Flying In-formation: A computational method for the classification of host seeking mosquito flight patterns using path segmentation and unsupervised machine learning

The rational design of effective vector control tools requires detailed knowledge of vector behaviour. Yet, behavioural observations, interpretations, evaluations and definitions by even the most experienced researcher are constrained by subjectivity and perceptual limits. Seeking an objective alternative to ‘expertise’, we developed and tested an unsupervised method for the automatic identification of videotracked mosquito flight behaviour. This method unites path-segmentation and unsupervised machine learning in an innovative workflow and is implemented using a combination of R and python. The workflow (1) records movement trajectories; (2) applies path-segmentation; (3) clusters path segments using unsupervised learning; and (4) interprets results. Analysis of the flight patterns of An. gambiae s.s., responding to human-baited insecticide-treated bednets (ITNs), by the new method identified four distinct behaviour modes: with ‘swooping’ and ‘approaching’ modes predominant at ITNs; increased ‘walking’ behaviours at untreated nets; similar rates of 'reacting' at both nets; and higher overall activity at treated nets. The method’s validity was tested by comparing these findings with those from a similar setting using an expertise-based method. The level of correspondence found between the studies validated the accuracy of the new method. While researcher-defined behaviours are inherently subjective, and prone to corollary shortcomings, the new approach’s mathematical method is objective, automatic, repeatable and a validated alternative for analysing complex vector behaviour. This method provides a novel and adaptable analytical tool and is freely available to vector biologists, ethologists and behavioural ecologists.

Groping in the Fog: Soaring Migrants Exhibit Wider Scatter in Flight Directions and Respond Differently to Wind Under Low Visibility Conditions

Atmospheric conditions are known to affect flight propensity, behaviour during flight, and migration route in birds. Yet, the effects of fog have only rarely been studied although they could disrupt orientation and hamper flight. Fog could limit the visibility of migrating birds such that they might not be able to detect landmarks that guide them during their journey. Soaring migrants modulate their flight speed and direction in relation to the wind vector to optimise the cost of transport. Consequently, landmark-based orientation, as well as adjustments of flight speed and direction in relation to wind conditions, could be jeopardised when flying in fog. Using a radar system operated in a migration bottleneck (Strait of Messina, Italy), we studied the behaviour of soaring birds under variable wind and fog conditions over two consecutive springs (2016 and 2017), discovering that migrating birds exhibited a wider scatter of flight directions and responded differently to wind under fog conditions. Birds flying through fog deviated more from the mean migration direction and increased their speed with increasing crosswinds. In addition, airspeed and groundspeed increased in the direction of the crosswind, causing the individuals to drift laterally. Our findings represent the first quantitative empirical evidence of flight behaviour changes when birds migrate through fog and explain why low visibility conditions could risk their migration journey.

Colin James Pennycuick. 11 June 1933—9 December 2019

Colin Pennycuick was almost single-handedly responsible for the successful, and continuing, merger of the engineering and mathematical sciences of aerodynamics and flight mechanics with ornithology, ecology and bird flight behaviour. He developed a mathematical/ aerodynamical/ecological model of bird flight that could explain and predict bird body and wing shapes and sizes, and hence flight behaviour over a broad range of length- and time-scales, for real birds. He sought to bring rigorous quantitative methods to the people, and insisted that no matter how complex and sophisticated a theoretical model may be, unless it showed some improvement and advance in its practical utility, then it was of questionable value. He similarly insisted that model predictions be testable, and that results be openly and quantifiably given. His approach was marked by two distinct characteristics: first he pioneered the use of small aircraft and powered and unpowered gliders to follow soaring and migrating birds in their natural environment, exploiting his top-level pilot skills; second, he invented, designed and built novel instrumentation for making hitherto unheard-of laboratory and field measurements. The most well-known were his tilting wind tunnels, in which birds and bats could be trained to perform steady gliding flight. His intellectually and geographically-broad range of interests and contacts led to his being a giant influence in theoretical and practical bird flight mechanics and behaviour, one that is likely to stay with us for many decades.

Flight performance and the factors affecting the flight behaviour of Philaenus spumarius the main vector of Xylella fastidiosa in Europe

The recent emergence of Xylella fastidiosa in Europe is a major threat to agriculture, including olive, almond and grape. Philaenus spumarius is the predominant vector of X. fastidiosa in Europe. Understanding vector movement is critical for developing effective control measures against bacterial spread. In this study, our goal was to set up a flight-mill protocol to assess P. spumarius flight potential and to analyse how different variables may affect its flight behaviour. We found that P. spumarius was able to fly ≈ 500 m in 30 min with a maximum single flight of 5.5 km in 5.4 h. Based on the observations, the flight potential of the females was higher in spring and autumn than in summer, and that of the males was highest in autumn. Moreover, we found that P. spumarius had a higher flight potential during the morning and the night than during the afternoon. Our results revealed that P. spumarius is likely to disperse much further than the established sizes of the infected and buffer zones designated by the EU. This knowledge on the flight potential of P. spumarius will be critical for improving management actions against P. spumarius and the spread of X. fastidiosa in Europe.

Adaptive shifts underlie the divergence in wing morphology in bombycoid moths

The evolution of flapping flight is linked to the prolific success of insects. Across Insecta, wing morphology diversified, strongly impacting aerodynamic performance. In the presence of ecological opportunity, discrete adaptive shifts and early bursts are two processes hypothesized to give rise to exceptional morphological diversification. Here, we use the sister-families Sphingidae and Saturniidae to answer how the evolution of aerodynamically important traits is linked to clade divergence and through what process(es) these traits evolve. Many agile Sphingidae evolved hover feeding behaviours, while adult Saturniidae lack functional mouth parts and rely on a fixed energy budget as adults. We find that Sphingidae underwent an adaptive shift in wing morphology coincident with life history and behaviour divergence, evolving small high aspect ratio wings advantageous for power reduction that can be moved at high frequencies, beneficial for flight control. By contrast, Saturniidae, which do not feed as adults, evolved large wings and morphology which surprisingly does not reduce aerodynamic power, but could contribute to their erratic flight behaviour, aiding in predator avoidance. We suggest that after the evolution of flapping flight, diversification of wing morphology can be potentiated by adaptative shifts, shaping the diversity of wing morphology across insects.

Delineating Ecosophy as a Counter Discourse in Barbara Kingsolver’s Flight Behaviour

Flight Behaviour by Barbara Kingsolver is a clarion call aimed at exposing the impending future that awaits humanity in the form of grievous climactic changes and its impact on the delicate ecosystem of the earth. The characters presented who maintain varying perspectives regarding ecological concerns may be seen as representing differing ideologies that persist in the society with respect to the same. The paper is an attempt to trace the dominant as well as alternate voices that pervade discussions on an apocalyptic future due to human actions that are ruthless and highly exploitative of ecological resources. The mystical encounter with nature that the protagonist undergoes will be examined to understand the significance of an ecological philosophy or “ecosophy.” The paper would also seek to discern a transition from anthropocentrism to ecocentrism and also the disruption of nature/culture binaries established by an anthropocentric worldview depicted in the text.

Groping in the fog: soaring migrants exhibit wider scatter and do not properly adjust their flight in response to wind under low visibility conditions

Atmospheric conditions are known to affect flight propensity, behaviour during flight, and migration route in birds. Yet, the effects of fog have only been rarely studied, although they could disrupt orientation and hamper the accomplishment of the journey. Soaring migrants modulate their flight speed and direction in relation to the wind vector to optimize the cost of transport. Fog could limit the visibility of migrating birds such that they might not be able to detect landmarks that guide them during their journey. Consequently, landmark-based orientation, as well as adjustments of flight speed and direction in relation to wind conditions, could be jeopardized when flying in fog. Using a radar system that operated in a migration bottleneck (Strait of Messina, Italy), we studied the behaviour of soaring birds under variable wind and fog conditions over two consecutive springs (2016 and 2017), discovering that migrating birds exhibited a wider scatter of flight directions and responded differently to wind conditions under fog conditions. Birds flying through fog deviated more from the mean migration direction and increased their speed with increasing crosswinds. In addition, airspeed and groundspeed increased in the direction of the crosswind, causing a lateral drift of the individuals. Furthermore, the response to tailwind was opposite to that predicted by optimal migration theory. Our findings represent the first quantitative empirical evidence of flight behaviour changes when birds migrate through fog and explain why low visibility conditions could risk their migration journey.

Characteristics of Middle European Holiday Highfliers

This article estimates a count-data model on the flight behaviour of Austrian holiday-makers based on information from a large representative quarterly survey spanning the years 2014–2016. On average, the number of holiday flights ranges between 0.6 and 1.2 per year for residents in the least populated region and the capital, respectively. Results of the estimations reveal that the number of holiday flights is highest for persons with tertiary degrees, of a young age (16–24 years) and capital city residents, while it is lowest for individuals with children and large households. Residents of the capital city fly 78 percent more often in a given quarter than those living in Carinthia, the most rural region. The Oaxaca-Blinder decomposition analysis reveals that the difference is rather related to location than to variations in individual characteristics. Socio-demographic aspects such as age, household size and travelling with children are of no relevance for the holiday flying behaviour of capital residents.

Emotional and behavioural responses to the 19 September 2017 earthquake: the case of the occupants of three multi-storey buildings

PurposeStudies on human behaviour during a seismic emergency in tall buildings are scant. During such emergencies, occupants need to reach a safe place. The purpose of this paper is to address some of the emotional and behavioural responses of the occupants of three multi-storey buildings during the 19 September earthquake that hit Mexico City in 2017.Design/methodology/approachA cross-sectional and non-probability study was conducted using a questionnaire-based survey; the sample size was n = 352, and the study was conducted from 4 October to 20 November 2017.Findings(1) In the 11 storey-building, women, age (18–49 years old [yo]) and participants with higher education exhibited flight behaviour, and those of the six storey-building within the age category 18–49 yo also exhibited a similar behaviour; (2) Women and age (18–49 yo) in the six and 11-storey buildings were significantly associated with fear of the earthquake; (3) Women were significantly more fearful and felt more intense the tremors than men in the 11-storey building; (4) Women were significantly more fearful of the 11-storey building collapsing; (5) The taller the building, the more fearful were the occupants of the building collapsing.Research limitations/implicationsFirst, the sample considered in the study was no probability; consequently, the results should not be generalised to the existing high-rising buildings in Mexico City. Second, some of the variables considered herein were of the Likert-type scale but have been assumed as continuous; in fact, some future work could be the design of a valid and reliable questionnaire to address human behaviour during earthquakes in tall buildings.Practical implicationsThe presented results may be the great value to key decision-makers on how to address the lack of earthquake preparedness during a seismic emergency. Further, the results have shed light on the negative emotions (fear) experienced by the occupants of tall buildings.Social implicationsGaining a better understanding of human behavioural in tall buildings is essential in devising measures to mitigate the impact of earthquake disasters.Originality/valueResearch on human behaviour during a seismic emergency in high-rise buildings is scant. To gain a better understanding of human emotional and behavioural response to earthquakes in tall buildings, it becomes necessary to conduct research such as the present case study. This may help decision-makers to devise measures so that the impact of earthquake disasters may be limited.