scholarly journals Design of Deployment Strategies to Monitor the Movement of Animals with Passive Electronic Devices

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 326
Author(s):  
Laila D. Kazimierski ◽  
Jorge P. Rodríguez ◽  
Víctor M. Eguíluz

Current animal monitoring systems have improved our knowledge of quantitative animal ecology. There are many electronic tracking technologies such as VHF/UHF telemetry, light-level geolocation, ARGOS satellite telemetry and GPS tracking. To reach the desired level of information retrieval requires the planning of adequate equipment effort and coverage, which depends on the properties of the system. We propose an equipment arrangement model consisting of a given number of receiver stations in a two-dimensional space in which the animals move according to a central place movement model. The objective is to characterize how the transmission of tracking data depends on the movement of the animals and the design of the equipment deployment: quantity and location of the receiver stations and their associated reception radius. We also implement the model using real trajectories of southern elephant seals and Australian sea lions publicly available online and tracked during the years 2010–2012. We characterize the data transmission based on different equipment configurations and we obtained analogous results to the theoretical model.

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Monique Ladds ◽  
David Rosen ◽  
Carling Gerlinsky ◽  
David Slip ◽  
Robert Harcourt

Abstract Physiology places constraints on an animal’s ability to forage and those unable to adapt to changing conditions may face increased challenges to reproduce and survive. As the global marine environment continues to change, small, air-breathing, endothermic marine predators such as otariids (fur seals and sea lions) and particularly females, who are constrained by central place foraging during breeding, may experience increased difficulties in successfully obtaining adequate food resources. We explored whether physiological limits of female otariids may be innately related to body morphology (fur seals vs sea lions) and/or dictate foraging strategies (epipelagic vs mesopelagic or benthic). We conducted a systematic review of the increased body of literature since the original reviews of Costa et al. (When does physiology limit the foraging behaviour of freely diving mammals? Int Congr Ser 2004;1275:359–366) and Arnould and Costa (Sea lions in drag, fur seals incognito: insights from the otariid deviants. In Sea Lions of the World Fairbanks. Alaska Sea Grant College Program, Alaska, USA, pp. 309–324, 2006) on behavioural (dive duration and depth) and physiological (total body oxygen stores and diving metabolic rates) parameters. We estimated calculated aerobic dive limit (cADL—estimated duration of aerobic dives) for species and used simulations to predict the proportion of dives that exceeded the cADL. We tested whether body morphology or foraging strategy was the primary predictor of these behavioural and physiological characteristics. We found that the foraging strategy compared to morphology was a better predictor of most parameters, including whether a species was more likely to exceed their cADL during a dive and the ratio of dive time to cADL. This suggests that benthic and mesopelagic divers are more likely to be foraging at their physiological capacity. For species operating near their physiological capacity (regularly exceeding their cADL), the ability to switch strategies is limited as the cost of foraging deeper and longer is disproportionally high, unless it is accompanied by physiological adaptations. It is proposed that some otariids may not have the ability to switch foraging strategies and so be unable adapt to a changing oceanic ecosystem.


Ocean Science ◽  
2015 ◽  
Vol 11 (1) ◽  
pp. 83-91 ◽  
Author(s):  
L. Biermann ◽  
C. Guinet ◽  
M. Bester ◽  
A. Brierley ◽  
L. Boehme

Abstract. Under high light intensity, phytoplankton protect their photosystems from bleaching through non-photochemical quenching processes. The consequence of this is suppression of fluorescence emission, which must be corrected when measuring in situ yield with fluorometers. We present data from the Southern Ocean, collected over five austral summers by 19 southern elephant seals tagged with fluorometers. Conventionally, fluorescence data collected during the day (quenched) were corrected using the limit of the mixed layer, assuming that phytoplankton are uniformly mixed from the surface to this depth. However, distinct deep fluorescence maxima were measured in approximately 30% of the night (unquenched) data. To account for the evidence that chlorophyll is not uniformly mixed in the upper layer, we propose correcting from the limit of the euphotic zone, defined as the depth at which photosynthetically available radiation is ~ 1% of the surface value. Mixed layer depth exceeded euphotic depth over 80% of the time. Under these conditions, quenching was corrected from the depth of the remotely derived euphotic zone Zeu, and compared with fluorescence corrected from the depth of the density-derived mixed layer. Deep fluorescence maxima were evident in only 10% of the day data when correcting from mixed layer depth. This was doubled to 21% when correcting from Zeu, more closely matching the unquenched (night) data. Furthermore, correcting from Zeu served to conserve non-uniform chlorophyll features found between the 1% light level and mixed layer depth.


2018 ◽  
Author(s):  
I. D. Jonsen ◽  
C. R. McMahon ◽  
T. A. Patterson ◽  
M. Auger-Méthé ◽  
R. Harcourt ◽  
...  

AbstractLike many species, movement patterns of southern elephant seals (Mirounga leonina) are being influenced by long-term environmental change. These seals migrate up to 4000 km from their breeding colonies, foraging for months in a variety of Southern Ocean habitats. Understanding how movement patterns vary with environmental features and how these relationships differ among individuals employing different foraging strategies can provide insight into foraging performance at a population level. We apply new fast-estimation tools to fit mixed effects within a random walk movement model, rapidly inferring among-individual variability in southern elephant seal environment-movement relationships. We found that seals making foraging trips to the sea-ice on or near the Antarctic continental shelf consistently reduced speed and directionality (move persistence) with increasing sea ice coverage and had variable responses to chlorophyll a concentration, whereas seals that foraged pelagically reduced move persistence in regions where circumpolar deep water shoaled. Given future climate scenarios, pelagic foragers may encounter more productive habitat but sea-ice foragers may see reduced habitat availability. Our approach is scalable to large telemetry data sets and allows flexible combinations of mixed effects to be evaluated via model selection, thereby illuminating the ecological context of animal movements that underlie habitat use.


2019 ◽  
Author(s):  
Simona Picardi ◽  
Brian J. Smith ◽  
Matthew E. Boone ◽  
Peter C. Frederick ◽  
Jacopo G. Cecere ◽  
...  

AbstractRecursive movement patterns have been used to detect behavioral structure within individual movement trajectories in the context of foraging ecology, home-ranging behavior, and predator avoidance. Some animals exhibit movement recursions to locations that are tied to reproductive functions, including nests and dens; while existing literature recognizes that, no method is currently available to explicitly target different types of revisited locations. Moreover, the temporal persistence of recursive movements to a breeding location can carry information regarding the fate of breeding attempts, but it has never been used as a metric to quantify recursive movement patterns. Here, we introduce a method to locate breeding attempts and estimate their fate from GPS-tracking data of central place foragers. We tested the performance of our method in three bird species differing in breeding ecology (wood stork (Mycteria americana), lesser kestrel (Falco naumanni), Mediterranean gull (Ichthyaetus melanocephalus)) and implemented it in the R package ‘nestR’. We identified breeding sites based on the analysis of recursive movements within individual tracks. Using trajectories with known breeding attempts, we estimated a set of species-specific criteria for the identification of nest sites, which we further validated using non-reproductive individuals as controls. We then estimated individual nest survival as a binary measure of reproductive fate (success, corresponding to fledging of at least one chick, or failure) from nest-site revisitation histories during breeding attempts, using a Bayesian hierarchical modeling approach that accounted for temporally variable revisitation patterns, probability of visit detection, and missing data. Across the three species, positive predictive value of the nest-site detection algorithm varied between 87-100% and sensitivity between 88-92%, and we correctly estimated the fate of 86-100% breeding attempts. By providing a method to formally distinguish among revisited locations that serve different ecological functions and introducing a probabilistic framework to quantify temporal persistence of movement recursions, we demonstrated how the analysis of recursive movement patterns can be applied to estimate reproduction in central place foragers. Beyond avian species, the principles of our method can be applied to other central place foraging breeders such as denning mammals. Our method estimates a component of individual fitness from movement data and will help bridge the gap between movement behavior, environmental factors, and their fitness consequences.


Wetlands ◽  
2021 ◽  
Vol 41 (7) ◽  
Author(s):  
Ole Thies Albrecht ◽  
Marion Glaser ◽  
Martin Zimmer

AbstractIntensive harvesting of the mangrove crab Ucides cordatus provides subsistence for food and main or additional income to many inhabitants of mangrove areas in Northern Brazil. In order to better understand the spatial patterns of use of this natural resource as basis for sustainable resource-management, we used a combination of GPS-tracking, field observations, semi-structured interviews and participatory mapping with crab-collectors. We quantified daily working hours, traveling distance and time to, as well as collecting time inside, the patches where crabs are collected. Based on preliminary findings for three different types of transportation to the fishing grounds, we conclude that crab-collectors in our study area act in accordance with the central place optimal foraging concept in that they invest more time in traveling to areas with higher catch. We hold these findings will prove relevant for sustainably managing the use of mangrove crabs as natural resource. The parallel occurrence of different collecting-behaviours possibly releases pressure from crab stocks in the potentially depleting fishing grounds adjacent to villages, and thus, may render crab-collecting in these areas more sustainable. Detailed studies are needed to quantify the catch from different mangrove areas and to make these data useful for the sustainable management of natural resource-exploitation in mangroves.


2016 ◽  
Author(s):  
Allen Aven ◽  
Ruth H. Carmichael ◽  
Elizabeth E Hieb ◽  
Monica Ross

Since the 1980s, West Indian manatees (Trichechus manatus) have been reported more frequently along the northern Gulf of Mexico (GOM) coast in areas that were recently considered to be outside the species' normal areas of occupancy. The ecological importance of the northern GOM region to manatees is currently unclear, but knowledge of the spatial ecology, population linkages, and habitat associations of individuals occupying the fringes of their known range is vital to bring context and improve understanding of demographic trends and potential threats to the species, rangewide. We tracked regional-scale movements of 13 manatees documented in Mobile Bay, AL using satellite telemetry and mark-recapture methods. We determined movement and occupancy patterns including origins, seasonal dispersal and site fidelity, and functional movement modes of those individuals during the tracking period. Focal manatees moved along the GOM coast between Tampa Bay, FL and Lake Pontchartrain, LA, and consistently returned to discrete locations in both the northern GOM and within the species' core range in peninsular FL. Functional movement model fits confirmed that most relatively long-range seasonal movements were migratory in nature, suggesting that consistently occupied migratory endpoints contain relatively important seasonal habitat for manatees and diminishing the possibility that tracked manatees were nomads or transient within the study area. These results provide evidence of shifting seasonal manatee distribution in the US, and highlight repeatedly used locations that may increase in importance to the species if manatee abundance in the northern GOM increases.


2006 ◽  
Vol 273 (1603) ◽  
pp. 2901-2907 ◽  
Author(s):  
Rebecca Lewis ◽  
Tamsin C O'Connell ◽  
Mirtha Lewis ◽  
Claudio Campagna ◽  
A. Rus Hoelzel

The evolution of resource specializations is poorly understood, especially in marine systems. The southern elephant seal ( Mirounga leonina ) is the largest of the phocid seals, sexually dimorphic, and thought to prey predominantly on fish and squid. We collected vibrissae from male and female southern elephant seals, and assessed stable C and N isotope ratios along the length of the vibrissae. Given that whiskers grow slowly, this sampling strategy reflects any variation in feeding behaviour over a period of time. We found that isotopic variation among females was relatively small, and that the apparent prey choice and trophic level of females was different from that for males. Further, males showed a very broad range of trophic/prey choice positions, grouped into several clusters, and this included isotopic values too low to match a broad range of potential fish and cephalopod prey tested. One of these clusters overlapped with data for South American sea lions ( Otaria flavescens ), which were measured for comparison. Both male southern elephant seals and southern sea lions forage over the continental shelf, providing the potential for competition. We discuss the possibility that individual southern elephant seals are pursuing specialist foraging strategies to avoid competition, both with one another, and with the South American sea lions that breed nearby.


2018 ◽  
Vol 29 (3) ◽  
pp. 328-344 ◽  
Author(s):  
Joseph Wherton ◽  
Trisha Greenhalgh ◽  
Rob Procter ◽  
Sara Shaw ◽  
James Shaw

Electronic tracking through global positioning systems (GPSs) is used to monitor people with cognitive impairment who “wander” outside the home. This ethnographic study explored how GPS-monitored wandering was experienced by individuals, lay carers, and professional staff. Seven in-depth case studies revealed that wandering was often an enjoyable and worthwhile activity and helped deal with uncertainty and threats to identity. In what were typically very complex care contexts, GPS devices were useful to the extent that they aligned with a wider sociomaterial care network that included lay carers, call centers, and health and social care professionals. In this context, “safe” wandering was a collaborative accomplishment that depended on the technology’s materiality, affordances, and aesthetic properties; a distributed knowledge of the individual and the places they wandered through, and a collective and dynamic interpretation of risk. Implications for design and delivery of GPS devices and services for cognitive impairment are discussed.


Author(s):  
Allen Aven ◽  
Ruth H. Carmichael ◽  
Elizabeth E Hieb ◽  
Monica Ross

Since the 1980s, West Indian manatees (Trichechus manatus) have been reported more frequently along the northern Gulf of Mexico (GOM) coast in areas that were recently considered to be outside the species' normal areas of occupancy. The ecological importance of the northern GOM region to manatees is currently unclear, but knowledge of the spatial ecology, population linkages, and habitat associations of individuals occupying the fringes of their known range is vital to bring context and improve understanding of demographic trends and potential threats to the species, rangewide. We tracked regional-scale movements of 13 manatees documented in Mobile Bay, AL using satellite telemetry and mark-recapture methods. We determined movement and occupancy patterns including origins, seasonal dispersal and site fidelity, and functional movement modes of those individuals during the tracking period. Focal manatees moved along the GOM coast between Tampa Bay, FL and Lake Pontchartrain, LA, and consistently returned to discrete locations in both the northern GOM and within the species' core range in peninsular FL. Functional movement model fits confirmed that most relatively long-range seasonal movements were migratory in nature, suggesting that consistently occupied migratory endpoints contain relatively important seasonal habitat for manatees and diminishing the possibility that tracked manatees were nomads or transient within the study area. These results provide evidence of shifting seasonal manatee distribution in the US, and highlight repeatedly used locations that may increase in importance to the species if manatee abundance in the northern GOM increases.


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