migratory flight
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2021 ◽  
Author(s):  
Sathishkumar Pragasam

Abstract The impact of artificial lighting on birds and animals has been a subject of research for many decades. These studies have established that light pollution from offshore facilities result in disturbing effects on migratory birds and marine animals. It is understood from the various studies that light emanating from offshore structures attract birds at night and disorient them during their migratory flight. As they are distracted from their flight path, they are either found trapped by the light that they keep circling around the installations or make them to take shelter in the installations, ultimately making them miss their migratory journey. This results in reduced winter survival and reduced reproduction success. Many birds are also found to die eventually because of bird strike or by getting themselves incinerated in flares. Congregation of birds in offshore installations also lead to risks related to helicopter landing / take-off. It is also observed that artificial light attracts marine species like turtles and fishes, which result in adverse effects like alteration of feeding habits, impacted circadian rhythm and interference with their reproductive function. From the knowledge of aforementioned disruptive effects of artificial lighting, significant efforts have been made to develop lighting systems for offshore installations that are eco-friendly. Various means of mitigating the undesirable effects of artificial lighting in offshore installations are being tried in the last couple of decades.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Richard Evan Feldman ◽  
Antonio Celis-Murillo ◽  
Jill L. Deppe ◽  
Michael P. Ward

Abstract Background For migrating birds, stopover requires spending time and energy that otherwise could be allocated to flying. Thus, birds optimally refuel their subsequent migratory flight by reducing stopover duration or foraging activity in food-rich environments. In coastal habitats, birds may forego refueling and take short stopovers irrespective of local food availability. Given the paucity of studies exploring how migrants adjust stopover behavior in response to temporal variation in food availability, especially in the Neotropics, we fixed radio tags to 51 Red-eyed Vireos (Vireo olivaceous) over two years at two sites on the coast of Mexico’s Yucatan Peninsula. Methods We applied VHF radio tags during the fall of 2016 and 2017, and tracked birds using automatic and manual receiving units. We estimated stopover duration and activity levels (one site only) for between six and fifteen birds, depending on site and year. We measured fruit availability weekly along the net lanes where we captured birds. We used a generalized linear model to estimate the relationships between stopover duration/activity level and fruit density, bird body mass and year. We interpreted relationships for the model with the lowest AICc value. Results We found that approximately half of the birds departed on the same day they were captured. For the birds that stayed longer, we could not discern whether they did so because they were light, or fruit density was high. On the other hand, lighter birds were more active than heavier birds but only in one of the two years. Conclusions Given our results, it is unlikely that Red-eyed Vireos refuel along the Yucatan coast. However, they still likely need to recuperate from crossing the Gulf of Mexico, which may necessitate foraging more often if in poor body condition. If the birds then move inland then stopover should be thought of as a large-scale phenomenon, where habitats with different functions may be spread out over a broad landscape.


2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Batbayar Galtbalt ◽  
Amanda Lilleyman ◽  
Jonathan T. Coleman ◽  
Chuyu Cheng ◽  
Zhijun Ma ◽  
...  

2021 ◽  
Vol 9 ◽  
Author(s):  
Johanna S. U. Hedlund ◽  
Hua Lv ◽  
Philipp Lehmann ◽  
Gao Hu ◽  
R. Charles Anderson ◽  
...  

Insect migration redistributes enormous quantities of biomass, nutrients and species globally. A subset of insect migrants perform extreme long-distance journeys, requiring specialized morphological, physiological and behavioral adaptations. The migratory globe skimmer dragonfly (Pantala flavescens) is hypothesized to migrate from India across the Indian Ocean to East Africa in the autumn, with a subsequent generation thought to return to India from East Africa the following spring. Using an energetic flight model and wind trajectory analysis, we evaluate the dynamics of this proposed transoceanic migration, which is considered to be the longest regular non-stop migratory flight when accounting for body size. The energetic flight model suggests that a mixed strategy of gliding and active flapping would allow a globe skimmer to stay airborne for up to 230–286 h, assuming that the metabolic rate of gliding flight is close to that of resting. If engaged in continuous active flapping flight only, the flight time is severely reduced to ∼4 h. Relying only on self-powered flight (combining active flapping and gliding), a globe skimmer could cross the Indian Ocean, but the migration would have to occur where the ocean crossing is shortest, at an exceptionally fast gliding speed and with little headwind. Consequently, we deem this scenario unlikely and suggest that wind assistance is essential for the crossing. The wind trajectory analysis reveals intra- and inter-seasonal differences in availability of favorable tailwinds, with only 15.2% of simulated migration trajectories successfully reaching land in autumn but 40.9% in spring, taking on average 127 and 55 h respectively. Thus, there is a pronounced requirement on dragonflies to be able to select favorable winds, especially in autumn. In conclusion, a multi-generational, migratory circuit of the Indian Ocean by the globe skimmer is shown to be achievable, provided that advanced adaptations in physiological endurance, behavior and wind selection ability are present. Given that migration over the Indian Ocean would be heavily dependent on the assistance of favorable winds, occurring during a relatively narrow time window, the proposed flyway is potentially susceptible to disruption, if wind system patterns were to be affected by climatic change.


2021 ◽  
pp. 104248
Author(s):  
Shishuai Ge ◽  
Xiaoxu Sun ◽  
Wei He ◽  
Kris A.G. Wyckhuys ◽  
Limei He ◽  
...  

PLoS ONE ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. e0245665
Author(s):  
Patil Jyothi ◽  
Prabhuraj Aralimarad ◽  
Vijaya Wali ◽  
Shivansh Dave ◽  
M. Bheemanna ◽  
...  

Despite its deleterious impact on farming and agriculture, the physiology and energetics of insect migration is poorly understood due to our inability to track their individual movements in the field. Many insects, e.g. monarch butterflies, Danaus plexippus (L.), are facultative migrants. Hence, it is important to establish whether specific insect populations in particular areas migrate. The polyphagous insect, Helicoverpa armigera (Hübner), is especially interesting in this regard due to its impact on a variety of crops. Here, we used a laboratory-based flight mill assay to show that Helicoverpa armigera populations clearly demonstrate facultative migration in South India. Based on various flight parameters, we categorized male and female moths as long, medium or short distance fliers. A significant proportion of moths exhibited long-distance flight behavior covering more than 10 km in a single night, averaging about 8 flight hours constituting 61% flight time in the test period. The maximum and average flight speeds of these long fliers were greater than in the other categories. Flight activity across sexes also varied; male moths exhibited better performance than female moths. Wing morphometric parameters including forewing length, wing loading, and wing aspect ratio were key in influencing long-distance flight. Whereas forewing length positively correlated with flight distance and duration, wing loading was negatively correlated.


2021 ◽  
Vol 288 (1943) ◽  
pp. 20202348
Author(s):  
Michael Griego ◽  
Joely DeSimone ◽  
Mariamar Gutierrez Ramirez ◽  
Alexander R. Gerson

Songbirds meet the extreme metabolic demands of migration by burning both stored fat and protein. However, catabolizing these endogenous tissues for energy leads to organ atrophy, and reductions in gastrointestinal tissue can be as great as 50% of the pre-flight mass. Remarkably, during stopover refuelling birds quickly regain digestive mass and performance. Aminopeptidase-N (APN) is a brush-border enzyme responsible for late-stage protein digestion and may critically assist tissue reconstruction during the stopover, thus compensating for reduced gut size. We hypothesized that birds recovering from a fast would differentially upregulate APN activity relative to disaccharidases to rapidly process and assimilate dietary protein into lean mass. We fasted 23 wild-caught migratory white-throated sparrows ( Zonotrichia albicollis ) for 48 h to mimic mass reductions experienced during migratory flight and measured intestinal APN activity before the fast, immediately after the fast, and during recovery at 24 h and 48 h post-fast. Total fat mass, lean mass and basal metabolic rate were measured daily. We show that fasted birds maintain APN activity through the fast, despite a 30% reduction in intestine mass, but during refuelling, APN activity increases nearly twofold over pre-fasted individuals. This suggests that dynamically regulating APN may be necessary for rapid protein reconstruction during the stopover.


Mercator ◽  
2020 ◽  
Vol 19 (2020) ◽  
pp. 1-14
Author(s):  
Ubirajara Ferreira ◽  
Antônio Pasqualetto ◽  
Fudio Matsuura

Of the total number of municipalities in the northern region of the State of Goiás, part of them have their own revenues below requirements, if current conditions are maintained, they tend to be incorporated into neighboring municipalities from 2025 onwards in compliance with PEC 188/2019.Would there be an alternative for municipal development and sustainability without the necessary population increase? In this sense, the purpose was to identify the economic and social weaknesses that characterize the municipalities in the northern region and to create a “Dependency Matrix”. The methodology consisted of consulting databases of federal, state and municipal agencies and programs. The results demonstrate the low level of economic activity, own revenues, high dependence on external revenues, high payroll on civil clerk, exposing themselves to the dictates of the Fiscal Responsibility Law (LRF) and high dependence on the Income Transfer Programs of the Federal Government such as the Bolsa Família Program (PBF) and the Continuous Payment Benefit (BPC). The Dependency Matrix assists the municipal manager in restraining the alleged migratory flight, the loss of economic relevance, as well as economic, environmental and social sustainability. Keywords: Dependency Matrix. Economy. Sustainability.


2020 ◽  
Vol 7 (2) ◽  
pp. 192031 ◽  
Author(s):  
Cas Eikenaar ◽  
Sven Hessler ◽  
Arne Hegemann

Migratory flight is physiologically highly demanding and has been shown to negatively affect multiple parameters of constitutive immune function (CIF), an animal's first line of physiological defence against infections. In between migratory flights, most birds make stopovers, periods during which they accumulate fuel for the next flight(s). Stopovers are also commonly thought of as periods of rest and recovery, but what this encompasses is largely undefined. Here, we show that during stopover, northern wheatears Oenanthe oenanthe, a long-distance migratory bird, can rapidly increase constitutive innate immune function. We caught and temporarily caged birds under ad libitum food conditions at a stopover site in autumn. Within 2 days, most birds significantly increased complement activity and their ability to kill microbes. Changes in immune function were not related to the birds' food intake or extent of fuel accumulation. Our study suggests that stopovers may not only be important to refuel but also to restore immune function. Additionally, the increase in CIF could help migrating birds to deal with novel pathogens they may encounter at stopover sites.


2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Vera Brust ◽  
Bianca Michalik ◽  
Ommo Hüppop

Abstract Background Although many aspects of passerine migration are genetically determined, routing appears to be flexibly adjusted to the conditions experienced on each individual journey. This holds especially true for routing decisions taken when confronted with large bodies of water. Once taken, these decisions can be hardly altered or revised. In this paper, we analysed stopover and routing decisions taken by three species of thrushes, blackbirds, redwings and song thrushes, at the German North Sea coast. Methods Birds were equipped with radio-telemetry tags at stopover sites along the coast during autumn migration and subsequently tracked by an automated receiver network covering the coastline and islands of the German Bight. Results The thrushes resumed migration in nights with a favourable northward wind component and clear skies. About 40% of the tagged individuals have taken an offshore instead of an alongshore oriented flight route. Routing decisions were influenced by the strength of the eastward wind component with offshore oriented flights taking place primarily under weak winds or winds blowing towards the west. Thrushes that took an offshore oriented route stopped over at the coast longer than those flying alongshore. Interestingly, offshore as well as alongshore oriented flights co-occurred within single nights and under comparable weather conditions. Conclusions Migratory flight and routing decisions of thrushes at the German North Sea coast are highly dependent on weather, in particular wind. Still, we found evidence that weather may not be the sole reason for individual routes taken. Physical condition, morphology or animal personality lend themselves as possible additional factors of influence. Enabling a more detailed understanding of thrush migration over and along the German North Sea, our data help to better judge risks that migratory birds are facing when en route conditions are altered, for example by artificial obstacles such as offshore wind turbines.


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