departure date
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2022 ◽  
Vol 10 (1) ◽  
Author(s):  
Florian G. Weller ◽  
William S. Beatty ◽  
Elisabeth B. Webb ◽  
Dylan C. Kesler ◽  
David G. Krementz ◽  
...  

Abstract Background The timing of autumn migration in ducks is influenced by a range of environmental conditions that may elicit individual experiences and responses from individual birds, yet most studies have investigated relationships at the population level. We used data from individual satellite-tracked mallards (Anas platyrhynchos) to model the timing and environmental drivers of autumn migration movements at a continental scale. Methods We combined two sets of location records (2004–2007 and 2010–2011) from satellite-tracked mallards during autumn migration in the Mississippi Flyway, and identified records that indicated the start of long-range (≥ 30 km) southward movements during the migration period. We modeled selection of departure date by individual mallards using a discrete choice model accounting for heterogeneity in individual preferences. We developed candidate models to predict the departure date, conditional on daily mean environmental covariates (i.e. temperature, snow and ice cover, wind conditions, precipitation, cloud cover, and pressure) at a 32 × 32 km resolution. We ranked model performance with the Bayesian Information Criterion. Results Departure was best predicted (60% accuracy) by a “winter conditions” model containing temperature, and depth and duration of snow cover. Models conditional on wind speed, precipitation, pressure variation, and cloud cover received lower support. Number of days of snow cover, recently experienced snow cover (snow days) and current snow cover had the strongest positive effect on departure likelihood, followed by number of experienced days of freezing temperature (frost days) and current low temperature. Distributions of dominant drivers and of correct vs incorrect prediction along the movement tracks indicate that these responses applied throughout the latitudinal range of migration. Among recorded departures, most were driven by snow days (65%) followed by current temperature (30%). Conclusions Our results indicate that among the tested environmental parameters, the dominant environmental driver of departure decision in autumn-migrating mallards was the onset of snow conditions, and secondarily the onset of temperatures close to, or below, the freezing point. Mallards are likely to relocate southwards quickly when faced with snowy conditions, and could use declining temperatures as a more graduated early cue for departure. Our findings provide further insights into the functional response of mallards to weather factors during the migration period that ultimately determine seasonal distributions.


2022 ◽  
Vol 14 (1) ◽  
pp. 0-0

In this article, we treat the problem of container storage in the export direction, exactly in the containership loading process. We propose an approach to the problem of container placement in a containership by describing a decision model to help decision-makers (handling operators) to minimize the total containers shifting. This is obtained by using a multicriteria decision method named Electre III (Elimination and Choice Expressing Reality) to identify the best location of any container. Here, we consider four criteria: the container destination, the container weight, the departure date of the container and the container type. This method has as input a matrix of performance and the subjective parameters and gives a ranking of alternatives as an output.


In this article, the authors treat the problem of container storage in the export direction, exactly in the containership loading process. The authors propose an approach to the problem of container placement in a containership by describing a decision model to help decision-makers (handling operators) to minimize the total container movement. This is obtained by using a multicriteria decision method AHP (analytic hierarchy process) to identify the best location of any container. Here, the authors consider four criteria: the container destination, the container weight, the departure date of the container, and the container type.


2021 ◽  
Vol 9 ◽  
Author(s):  
Jean-François Lamarre ◽  
Gilles Gauthier ◽  
Richard B. Lanctot ◽  
Sarah T. Saalfeld ◽  
Oliver P. Love ◽  
...  

Long-distance migrants are under strong selection to arrive on their breeding grounds at a time that maximizes fitness. Many arctic birds start nesting shortly after snow recedes from their breeding sites and timing of snowmelt can vary substantially over the breeding range of widespread species. We tested the hypothesis that migration schedules of individuals co-occurring at the same non-breeding areas are adapted to average local environmental conditions encountered at their specific and distant Arctic breeding locations. We predicted that timing of breeding site availability (measured here as the average snow-free date) should explain individual variation in departure time from shared non-breeding areas. We tested our prediction by tracking American Golden-Plovers (Pluvialis dominica) nesting across the North-American Arctic. These plovers use a non-breeding (wintering) area in South America and share a spring stopover area in the nearctic temperate grasslands, located >1,800 km away from their nesting locations. As plovers co-occur at the same non-breeding areas but use breeding sites segregated by latitude and longitude, we could disentangle the potential confounding effects of migration distance and timing of breeding site availability on individual migration schedule. As predicted, departure date of individuals stopping-over in sympatry was positively related to the average snow-free date at their respective breeding location, which was also related to individual onset of incubation. Departure date from the shared stopover area was not explained by the distance between the stopover and the breeding location, nor by the stopover duration of individuals. This strongly suggests that plover migration schedule is adapted to and driven by the timing of breeding site availability per se. The proximate mechanism underlying the variable migration schedule of individuals is unknown and may result from genetic differences or individual learning. Temperatures are currently changing at different speeds across the Arctic and this likely generates substantial heterogeneity in the strength of selection pressure on migratory schedule of arctic birds migrating sympatrically.


2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Michelle Modest ◽  
Ladd Irvine ◽  
Virginia Andrews-Goff ◽  
William Gough ◽  
David Johnston ◽  
...  

Abstract Background Despite exhibiting one of the longest migrations in the world, half of the humpback whale migratory cycle has remained unexamined. Until now, no study has provided a continuous description of humpback whale migratory behavior from a feeding ground to a calving ground. We present new information on satellite-derived offshore migratory movements of 16 Breeding Stock G humpback whales from Antarctic feeding grounds to South American calving grounds. Satellite locations were used to demonstrate migratory corridors, while the impact of departure date on migration speed was assessed using a linear regression. A Bayesian hierarchical state–space animal movement model (HSSM) was utilized to investigate the presence of Area Restricted Search (ARS) en route. Results 35,642 Argos locations from 16 tagged whales from 2012 to 2017 were collected. The 16 whales were tracked for a mean of 38.5 days of migration (range 10–151 days). The length of individually derived tracks ranged from 645 to 6381 km. Humpbacks were widely dispersed geographically during the initial and middle stages of their migration, but convened in two convergence regions near the southernmost point of Chile as well as Peru’s Illescas Peninsula. The state–space model showed almost no instances of ARS along the migratory route. The linear regression assessing whether departure date affected migration speed showed suggestive but inconclusive support for a positive trend between the two variables. Results suggestive of stratification by sex and reproductive status were found for departure date and route choice. Conclusions This multi-year study sets a baseline against which the effects of climate change on humpback whales can be studied across years and conditions and provides an excellent starting point for the investigation into humpback whale migration.


2021 ◽  
Vol 17 (9) ◽  
pp. 20210331
Author(s):  
Françoise Amélineau ◽  
Nicolas Delbart ◽  
Philipp Schwemmer ◽  
Riho Marja ◽  
Jérôme Fort ◽  
...  

Precise timing of migration is crucial for animals targeting seasonal resources at locations encountered across their annual cycle. Upon departure, long-distance migrants need to anticipate unknown environmental conditions at their arrival site, and they do so with their internal annual clock. Here, we tested the hypothesis that long-distance migrants synchronize their circannual clock according to the phenology of their environment during the breeding season and therefore adjust their spring departure date according to the conditions encountered at their breeding site the year before. To this end, we used tracking data of Eurasian curlews from different locations and combined movement data with satellite-extracted green-up dates at their breeding site. The spring departure date was better explained by green-up date of the previous year, while arrival date at the breeding site was better explained by latitude and longitude of the breeding site, suggesting that other factors impacted migration timing en route . On a broader temporal scale, our results suggest that long-distance migrants may be able to adjust their migration timing to advancing spring dates in the context of climate change.


2021 ◽  
Author(s):  
Ivan Literák ◽  
Jan Škrábal ◽  
Igor V. Karyakin ◽  
Natalya G. Andreyenkova ◽  
Sergey V. Vazhov

Abstract Background The Black Kite (Milvus migrans) is one of the most widespread raptors in the World. The Palaearctic is populated by two migrating subspecies, Milvus migrans migrans and Milvus migrans lineatus, in the western and eastern part of this realm, respectively. The intergradation zone of M. m. migrans/M. m. lineatus covers large areas in-between. Migration routes of M. m. migrans from Europe to Sub-Saharan Africa and the Middle East are well known including large waterbodies as main environmental obstacle. MethodsWe tagged with GPS/SMS/GPRS telemetry loggers 13 and 6 Black Kite pulli in lowland around Biysk and in mountains around Kosh-Agach. ResultsBlack Kites originating from Biysk migrated through the Western Circum-Himalayan Corridor. Black Kites originating from Kosh-Agach used the Trans-Himalayan Corridor crossing the Himalayas in altitudes of up to 6 256 m asl. The average total distance travelled of Black Kites from both subpopulations was 9 166 m without any significant differences between these subpopulations. Timing of autumn migration varied slightly among individuals in departure date (30 August ± 9 days) and differed more in arrival date (26 October ± 92 days). The timing of spring migration varied less in both departure date (17 April ± 12 days) and arrival date (09 May ± 14 days). Black Kites from both subpopulations wintered in low elevations of anthropogenic areas of Pakistan and India. Birds wintered on average for 190 days, and the mean area of individual home ranges was 4 704 km2. During the breeding period, birds occupied mainly natural or semi-natural habitats in southwestern Siberia, where they spent on average 106 days with an average home range size 3 554 km2. Conclusion Black Kites crossing the Himalayas fly and, moreover, stay for hours resting at night in the environment of mountains at altitudes over 5000 m. It seems that the vast breeding territory of Black Kites in the Palearctic realm is connected with the unusual behavioural flexibility of Black Kites to surmount various environmental obstacles on their migration routes.


2021 ◽  
Vol 10 (8) ◽  
pp. 278
Author(s):  
Henrietta McNeill

While global travel largely stopped and borders closed during the COVID-19 pandemic, states continued to deport individuals who had been sentenced for committing criminal offences. In Australia and New Zealand, questions over whether and how deportation of migrants during a global pandemic should occur were raised: weighing up arguments of legality, public health, and security. This left many migrants uncertain, isolated in immigration detention waiting for an unknown departure date. The decision was made to continue the deportation process for many, and in some cases breaches of public health restrictions were the basis for deportation. Once deported, mandatory quarantine on arrival under COVID-19 restrictions highlights and exacerbates the challenges that returning offenders normally face. These include extended detention periods; surveillance through detention and monitoring; and securitised discourse by the media and public creating ongoing stigma. This snapshot enables us to understand how states prioritised the removal of ‘the crimmigrant other’, a securitised threat, while facing the material threat of COVID-19.


Author(s):  
Tudor A. Codreanu ◽  
Nevada Pingault ◽  
Edmond O’Loughlin ◽  
Paul K. Armstrong ◽  
Benjamin Scalley

Abstract Background: A variety of infectious diseases can cause outbreaks on board vessels, with both health and economic effects. Internationally, Coronavirus Disease 2019 (COVID-19) outbreaks have occurred on numerous cruise and cargo vessels and the containment measures, travel restrictions, and border closures continue to make it increasingly difficult for ship operators world-wide to be granted pratique, effect crew changes, and conduct trade. An effective outbreak management strategy is essential to achieve the outcome triad – healthy crew, clean vessel, and set departure date – while maintaining the safety of the on-shore workers and broader community and minimizing disruption to trade. This report describes the principles of COVID-19 outbreak responses on four cargo vessels, including the successful use of one vessel as a quarantine facility. Methods: Established principles of management and the experiences of COVID-19 outbreaks on cruise ships elsewhere informed a health-lead, multi-agency, strict 14-day quarantine (Q) regime based on: population density reduction on board; crew segregation; vessel cleaning and sanitation; infection risk zones, access, and control measures; health monitoring; case identification and management; food preparation and delivery; waste management control; communication; and welfare and security. Findings: Sixty-five crew were diagnosed with Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) infection (range 2-25; attack rate 10%-81%; 15 asymptomatic). No deaths were recorded, and only one crew was hospitalized for COVID-19-related symptoms but did not require intensive care support. Catering crew were among the cases on three vessels. All non-essential crew (n-EC) and most of the cases were disembarked. During the vessel’s Q period, no further cases were diagnosed on board, and no crew became symptomatic after completion of Q. The outbreak response duration was 15-17 days from initial decision. No serious health issues were reported, no response staff became infected, and only two Q protocol breaches occurred among crew. Interpretation: Despite increasing risk of outbreaks on cargo vessels, maritime trade and crew exchanges must continue. The potential consequences of COVID-19 outbreaks to human life and to trade necessitate a balanced response. The principles described can offer health, financial, operational, and safety advantages.


2021 ◽  
Author(s):  
Armando J B Santos ◽  
Daniel H. G. Vieira ◽  
Claudio Bellini ◽  
Gilberto Corso ◽  
Simona Ceriani ◽  
...  

Abstract Population abundance data is often used to define species’ conservation status. Abundance of marine turtles is typically determined using information from nesting beach monitoring such as clutch frequency and remigration interval of nesting females. However, studies have shown that clutch frequency determined solely from nesting beach monitoring data can be underestimated. To obtain reliable estimates of clutch frequency for hawksbill turtles in northeastern Brazil (-6.273356 S., -35.036271 W), the region with the highest nesting density in the South Atlantic, data from beach monitoring and satellite telemetry were combined from 2014 to 2019. Beach monitoring data indicated the date of first nesting event, whilst state space modelling of satellite telemetry data indicated the departure date of turtles, allowing calculations of residence length at breeding site and therefore estimation of clutch frequency based on internesting intervals. Nesting females were estimated to nest up to six times within the nesting season and had an average clutch frequency of 4.7 nests per female. This estimate is almost twice larger than previous estimates based only on beach monitoring. The new estimates of clutch frequency will allow for more reliable population abundance estimates for this critically endangered population. Further, to guide future estimates of marine turtle clutch frequency methods to estimate clutch frequency were compared and their advantages and biases were discussed. Our approach and findings highlight the need for reconsideration of how clutch frequency is commonly determined for marine turtle populations and the use of beach monitoring data and satellite telemetry for estimations of clutch frequency.


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