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Article ; Online: A bird's-eye view on turbulence: seabird foraging associations with evolving surface flow features.

Lieber, Lilian / Langrock, Roland / Nimmo-Smith, W Alex M

2021 Volume 288, Issue 1949, Page(s) 20210592

Abstract: Understanding physical mechanisms underlying seabird foraging is fundamental to predict responses to coastal change. For instance, turbulence in the water arising from natural or anthropogenic structures can affect foraging opportunities in tidal seas. ... ...

Abstract	Understanding physical mechanisms underlying seabird foraging is fundamental to predict responses to coastal change. For instance, turbulence in the water arising from natural or anthropogenic structures can affect foraging opportunities in tidal seas. Yet, identifying ecologically important localized turbulence features (e.g. upwellings approximately 10-100 m) is limited by observational scale, and this knowledge gap is magnified in volatile predators. Here, using a drone-based approach, we present the tracking of surface-foraging terns (143 trajectories belonging to three tern species) and dynamic turbulent surface flow features in synchrony. We thereby provide the earliest evidence that localized turbulence features can present physical foraging cues. Incorporating evolving vorticity and upwelling features within a hidden Markov model, we show that terns were more likely to actively forage as the strength of the underlying vorticity feature increased, while conspicuous upwellings ahead of the flight path presented a strong physical cue to stay in transit behaviour. This clearly encapsulates the importance of prevalent turbulence features as localized foraging cues. Our quantitative approach therefore offers the opportunity to unlock knowledge gaps in seabird sensory and foraging ecology on hitherto unobtainable scales. Finally, it lays the foundation to predict responses to coastal change to inform sustainable ocean development.
MeSH term(s)	Animals ; Charadriiformes ; Ecology ; Oceans and Seas
Language	English
Publishing date	2021-04-28
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	209242-6
ISSN	1471-2954 ; 0080-4649 ; 0962-8452 ; 0950-1193
ISSN (online)	1471-2954
ISSN	0080-4649 ; 0962-8452 ; 0950-1193
DOI	10.1098/rspb.2021.0592
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Article ; Online: Semi-Markov Arnason-Schwarz models.

King, Ruth / Langrock, Roland

Biometrics

2016 Volume 72, Issue 2, Page(s) 619–628

Abstract: We consider multi-state capture-recapture-recovery data where observed individuals are recorded in a set of possible discrete states. Traditionally, the Arnason-Schwarz model has been fitted to such data where the state process is modeled as a first- ... ...

Abstract	We consider multi-state capture-recapture-recovery data where observed individuals are recorded in a set of possible discrete states. Traditionally, the Arnason-Schwarz model has been fitted to such data where the state process is modeled as a first-order Markov chain, though second-order models have also been proposed and fitted to data. However, low-order Markov models may not accurately represent the underlying biology. For example, specifying a (time-independent) first-order Markov process involves the assumption that the dwell time in each state (i.e., the duration of a stay in a given state) has a geometric distribution, and hence that the modal dwell time is one. Specifying time-dependent or higher-order processes provides additional flexibility, but at the expense of a potentially significant number of additional model parameters. We extend the Arnason-Schwarz model by specifying a semi-Markov model for the state process, where the dwell-time distribution is specified more generally, using, for example, a shifted Poisson or negative binomial distribution. A state expansion technique is applied in order to represent the resulting semi-Markov Arnason-Schwarz model in terms of a simpler and computationally tractable hidden Markov model. Semi-Markov Arnason-Schwarz models come with only a very modest increase in the number of parameters, yet permit a significantly more flexible state process. Model selection can be performed using standard procedures, and in particular via the use of information criteria. The semi-Markov approach allows for important biological inference to be drawn on the underlying state process, for example, on the times spent in the different states. The feasibility of the approach is demonstrated in a simulation study, before being applied to real data corresponding to house finches where the states correspond to the presence or absence of conjunctivitis.
MeSH term(s)	Animals ; Biometry/methods ; Computer Simulation ; Conjunctivitis/diagnosis ; Data Interpretation, Statistical ; Disease Progression ; Finches ; Humans ; Likelihood Functions ; Markov Chains ; Models, Statistical ; Time Factors
Language	English
Publishing date	2016-06
Publishing country	United States
Document type	Journal Article
ZDB-ID	213543-7
ISSN	1541-0420 ; 0099-4987 ; 0006-341X
ISSN (online)	1541-0420
ISSN	0099-4987 ; 0006-341X
DOI	10.1111/biom.12446
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Book ; Thesis: On some special-purpose hidden Markov models

Langrock, Roland

2011

Author's details	by Roland Langrock
Language	English
Size	145 S., graph. Darst.
Document type	Book ; Thesis
Thesis / German Habilitation thesis	Univ., Diss.--Göttingen, 2011
Database	Former special subject collection: coastal and deep sea fishing

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Book ; Online ; Thesis: On some special-purpose hidden Markov models

Langrock, Roland

Einige Erweiterungen von Hidden Markov Modellen für spezielle Zwecke

2011

Abstract: Hidden Markov models (HMMs) provide flexible devices for modelling time series of observations that depend on underlying serially correlated states. They constitute a specific class of dependent mixtures that have proved useful in many application fields. ...

Title variant	Einige Erweiterungen von Hidden Markov Modellen für spezielle Zwecke
Author's details	vorgelegt von Roland Langrock
Abstract	Hidden Markov models (HMMs) provide flexible devices for modelling time series of observations that depend on underlying serially correlated states. They constitute a specific class of dependent mixtures that have proved useful in many application fields. This thesis exploits the flexible mathematical structure of HMMs to develop three types of special-purpose HMMs, i.e. HMMs that differ from the standard setting and that are designed to address special demands. The first main part of the thesis considers HMMs whose matrix of state transition probabilities is structured such that it allows for arbitrary state dwell-time distributions while preserving the Markov property of the latent process. Such HMMs represent a convenient tool for approximating more flexible, but also more complicated hidden semi Markov models (HSMMs). They require fewer assumptions and enable the fitting of stationary HSMMs. Several applications illustrate the feasibility of the proposed method ...
Language	English
Size	Online-Ressource (PDF-Datei: 144 S., 1.599 KB), Graph. Darst
Document type	Book ; Online ; Thesis
Thesis / German Habilitation thesis	Univ., Diss.--Göttingen, 2011
Database	Library catalogue of the German National Library of Science and Technology (TIB), Hannover

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Book ; Online ; Thesis: On some special-purpose hidden Markov models

Langrock, Roland

Einige Erweiterungen von Hidden Markov Modellen für spezielle Zwecke

2011

Title variant	Einige Erweiterungen von Hidden Markov Modellen für spezielle Zwecke
Author's details	vorgelegt von Roland Langrock
Abstract	Hidden Markov models (HMMs) provide flexible devices for modelling time series of observations that depend on underlying serially correlated states. They constitute a specific class of dependent mixtures that have proved useful in many application fields. This thesis exploits the flexible mathematical structure of HMMs to develop three types of special-purpose HMMs, i.e. HMMs that differ from the standard setting and that are designed to address special demands. The first main part of the thesis considers HMMs whose matrix of state transition probabilities is structured such that it allows for arbitrary state dwell-time distributions while preserving the Markov property of the latent process. Such HMMs represent a convenient tool for approximating more flexible, but also more complicated hidden semi Markov models (HSMMs). They require fewer assumptions and enable the fitting of stationary HSMMs. Several applications illustrate the feasibility of the proposed method ...
Language	English
Size	Online-Ressource (PDF-Datei: 144 S., 1.599 KB), Graph. Darst
Document type	Book ; Online ; Thesis
Thesis / German Habilitation thesis	Univ., Diss.--Göttingen, 2011
Database	Former special subject collection: coastal and deep sea fishing

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Article ; Online: Performance under pressure in skill tasks: An analysis of professional darts.

Ötting, Marius / Deutscher, Christian / Schneemann, Sandra / Langrock, Roland / Gehrmann, Sebastian / Scholten, Hendrik

PloS one

2020 Volume 15, Issue 2, Page(s) e0228870

Abstract: Understanding and predicting how individuals perform in high-pressure situations is of importance in designing and managing workplaces. We investigate performance under pressure in professional darts as a near-ideal setting with no direct interaction ... ...

Abstract	Understanding and predicting how individuals perform in high-pressure situations is of importance in designing and managing workplaces. We investigate performance under pressure in professional darts as a near-ideal setting with no direct interaction between players and a high number of observations per subject. Analyzing almost one year of tournament data covering 32,274 dart throws, we find no evidence in favor of either choking or excelling under pressure.
MeSH term(s)	Athletic Performance/physiology ; Athletic Performance/psychology ; Athletic Performance/statistics & numerical data ; Humans ; Models, Psychological ; Models, Statistical ; Motor Skills/physiology ; Sports/psychology ; Sports/statistics & numerical data ; Stress, Psychological
Language	English
Publishing date	2020-02-21
Publishing country	United States
Document type	Journal Article
ISSN	1932-6203
ISSN (online)	1932-6203
DOI	10.1371/journal.pone.0228870
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article: Seasonal activity levels of a farm-island population of striated caracaras (Phalcoboenus australis) in the Falkland Islands

Harrington, Katie J / Fahlbusch, James A / Langrock, Roland / Therrien, Jean-François / Houtz, Jennifer L / McDonald, Birgitte I

Animal biotelemetry. 2020 Dec., v. 8, no. 1

2020

Abstract: BACKGROUND: Animals need adaptive strategies to cope with seasonal changes in prey availability to survive and reproduce, which can include migrating, prey-switching, or reducing metabolic needs. Human settlements can disrupt spatiotemporal patterning in ...

Abstract	BACKGROUND: Animals need adaptive strategies to cope with seasonal changes in prey availability to survive and reproduce, which can include migrating, prey-switching, or reducing metabolic needs. Human settlements can disrupt spatiotemporal patterning in resource availability, which can affect animals’ foraging success, particularly for juveniles who are behaviorally developing and learning efficient foraging skills. Here, we investigate behavioral responses of juvenile striated caracaras, a near-threatened scavenging falconid, to seasonally migratory seabird prey and a farm settlement on Saunders Island, Falklands. We deployed accelerometer–GPS dataloggers (n = 27) to measure seasonal differences in daily and hourly vectorial dynamic body acceleration (VeDBA; an activity index measured in gravitational g) and space use, and investigated seasonal variation in body mass of the tagged subset and an additional 65 caracaras. RESULTS: Juvenile caracaras were overall similarly active in winter and summer. However, during winter, caracaras made the most of limited daylight by increasing average daytime activity (winter males: 0.16 ± 0.03 g, summer males: 0.09 ± 0.01 g, winter females: 0.12 ± 0.02 g, summer females: 0.08 ± 0.01 g). During winter, both sexes increased the percentage of daylight spent in high activity (winter males: 35 ± 5%, summer males: 21 ± 3%, winter females: 25 ± 6%, summer females: 16 ± 3%, p < 0.001) and ranged nearly 4 times farther (95% kernel density estimate winter: 2.36 ± 0.96 km², summer: 0.61 ± 0.20 km²; p < 0.001). Furthermore, on a daily scale, males were 21% more active than females year-round (24-h average VeDBA: males 0.07 ± 0.01 g, females 0.06 ± 0.01 g; p < 0.01). We did not observe a significant seasonal difference in mass. CONCLUSION: That caracaras’ daily activity and body mass did not vary between seasons suggests that wintering birds on Saunders are meeting resource requirements despite the absence of seasonally migratory prey. We hypothesize that human subsidies may mitigate the effect of seasonal food limitations. Further research should include studies on seasonal energetics to improve our understanding of baseline body condition, and comparative studies on other islands and including adults to understand the importance of human subsidies.
Keywords	acceleration ; adults ; biotelemetry ; body condition ; comparative study ; density ; farms ; females ; foraging ; human settlements ; humans ; islands ; juveniles ; learning ; males ; mass ; microprocessors ; migratory behavior ; population ; research ; seabirds ; seasonal variation ; seeds ; solar radiation ; subsidies ; summer ; winter ; Falkland Islands
Language	English
Dates of publication	2020-12
Size	p. 27.
Publishing place	BioMed Central
Document type	Article
Note	NAL-light
ZDB-ID	2711027-8
ISSN	2050-3385
ISSN	2050-3385
DOI	10.1186/s40317-020-00214-y
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Movement patterns and activity levels are shaped by the neonatal environment in Antarctic fur seal pups.

Nagel, Rebecca / Mews, Sina / Adam, Timo / Stainfield, Claire / Fox-Clarke, Cameron / Toscani, Camille / Langrock, Roland / Forcada, Jaume / Hoffman, Joseph I

Scientific reports

2021 Volume 11, Issue 1, Page(s) 14323

Abstract: Tracking studies of juveniles are rare compared to those of adults, and consequently little is known about the influence of intrinsic and extrinsic factors on activity during this critical life stage. We used hourly GPS data, collected from 66 Antarctic ... ...

Abstract	Tracking studies of juveniles are rare compared to those of adults, and consequently little is known about the influence of intrinsic and extrinsic factors on activity during this critical life stage. We used hourly GPS data, collected from 66 Antarctic fur seal pups from birth until moulting, to investigate the explanatory power of multiple individual-based and environmental variables on activity levels. Pups were sampled from two nearby breeding colonies of contrasting density during two subsequent years, and a two-state hidden Markov model was used to identify modalities in their movement behaviour, specifically 'active' and 'inactive' states. We found that movement was typified by central place exploration, with active movement away from and subsequent return to a location of inactivity. The probability of such directed exploration was unaffected by several factors known to influence marine mammal movement including sex, body condition, and temperature. Compared to pups born at the high-density colony, pups at low-density were more active, increased their activity with age, and transitioned earlier into the tussock grass, which offers protection from predators and extreme weather. Our study illustrates the importance of extrinsic factors, such as colony of birth, to early-life activity patterns and highlights the adaptive potential of movement.
MeSH term(s)	Animals ; Fur Seals/physiology ; Markov Chains ; Temperature
Language	English
Publishing date	2021-07-12
Publishing country	England
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	2615211-3
ISSN	2045-2322 ; 2045-2322
ISSN (online)	2045-2322
ISSN	2045-2322
DOI	10.1038/s41598-021-93253-1
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Individuality counts: A new comprehensive approach to foraging strategies of a tropical marine predator.

Schwarz, Jonas F L / Mews, Sina / DeRango, Eugene J / Langrock, Roland / Piedrahita, Paolo / Páez-Rosas, Diego / Krüger, Oliver

Oecologia

2021 Volume 195, Issue 2, Page(s) 313–325

Abstract: Foraging strategies are of great ecological interest, as they have a strong impact on the fitness of an individual and can affect its ability to cope with a changing environment. Recent studies on foraging strategies show a higher complexity than ... ...

Abstract	Foraging strategies are of great ecological interest, as they have a strong impact on the fitness of an individual and can affect its ability to cope with a changing environment. Recent studies on foraging strategies show a higher complexity than previously thought due to intraspecific variability. To reliably identify foraging strategies and describe the different foraging niches they allow individual animals to realize, high-resolution multivariate approaches which consider individual variation are required. Here we dive into the foraging strategies of Galápagos sea lions (Zalophus wollebaeki), a tropical predator confronted with substantial annual variation in sea surface temperature. This affects prey abundance, and El Niño events, expected to become more frequent and severe with climate change, are known to have dramatic effects on sea lions. This study used high-resolution measures of depth, GPS position and acceleration collected from 39 lactating sea lion females to analyze their foraging strategies at an unprecedented level of detail using a novel combination of automated broken stick algorithm, hierarchical cluster analysis and individually fitted multivariate hidden Markov models. We found three distinct foraging strategies (pelagic, benthic, and night divers), which differed in their horizontal, vertical and temporal distribution, most likely corresponding to different prey species, and allowed us to formulate hypotheses with regard to adaptive values under different environmental scenarios. We demonstrate the advantages of our multivariate approach and inclusion of individual variation to reliably gain a deeper understanding of the adaptive value and ecological relevance of foraging strategies of marine predators in dynamic environments.
MeSH term(s)	Animals ; Cluster Analysis ; Diving ; Feeding Behavior ; Female ; Lactation ; Sea Lions
Language	English
Publishing date	2021-01-24
Publishing country	Germany
Document type	Journal Article
ZDB-ID	123369-5
ISSN	1432-1939 ; 0029-8549
ISSN (online)	1432-1939
ISSN	0029-8549
DOI	10.1007/s00442-021-04850-w
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Article ; Online: Reducing vessel noise increases foraging in endangered killer whales.

Williams, Rob / Ashe, Erin / Yruretagoyena, Laurel / Mastick, Natalie / Siple, Margaret / Wood, Jason / Joy, Ruth / Langrock, Roland / Mews, Sina / Finne, Emily

Marine pollution bulletin

2021 Volume 173, Issue Pt A, Page(s) 112976

Abstract: Disturbance from underwater noise is one of the primary threats to the critically endangered southern resident killer whales (SRKWs). Previous studies have demonstrated that SRKWs spend less time feeding when vessels are present. In 2018, we measured the ...

Abstract	Disturbance from underwater noise is one of the primary threats to the critically endangered southern resident killer whales (SRKWs). Previous studies have demonstrated that SRKWs spend less time feeding when vessels are present. In 2018, we measured the effects of a voluntary vessel slowdown action in SRKW critical habitat to assess whether ship speed (and related source level) affects foraging behaviour. Observations of SRKWs and ships were collected from land-based sites on San Juan Island, WA, USA, overlooking the Haro Strait slow-down area. Exploratory analyses found little support for a linear relationship between ship speed and SRKW behaviour, but strong support between received noise level from ships and the probability of SRKWs engaging in foraging activity. Reducing ship speed, and therefore ship noise amplitude will help decrease the probability of ship noise disrupting SRKW foraging activity and may help to increase the proportion of accessible salmon.
MeSH term(s)	Animals ; Ecosystem ; Noise ; Salmon ; Ships ; Whale, Killer
Language	English
Publishing date	2021-09-23
Publishing country	England
Document type	Journal Article
ZDB-ID	2001296-2
ISSN	1879-3363 ; 0025-326X
ISSN (online)	1879-3363
ISSN	0025-326X
DOI	10.1016/j.marpolbul.2021.112976
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