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1. Large birds travel farther in homogeneous environments

   https://doi.org/10.1111/geb.12875  

   Tucker, Marlee A. ; Alexandrou, Olga ; Bierregaard, Jr., Richard O. ; Bildstein, Keith L. ; Böhning‐Gaese, Katrin ; Bracis, Chloe ; Brzorad, John N. ; Buechley, Evan R. ; Cabot, David ; Calabrese, Justin M. ; et al ( January 2019 , Global Ecology and Biogeography)

   Animal movement is an important determinant of individual survival, population dynamics and ecosystem structure and function. Nonetheless, it is still unclear how local movements are related to resource availability and the spatial arrangement of resources. Using resident bird species and migratory bird species outside the migratory period, we examined how the distribution of resources affects the movement patterns of both large terrestrial birds (e.g., raptors, bustards and hornbills) and waterbirds (e.g., cranes, storks, ducks, geese and flamingos).

   Global.

   2003–2015.

   Birds.

   We compiled GPS tracking data for 386 individuals across 36 bird species. We calculated the straight‐line distance between GPS locations of each individual at the 1‐hr and 10‐day time‐scales. For each individual and time‐scale, we calculated the median and 0.95 quantile of displacement. We used linear mixed‐effects models to examine the effect of the spatial arrangement of resources, measured as enhanced vegetation index homogeneity, on avian movements, while accounting for mean resource availability, body mass, diet, flight type, migratory status and taxonomy and spatial autocorrelation.

   We found a significant effect of resource spatial arrangement at the 1‐hr and 10‐day time‐scales. On average, individual movements were seven times longer in environments with homogeneously distributed resources compared with areas of low resource homogeneity. Contrary to previous work, we found no significant effect of resource availability, diet, flight type, migratory status or body mass on the non‐migratory movements of birds.

   We suggest that longer movements in homogeneous environments might reflect the need for different habitat types associated with foraging and reproduction. This highlights the importance of landscape complementarity, where habitat patches within a landscape include a range of different, yet complementary resources. As habitat homogenization increases, it might force birds to travel increasingly longer distances to meet their diverse needs.

    

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2. Bridging the gap between movement data and connectivity analysis using the Time-Explicit Habitat Selection (TEHS) model

   https://doi.org/10.1186/s40462-024-00461-1  

   Valle, Denis ; Attias, Nina ; Cullen, Joshua A. ; Hooten, Mevin B. ; Giroux, Aline ; Oliveira-Santos, Luiz Gustavo R. ; Desbiez, Arnaud L. J. ; Fletcher, Jr., Robert J. ( March 2024 , Movement Ecology)

   Understanding how to connect habitat remnants to facilitate the movement of species is a critical task in an increasingly fragmented world impacted by human activities. The identification of dispersal routes and corridors through connectivity analysis requires measures of landscape resistance but there has been no consensus on how to calculate resistance from habitat characteristics, potentially leading to very different connectivity outcomes.

   We propose a new model, called the Time-Explicit Habitat Selection (TEHS) model, that can be directly used for connectivity analysis. The TEHS model decomposes the movement process in a principled approach into a time and a selection component, providing complementary information regarding space use by separately assessing the drivers of time to traverse the landscape and the drivers of habitat selection. These models are illustrated using GPS-tracking data from giant anteaters (Myrmecophaga tridactyla) in the Pantanal wetlands of Brazil.

   The time model revealed that the fastest movements tended to occur between 8 p.m. and 5 a.m., suggesting a crepuscular/nocturnal behavior. Giant anteaters moved faster over wetlands while moving much slower over forests and savannas, in comparison to grasslands. We also found that wetlands were consistently avoided whereas forest and savannas tended to be selected. Importantly, this model revealed that selection for forest increased with temperature, suggesting that forests may act as important thermal shelters when temperatures are high. Finally, using the spatial absorbing Markov chain framework, we show that the TEHS model results can be used to simulate movement and connectivity within a fragmented landscape, revealing that giant anteaters will often not use the shortest-distance path to the destination patch due to avoidance of certain habitats.

   The proposed approach can be used to characterize how landscape features are perceived by individuals through the decomposition of movement patterns into a time and a habitat selection component. Additionally, this framework can help bridge the gap between movement-based models and connectivity analysis, enabling the generation of time-explicit connectivity results.

    

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3. Urban specialization reduces habitat connectivity by a highly mobile wading bird

   https://doi.org/10.1186/s40462-020-00233-7  

   Teitelbaum, Claire S. ; Hepinstall-Cymerman, Jeffrey ; Kidd-Weaver, Anjelika ; Hernandez, Sonia M. ; Altizer, Sonia ; Hall, Richard J. ( December 2020 , Movement Ecology)

   null (Ed.)

   Abstract Background Mobile animals transport nutrients and propagules across habitats, and are crucial for the functioning of food webs and for ecosystem services. Human activities such as urbanization can alter animal movement behavior, including site fidelity and resource use. Because many urban areas are adjacent to natural sites, mobile animals might connect natural and urban habitats. More generally, understanding animal movement patterns in urban areas can help predict how urban expansion will affect the roles of highly mobile animals in ecological processes. Methods Here, we examined movements by a seasonally nomadic wading bird, the American white ibis ( Eudocimus albus ), in South Florida, USA. White ibis are colonial wading birds that forage on aquatic prey; in recent years, some ibis have shifted their behavior to forage in urban parks, where they are fed by people. We used a spatial network approach to investigate how individual movement patterns influence connectivity between urban and non-urban sites. We built a network of habitat connectivity using GPS tracking data from ibis during their non-breeding season and compared this network to simulated networks that assumed individuals moved indiscriminately with respect to habitat type. Results We found that the observed network was less connected than the simulated networks, that urban-urban and natural-natural connections were strong, and that individuals using urban sites had the least-variable habitat use. Importantly, the few ibis that used both urban and natural habitats contributed the most to connectivity. Conclusions Habitat specialization in urban-acclimated wildlife could reduce the exchange of propagules and nutrients between urban and natural areas, which has consequences both for beneficial effects of connectivity such as gene flow and for detrimental effects such as the spread of contaminants or pathogens. 

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4. Impairments in Proprioceptively-Referenced Limb and Eye Movements in Chronic Stroke

   https://doi.org/10.1177/15459683241289123  

   Tulimieri, Duncan_T ; Decarie, Amelia ; Singh, Tarkeshwar ; Semrau, Jennifer_A ( October 2024 , Neurorehabilitation and Neural Repair)

   Upper limb proprioceptive impairments are common after stroke and affect daily function. Recent work has shown that stroke survivors have difficulty using visual information to improve proprioception. It is unclear how eye movements are impacted to guide action of the arm after stroke. Here, we aimed to understand how upper limb proprioceptive impairments impact eye movements in individuals with stroke.

   Control (N = 20) and stroke participants (N = 20) performed a proprioceptive matching task with upper limb and eye movements. A KINARM exoskeleton with eye tracking was used to assess limb and eye kinematics. The upper limb was passively moved by the robot and participants matched the location with either an arm or eye movement. Accuracy was measured as the difference between passive robot movement location and active limb matching (Hand-End Point Error) or active eye movement matching (Eye-End Point Error).

   We found that individuals with stroke had significantly larger Hand (2.1×) and Eye-End Point (1.5×) Errors compared to controls. Further, we found that proprioceptive errors of the hand and eye were highly correlated in stroke participants ( r = .67, P = .001), a relationship not observed for controls.

   Eye movement accuracy declined as a function of proprioceptive impairment of the more-affected limb, which was used as a proprioceptive reference. The inability to use proprioceptive information of the arm to coordinate eye movements suggests that disordered proprioception impacts integration of sensory information across different modalities. These results have important implications for how vision is used to actively guide limb movement during rehabilitation.

    

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5. Foraging strategies by a frugivorous primate ( Eulemur rubriventer ) shape spatial patterns of seed dispersal

   https://doi.org/10.1111/1365-2435.14702  

   Tonos, Jadelys ; Jones, Landon_R ; Razafindratsima, Onja ; Dunham, Amy_E ( December 2024 , Functional Ecology)

   The movement decisions of frugivores shape spatial patterns of seed deposition, with considerable impacts for plant individuals, populations and communities.

   However, we have limited understanding of the mechanisms determining the foraging strategies behind the movements of frugivorous animals and their interaction with the landscape.

   Using spatially explicit simulations we examined the movements and seed dispersal of red‐bellied lemur (Eulemur rubriventer) groups dispersing seeds of the tropical treeHarungana madagascariensisunder four theorized foraging strategies.

   These included scenarios in which frugivores move directly to the (1) most rewarding plant in the landscape, (2) nearest fruiting plant, or towards the most rewarding plant in the landscape, with stops at any fruiting plants encountered along the way according to a local attraction distance of (3) 10 m and (4) 20 m.

   We then compared 12 metrics and data distributions for seed dispersal and movement patterns from these models to empirical observations.

   Simulations of foraging strategies with directed movement towards highly rewarding resources (strategy 1) produced the longest seed dispersal distances and best matched observed patterns.

   Observed data of lemur movements and directionality best matched results from three strategies, simulations towards highly rewarding resources without stops (strategy 1) and with either stops along the way with a 10 m (strategy 3) or 20 m (strategy 4) attraction distance.

   Collectively, our results supported the strategies in which lemurs moved consistently towards the small number of trees that produced the most fruit in the landscape.

   Our work supports incorporating a mechanistic understanding of animal foraging, movement behaviour and landscape patterns in fruit production for the prediction of seed movement. Explicit considerations of these mechanisms can improve our understanding of the maintenance and structure of diversity in plant communities, with implications for the conservation of forest ecosystems relying on animals for seed dispersal.

   Read the freePlain Language Summaryfor this article on the Journal blog.

    

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