratory species are less threatened overall than sedentary species, this trend is driven by the larger breeding range size of migratory species and, having accounted for this, we found the migratory behaviour promotes extinction risk. This is expected because migrants are sensitive to human pressures not only in their breeding distribution but also along their migratory routes and in their wintering range [54]. We also show that this effect of migration interacts with body size to determine threat. ...
Preprint
Full-text available
Insights into animal behaviour play an increasingly central role in species-focused conservation practice. However, progress towards incorporating behaviour into regional or global conservation strategies has been far more limited, not least because standardised datasets of behavioural traits are generally lacking at wider taxonomic or spatial scales. Here we make use of the recent expansion of global datasets for birds to assess the prospects for including behavioural traits in systematic conservation priority-setting and monitoring programmes. Using IUCN Red List classification for >9500 bird species, we show that the incidence of threat can vary substantially across different behavioural syndromes, and that some types of behaviour - including particular foraging, mating and migration strategies - are significantly more threatened than others. When all factors are included in a combined model, behavioural traits have a weaker effect than well-established geographical and ecological factors, including range size, body mass and human population pressures. We also show that the association between behavior and extinction risk is partly driven by correlations with these underlying factors. Overall, these results suggest that a multi-species approach at the scale of communities, continents and ecosystems can be used to identify and monitor threatened behaviours, and to flag up cases of latent extinction risk, where threatened status may currently be underestimated. Our findings also highlight the importance of comprehensive standardized descriptive data for ecological and behavioural traits, and point the way forward to a deeper integration of behaviour into quantitative conservation assessments.
... Movement, or lack thereof, ultimately drives encounter rates between congeners and across species (Lowerre-Barbieri et al., this issue;Rooker et al., 2018;Westley et al., 2018), affecting trophic dynamics and energy flows (Fenkes et al., 2016) as well as fitness and reproductive resil- ience to external stressors (Lowerre- . The locations and associated environments that a given species seeks out and uses as essential habitat are driven by species-specific physiological constraints selected for over evolutionary time (Metcalfe et al., 2012;Cooke et al., 2014;Rangel et al., 2018), and affect a species' vulnerability to the rapid changes associated with the Anthropocene ( Hardesty-Moore et al., 2018). To address the Published by International Council for the Exploration of the Sea 2019. ...
Article
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Marine resource management is shifting from optimizing single species yield to redefining sustainable fisheries within the context of managing ocean use and ecosystem health. In this introductory article to the theme set, "Plugging spatial ecology into ecosystem-based management (EBM)" we conduct an informal horizon scan with leaders in EBM research to identify three rapidly evolving areas that will be game changers in integrating spatial ecology into EBM. These are: (1) new data streams from fishers, genomics, and technological advances in remote sensing and bio-logging; (2) increased analytical power through "Big Data" and artificial intelligence; and (3) better integration of social dimensions into management. We address each of these areas by first imagining capacity in 20 years from now, and then highlighting emerging efforts to get us there, drawing on articles in this theme set, other scientific literature, and presentations/discussions from the symposium on "Linkages between spatial ecology and sustainable fisheries" held at the ICES Annual Science Conference in September 2017.
... be/TG4eCWkdyQY) can greatly expand how we understand life processes. Similar to the role the microscope played in allowing us to understand life at scales smaller than humanly possible, global movement data of multiple species provides insights into processes too large to be observed unaugmented, but critical to understanding and maintaining ecosystem functionality (Hussey et al., 2015;Kays et al., 2015), and assessing how a species' movement ecology may affect its ability to survive and thrive in the Anthropocene (Flack et al., 2016;Hardesty-Moore et al., 2018;Tucker et al., 2018). ...
Article
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Although movement has always played an important role in fisheries science, movement patterns are changing with changing ocean conditions. This affects availability to capture, the spatial scale of needed governance, and our food supply. Technological advances make it possible to track marine fish (and fishermen) in ways not previously possible and tracking data is expected to grow exponentially over the next ten years - the bio-logging decade. In this article, we identify fisheries management data needs that tracking data can help fill, ranging from: improved estimates of natural mortality and abundance to providing the basis for short-term fisheries closures (i.e. dynamic closures) and conservation of biodiversity hotspots and migratory corridors. However, the sheer size of the oceans, lack of GPS capability, and aspects of marine fish life history traits (e.g., adult/offspring size ratios, high mortality rates) create challenges to obtaining this data. We address these challenges and forecast how they will be met in the next 10 years through increased use of drones and sensor networks, decreasing tag size with increased sensor capacity trends, the ICARUS initiative to increase satellite tracking capacity, and improved connectivity between marine and terrestrial movement researchers and databases. © International Council for the Exploration of the Sea 2019. All rights reserved.
... Many migratory species of conservation concern are declining worldwide (Hardesty- Moore et al. 2018). Comprehensive conservation strategies for these species must take into account breeding, migratory stopover, and overwintering sites. ...
Article
Road mortality may contribute to the population decline of eastern monarch butterflies (Danaus plexippus L.). We estimated autumn monarch roadkill rates within the primary Oklahoma to Mexico southern migration corridor (i.e., Central Funnel). Dead monarchs were surveyed along Texas roadsides during four weeks of autumn migration in 2016 and 2017. Roadkill averaged 3.4 monarchs per 100 m transect, reaching 66 per 100 m in a roadkill hotspot in southwestern Texas. Extrapolations of Central Funnel roadkill based on survey data and road types were 3.6 and 1.1 million in 2016 and 2017, respectively. Spatial distribution of roadkill across the Central Funnel was projected from Texas survey data using 30 m resolution MaxEnt niche models. Highest roadkill probability was linked to arid climate and low human population density. The latter variables may not be directly related to roadkill, but instead represent indirect correlates of increased densities of monarchs where the migration corridor narrows southwards. The higher roadkill projected in southwest Texas and Mexico by MaxEnt models agrees with previously reported monarch roadkill hotspots. MaxEnt-based 2016–2017 projections for annual roadkill rates throughout the Central Funnel averaged 2.1 million. This figure is similar to the result by simple extrapolation, and represents about 3% of the overwintering monarch population for these years. Mitigation at roadkill hotspots in the Central Funnel could reduce monarch roadkill mortality during migration and contribute towards conservation efforts for the monarch butterfly.
... Studies of migratory behavior are advancing our understanding of when, where, how, and why animals move across landscapes (Milner-Guland et al. 2011) and the role of this behavior within ecosystems (Bauer and Hoye 2014). As a result, more emphasis has been placed on conserving migratory species and their corridors (Berger and Cain 2014, Hardesty-Moore et al. 2018, Hays et al. 2019. ...
Article
Fine‐scale movement data has transformed our knowledge of ungulate migration ecology and now provides accurate, spatially explicit maps of migratory routes that can inform planning and management at local, state, and federal levels. Among the most challenging land use planning issues has been developing energy resources on public lands that overlap with important ungulate habitat, including the migratory routes of mule deer (Odocoileus hemionus). We generally know that less development is better for minimizing negative effects and maintaining habitat function, but we lack information on the amount of disturbance that animals can tolerate before reducing use of or abandoning migratory habitat. We used global positioning system data from 56 deer across 15 years to evaluate how surface disturbance from natural gas well pads and access roads in western Wyoming, USA, affected habitat selection of mule deer during migration and whether any disturbance threshold(s) existed beyond which use of migratory habitat declined. We used resource and step selection functions to examine disturbance thresholds at 3 different spatial scales. Overall, migratory use by mule deer declined as surface disturbance increased. Based on the weight of evidence from our 3 independent but complementary metrics, declines in migratory use related to surface disturbance were non‐linear, where migratory use sharply declined when surface disturbance from energy development exceeded 3%. Disturbance thresholds may vary across regions, species, or migratory habitats (e.g., stopover sites). Such information can help with management and land use decisions related to mineral leasing and energy development that overlap with the migratory routes of ungulates. © 2020 The Wildlife Society. Mule deer were sensitive to energy development during migration and migratory use declined when surface disturbance exceeded 3%. Better understanding the relationship between surface disturbance and migratory behavior can help identify tradeoffs and potential mitigation measures associated with mineral leasing and energy development that overlap with the migratory routes of ungulates.
... Movement allows the population of wildebeest to persist at high levels and this vast biomass has huge impacts as it moves around the park [19]. In the Serengeti region, as elsewhere, greater understanding of the mechanisms that drive keystone ecological processes is vital due to increased human activity [102] and the need to make informed and effective management decisions [103,104]. ...
Article
A central question in ecology is how to link processes that occur over different scales. The daily interactions of individual organisms ultimately determine community dynamics, population fluctuations and the functioning of entire ecosystems. Observations of these multiscale ecological processes are constrained by various technological, biological or logistical issues, and there are often vast discrepancies between the scale at which observation is possible and the scale of the question of interest. Animal movement is characterized by processes that act over multiple spatial and temporal scales. Second-by-second decisions accumulate to produce annual movement patterns. Individuals influence, and are influenced by, collective movement decisions, which then govern the spatial distribution of populations and the connectivity of meta-populations. While the field of movement ecology is experiencing unprecedented growth in the availability of movement data, there remain challenges in integrating observations with questions of ecological interest. In this article, we present the major challenges of addressing these issues within the context of the Serengeti wildebeest migration, a keystone ecological phenomena that crosses multiple scales of space, time and biological complexity. This article is part of the theme issue 'Collective movement ecology'.
... A recent meta-analysis across 57 different species demonstrated that movement rates by terrestrial mammals have declined substan- tially in landscapes that are heavily disturbed by human activities [62]. Hence roads, fences, pipelines and other linear features may represent conservation threats of surprising magnitude [63]. ...
Article
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Collective behaviours contributing to patterns of group formation and coordinated movement are common across many ecosystems and taxa. Their ubiquity is presumably due to altering interactions between individuals and their predators, resources and physical environment in ways that enhance individual fitness. On the other hand, fitness costs are also often associated with group formation. Modifications to these interactions have the potential to dramatically impact population-level processes, such as trophic interactions or patterns of space use in relation to abiotic environmental variation. In a wide variety of empirical systems and models, collective behaviour has been shown to enhance access to ephemeral patches of resources, reduce the risk of predation and reduce vulnerability to environmental fluctuation. Evolution of collective behaviour should accordingly depend on the advantages of collective behaviour weighed against the costs experienced at the individual level. As an illustrative case study, we consider the potential trade-offs on Malthusian fitness associated with patterns of group formation and movement by migratory Thomson's gazelles in the Serengeti ecosystem. This article is part of the theme issue ‘Collective movement ecology’.
... Thus, on the one hand, collective navigation and search strategies should help animals that migrate as groups adapt to this change, yet conversely, migratory culture could make current migratory tendencies more persistent and less adaptable to change [55,108]. Ultimately, it remains unclear whether collective movement may be a net promoter or inhibi- tor of survival in a world increasingly dominated by human activity [63]. ...
Article
Recent advances in technology and quantitative methods have led to the emergence of a new field of study that stands to link insights of researchers from two closely related, but often disconnected disciplines: movement ecology and collective animal behaviour. To date, the field of movement ecology has focused on elucidating the internal and external drivers of animal movement and the influence of movement on broader ecological processes. Typically, tracking and/or remote sensing technology is employed to study individual animals in natural conditions. By contrast, the field of collective behaviour has quantified the significant role social interactions play in the decision-making of animals within groups and, to date, has predominantly relied on controlled laboratory-based studies and theoretical models owing to the constraints of studying interacting animals in the field. This themed issue is intended to formalize the burgeoning field of collective movement ecology which integrates research from both movement ecology and collective behaviour. In this introductory paper, we set the stage for the issue by briefly examining the approaches and current status of research in these areas. Next, we outline the structure of the theme issue and describe the obstacles collective movement researchers face, from data acquisition in the field to analysis and problems of scale, and highlight the key contributions of the assembled papers. We finish by presenting research that links individual and broad-scale ecological and evolutionary processes to collective movement, and finally relate these concepts to emerging challenges for the management and conservation of animals on the move in a world that is increasingly impacted by human activity. This article is part of the theme issue ‘Collective movement ecology’.
... Broad-scale quantitative assessments on the impact of threats on population trends are rare. Recently, several studies have investigated large-scale relationships between predictor variables and vertebrate population trends, many of which rely on data from the Living Planet Index (LPI) Data Portal (Craigie et al. 2010;Collen et al. 2011;Barnes et al. 2016;Leung et al. 2017;Daskalova et al. 2018;Hardesty-Moore et al. 2018;Spooner et al. 2018). For those that incorporated biodiversity threats, only a subset of threat categories was included. ...
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The identification of factors that predict trends in population abundance is critical to formulate successful conservation strategies. Here, we explore population trends of Canadian vertebrates assessed as “at-risk” by the Committee on the Status of Endangered Wildlife in Canada and the threats affecting these trends using data from the Canadian Living Planet Index. We investigate how threat profiles—the combination of threats for a given species—vary among species and taxonomic groups. We then investigate threat profile as a predictor of temporal trends—both exclusively and in combination with additional biotic and abiotic factors. Species had 5.06 (±2.77) threats listed on average, and biological resource use (BRU) was the most frequently cited. Our analysis also revealed an association between taxonomic group and population trends, as measured by the proportion of annual increases (years with a positive interannual change). By contrast, the predictive power of threat profile was poor. This analysis yielded some useful insight for conservation action, particularly the prioritization of abating BRU. However, the predictive models were not as meaningful as originally anticipated. We provide recommendations on methodological improvements to advance the understanding of factors that predict trends in population abundance for prioritizing conservation action.
... As, by their nature, migratory populations cover a large area, the effect of a cessation of a migration has far-reaching ecological and sociological implications for the communities and ecosystems involved [1,58,59]. In the case of caribou, extensive efforts have been made to model their movement in an attempt to better understand their ecology and predict the future impacts of development and climate change [60][61][62][63][64]. Collec- tive behaviour is ubiquitous in migratory populations such as these, and is thought to play a key role in driving patterns of migration and dispersal [65][66][67][68]. As movement decisions are frequently collective decisions that are influenced by the nature of social interactions and group level properties, it is essential that collective behaviour is incorporated into the modelling framework [69,70]. ...
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Social interactions are a significant factor that influence the decision-making of species ranging from humans to bacteria. In the context of animal migration, social interactions may lead to improved decision-making, greater ability to respond to environmental cues, and the cultural transmission of optimal routes. Despite their significance, the precise nature of social interactions in migrating species remains largely unknown. Here we deploy unmanned aerial systems to collect aerial footage of caribou as they undertake their migration from Victoria Island to mainland Canada. Through a Bayesian analysis of trajectories we reveal the fine-scale interaction rules of migrating caribou and show they are attracted to one another and copy directional choices of neighbours, but do not interact through clearly defined metric or topological interaction ranges. By explicitly considering the role of social information on movement decisions we construct a map of near neighbour influence that quantifies the nature of information flow in these herds. These results will inform more realistic, mechanism-based models of migration in caribou and other social ungulates, leading to better predictions of spatial use patterns and responses to changing environmental conditions. Moreover, we anticipate that the protocol we developed here will be broadly applicable to study social behaviour in a wide range of migratory and non-migratory taxa. This article is part of the theme issue ‘Collective movement ecology’.
... These species maintain important ecological roles (e.g., nutrient transfer; Willson and Halupka 1995) and have a pronounced impact on human culture and economy (Barlow et al. 2008; Baran and Myschowoda 2009). Despite their human value, migratory fish, which use freshwater at some point during their life, have become increasingly atrisk to human disturbance in the current Anthropocene era (Dugan et al. 2010;Hardesty-Moore et al. 2018;Walters et al. 2019), and have seen a 41% decline in abundance between 1970WWF 2016). Most of these declines are a direct result of damming approximately half of global river volume (Grill 2015), putting at risk some of the world's most biodiverse fish communities (Winemiller et al. 2016). ...
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Widespread declines in migratory fish highlight the need for increased global efforts to raise awareness of their value and abate threats they face. World Fish Migration Day (WFMD), coordinated by the World Fish Migration Foundation, is a biennial global celebration of open rivers and migratory fish achieved through locally organized events with the common theme of connecting fish, rivers, and people. Since 2014, over 1,200 events have been organized in 80 different countries across all inhabited continents. Here we provide an overview of the WFMD social movement, highlighting its ability to raise awareness surrounding the plight of migratory fish. We provide pertinent case studies to illustrate the creative events held throughout the world intended to build the public and political will to enable protection and restoration of migratory fish populations. From a coordination perspective, there are several key principles that underlay the success of WFMD, including taking an optimistic approach, identifying change‐makers in the community, and carefully timing the growth of the movement. By reflecting on the approach and growth of WFMD, we feel this perspective piece will prove useful to other groups and organizations considering using the power of social movements to achieve common goals related to environmental conservation.
... Detailed assessments of outcomes of interventions, based on thorough monitoring, are key to informing the efficacy of conservation management and guiding future strategies (Towns 2018). Ch. 3 highlights that for the conservation of vulnerable migratory species threats should be quantified across their range (Hardesty- Moore et al. 2018). In addition, accounting for temporal variation in exposure to these threats is key to effective conservation management . ...
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Seabirds are one of the most threatened taxa on the planet. These species are also considered ecosystem engineers. Therefore, seabirds are of particular conservation interest. One of the most threatened seabirds is the critically endangered Whenua Hou Diving Petrel (Pelecanoides whenuahouensis; WHDP). The WHDP is restricted to a minute (0.018 km2) breeding colony on a single island — Whenua Hou (Codfish Island), Aotearoa (New Zealand). The WHDP population was estimated at 150 adults in 2005. The WHDP is threatened by storms and storm surges, which erode its breeding habitat (fragile foredunes), and potentially by competition for burrows with congenerics. I aimed to inform suitable conservation strategies for the WHDP. I first quantified the efficacy of past conservation actions (eradications of invasive predators). I compiled burrow counts across four decades to estimate and compare population growth before and after predator eradications. I then investigated offshore threats using tracking data to quantify WHDP offshore distribution, behaviour, and overlap with commercial fishing efforts. Subsequently, I estimated the potential impact and success of WHDP translocations. Specifically, I combined capture-recapture, nest-monitoring, and count data in an integrated population model (IPM) to predict the impact of harvesting chicks for translocations on the source population and to project the establishment of a second population. I then informed future translocation protocols using nest-monitoring data to quantify nest survival and breeding biology. Finally, I tested if WHDP presence had a positive influence on unrelated species groups. I counted two skink species at sites with and without burrows and used occupancy modelling to quantify the influence WHDP burrows had on skink occurrence. Estimates of population growth before and after predator eradications illustrated that WHDP population growth remained comparatively low and unaffected by this conservation strategy. Therefore, additional interventions are required. WHDP tracking revealed that the non-breeding distribution did not overlap with commercial fishing efforts. However, considerable fishing efforts were present within the breeding distribution. Despite these findings, onshore threats remain present and conservation strategies aimed at addressing terrestrial threats may be more feasible. Results from my IPM showed that translocations could successfully establish a second WHDP population without impacting the source excessively, provided translocation cohorts remain small and translocations are repeated over long time periods (5-10 years). Nest survival was not clearly influenced by interannual variation, distance to sea, and intra- or interspecific competition. Furthermore, I informed future translocation protocols by identifying the preferred harvest window, measurements of ideal translocation candidates, and feeding regimes. Occurrence of one skink species was 114% higher at sites with burrows than at sites without, suggesting that WHDP presence benefits unrelated species. The information provided in this thesis facilitates the identification of future management strategies for this critically endangered species. However, future conservation management of the WHDP should be based on structured decision-making frameworks that apply iterative adaptive management loops and must acknowledge the unique position of tangata whenua (people of the land). This approach could address the consequences and trade-offs of each alternative, account for uncertainty, facilitate the decolonisation of conservation biology, and would ultimately result in the best potential outcome of the target species in a truly integrated fashion.
... En effet, les espèces qui parcourent de longues distances et dépendent de plusieurs types d'habitats sont susceptibles d'être affectées de manière disproportionnée par les actions humaines (Sanderson et al., 2006). La construction de routes, le développement agricole et la construction de barrages créent des barrières pour les espèces migratrices à longue distance (Hardesty-Moore et al., 2018). Par exemple, Harris et al. (2009) ont rapporté que sur les 24 ongulés migrateurs de grande taille qu'ils ont examiné, six migrations ont été perdues du fait des infrastructures anthropiques. ...
Thesis
Les effets des changements globaux sur les habitats naturels sont de plus en plus perceptibles, et comprendre comment les animaux y répondent est nécessaire pour une meilleure gestion de leurs populations. C’est en effet à travers leur impact sur l’environnement, et essentiellement sur les habitats, que les activités humaines ont souvent le plus grand effet sur les écosystèmes, à travers le changement climatique, la fragmentation, la destruction de l'habitat, les changements dans l'utilisation des terres ou la surexploitation des ressources. Les ongulés constituent un exemple marquant de progression numérique et spatiale d’une guilde d’espèces dans des écosystèmes impactés par l’Homme. Cet essor démographique est à l’origine d’un nombre croissant d’interactions entre Homme et faune et place la gestion de ces espèces au cœur des préoccupations des politiques publiques. Dans ce contexte, j’ai étudié cinq espèces de grands ongulés sauvages : le chamois, le mouflon, le bouquetin, le chevreuil et le cerf, dans le cadre du projet Mov-It (Ungulates MOVing across heterogeneous landscapes: identifying behavioural processes linking global change to spatially-explicIT demographic performance and management), soutenu par l’Agence Nationale de la Recherche (ANR). Dans un premier temps, je mets en évidence les liens entre variations intraspécifiques de la taille du domaine vital saisonnier des ongulés, le paysage (i.e. les ressources, le risque et l’hétérogénéité) et les traits d’histoire de vie de ces espèces. Je me suis ensuite intéressée plus particulièrement à l’influence des structures linéaires anthropiques et naturelles du paysage sur l'utilisation individuelle de l'espace. Je montre ainsi que les grands herbivores utilisent des structures linéaires du paysage pour délimiter leur domaine vital mensuel, mais que l'importance relative de ces structures linéaires dans la délimitation du domaine vital mensuel diminuait à mesure que leur densité augmentait dans le paysage local. Je mets également en évidence le caractère risqué des structures anthropiques pour les ongulés, en particulier l'effet de l'intensité de l’utilisation humaine de ces structures sur le nombre de traversées par les mouflons. Enfin, l’importance de la prise en compte du paysage du risque et des ressources sur l’organisation sociale est démontré. En effet, la formation de dyades (i.e. paires d’individus) est plus probable dans les milieux ouverts riche en ressources et lorsque le risque, incluant prédation et dérangement, est le plus fort (i.e. le jour). L’ensemble des résultats présentés dans ce travail de thèse a permis d’améliorer notre compréhension des effets de la structure du paysage et de la socialité sur la sélection d’habitat et le mouvement chez différentes espèces d’ongulés.
... Migratory caribou and reindeer Rangifer tarandus, for example, are several orders of magnitude more abundant than non-migratory woodland, mountain and forest ecotypes (Festa-Bianchet et al., 2011;Uboni et al., 2016). However, the question of whether migratory animals are more or less resilient to environmental disruptions in the environment remains open and largely case-specific (Moore and Huntington, 2008;Hardesty-Moore et al., 2018;Xu et al., 2021). On the one hand, migratory species may be more vulnerable as disruptions in either of the seasonal ranges or along a migratory corridor can have significant negative impacts (Wilcove and Wikelski, 2008;Seebacher and Post, 2015;Kauffman et al., 2021). ...
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Seasonal migrations are a widespread and broadly successful strategy for animals to exploit periodic and localized resources over large spatial scales. It remains an open and largely case-specific question whether long-distance migrations are resilient to environmental disruptions. High levels of mobility suggest an ability to shift ranges that can confer resilience. On the other hand, a conservative, hard-wired commitment to a risky behavior can be costly if conditions change. Mechanisms that contribute to migration include identification and responsiveness to resources, sociality, and cognitive processes such as spatial memory and learning. Our goal was to explore the extent to which these factors interact not only to maintain a migratory behavior but also to provide resilience against environmental changes. We develop a diffusion-advection model of animal movement in which an endogenous migratory behavior is modified by recent experiences via a memory process, and animals have a social swarming-like behavior over a range of spatial scales. We found that this relatively simple framework was able to adapt to a stable, seasonal resource dynamic under a broad range of parameter values. Furthermore, the model was able to acquire an adaptive migration behavior with time. However, the resilience of the process depended on all the parameters under consideration, with many complex trade-offs. For example, the spatial scale of sociality needed to be large enough to capture changes in the resource, but not so large that the acquired collective information was overly diluted. A long-term reference memory was important for hedging against a highly stochastic process, but a higher weighting of more recent memory was needed for adapting to directional changes in resource phenology. Our model provides a general and versatile framework for exploring the interaction of memory, movement, social and resource dynamics, even as environmental conditions globally are undergoing rapid change.
... For ocean-run sockeye salmon, to use our focal example, adaptation could be possible, since the species has repeatedly evolved a landlocked form (kokanee; Wood et al. 2008) and a small proportion of Fraser-River sockeye already use a less salmon-farm-exposed southern migration route (Tucker et al. 2009;Morton and Routledge 2016). Many other species might not be so lucky (Hardesty-Moore et al. 2018). For those species that evolved migration strategies in response to disease pressure, migration barriers -disease-induced or otherwise imposed -could even trap populations in the same maladaptive scenarios they originally evolved to evade (Satterfield et al. 2015). ...
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Infectious disease from domestic hosts, held for agriculture, can impact wild species that migrate in close proximity, potentially reversing selective advantages afforded by migration. For sockeye salmon in British Columbia, Canada, juveniles migrate past numerous Atlantic salmon farms from which they may acquire a number of infectious agents. We analyse patterns of molecular detection in juvenile sockeye salmon for one bacterial pathogen, Tenacibaculum maritimum, known to cause disease in fish species around the globe and to cause mouthrot disease in farmed Atlantic salmon in BC. Our data show a clear peak in T. maritimum detections in the Discovery Islands region of BC, where sockeye migrate close to salmon farms. Using well established differential-equation models to describe sockeye migration and T. maritimum infection spread, we fit models to our detection data to assess support for multiple hypotheses describing farm- and background-origin infection. Despite a data-constrained inability to resolve certain epidemiological features of the system, such as the relative roles of post-infection mortality and recovery, our models clearly support the role of Discovery-Islands salmon farms in producing the observed patterns. Our best models (with 99.8% empirical model support) describe relatively constant (background) infection pressure, except around Discovery-Islands salmon farms, where farm-origin infection pressure peaked at 12.7 (approximate 95% CI: 4.5 to 31) times background levels. Given the evidence for farm-origin transfer of T. maritimum to Fraser-River sockeye salmon, the severity of associated disease in related species, and the imperilled nature of Fraser River sockeye generally, our results suggest the need for a more precautionary approach to managing farm/wild interactions in sockeye salmon.
... In the case of planned migration, migrants chose their destination country not only based on its immigration policies -that could affect a migrant's paths to citizenship, labor market prospects, integration supports, or deportation rate -but also based on existing socioeconomic and political ties between the origin and destination countries ( D.S. Massey and Taylor, 2004 ;Arango, 2017 ;ILO 2004 ). In contrast, refugees who flee war or civil conflict, persecution, global warming, environmental degradation, and other effects of the Anthropocene or the age of humans on our planet ( Abubakar, 2020 ;Hardesty-Moore et al., 2018 ), their choice is limited or non-existent, since their destination countries are dictated by geographical vicinity or other immediate survival reasons ( Mayers and Freedman, 2019 ;Sassen, 2014 ). ...
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The main purpose of this article is to review several ways in which health care workers could either impact migrant health or be directly impacted by migration and, based on this, suggest the expansion of the current research agenda on migration and health to address a range of topics that are currently either neglected, insufficiently researched, or researched from different perspectives. To ground this suggestion and emphasize the complexity and significance of migrant health research, we start by briefly reviewing several migration-related notions including the process of migration and its key facilitators and benefits; existing barriers to the provision of migrant health care; and the intricate links between health systems, health professionals, and migrant health. The three areas of research examined in this article address (i) the specific role of health workers in providing care to migrants and refugees and their capacity to do so, (ii) the health problems experienced by health workers who become migrants or refugees, and (iii) the precarious employment conditions experienced by both migrant and non-migrant health care workers. After summarizing the current available evidence on these topics, we discuss key information gaps and strategies to address them, while also incorporating several relevant COVID-19 pandemic considerations and research implications. Expanding the focus of research studies on migration and health could not only enhance the results of current strategies by supplying additional information to support their implementation but also spearhead the development of new solutions to the migrant health problem. https://doi.org/10.1016/j.jmh.2021.100048
... Migratory species are sentinels of global change [12,14,78]. Given their widespread populations, large-scale movements and the intimate relationship they hold with their environments, research on the ecology and behaviour of migratory species has provided important insight into the broad effects of environmental change on biodiversity [10,[79][80][81]. ...
Article
Temporal variation in the connectivity of populations of migratory animals has not been widely documented, despite having important repercussions for population ecology and conservation. Because the long-distance movements of migratory animals link ecologically distinct and geographically distant areas of the world, changes in the abundance and migratory patterns of species may reflect differential drivers of demographic trends acting over various spatial scales. Using stable hydrogen isotope analyses ( δ ² H) of feathers from historical museum specimens and contemporary samples obtained in the field, we provide evidence for an approximately 600 km northward shift over 45 years in the breeding origin of a species of songbird of major conservation concern (blackpoll warbler, Setophaga striata ) wintering in the foothills of the eastern Andes of Colombia. Our finding mirrors predictions of range shifts for boreal-breeding species under warming climate scenarios and habitat loss in the temperate zone, and underscores likely drivers of widespread declines in populations of migratory birds. Our work also highlights the value of natural history collections to document the effects of global change on biodiversity.
... Migration is a widespread behavioral pattern in animals (1,2), with profound consequences for the fitness of individuals and the conservation status of the population or species. Migration affects exposure to predators, pathogens, and contaminants, access to optimal feeding and breeding areas, spatio-temporal changes in abiotic conditions, and exploitation by humans (3)(4)(5). In many cases, migratory species, or the migratory forms of species, are in greater jeopardy than non-migratory species and forms (6)(7)(8). ...
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Migrations affect the population dynamics, life history, evolution, and connections of animals to natural ecosystems and humans. Many species and populations display partial migration (some individuals migrate and some do not), and differential migration (migration distance varies). Partial migration is widely distributed in fishes but the term differential migration is much less commonly applied, despite the occurrence of this phenomenon. This paper briefly reviews the extent of differential migration in Pacific salmon and trout (genus Oncorhynchus ), a very extensively studied group. Three hypotheses are presented to explain the patterns among species: 1) phylogenetic relationships, 2) the prevalence of partial migration (i.e., variation in anadromy), and 3) life history patterns (iteroparous or semelparous, and duration spent feeding at sea prior to maturation). Each hypothesis has some support but none is consistent with all patterns. The prevalence of differential migration, ranging from essentially non-existent to common within a species, reflects phylogeny and life history, interacting with the geographic features of the region where juvenile salmon enter the ocean. Notwithstanding the uncertain evolution of this behavior, it has very clear implications for salmon conservation, as it strongly affects exposure to predators, patterns of fishery exploitation and also uptake of toxic contaminants.
... Such insights are important, as migratory bird species are more vulnerable than residents (e.g. Hardesty-Moore et al. 2018). Therefore, objective and clear delineations of breeding and non-breeding periods and the associated areas of use are crucial to spatiotemporal conservation management (Spitz et al. 2017). ...
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Without insights into the threats affecting species across their distributions and throughout their annual cycles, effective conservation management cannot be applied. The Whenua Hou diving petrel Pelecanoides whenuahouensis (WHDP) is a Critically Endangered small seabird whose offshore habits and threats are poorly understood. We tracked WHDPs year-round in 2015/16, 2017/18, and 2018/19 using global location-sensing immersion loggers to identify offshore distribution, movements, behaviour, and overlap with commercial fishing effort. During the breeding period, WHDPs ranged from southern Aotearoa (New Zealand) to Maukahuka (Auckland Islands). After breeding, WHDPs migrated southwest towards the Polar Front south of Australia, exhibited clockwise movements, and returned to their breeding grounds via the Subantarctic Front. During the non-breeding period, WHDPs exhibited extreme aquatic behaviour and spent >95% of their time on, or under, water. The core areas used consistently during breeding and non-breeding periods warrant listing as Important Bird and Biodiversity Areas. Spatiotemporal overlap of commercial fishing effort with breeding distributions was considerable (35%), in contrast with non-breeding distributions (0%). Spatial restrictions of anthropogenic activity around the breeding colony during the breeding period could help protect WHDPs, but such measures should be subjected to a structured decision-making framework. Our results illustrate the importance of year-round studies to inform conservation of marine species.
... Due to human modifications of the global landscape, animals face increased migratory challenges [44]. Salmon returning to spawning grounds in the Columbia River basin are confronted with multiple main stem dams. ...
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The mass migration of animals is one of the great wonders of the natural world. Although there are multiple benefits for individuals migrating in groups, an increasingly recognized benefit is collective navigation, whereby social interactions improve animals’ ability to find their way. Despite substantial evidence from theory and laboratory-based experiments, empirical evidence of collective navigation in nature remains sparse. Here we used a unique large-scale radiotelemetry dataset to analyse the movements of adult Pacific salmon ( Oncorhynchus sp.) in the Columbia River Basin, USA. These salmon face substantial migratory challenges approaching, entering and transiting fishways at multiple large-scale hydroelectric mainstem dams. We assess the potential role of collective navigation in overcoming these challenges and show that Chinook salmon ( O. tshawytscha ), but not sockeye salmon ( O. nerka ) locate fishways faster and pass in fewer attempts at higher densities, consistent with collective navigation. The magnitude of the density effects were comparable to major established drivers such as water temperature, and model simulations predicted that major fluctuations in population density can have substantial impacts on key quantities including mean passage time and fraction of fish with very long passage times. The magnitude of these effects indicates the importance of incorporating conspecific density and social dynamics into models of the migration process. Density effects on both ability to locate fishways and number of passage attempts have the potential to enrich our understanding of migratory energetics and success of migrating anadromous salmonids. More broadly, our work reveals a potential role of collective navigation, in at least one species, to mitigate the effects of anthropogenic barriers to animals on the move.
... Migratory animals are under escalating threat due to growth in human activity (Hardesty- Moore et al., 2018;Wilcove & Wikelski, 2008). Compared to other groups of species, migratory birds appear to suffer disproportionately higher mortality from solar facilities, particularly those located on migration routes and/or near breeding and wintering grounds (Walston et al., 2016). ...
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Solar power is a renewable energy source with great potential to help meet increasing global energy demands and reduce our reliance on fossil fuels. However, research is scarce on how solar facilities affect wildlife. With input from professionals in ecology, conservation, and energy, we conducted a research-prioritization process and identified key questions needed to better understand impacts of solar facilities on wildlife. We focused on animal behavior, which can be used to identify population responses before mortality or other fitness consequences are documented. Behavioral studies can also offer approaches to understand the mechanisms leading to negative interactions (e.g., collision, singeing, avoidance) and provide insight into mitigating effects. Here, we review how behavioral responses to solar facilities, including perception, movement, habitat use, and interspecific interactions are priority research areas. Addressing these themes will lead to a more comprehensive understanding of the effects of solar power on wildlife and guide future mitigation.
... Migration is a complex natural phenomenon which profoundly influences the life cycles of many species. It is a solution to avoid seasonal unfavorable conditions, but it also involves major threats: migrants are vulnerable to habitat changes that may occur along their migration routes, affecting their orientation, reducing the availability of stepping stones or exposing them to direct mortality factors (Hardesty-Moore et al. 2018). ...
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Information about bat migration routes across the Alps is generally scarce and there is no existing data available for the Italian part of the chain. Through acoustic surveys, we explored the possibility that even a region characterized by high Alpine mountains may be crossed by migrant bats. Data were recorded in August–September 2016 at two sites located near mountain passes in the Aosta Valley (NW Italy), respectively for 29 and 53 entire nights. Activity of different species/acoustic groups of species was associated with period and weather variables, the most important of which was wind speed (negatively related), followed by temperature (positively related). Only the acoustic group N. leisleri/N. noctula/V. murinus/E. serotinus, at both sites, showed a significant increase in activity in the period 31 August–14 September. Additional elements suggesting the occurrence of a late-summer migratory flow involving this group were the fact that it mainly consists of migratory species; the attribution to N. leisleri of the sequences that could be identified at the species level; and the timing of activity through the night (generally later than the other bats) and some characteristics of the recorded calls. Contacts with B. barbastellus were recorded at both study sites, possibly due to migrating individuals or, as an alternative, to resident bats using open environments located far from woods during the summer. The occurrence of P. kuhlii was ascertained at the highest elevation so far reported for this species in the Alps (2208 m a.s.l.).
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Migrations of diverse wildlife species often converge in space and time, with their journeys shaped by similar forces (i.e. geographic barriers and seasonal resources and conditions); we term this ‘co‐migration’. Recent studies have illuminated multi‐speciesmigrations by land and sea including the simultaneous movements of numerous insects, birds, bats and of fish invertebrates marine predators. Beyond their significance as natural wonders, species with overlapping migrations may interact ecologically, with potential effects on population and community dynamics. Direct and indirect ecological interactions (including predation and competition) between migrant species remain poorly understood, in part because migration is the least‐studied phase of animals’ annual cycles. To address this gap, we conducted a literature review to examine whether animal migration studies incorporate multiple species and to what extent they investigate interspecific interactions between co‐migrants. Following a key word search, we read all migration research papers in 23 relevant peer‐reviewed journals during 2008–2017. Thirty percent of animal migration papers reported two or more species with coinciding migrations, suggesting that co‐migrations are common, although few studies investigated or discussed these mixed‐species migrations further. Synthesizing these, we present examples and describe five types of ecological interactions between migrating species, including predator–prey, host–parasite and commensal relationships. Considering migratory animals as interacting with migrant communities will enhance understanding of the drivers of migration and could improve predictions about wildlife responses to global change. Further research focused on multi‐species migrations could also inform conservation efforts for migratory animal populations, many of which are declining or shifting, with unexplored consequences for other co‐migratory species.
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The sustainable use of wildlife is a core aspiration of multi-lateral conservation policy but is the subject to intense debate in the scientific literature. We use a global data set of over 11,000 population time-series to derive indices of ‘used’ and ‘unused’ species and assess global and regional changes in wildlife populations – principally for mammals, birds and fishes. We also assess whether ‘management’ makes a measurable difference to wildlife population trends, especially for the used species populations. Our results show that wildlife population trends globally are negative, but with used populations tending to decline more rapidly, especially in Africa and the Americas. Crucially, where used populations are managed, using a variety of mechanisms, there is a positive impact on the trend. It is therefore true that use of species can both be a driver of negative population trends, or a driver of species recovery, with numerous species and population specific case examples making up these broader trends. This work is relevant to the evidence base for the IPBES Sustainable Use Assessment, and to the development of indicators of sustainable use of species under the post-2020 Global Biodiversity Framework being developed under the Convention on Biological Diversity.
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Each year, juveniles of eight salmonid species enter the Salish Sea - the inland marine waters between northwestern Washington, USA and British Columbia, Canada. These species vary in the proportions remaining there and migrating to feed in the Pacific Ocean. Such differential migration affects their growth rates, and exposure to habitat alteration, predators, fisheries, and contaminants. We review these diverse migration patterns and present data from Puget Sound illustrating the variation in downstream migration timing, residency in the Salish Sea, and upriver return timing. Recreational catch records indicate that proportionally fewer remain in the Salish Sea than in past decades for several species, and the declines began after peaks in the late 1970s – early 1980s. These declines resist easy explanation because the factors controlling residency are poorly understood, and the Salish Sea has changed over the past decades. Regardless of the cause, the diversity of migration patterns is important to the ecology of the salmon and trout species, and to the humans and other members of the Salish Sea community with which they interact.
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Sustainable use of wildlife is a core aspiration of biodiversity conservation but is the subject of intense debate in the scientific literature, including the extent to which use is impacting species and whether management can mitigate any impact. Although positive and negative outcomes of sustainable use are known for specific taxa or local communities, a global and regional picture of trends in wildlife populations in use is lacking. We use a global dataset of more than 11,000 time series to derive indices of “utilized” and “not utilized” wildlife populations. Our results show that population trends globally are negative on average but that utilized populations tend to decline more rapidly, especially in Africa and the Americas. Crucially, where populations are managed, they are more likely to be increasing. This evidence can inform global biodiversity assessments and provide an operational indicator to track progress toward the Post-2020 Global Biodiversity Framework.
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The lemurs of Madagascar make up 20% of the world’s primate species and are considered one of the most threatened mammal taxa on earth with an estimated 95% of all species currently facing extinction. Species responses to increasing levels of anthropogenic disturbance are generally thought to be negative but remain poorly understood, particularly in regards to primate species and lemurs. This study aimed to assess and compare how two sympatric lemur species the Coquerel’s sifaka (Propithecus coquereli) and the Common Brown lemur (Eulemur fulvus), are utilising their habitat in response to anthropogenic disturbance. Species disturbance, habitat use and activity budgets were assessed across two forest fragments with differing levels of human disturbance in the remote dry forests of Northwest Madagascar. Findings show that the distribution of each species does not appear to differ significantly across disturbed and undisturbed habitats, or in relation to distance from human disturbance (villages, roads and camps). However, a significantly larger amount of P. coquereli were observed compared with E. fulvus, 61 and 19 groups respectively. P. coquereli were found more often on introduced trees, as well as in higher percentage canopy cover, taller trees and higher positions in the tree, compared with E. fulvus. Additionally, analysis of activity budgets found P. coquereli observed in disturbed habitats spent on average, increased time feeding and decreased time resting and in locomotion, compared with those in undisturbed forest habitats. Findings suggest P. coquereli are responding more positively to increased human disturbance in the Mahamavo region, compared to E. fulvus. The ability to successfully determine and understand the responses of endangered primate species to anthropogenic disturbance is key to their conservation, and survival in a world dominated by human activity.
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Collective behaviours contributing to patterns of group formation and coordinated movement are common across many ecosystems and taxa. Their ubiquity is presumably due to altering interactions between individuals and their predators, resources and physical environment in ways that enhance individual fitness. On the other hand, fitness costs are also often associated with group formation. Modifications to these interactions have the potential to dramatically impact population-level processes, such as trophic interactions or patterns of space use in relation to abiotic environmental variation. In a wide variety of empirical systems and models, collective behaviour has been shown to enhance access to ephemeral patches of resources, reduce the risk of predation and reduce vulnerability to environmental fluctuation. Evolution of collective behaviour should accordingly depend on the advantages of collective behaviour weighed against the costs experienced at the individual level. As an illustrative case study, we consider the potential trade-offs on Malthusian fitness associated with patterns of group formation and movement by migratory Thomson's gazelles in the Serengeti ecosystem. This article is part of the theme issue ‘Collective movement ecology’.
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Animals often travel in groups, and their navigational decisions can be influenced by social interactions. Both theory and empirical observations suggest that such collective navigation can result in individuals improving their ability to find their way and could be one of the key benefits of sociality for these species. Here, we provide an overview of the potential mechanisms underlying collective navigation, review the known, and supposed, empirical evidence for such behaviour and highlight interesting directions for future research. We further explore how both social and collective learning during group navigation could lead to the accumulation of knowledge at the population level, resulting in the emergence of migratory culture. This article is part of the theme issue ‘Collective movement ecology’.
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Animal collective movements are a key example of a system that links two clearly defined levels of organization: the individual and the group. Most models investigating collective movements have generated coherent collective behaviours without the inclusion of individual variability. However, new individual-based models, together with emerging empirical information, emphasize that within-group heterogeneity may strongly influence collective movement behaviour. Here we (i) review the empirical evidence for individual variation in animal collective movements, (ii) explore how theoretical investigations have represented individual heterogeneity when modelling collective movements and (iii) present a model to show how within-group heterogeneity influences the collective properties of a group. Our review underscores the need to consider variability at the level of the individual to improve our understanding of how individual decision rules lead to emergent movement patterns, and also to yield better quantitative predictions of collective behaviour. This article is part of the theme issue ‘Collective movement ecology’.
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While many animal species exhibit strong conspecific interactions, movement analyses of wildlife tracking datasets still largely focus on single individuals. Multi-individual wildlife tracking studies provide new opportunities to explore how individuals move relative to one another, but such datasets are frequently too sparse for the detailed, acceleration-based analytical methods typically employed in collective motion studies. Here, we address the methodological gap between wildlife tracking data and collective motion by developing a general method for quantifying movement correlation from sparsely sampled data. Unlike most existing techniques for studying the non-independence of individual movements with wildlife tracking data, our approach is derived from an analytically tractable stochastic model of correlated movement. Our approach partitions correlation into a deterministic tendency to move in the same direction termed ‘drift correlation’ and a stochastic component called ‘diffusive correlation’. These components suggest the mechanisms that coordinate movements, with drift correlation indicating external influences, and diffusive correlation pointing to social interactions. We use two case studies to highlight the ability of our approach both to quantify correlated movements in tracking data and to suggest the mechanisms that generate the correlation. First, we use an abrupt change in movement correlation to pinpoint the onset of spring migration in barren-ground caribou. Second, we show how spatial proximity mediates intermittently correlated movements among khulans in the Gobi desert. We conclude by discussing the linkages of our approach to the theory of collective motion. This article is part of the theme issue 'Collective movement ecology'.
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Social interactions are a significant factor that influence the decision-making of species ranging from humans to bacteria. In the context of animal migration, social interactions may lead to improved decision-making, greater ability to respond to environmental cues, and the cultural transmission of optimal routes. Despite their significance, the precise nature of social interactions in migrating species remains largely unknown. Here we deploy unmanned aerial systems to collect aerial footage of caribou as they undertake their migration from Victoria Island to mainland Canada. Through a Bayesian analysis of trajectories we reveal the fine-scale interaction rules of migrating caribou and show they are attracted to one another and copy directional choices of neighbours, but do not interact through clearly defined metric or topological interaction ranges. By explicitly considering the role of social information on movement decisions we construct a map of near neighbour influence that quantifies the nature of information flow in these herds. These results will inform more realistic, mechanism-based models of migration in caribou and other social ungulates, leading to better predictions of spatial use patterns and responses to changing environmental conditions. Moreover, we anticipate that the protocol we developed here will be broadly applicable to study social behaviour in a wide range of migratory and non-migratory taxa. This article is part of the theme issue ‘Collective movement ecology’.
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A wide range of measurements can be made on the collective motion of groups, and the movement of individuals within them. These include, but are not limited to: group size, polarization, speed, turning speed, speed or directional correlations, and distances to near neighbours. From an ecological and evolutionary perspective, we would like to know which of these measurements capture biologically meaningful aspects of an animal's behaviour and contribute to its survival chances. Previous simulation studies have emphasized two main factors shaping individuals' behaviour in groups; attraction and alignment. Alignment responses appear to be important in transferring information between group members and providing synergistic benefits to group members. Likewise, attraction to conspecifics is thought to provide benefits through, for example, selfish herding. Here, we use a factor analysis on a wide range of simple measurements to identify two main axes of collective motion in guppies (Poecilia reticulata): (i) sociability, which corresponds to attraction (and to a lesser degree alignment) to neighbours, and (ii) activity, which combines alignment with directed movement. We show that for guppies, predation in a natural environment produces higher degrees of sociability and (in females) lower degrees of activity, while female guppies sorted for higher degrees of collective alignment have higher degrees of both sociability and activity. We suggest that the activity and sociability axes provide a useful framework for measuring the behaviour of animals in groups, allowing the comparison of individual and collective behaviours within and between species. This article is part of the theme issue ‘Collective movement ecology’.
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As threats to species continue to increase, precise and unbiased measures of the impact these pressures are having on global biodiversity are urgently needed. Some existing indicators of the status and trends of biodiversity largely rely on publicly available data from the scientific and grey literature, and are therefore prone to biases introduced through over-representation of well-studied groups and regions in monitoring schemes. This can give misleading estimates of biodiversity trends. Here, we report on an approach to tackle taxonomic and geographic bias in one such indicator (Living Planet Index) by accounting for the estimated number of species within biogeographical realms, and the relative diversity of species within them. Based on a proportionally weighted index, we estimate a global population decline in vertebrate species between 1970 and 2012 of 58% rather than 20% from an index with no proportional weighting. From this data set, comprising 14,152 populations of 3,706 species from 3,095 data sources, we also find that freshwater populations have declined by 81%, marine populations by 36%, and terrestrial populations by 38% when using proportional weighting (compared to trends of -46%, +12% and +15% respectively). These results not only show starker declines than previously estimated, but suggests that those species for which there is poorer data coverage may be declining more rapidly.
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Anthropocene defaunation, the global extinction of faunal species and populations and the decline in abundance of individuals within populations, has been predominantly documented in terrestrial ecosystems, but indicators suggest defaunation has been more severe in freshwater ecosystems. Marine defaunation is in a more incipient stage, yet pronounced effects are already apparent and its rapid acceleration seems likely. Defaunation now impacts the planet’s wildlife with profound cascading consequences, ranging from local to global coextinctions of interacting species to the loss of ecological services critical for humanity. Slowing defaunation will require aggressively reducing animal overexploitation and habitat destruction; mitigating climate disruption; and stabilizing the impacts of human population growth and uneven resource consumption. Given its omnipresence, defaunation should receive status of major global environmental change and should be addressed with the same urgency as deforestation, pollution, and climatic change. Global action is needed to prevent defaunation’s current trajectory from catalyzing the planet’s sixth major extinction. Expected final online publication date for the Annual Review of Ecology, Evolution, and Systematics Volume 47 is November 01, 2016. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Background: Mass migrations are among the most striking examples of animal movement in the natural world. Such migrations are major drivers of ecosystem processes and strongly influence the survival and fecundity of individuals. For migratory animals, a formidable challenge is to find their way over long distances and through complex, dynamic environments. However, recent theoretical and empirical work suggests that by traveling in groups, individuals are able to overcome these challenges and increase their ability to navigate. Here we use models to explore the implications of collective navigation on migratory, and population, dynamics, for both breeding migrations (to-and-fro migrations between distinct, fixed, end-points) and feeding migrations (loop migrations that track favorable conditions). Results: We show that while collective navigation does improve a population's ability to migrate accurately, it can lead to Allee effects, causing the sudden collapse of populations if numbers fall below a critical threshold. In some scenarios, hysteresis prevents the migration from recovering even after the cause of the collapse has been removed. In collectively navigating populations that are locally adapted to specific breeding sites, a slight increase in mortality can cause a collapse of genetic population structure, rather than population size, making it more difficult to detect and prevent. Conclusions: Despite the large interest in collective behavior and its ubiquity in many migratory species, there is a notable lack of studies considering the implications of social navigation on the ecological dynamics of migratory species. Here we highlight the potential for a previously overlooked Allee effect in socially migrating species that may be important for conservation and management of such species.
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Least-squares means are predictions from a linear model, or averages thereof. They are useful in the analysis of experimental data for summarizing the effects of factors, and for testing linear contrasts among predictions. The lsmeans package (Lenth 2016) provides a simple way of obtaining least-squares means and contrasts thereof. It supports many models fitted by R (R Core Team 2015) core packages (as well as a few key contributed ones) that fit linear or mixed models, and provides a simple way of extending it to cover more model classes.
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Quantifying the ecological importance of individual habitats to highly mobile animals is challenging because patterns of habitat reliance for these taxa are complex and difficult to observe. We investigated the importance of lagoons to the manta ray, Manta alfredi, a wide-ranging and vulnerable species in a less-disturbed atoll ecosystem. Lagoons are highly sensitive to anthropogenic disturbance and are known to be ecologically important to a wide variety of mobile species. We used a novel combination of research tools to examine the reliance of M. alfredi on lagoon habitats. Stable isotope analysis was used to assay the recent energetic importance of lagoons to M. alfredi; high-resolution tracking data provided information about how M. alfredi utilised lagoonal habitats over long and short time periods; acoustic cameras logged patterns of animal entrances and departures from lagoons; and photo identification/laser photogrammetry provided some insight into why they may be using this habitat. M. alfredi showed strong evidence of energetic dependence on lagoon resources during the course of the study and spent long periods of residence within lagoons or frequently transited into them from elsewhere. While within lagoons, they demonstrated affinities for particular structural features within this habitat and showed evidence of temporal patterning in habitat utilization. This work sheds light on how and why M. alfredi uses lagoons and raises questions about how this use may be altered in disturbed settings. More generally, these observations contribute to our knowledge of how to assess the ecological importance of particular habitats situated within the broader home range of mobile consumers.
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Human population growth, economic development, climate change, and the need to close the electricity access gap have stimulated the search for new sources of renewable energy. In response to this need, major new initiatives in hydropower development are now under way. At least 3,700 major dams, each with a capacity of more than 1 MW, are either planned or under construction, primarily in countries with emerging economies. These dams are predicted to increase the present global hydroelectricity capacity by 73 % to about 1,700 GW. Even such a dramatic expansion in hydropower capacity will be insufficient to compensate for the increasing electricity demand. Furthermore, it will only partially close the electricity gap, may not substantially reduce greenhouse gas emission (carbon dioxide and methane), and may not erase interdependencies and social conflicts. At the same time, it is certain to reduce the number of our planet’s remaining free-flowing large rivers by about 21 %. Clearly, there is an urgent need to evaluate and to mitigate the social, economic, and ecological ramifications of the current boom in global dam construction.
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Marine defaunation, or human-caused animal loss in the oceans, emerged forcefully only hundreds of years ago, whereas terrestrial defaunation has been occurring far longer. Though humans have caused few global marine extinctions, we have profoundly affected marine wildlife, altering the functioning and provisioning of services in every ocean. Current ocean trends, coupled with terrestrial defaunation lessons, suggest that marine defaunation rates will rapidly intensify as human use of the oceans industrializes. Though protected areas are a powerful tool to harness ocean productivity, especially when designed with future climate in mind, additional management strategies will be required. Overall, habitat degradation is likely to intensify as a major driver of marine wildlife loss. Proactive intervention can avert a marine defaunation disaster of the magnitude observed on land. Copyright © 2015, American Association for the Advancement of Science.
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Long-distance migrations are among the wonders of the natural world, but this multitaxon review shows that the characteristics of species that undertake such movements appear to make them particularly vulnerable to detrimental impacts of climate change. Migrants are key components of biological systems in high latitude regions, where the speed and magnitude of climate change impacts are greatest. They also rely on highly productive seasonal habitats, including wetlands and ocean upwellings that, with climate change, may become less food-rich and predictable in space and time. While migrants are adapted to adjust their behaviour with annual changes in the weather, the decoupling of climatic variables between geographically separate breeding and nonbreeding grounds is beginning to result in mistimed migration. Furthermore, human land-use and activity patterns will constrain the ability of many species to modify their migratory routes and may increase the stress induced by climate change. Adapting conservation strategies for migrants in the light of climate change will require substantial shifts in site designation policies, flexibility of management strategies and the integration of forward planning for both people and wildlife. While adaptation to changes may be feasible for some terrestrial systems, wildlife in the marine ecosystem may be more dependent on the degree of climate change mitigation that is achievable.
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Maximum likelihood or restricted maximum likelihood (REML) estimates of the parameters in linear mixed-effects models can be determined using the lmer function in the lme4 package for R. As for most model-fitting functions in R, the model is described in an lmer call by a formula, in this case including both fixed- and random-effects terms. The formula and data together determine a numerical representation of the model from which the profiled deviance or the profiled REML criterion can be evaluated as a function of some of the model parameters. The appropriate criterion is optimized, using one of the constrained optimization functions in R, to provide the parameter estimates. We describe the structure of the model, the steps in evaluating the profiled deviance or REML criterion, and the structure of classes or types that represents such a model. Sufficient detail is included to allow specialization of these structures by users who wish to write functions to fit specialized linear mixed models, such as models incorporating pedigrees or smoothing splines, that are not easily expressible in the formula language used by lmer.
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Animal migrations span the globe, involving immense numbers of individuals from a wide range of taxa. Migrants transport nutrients, energy, and other organisms as they forage and are preyed upon throughout their journeys. These highly predictable, pulsed movements across large spatial scales render migration a potentially powerful yet underappreciated dimension of biodiversity that is intimately embedded within resident communities. We review examples from across the animal kingdom to distill fundamental processes by which migratory animals influence communities and ecosystems, demonstrating that they can uniquely alter energy flow, food-web topology and stability, trophic cascades, and the structure of metacommunities. Given the potential for migration to alter ecological networks worldwide, we suggest an integrative framework through which community dynamics and ecosystem functioning may explicitly consider animal migrations.
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Habitat fragmentation undermines the functioning of ecosystems, and so biodiversity conservation often entails maintaining or restoring landscape connections. However, conservationists also destroy connectivity by constructing wildlife fences. A recent debate about the use of fences to protect African lions (1–3) highlights a more general need to evaluate the role of fencing in conservation.
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Animals form groups for many reasons, but there are costs and benefits associated with group formation. One of the benefits is collective memory. In groups on the move, social interactions play a crucial role in the cohesion and the ability to make consensus decisions. When migrating from spawning to feeding areas, fish schools need to retain a collective memory of the destination site over thousands of kilometres, and changes in group formation or individual preference can produce sudden changes in migration pathways. We propose a modelling framework, based on stochastic adaptive networks, that can reproduce this collective behaviour. We assume that three factors control group formation and school migration behaviour: the intensity of social interaction, the relative number of informed individuals and the strength of preference that informed individuals have for a particular migration area. We treat these factors independently and relate the individuals' preferences to the experience and memory for certain migration sites. We demonstrate that removal of knowledgeable individuals or alteration of individual preference can produce rapid changes in group formation and collective behaviour. For example, intensive fishing targeting the migratory species and also their preferred prey can reduce both terms to a point at which migration to the destination sites is suddenly stopped. The conceptual approaches represented by our modelling framework may therefore be able to explain large-scale changes in fish migration and spatial distribution.
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We used phylogenetically based comparative analyses to test for associations between extinction risk in European freshwater fishes and a variety of life history, ecological, and biogeographical traits. Based on the World Conservation Union classification scheme, a total of 47% of Europe's 287 native species are classified as threatened with extinction. Threatened species are significantly smaller than less-threatened species in the same genera when analyses are restricted to fully freshwater species. This trend is reversed when anadromous genera are included. These comprise many large-bodied species in which fishing has often played a greater role in declines than in other taxa. Threatened species did not differ significantly in their habitats, although they tended to occupy a narrower variety of habitats biased toward streams and rivers. Threatened species occupy much narrower latitudinal ranges than close relatives that are less threatened, and they also have more southerly distributions where pressures on habitats are intense. This study suggests that links between life histories and threat status of freshwater fishes are not as clearcut as for marine species. For fish restricted entirely to freshwater, small-bodied species are most at risk owing to their naturally small ranges, which may put them in a more precarious position when their habitats are impacted by humans.
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This second volume of the “Global Register of Migratory Species” (GROMS) complements the reference list of migratory vertebrate species with fishes and songbirds, in printed and digital format. The enclosed GROMS CD contains an improved and updated version of the GROMS database, including 5,500 refer- ences, full-text documents and 1,000 species distribution maps in GIS format. These are complemented by additional, relevant geodata sets such as political boundaries, lakes, rivers, protected wetlands or oil spills. The user guide empowers the novice to make simple database searches, and customize his own maps with the enclosed lightweight GIS freeware. Advanced users will find the full tutorial of a ‘GROMS Workshop for Power Users’ on CD, with examples of advanced data-mining and GIS intersections, to enable pursuit of their own research questions related to migratory species conservation. Up to now, 4,358 species have been identified as definitely or most probably “migratory” according to the definition of GROMS, showing predictable and cyclical migrations of more than 100 km. Wherever pos- sible, the database has been enriched with full-text citations from the literature, giving details on migra- tion. However, precise data are still lacking for many species, in spite of clear indications of some migra- tory activity. Using the GROMS literature table for data mining, knowledge gaps with respect to migra- tion routes and seasonal timing were diagnosed for more than 150 bird species (migration unknown, poorly known, surprisingly little known, thought to be sedentary but....). A closer look at migratory freshwater fishes, especially from tropical Asia, revealed a considerable number of additional species migrating along rivers, raising the total number of migratory fishes to 1,895. This detailed study, together with other background reports for GROMS, are published as full-text documents on CD. Though comprehensive, they indicate that more migrants will probably be discovered in the future, in particular within lesser-known regions, such as oceans and the inner tropics. Though still on a global scale, the comprehensive GIS data set of around 1,000 maps allowed a wide variety of overall analysis by merging or intersecting distribution maps with other geodata, such as - Range state calculation by intersection with political boundaries - Global diversity map of migrants per administrative unit or grid cell - Diversity map of migrants per ecoregion - Identification of threatened migrants per geographic unit All results are re-imported into the GROMS database, allowing easy geodata search with standardized and fast relational database query tools. The identification of threatened migrants enabled the production of a list of endangered species which regularly cross international borders, but are not yet protected by CMS, through listing in its Appendices I and II. The respective distribution map shows the highest num- ber of unprotected migrants in South Africa, North America, Asia and Australia. In a similar way, the user can easily generate concordance list between CMS, its agreements, and other conventions such as CITES. For the first time, individual species protected within entire families listed in CMS Appendix II, such as Old-World flycatchers (Muscicapidae), can be identified. Of these, 12 are threatened according to the IUCN International Red List 2000, but up to now only the aquatic warbler ( Acrocephalus paludicola) is a target species for a Memorandum of Understanding on its conservation under CMS. Another over-looked songbird group are the shrikes (Laniidae). Though not listed on the International Red List, 5 spe- cies of the genus Lanius are threatened within their European range, according to SPEC categories, which means that their conservation status is unfavourable, making them candidates for listing under CMS. Additional range state lists are provided by the International Red List 2000, UNEP-WCMC and the CMS Se- cretariat. A comparison of range state lists from 4 sources (including GROMS) showed complete concordance for only 30% of range states for the greater spotted eagle ( Aquila clanga ). Such contradictions are rather the rule than the exception. They are caused by taxonomic inconsistencies, different assessment criteria in particu- lar for passage countries, geographic inconsistencies, and inaccuracies of GIS maps. The CMS convention has some particular definitions of range states, which compli cate the issue. It includes “states which take the spe- cies outside national boundaries”, referring particularly to flag vessels engaged in fishing operations. Therefore, changes of a nation’s fishing operation would eventually affect range state lists, making it necessary to deal with “floating range states”. Though this definition seemed never to have been applied consistently by the con- vention, it shows how different definitions can easily affect a seemingly clear data set such as a “range state list”. The GROMS information system cooperates with several other biodiversity informatics initiatives, by integrat- ing relevant information directly, or by hyperlinks. Distinct Web interfaces are described and evaluated. They include an interactive map server based on Open-GIS technology, animated display of migration routes and dynamic database access to the entire GROMS dataset. Static web pages were generated for each mapped species. These “species fact sheets” contain core information on names, threat and CMS status, together with a map and a short account of migratory behaviour. As stand- alone web pages, they can be detected by Web search engines. However, none of these Web products provides full data-mining and GIS analysis capability, which requires full access to database tables and GIS shape files. This volume presents examples of what can be achieved by combining GROMS with other species databases or regional GIS datasets, thereby zooming in from global to regional scales. Freely available point data sets based on museum specimens were downloaded from the Species Analyst Network (www.speciesanalyst.net) and compared with GROMS GIS shapes. Natural History Museum data provide reliable information on historical distribution, but only a small fraction of these valuable data is available in digital format. In contrast, satellite telemetry provides up-to-date, time-stamped data on migration routes. However, most of these datasets are not available due to intellectual property rights or sensitive data issues. In addition, there is neither a centralized nor distributed database storing these valuable data sets. Satellite data have been integrated into the GROMS data model by conversion into line geo-objects, which allow sensitive data to be hidden. This was demonstrated with high-resolution data sets on white storks and eagles. The GROMS CD contains some first examples of entire satellite tracks animated using special software. Taking the comprehensive register of migratory vertebrates as a starting point, both volumes together illustrate the particular requirements of an information system serving the conservation of migratory species. The GROMS information system models th e complexities of migration, usin g time-stamped GIS maps, together with computer-animation software to visualize migrati on routes. Because distinct populations within one spe- cies might show different migration behaviour, GROMS provides a higher taxonomic resolution at subspecies or population level. In summary, GROMS is unique in providing a data model specifically tailored to cover migratory species, because �� populations and subspecies are the smallest taxonomic units �� it covers temporal aspects of migration within GIS attribute tables �� it provides an efficient linkage between the relational database and geodata stored within a GIS Global register of migratory species: from global to regional scales: final report of the R&D-Projekt 808 05 081. Available from: https://www.researchgate.net/publication/235225727_Global_register_of_migratory_species_from_global_to_regional_scales_final_report_of_the_RD-Projekt_808_05_081 [accessed May 29 2018].
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Long-distance migrations are among the wonders of the natural world, but this multi-taxon review shows that the characteristics of species that undertake such movements appear to make them particularly vulnerable to detrimental impacts of climate change. Migrants are key components of biological systems in high latitude regions, where the speed and magnitude of climate change impacts are greatest. They also rely on highly productive seasonal habitats, including wetlands and ocean upwellings that, with climate change, may become less food-rich and predictable in space and time. While migrants are adapted to adjust their behaviour with annual changes in the weather, the decoupling of climatic variables between geographically separate breeding and non-breeding grounds is beginning to result in mistimed migration. Furthermore, human land-use and activity patterns will constrain the ability of many species to modify their migratory routes and may increase the stress induced by climate change. Adapting conservation strategies for migrants in the light of climate change will require substantial shifts in site designation policies, flexibility of management strategies and the integration of forward planning for both people and wildlife. While adaptation to changes may be feasible for some terrestrial systems, wildlife in the marine ecosystem may be more dependent on the degree of climate change mitigation that is achievable.
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Many criteria for statistical parameter estimation, such as maximum likelihood, are formulated as a nonlinear optimization problem. Automatic Differentiation Model Builder (ADMB) is a programming framework based on automatic differentiation, aimed at highly nonlinear models with a large number of parameters. The benefits of using AD are computational efficiency and high numerical accuracy, both crucial in many practical problems. We describe the basic components and the underlying philosophy of ADMB, with an emphasis on functionality found in no other statistical software. One example of such a feature is the generic implementation of Laplace approximation of high-dimensional integrals for use in latent variable models. We also review the literature in which ADMB has been used, and discuss future development of ADMB as an open source project. Overall, the main advantages of ADMB are flexibility, speed, precision, stability and built-in methods to quantify uncertainty.
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Rinderpest is only the second infectious disease to have been globally eradicated. In the final stages of eradication, the virus was entrenched in pastoral areas of the Greater Horn of Africa, a region with weak governance, poor security, and little infrastructure that presented profound challenges to conventional control methods. Although the eradication process was a development activity rather than scientific research, its success owed much to several seminal research efforts in vaccine development and epidemiology and showed what scientific decision-making and management could accomplish with limited resources. The keys to success were the development of a thermostable vaccine and the application of participatory epidemiological techniques that allowed veterinary personnel to interact at a grassroots level with cattle herders to more effectively target control measures.
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Knowledge of mammal migrations is low, and human impacts on migrations high. This jeopardizes efforts to conserve terrestrial migrations. To aid the conservation of these migrations, we synthesized information worldwide, describing 24 large-bodied ungulates that migrate in aggregations. This synthesis includes maps of extinct and extant migrations, numbers of migrants, summaries of ecological drivers and threats migrants confront. As data are often lacking, we outlined steps for science to address and inform conservation actions. We evaluated migrants against this framework, and reported their status. Mass migrations for 6 species are extinct or unknown. Most remaining migrants (n = 9) occur from 6 locations in Africa, with Eurasia and North America containing 6 and 4 remaining mass migrants, respectively (with caribou/reindeer Rangifer tarandus occurring in both regions). All migrants declined in abundance, except wildebeest and other migrants in the Serengeti- Mara Ecosystem (SME), white-eared kob and tiang in Sudan, and some caribou populations. Protected areas only contain migrations for 5 species in the SME, chiru on the Tibetan Plateau, and some caribou populations in North America. Most mass migrants track the seasonal and shifting patterns of greening vegetation over expanses of savannahs, steppes, and grasslands. Principal threats include overhunting and habitat loss from livestock, agriculture, and fencing that excludes animals from forage or water. Conservation science overlooks numerous migrations, so many have already disappeared and continue to do so. Key principles for conserving migrants, exemplified by the SME and Greater Yellowstone Ecosystem (GYE), include securing seasonal ranges, resource protection, government support and minimizing fences. This review forms a baseline for initiating conservation action for many ungulate migrations needing attention.
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1. We examined the effects of habitat fragmentation caused by dams on freshwater fish species using a database of 7848 fish presence/absence surveys, conducted between 1953–2003 in Hokkaido, Japan. 2. A series of generalised linear models showed that for 11 of 41 taxa examined, the probability of occurrence had been influenced either negatively (eight taxa) or positively (three taxa) by the presence of a dam downstream from their habitat. 3. Maps of modelled predictions revealed that dams had had widespread negative impacts on certain taxa, while for other taxa the impact was limited to specific basins. Two of the three taxa whose probability of occurrence was increased in areas above dams have long been transplanted into reservoirs in Japan. 4. For four of the eight taxa whose probability of occurrence was reduced above dams and all three taxa whose probability of occurrence increased above dams, the temporal length of habitat isolation (i.e. the number of years between dam construction and sampling) was also a significant predictor of the probability of occurrence. This pattern indicates that these taxa experienced a gradual rather than an instantaneous population impact as a result of dam construction. 5. The eight taxa whose probability of occurrence was reduced as a consequence of dams all exhibit migratory life cycles. Although migratory taxa are probably more susceptible to the negative effect of dams, we could not detect significant relationships between migration life histories and the effect of fragmentation by dams. 6. These analyses enable stream and fisheries managers to quantify the impacts of habitat fragmentation because of dams for individual species. The spatially explicit nature of our analyses also enables identification of the areas of the impact at broad geographical scales. Using our results, managers can take effective conservation and restoration measures to predict, mitigate or remove the impact of dams. For example, our results can be used to prioritise dams for removal or to predict losses of biodiversity and ecosystem services in advance of dam construction.
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Many migratory species are in decline and understanding these declines is challenging because individuals occupy widely divergent and geographically distant habitats during a single year and therefore populations across the range are interconnected in complex ways. Network modeling has been used to show, theoretically, that shifts in migratory connectivity patterns can occur in response to habitat or climate changes and that habitat loss in one region can affect sub-populations in regions that are not directly connected. Here, we use a network model, parameterized by integrating long-term monitoring data with direct tracking of ~100 individuals, to explain population trends in the rapidly declining Wood Thrush (Hylocichla mustelina) and to predict future trends. Our model suggests that species-level declines in Wood Thrush are driven primarily by tropical deforestation in Central America but that protection of breeding habitat in some regions is necessary to prevent shifts in migratory connectivity and to sustain populations in all breeding regions. The model illustrates how shifts in migratory connectivity may lead to unexpected population declines in key regions. We highlight current knowledge gaps that make modeling full life-cycle population demographics in migratory species challenging but also demonstrate that modeling can inform conservation while these gaps are being filled.
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In this chapter I intend to discuss relationships between migratoriness of bird species on the one hand and their range characteristics, phylogeographic structure and phylogeny on the other. I will do this by proposing a number of hypotheses based on present knowledge of migration behaviour and range characteristics of migratory landbirds in general. These hypotheses will then be discussed and, in two cases, tested quantitatively using published and unpublished DNA sequence data. The discussion will be restricted to the Northern Hemisphere. As migratory species I regard those in which at least some populations undertake annual return migrations over several thousand kilometres (altitudinal migrants are not considered). Testing hypotheses about the evolution of migration requires robust estimates of the phylogeny of some model groups which, ideally, should contain many species of varying degrees of relatedness and migratoriness. Such phylogeny estimates have become available only recently, e.g. for the genera Phylloscopus (Price et al. 1997, Acrocephalus-Hippolais (Helbig and Seibold 1999), Sylvia (Blondel et al. 1996; Helbig in Shirihai et al. 2001) and the subfamiliy Parulinae (mainly genus Dendroica Lovette and Bermingham 1999, 2001). With the continuing extension and refinement of molecular phylogenies, in the near future we can expect much better opportunities to subject ideas about the evolution of migration to rigorous analysis. Results presented here are intended as a first step in this direction.
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Many Pacific salmon populations have declined to levels that have prompted their listing under the Endangered Species Act. In order to protect these populations and provide harvest opportunities for recreational anglers, the fishery is often managed with separate regulations for wild and hatchery salmon. This article examines how the value of recreational fishing is affected by changes in wild and hatchery salmon regulations and catch rates in the Northwest region of the US. Using a discrete choice experiment, we estimate saltwater fishing trip preferences. We integrate the estimated preferences with auxiliary creel data in order to conduct simulations of willingness to pay that vary in bag limits and catch rates, conditioning on current fishery conditions. We find statistically significant differences between the recreational values for wild and hatchery salmon, and our simulations highlight the fact that these differences depend on baseline levels of catch rates and bag limits.