scholarly journals What you see is where you go: visibility influences movement decisions of a forest bird navigating a three-dimensional-structured matrix

2021 ◽  
Vol 17 (1) ◽  
pp. 20200478
Author(s):  
Job Aben ◽  
Johannes Signer ◽  
Janne Heiskanen ◽  
Petri Pellikka ◽  
Justin M. J. Travis
Keyword(s):  
Physical Environment ◽  
Visual Cues ◽  
Three Dimensional ◽  
Forest Birds ◽  
Lidar Data ◽  
Perceptual Range ◽  
Movement Data ◽  
Structured Matrix ◽  
Viewshed Analysis ◽  
Step Selection

Animal spatial behaviour is often presumed to reflect responses to visual cues. However, inference of behaviour in relation to the environment is challenged by the lack of objective methods to identify the information that effectively is available to an animal from a given location. In general, animals are assumed to have unconstrained information on the environment within a detection circle of a certain radius (the perceptual range; PR). However, visual cues are only available up to the first physical obstruction within an animal's PR, making information availability a function of an animal's location within the physical environment (the effective visual perceptual range; EVPR). By using LiDAR data and viewshed analysis, we modelled forest birds' EVPRs at each step along a movement path. We found that the EVPR was on average 0.063% that of an unconstrained PR and, by applying a step-selection analysis, that individuals are 1.55 times more likely to move to a tree within their EVPR than to an equivalent tree outside it. This demonstrates that behavioural choices can be substantially impacted by the characteristics of an individual's EVPR and highlights that inferences made from movement data may be improved by accounting for the EVPR.

scholarly journals Can't tell the caterpillars from the trees: countershading enhances survival in a woodland

2008 ◽  
Vol 275 (1651) ◽  
pp. 2539-2545 ◽  
Author(s):  
Hannah M Rowland ◽  
Innes C Cuthill ◽  
Ian F Harvey ◽  
Michael P Speed ◽  
Graeme D Ruxton
Keyword(s):  
Visual Cues ◽  
Field Experiments ◽  
Three Dimensional ◽  
Shape From Shading ◽  
The Body ◽  
Colour Pattern ◽  
Free Living ◽  
Background Matching ◽  
Lepidopteran Larvae ◽  
Beech Tree

Perception of the body's outline and three-dimensional shape arises from visual cues such as shading, contour, perspective and texture. When a uniformly coloured prey animal is illuminated from above by sunlight, a shadow may be cast on the body, generating a brightness contrast between the dorsal and ventral surfaces. For animals such as caterpillars, which live among flat leaves, a difference in reflectance over the body surface may degrade the degree of background matching and provide cues to shape from shading. This may make otherwise cryptic prey more conspicuous to visually hunting predators. Cryptically coloured prey are expected to match their substrate in colour, pattern and texture (though disruptive patterning is an exception), but they may also abolish self-shadowing and therefore either reduce shape cues or maintain their degree of background matching through countershading: a gradation of pigment on the body of an animal so that the surface closest to illumination is darker. In this study, we report the results from a series of field experiments where artificial prey resembling lepidopteran larvae were presented on the upper surfaces of beech tree branches so that they could be viewed by free-living birds. We demonstrate that countershading is superior to uniform coloration in terms of reducing attack by free-living predators. This result persisted even when we fixed prey to the underside of branches, simulating the resting position of many tree-living caterpillars. Our experiments provide the first demonstration, in an ecologically valid visual context, that shadowing on bodies (such as lepidopteran larvae) provides cues that visually hunting predators use to detect potential prey species, and that countershading counterbalances shadowing to enhance cryptic protection.

scholarly journals Lure, retain, and catch malaria mosquitoes. How heat and humidity improve odour-baited trap performance

2020 ◽  
Vol 19 (1) ◽  
Author(s):  
Antoine Cribellier ◽  
Jeroen Spitzen ◽  
Henry Fairbairn ◽  
Cedric van de Geer ◽  
Johan L. van Leeuwen ◽  
...  
Keyword(s):  
Short Range ◽  
Visual Cues ◽  
Three Dimensional ◽  
Field Testing ◽  
Counter Flow ◽  
Flight Behaviour ◽  
Baited Traps ◽  
Close Range ◽  
Malaria Mosquitoes ◽  
Host Cues

Abstract Background When seeking a human for a blood meal, mosquitoes use several cues to detect and find their hosts. From this knowledge, counter-flow odour-baited traps have been developed that use a combination of CO2, human-mimicking odour, visual cues and circulating airflow to attract and capture mosquitoes. Initially developed for monitoring, these traps are now also being considered as promising vector control tools. The traps are attractive to host-seeking mosquitoes, but their capture efficiency is low. It has been hypothesized that the lack of short-range host cues, such as heat and increased local humidity, often prevent mosquitoes from getting close enough to get caught; this lack might even trigger avoidance manoeuvres near the capture region. Methods This study investigated how close-range host cues affect the flight behaviour of Anopheles female malaria mosquitoes around odour-baited traps, and how this affects trap capture performance. For this, a novel counter-flow odour-baited trap was developed, the M-Tego. In addition to the usual CO2 and odour-blend, this trap can provide the short-range host cues, heat and humidity. Systematically adding or removing these two cues tested how this affected the trap capture percentages and flight behaviour. First, capture percentages of the M-Tego with and without short-range host cues to the BG-Suna trap were compared, in both laboratory and semi-field testing. Then, machine-vision techniques were used to track the three-dimensional flight movements of mosquitoes around the M-Tego. Results With heat and humidity present, the M-Tego captured significantly more mosquitoes as capture percentages almost doubled. Comparing the flight behaviour around the M-Tego with variable close-range host cues showed that when these cues were present, flying mosquitoes were more attracted to the trap and spent more time there. In addition, the M-Tego was found to have a better capture mechanism than the BG-Suna, most likely because it does not elicit previously observed upward avoiding manoeuvres. Conclusions Results suggest that adding heat and humidity to an odour-baited trap lures more mosquitoes close to the trap and retains them there longer, resulting in higher capture performance. These findings support the development of control tools for fighting mosquito-borne diseases such as malaria.

Exploring the effect of eye gaze cues on novel L2 morphosyntactic pattern learning

2020 ◽  
pp. 026765831989682
Author(s):  
Dato Abashidze ◽  
Kim McDonough ◽  
Yang Gao
Keyword(s):  
Visual Cues ◽  
Eye Gaze ◽  
Generalization Test ◽  
Pattern Learning ◽  
The Gaze ◽  
Movement Data ◽  
Visual Events ◽  
Static Images ◽  
Post Hoc ◽  
Gaze Cues

Recent research that explored how input exposure and learner characteristics influence novel L2 morphosyntactic pattern learning has exposed participants to either text or static images rather than dynamic visual events. Furthermore, it is not known whether incorporating eye gaze cues into dynamic visual events enhances dual pattern learning. Therefore, this exploratory eye-tracking study examined whether eye gaze cues during dynamic visual events facilitate novel L2 pattern learning. University students ( n = 72) were exposed to 36 training videos with two dual novel morphosyntactic patterns in pseudo-Georgian: completed events ( bich-ma kocn-ul gogoit, ‘boy kissed girl’) and ongoing actions ( bich-su kocn-ar gogoit, ‘boy is kissing girl’). They then carried out an immediate test with 24 items using the same vocabulary words, followed by a generalization test with 24 items created from new vocabulary words. Results indicated that learners who received the eye gaze cues scored significantly higher on the immediate test and relied on the verb cues more than on the noun cues. A post-hoc analysis of eye-movement data indicated that the gaze cues elicited longer looks to the correct images. Findings are discussed in relation to visual cues and novel morphosyntactic pattern learning.

Responsiveness of Clare-Bishop neurons to visual cues associated with motion of a visual stimulus in three-dimensional space

1985 ◽  
Vol 25 (3) ◽  
pp. 407-414 ◽  
Author(s):  
Keisuke Toyama ◽  
Yukio Komatsu ◽  
Haruo Kasai ◽  
Kei Fujii ◽  
Kazukiyo Umetani
Keyword(s):  
Visual Stimulus ◽  
Visual Cues ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Three Dimensional Space

Cuttlefish use visual cues to control three-dimensional skin papillae for camouflage

2009 ◽  
Vol 195 (6) ◽  
pp. 547-555 ◽  
Author(s):  
Justine J. Allen ◽  
Lydia M. Mäthger ◽  
Alexandra Barbosa ◽  
Roger T. Hanlon
Keyword(s):  
Visual Cues ◽  
Three Dimensional
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