Foraging Movements Research Articles

Spring foraging movements of an urban population of grey-headed flying foxes (Pteropus poliocephalus)

Abstract Flying foxes provide ecologically and economically important ecosystem services but extensive clearing and modification of habitat and drought combined with the planting of commercial and non-commercial trees across various landscapes, has meant flying foxes in Australia are increasingly seeking foraging resources in new areas. In 2011, grey-headed flying foxes formed a camp in Adelaide, South Australia, outside their previously recorded range. We used global positioning system telemetry to study the movements and foraging behaviour of this species in Adelaide in spring (September to November) 2015. High-frequency location data were used to determine the foraging range and the most frequently visited foraging sites used by each bat which were ground-truthed to identify forage plants. A total of 7239 valid locations were collected over 170 nights from four collars. Despite being a highly mobile species, the mean core foraging range estimate was only 7.30 km2 (range 3.3–11.2 km2). Maximum foraging distance from the camp in the Botanic Park was 9.5 km but most foraging occurred within a 4-km radius. The most common foraging sites occurred within the residential area of Adelaide and included introduced forage plant species, Lemon-scented gum (Corymbia citriodora) and Port Jackson fig (Ficus rubiginosa). Other observed movement activities included dipping behaviour on inland and marine waters and travel across flight paths around Adelaide airport. Our findings suggest that urban habitats in Adelaide provide sufficient foraging resources for grey-headed flying foxes to use these areas exclusively, at least in spring. This creates substantial opportunities for bats to interact with humans and their infrastructure.

AgentSeal: Agent-based model describing movement of marine central-place foragers

Understanding why animals move as they do when searching for resources is a central question in ecology, and a prerequisite for the development of predictive process-based models for conservation and management. Many species are central-place foragers (CPF). While several models for CPFs have been proposed, they often assume well-defined return rules to the focal point (like breeding). For some CPFs, however, the decisions to return to central sites are governed by multiple interactions between environmental and physiological factors.We present AgentSeal, a behaviour- and physiology-based, spatially explicit, agent-based model. We use harbour seals, a marine CPF, as a case study and focus on individuals outside their breeding and moulting seasons to capture general fine- and large-scale movements and drivers behind CPF. We model movement decisions based on optimal foraging strategy, cognitive and physiological processes in a realistic landscape, coupled with realistic prey distribution and tuned to a range of behavioural and physiological patterns observed at different scales and levels of organisation (pattern-orientated modelling, POM).The model can reproduce energetic, movement and other behavioural patterns such as net energy balance, at-sea and on land site fidelity, daily activity budgets and trip extents. The model reveals the crucial elements needed to model return-trips of CPFs including movement characteristics that vary as a function of local environmental conditions, cognitive mapping of foraging areas as points of attraction in subsequent foraging trips, and physiological requirements defining switches between resting and foraging.We discuss potential applications and extensions of the model, including investigations of fundamental questions in foraging ecology: how spatial distribution and aggregation of resources affect movement of marine CPFs; what are the main drivers behind their at-sea site-fidelity to foraging patches? We also discuss applied objectives such as improving our understanding of population-level consequences of anthropogenic disturbances and ultimately evolving AgentSeal into a practical management tool.

Annual flowers strips benefit bumble bee colony growth and reproduction

Bumble bees are important crop pollinators but are negatively impacted by agricultural intensification and concomitant loss of floral resources. Flower strips can increase the abundance and sometimes the diversity of bumble bees at local scales, but the importance of flower strips for bumble bee populations at larger scales remains poorly understood. We investigated the effect of flower strips on bumble bee colony growth and reproduction at landscape scales. Commercial bumble bee colonies of a native species (Bombus terrestris) were placed and monitored at different distances from flower strips that were sown on existing ecological focus areas (European Common Agricultural Policy) in southern Sweden. Both the average colony growth (weight) and the production of reproductives (drones and queens) were highest for colonies adjacent to flower strips and declined with increasing distance. Colonies close to the flower strip also produced more reproductives per colony weight. Colony foraging activity was negatively related to the distance to flower strips whereas worker size was not affected. Annual flower strips in ecological focus areas benefit bumble bee colonies by increasing foraging success, colony growth and finally boosting sexual reproduction, demonstrating potential benefits for pollination within and between seasons. These effects were spatially limited but extended to foraging ranges of bumble bees. However, effects of increased colony growth on the abundance of foraging bees in the landscape may extend to larger distances because of forager movements within seasons and queen dispersal between seasons, suggesting that voluntary or incentivised collaboration between farmers may be needed to achieve optimal implementation of flower strips.

Movements of loggerhead sea turtles (Caretta caretta) in the Gulf of California: integrating satellite telemetry and remotely sensed environmental variables

AbstractThe loggerhead turtle (Caretta caretta) is a circumglobal species and is listed as vulnerable globally. The North Pacific population nests in Japan and migrates to the Central North Pacific and Pacific coast of North America to feed. In the Mexican Pacific, records of loggerhead presence are largely restricted to the Gulf of Ulloa along the Baja California Peninsula, where very high fisheries by-catch mortality has been reported. Records of loggerhead turtles within the Sea of Cortez also known as the Gulf of California (GC) exist; however, their ecology in this region is poorly understood. We used satellite tracking and an environmental variable analysis (chlorophyll-a(Chl-a) and sea surface temperature (SST)) to determine movements and habitat use of five juvenile loggerhead turtles ranging in straight carapace length from 62.7–68.3 cm (mean: 66.7 ± 2.3 cm). Satellite tracking durations ranged from 73–293 days (mean: 149 ± 62.5 days), transmissions per turtle from 14–1006 (mean: 462 ± 379.5 transmissions) and total travel distance from 1237–5222 km (mean: 3118 ± 1490.7 km). We used travel rate analyses to identify five foraging areas in the GC, which occurred mainly in waters from 10–80 m deep, with mean Chl-aconcentrations ranging from 0.28–13.14 mg m−3and SST ranging from 27.8–34.4°C. This is the first study to describe loggerhead movements in the Gulf of California and our data suggest that loggerhead foraging movements are performed in areas with eutrophic levels of Chl-a.

Foraging Far from Home: Gps-Tracking of Mediterranean Storm-Petrels Hydrobates pelagicus melitensis Reveals Long-Distance Foraging Movements

Identifying important foraging areas is fundamental to detecting the demographic drivers of a species and ultimately to plan conservation measures. For some species, such as small pelagic seabirds, foraging grounds are difficult to locate and remain largely unknown. We used miniaturised GPS devices (∼0.95g) to study foraging movements of Mediterranean Storm-petrels Hydrobates pelagicus melitensis during the incubation period. A total of 43 individuals at Benidorm colony (southwestern Mediterranean Sea) were tracked during a single foraging trip. We first assessed potential negative effects of the tracking devices. We recorded 22 complete foraging trips and measured home-range, foraging areas and the degree of overlap among individuals. We used first passage time analyses (FPT) to differentiate foraging/resting from flying/travelling activities and to infer potential foraging areas. All tracked birds returned to the colony. On average, individual body weight slightly decreased after foraging trips, suggesting a small immediate negative effect of the device. Tracked birds had high breeding success (0.71). Foraging trips lasted between 1 and 4.5 days with the total distance travelled ranging between 303.14 and 1,726.53km. The visited areas covered the whole south-western part of the Mediterranean Sea. Tracked individuals shared more than 50% of their home-range areas. Foraging areas were located further from the colony than previously thought (from 240 to 469km away) on deep sea areas of the Alboran Sea and Cartagena Canyons. Further studies are needed to locate foraging grounds during other life-cycle periods and to evaluate repeatability yearly, in order to determine the important marine areas for the species.—Rotger, A., Sola, A., Tavecchia, G. & Sanz-Aguilar, A. (2021). Foraging far from home: GPS-tracking of Mediterranean Storm-petrels Hydrobates pelagicus melitensis reveals long-distance foraging movements. Ardeola, 68: 3-16.

The power of odour cues in shaping fine-scale search patterns of foraging mammalian herbivores.

Foraging by mammalian herbivores has profound impacts on natural and modified landscapes, yet we know little about how they find food, limiting our ability to predict and manage their influence. Mathematical models show that foragers exploiting odour cues outperform a random walk strategy. However, discovering how free-ranging foragers exploit odours in real, complex landscapes has proven elusive because of technological constraints. We took a novel approach, using a sophisticated purpose-built thermal camera system to record fine-scale foraging by a generalist mammalian herbivore, the swamp wallaby (Wallabia bicolor). We tested the hypothesis that odour cues shape forager movement and behaviour in vegetation patches. To do this, we compared wallaby foraging in two odour landscapes: Control (natural vegetation with food and non-food plants interspersed) and +Apple (the same natural vegetation plus a single, highly palatable food source with novel odour (apple)). The +Apple treatment led to strongly directed foraging by wallabies: earlier visits to vegetation patches, straighter movement paths, more hopping and fewer stops than in the Control treatment. Our results provide clear empirical evidence that odour cues are harnessed for efficient, directed search even at this fine scale. We conclude that random walk models miss a key feature shaping foraging within patches.

High spatial fidelity among foraging trips of Masked Boobies from Pedro Cays, Jamaica.

In marine environments, tropical and subtropical habitats are considered to be inherently less productive than more temperate systems. As such, foraging site fidelity among vertebrate predators occupying low-latitude marine systems is generally low as a response to an increased unpredictability of resources. We investigated the foraging movements of Masked Boobies breeding on Middle Cay, Jamaica using GPS loggers to examine if the presence of a nearby bathymetric feature influenced foraging site fidelity in a tropical system, the Caribbean Sea. According to the movements of tracked individuals, this population of boobies shows a high degree of spatial fidelity in foraging site selection, concentrated on the northern edge of Pedro Bank. We suggest this feature as an important location for marine conservation in the region and demonstrate its utility to foraging boobies via habitat modeling using a maximum entropy approach of relevant habitat variables. Finally, we place this study into the global context of Masked Booby foraging by examining the published literature of relevant tracking studies for population-level similarity in foraging metrics. According to hierarchical clustering of foraging effort, Masked Boobies demonstrate a density-dependent response to foraging effort regardless of colony origin or oceanic basin consistent with the principles of Ashmole's Halo.

Do orientation and substrate influence apparent turning biases by the 7-spot ladybird, Coccinella septempunctata?

Abstract How foraging predators explore their environment is a fundamental aspect of predator-prey interactions. Girling et al. (2007) tested Coccinella septempunctata in a Y-maze, finding that approximately 45% of individuals displayed significant turning biases. We extend the work of Girling et al. in three ways: (1) turning bias was tested on vertical as well as horizontal structures, (2) turning bias was tested on natural Y-shaped twigs as well as artificial twigs and (3) turning bias was recorded both as the pre-designated ‘left’ or ‘right’ physical branch selected and from the perspective of ladybirds. No significant patterns of ‘handedness’ were apparent with vertical orientation, on either substrate. With horizontal orientation, significant turning biases were exhibited on artificial but not natural twigs. Overall, although turning biases are theoretically efficient when searching branched structures, we propose that in natural environments ladybirds will base their foraging movements on environmental cues.

Predicting defaunation: accurately mapping bushmeat hunting pressure over large areas.

Unsustainable hunting is emptying forests of large animals around the world, but current understanding of how human foraging spreads across landscapes has been stymied by data deficiencies and cryptic hunter behaviour. Unlike other global threats to biodiversity like deforestation, climate change and overfishing, maps of wild meat hunters' movements-often based on forest accessibility-typically cover small scales and are rarely validated with real-world observations. Using camera trapping data from rainforests across Malaysian Borneo, we show that while hunter movements are strongly correlated with the accessibility of different parts of the landscape, accessibility measures are most informative when they integrate fine-scale habitat features like topography and land cover. Measures of accessibility naive to fine-scale habitat complexity, like distance to the nearest road or settlement, generate poor approximations of hunters' movements. In comparison, accessibility as measured by high-resolution movement models based on circuit theory provides vastly better reflections of real-world foraging movements. Our results highlight that simple models incorporating fine-scale landscape heterogeneity can be powerful tools for understanding and predicting widespread threats to biodiversity.

Trophic plasticity in the sea urchin Paracentrotus lividus, as a function of resource availability and habitat features

Factors controlling herbivory pressure are of central importance in shaping the seascape. In the Mediterranean, the sea urchin Paracentrotus lividus is considered as a keystone herbivore in seagrass meadows and macroalgal communities. Here we explored the trophic behavior of this sea urchin in a shallow seagrass habitat of Cymodocea nodosa mixed with Caulerpa prolifera and interspersed with sandy areas in Alfacs Bay, Ebro Delta (NW Mediterranean). The seasonal pseudo-indigenous bryozoan Amathia verticillata is locally very abundant, and there is also an important population of pen shells Pinna nobilis, providing hard substrate and cover, thus being a unique environment for assessing sea urchin trophic behavior. To this end, we conducted an ensemble of food preference and foraging experiments and stomach content and stable isotope analyses. Our results showed that sea urchins strongly prefer A. verticillata over other local resources, and there was also an important presence of the bryozoan in stomach contents (ca. 44%), coupled with green and decayed seagrass leaves. Stable isotope analyses revealed that over the long term, ca. 65% of the diet of P. lividus was based on decayed seagrass leaves, followed by the bryozoan and green seagrass leaves (21.7 and 13.3%, respectively). The local availability of P. nobilis provides a preferred substrate for sea urchins, which showed limited foraging movements into the surrounding seagrass beds, particularly when A. verticillata was attached to the pen shells. The apparently high contribution of animal and detrital food to P. lividus diet is unprecedented, and suggests an opportunistic feeding behavior in sea urchins in those habitats.

Scale‐appropriate spatial modelling to support area‐wide management of a polyphagous fruit fly (Diptera: Tephritidae)

AbstractControl of mobile pests frequently requires area‐wide management (AWM) that spans commercial and non‐commercial habitats. Spatial modelling of habitat suitability can guide investment and implementation of AWM, but current approaches rarely capture population drivers, including local foraging, at an appropriate spatial resolution. To support the development of AWM for the fruit fly pest, Bactrocera tryoni (Tephritidae), we developed a habitat suitability model for the three premier fruit‐growing regions in south‐eastern Australia (~34,780 km2). Expert elicitation and published literature was used to develop a Bayesian network to model the drivers of B. tryoni habitat suitability, as determined by the ability of populations to persist and increase. The effect of uncertainty was tested through sensitivity analysis. The model was then linked with spatially explicit data (at 10 m resolution) to generate risk maps, using moving windows to capture local foraging movement. Habitat suitability was most strongly influenced by host availability within a distance of 200 m. Climate stress, and soil moisture for pupation, was also limiting. Experts were uncertain regarding the relative importance of drivers of host availability (host preference, host density, fruit seasonality), but this did not greatly affect model outputs. Independent trapping data supported model predictions, but their value was limited as traps were placed almost exclusively in optimal or suitable habitat. Amenability to AWM, when assessed as the ratio of suitable or optimal habitat that was under non‐horticultural versus horticultural land‐uses, differed by region (0.15–1.17). However, risk‐mapping did identify where ratios were locally most favourable (lowest). Also, predominantly local dispersal by B. tryoni suggests AWM for pest suppression could be applied at a landscape‐scale. Results show that a relatively simple model could capture the multi‐scale drivers of population dynamics and the complexity of landscapes sufficiently to guide AWM of a mobile pest.

Preferred, small-scale foraging areas of two Southern Ocean fur seal species are not determined by habitat characteristics

BackgroundTo understand and predict the distribution of foragers, it is crucial to identify the factors that affect individual movement decisions at different scales. Individuals are expected to adjust their foraging movements to the hierarchical spatial distribution of resources. At a small local scale, spatial segregation in foraging habitat happens among individuals of closely situated colonies. If foraging segregation is due to differences in distribution of resources, we would expect segregated foraging areas to have divergent habitat characteristics.ResultsWe investigated how environmental characteristics of preferred foraging areas differ between two closely situated Subantarctic fur seal (Arctocephalus tropicalis) colonies and a single Antarctic fur seal (A. gazella) colony that forage in different pelagic areas even though they are located well within each other’s foraging range. We further investigated the influence of the seasonal cycle on those environmental factors. This study used tracking data from 121 adult female Subantarctic and Antarctic fur seals, collected during summer and winter (2009–2015), from three different colonies. Boosted Regression Tree species distribution models were used to determine key environmental variables associated with areas of fur seal restricted search behaviour. There were no differences in the relative influence of key environmental variables between colonies and seasons. The variables with the most influence for each colony and season were latitude, longitude and magnitude of sea-currents. The influence of latitude and longitude is a by-product of the species’ distinct foraging areas, despite the close proximity (< 25 km) of the colonies. The predicted potential foraging areas for each colony changed from summer to winter, reflecting the seasonal cycle of the Southern Ocean. The model predicted that the potential foraging areas of females from the three colonies should overlap, and the fact they do not in reality indicates that factors other than environmental are influencing the location of each colony’s foraging area.ConclusionsThe results indicated that small scale spatial segregation of foraging habitats is not driven by bottom-up processes. It is therefore important to also consider other potential drivers, e.g. competition, information transfer, and memory, to understand animal foraging decisions and movements.

Environmental evidence for a pygmy blue whale aggregation area in the Subtropical Convergence Zone south of Australia

AbstractThe importance of the Subtropical Convergence Zone south of Australia as a feeding area to the pygmy blue whale of the eastern Indian Ocean was investigated to better understand migration patterns and habitat use. A combination of satellite tagging studies during 2003–2005 and acoustic and visual surveys during the austral summer of 2013 confirmed the presence of pygmy blue whales in the Subtropical Convergence Zone and provided evidence for feeding throughout the region. Of the 67 pygmy blue whales acoustically detected, many were localized in proximity to sea surface temperature fronts and high chlorophyll concentrations, which could be a behavioral strategy to attract conspecifics to good feeding sites. Aggregations of up to four pygmy blue whales, along with decreased call rates during the day, may suggest feeding despite no direct observations of pygmy blue whales consuming euphausiids. The oceanographic features present throughout the Subtropical Convergence Zone continue to create an environment productive enough to support the world's largest living mammals during their migratory foraging movements between the Southern Ocean and Indonesia.

DIURNAL FORAGING BEHAVIOR OF AN APHIDOPHAGOUS HOVERFLY IN AN INSECTARY PLANT PATCH

ABSTRACT A series of foraging bouts of Episyrphus balteatus (DeGeer) females were observed and recorded throughout the day in phacelia (Phacelia tanacetifolia Bentham) patches. The dominant transitions of interplant movement, approaching and probing bouts were statistically more frequent in the morning than in the afternoon. In the morning, interplant movement of foragers was significantly longer and they were moving at higher places of phacelia patches. They approached and probed flowers considerably longer in morning compared to afternoon. A significant positive relationship between the number of open flowers in a patch and the patch residence time was observed in the morning. The proportion of females having swollen abdomen filled with phacelia pollen (68.2%) in the afternoon was significantly higher than that (31.82%)in the morning. In our study, E. balteatus females spent more time foraging in phacelia patches in morning compared to afternoon. Based on the results and by considering the dual resources requirements of a female hoverfly (flower foraging and searching for aphids to lay eggs), we will discuss the effective diurnal foraging of E. balteatus females in phacelia patches.

DIURNAL FORAGING BEHAVIOR OF AN APHIDOPHAGOUS HOVERFLY IN AN INSECTARY PLANT PATCH

A series of foraging bouts of Episyrphus balteatus (DeGeer) females were observed and recorded throughout the day in phacelia (Phacelia tanacetifolia Bentham) patches. The dominant transitions of interplant movement, approaching and probing bouts were statistically more frequent in the morning than in the afternoon. In the morning, interplant movement of foragers was significantly longer and they were moving at higher places of phacelia patches. They approached and probed flowers considerably longer in morning compared to afternoon. A significant positive relationship between the number of open flowers in a patch and the patch residence time was observed in the morning. The proportion of females having swollen abdomen filled with phacelia pollen (68.2%) in the afternoon was significantly higher than that (31.82%)in the morning. In our study, E. balteatus females spent more time foraging in phacelia patches in morning compared to afternoon. Based on the results and by considering the dual resources requirements of a female hoverfly (flower foraging and searching for aphids to lay eggs), we will discuss the effective diurnal foraging of E. balteatus females in phacelia patches.

Environmentally driven sexual segregation in a marine top predator

Sexual segregation in foraging occurs in many animal species, resulting in the partitioning of resources and reduction of competition between males and females, yet the patterns and drivers of such segregation are still poorly understood. We studied the foraging movements (GPS-tracking), habitat use (habitat modelling) and trophic ecology (stable isotope analysis) of female and male Cory’s shearwaters Calonectris borealis during the mid chick-rearing period of six consecutive breeding seasons (2010–2015). We found a clear sexual segregation in foraging in years of greater environmental stochasticity, likely years of lower food availability. When food became scarce, females undertook much longer foraging trips, exploited more homogeneous water masses, had a larger isotopic niche, fed on lower trophic level prey and exhibited a lower body condition, when compared to males. Sexual competition for trophic resources may be stronger when environmental conditions are poor. A greater foraging success of one sex may result in differential body condition of pair mates when enduring parental effort, and ultimately, in an increased probability of breeding failure.

Four sympatrically nesting auks show clear resource segregation in their foraging environment

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 572:243-254 (2017) - DOI: https://doi.org/10.3354/meps12144 Four sympatrically nesting auks show clear resource segregation in their foraging environment Isabeau Pratte1,*, Gregory J. Robertson2, Mark L. Mallory1 1Department of Biology, Acadia University, Wolfville, Nova Scotia B4P 2R6, Canada 2Wildlife Research Division, Environment and Climate Change Canada, Mount Pearl, Newfoundland A1N 4T3, Canada *Corresponding author: pratteisabeau@gmail.com ABSTRACT: Auks share ecological similarities and are often found in sympatrically nesting assemblages at suitable nesting sites. It is expected that co-existing species would have evolved strategies to reduce niche overlap in response to resource competition. The presence of Atlantic puffins Fratercula arctica, razorbills Alca torda, thick-billed murres Uria lomvia and common murres U. aalge at the Gannet Islands, Labrador, is an opportunity to study interspecific interactions in a major seabird community. We compared the foraging movements of adult breeding birds and the diet of the birds inferred through (1) stable isotopes in the blood of adults, and (2) prey delivered to the chicks, as dimensions in the foraging niche among these 4 auks. Our results revealed that puffins and thick-billed murres headed offshore to forage, while razorbills and common murres were more coastal, heading towards mainland Labrador. The patterns of spatial segregation found among coastal and pelagic birds were mirrored by their stable isotope ratios, with one group of species foraging at a higher trophic level of an inshore food web and the other foraging on a lower trophic level of an offshore, pelagic food web. The ‘pelagic’ species segregated by prey choice for their chicks while differential alternate prey selection was the source of segregation between the ‘coastal’ species. Our research highlights the importance of segregation patterns in both spatial and diet dimensions of the foraging niche among the 4 auks—a potential mechanism for reducing interspecific competition among ecologically similar seabirds and explaining the persistence of such seabird assemblages through time. KEY WORDS: Seabird · Foraging distribution · Niche overlap · Diet · Isotopic niche Full text in pdf format Supplementary material PreviousNextCite this article as: Pratte I, Robertson GJ, Mallory ML (2017) Four sympatrically nesting auks show clear resource segregation in their foraging environment. Mar Ecol Prog Ser 572:243-254. https://doi.org/10.3354/meps12144 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 572. Online publication date: May 31, 2017 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2017 Inter-Research.

Satellite tracking of red-listed nominate lesser black-backed gulls (Larus f. fuscus): Habitat specialisation in foraging movements raises novel conservation needs

In contrast to many other gull species, nominate lesser black-backed gulls (Larus fuscus fuscus, nLBBG) have shown generally decreasing population trends throughout their breeding area in northern and eastern Fennoscandia over the past decades and are now red-listed. Interspecific competition, predation, increased disturbance, organochlorine poisoning and food shortages were suggested as main reasons for the overall decrease. Here we contribute to a better understanding of population declines by comparing foraging movements of satellite tracked adult gulls in three geographical areas of Finland (West, South, and East) that differ in their population trends. Our analysis examines potential differences and preferences in the feeding site behaviour of adult gulls. Our comparison of the three geographical areas showed that nLBBGs preferred feeding at fur farms in West Finland, waste dumps in South Finland, and lakes and fields in East Finland. We found individual gulls of this purportedly generalist species to be highly specialised in their foraging behaviour, particularly those that might be associated with their survival probabilities. We hypothesise that differences in foraging behaviour and food availability during the breeding season are partially responsible for differences in demographic trends between populations. Specifically, we identify potential local conservation problems such as shooting in birds visiting fur farms. Our data suggest that the effective conservation and management of endangered nLBBGs could be aided by simple actions in the breeding areas in addition to better protection throughout the annual movement cycle.

Fine-scale foraging movements by fish-eating killer whales (Orcinus orca) relate to the vertical distributions and escape responses of salmonid prey (Oncorhynchus spp.)

BackgroundWe sought to quantitatively describe the fine-scale foraging behavior of northern resident killer whales (Orcinus orca), a population of fish-eating killer whales that feeds almost exclusively on Pacific salmon (Oncorhynchus spp.). To reconstruct the underwater movements of these specialist predators, we deployed 34 biologging Dtags on 32 individuals and collected high-resolution, three-dimensional accelerometry and acoustic data. We used the resulting dive paths to compare killer whale foraging behavior to the distributions of different salmonid prey species. Understanding the foraging movements of these threatened predators is important from a conservation standpoint, since prey availability has been identified as a limiting factor in their population dynamics and recovery.ResultsThree-dimensional dive tracks indicated that foraging (N = 701) and non-foraging dives (N = 10,618) were kinematically distinct (Wilks’ lambda: λ16 = 0.321, P < 0.001). While foraging, killer whales dove deeper, remained submerged longer, swam faster, increased their dive path tortuosity, and rolled their bodies to a greater extent than during other activities. Maximum foraging dive depths reflected the deeper vertical distribution of Chinook (compared to other salmonids) and the tendency of Pacific salmon to evade predators by diving steeply. Kinematic characteristics of prey pursuit by resident killer whales also revealed several other escape strategies employed by salmon attempting to avoid predation, including increased swimming speeds and evasive maneuvering.ConclusionsHigh-resolution dive tracks reconstructed using data collected by multi-sensor accelerometer tags found that movements by resident killer whales relate significantly to the vertical distributions and escape responses of their primary prey, Pacific salmon.

Sex-Related Differences in the Foraging Movement of Streaked ShearwatersCalonectris leucomelasBreeding on Awashima Island in the Sea of Japan

Abstract Sex-related differences in foraging habitat are common among seabirds. Streaked Shearwaters Calonectris leucomelas breeding on Awashima Island in the Sea of Japan are considered to exhibit gender differences in foraging habitat: only males cross the windy Tsugaru Strait into the Pacific Ocean. Since males are larger, with greater wing loading than females, winds are expected to increase the effect of sexual size dimorphism on their flight performance, which may determine accessibility to foraging habitats. To assess the sex-related differences in foraging movements among years in which environmental and wind conditions differed, we analyzed foraging trips of male (N=243) and female (N=241) Streaked Shearwaters during the chick-rearing period by using GPS loggers in 2011, 2012, and 2013. Both males and females were found to travel through the Tsugaru Strait into the Pacific Ocean, but the frequency was higher for males than for females. Nevertheless, we found that wind velocities had no effect on ...