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- Smolka, Jochen, et al.
(author)
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Natural visual cues eliciting predator avoidance in fiddler crabs
- 2011
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In: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954. ; 278:1724, s. 3584-3592
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Journal article (peer-reviewed)abstract
- To efficiently provide an animal with relevant information, the design of its visual system should reflect the distribution of natural signals and the animal’s tasks. In many behavioural contexts, however, we know comparatively little about the moment-to-moment information-processing challenges animals face in their daily lives. In predator avoidance, for instance, we lack an accurate description of the natural signal stream and its value for risk assessment throughout the prey’s defensive behaviour.We characterized the visual signals generated by real, potentially predatory events by video-recording bird approaches towards an Uca vomeris colony. Using four synchronized cameras allowed us to simultaneously monitor predator avoidance responses of crabs. We reconstructed the signals generated by dangerous and non-dangerous flying animals, identified the cues that triggered escape responses and compared them with those triggering responses to dummy predators. Fiddler crabs responded to a combination of multiple visual cues (including retinal speed, elevation and visual flicker) that reflect the visual signatures of distinct bird and insect behaviours. This allowed crabs to discriminate between dangerous and non-dangerous events. The results demonstrate the importance of measuring natural sensory signatures of biologically relevant events in order to understand biological information processing and its effects on behavioural organization.
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| 2. |
- Greiner, Birgit, et al.
(author)
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Eye structure correlates with distinct foraging-bout timing in primitive ants
- 2007
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In: Current Biology. - : Elsevier BV. - 1879-0445 .- 0960-9822. ; 17:20, s. 879-880
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Journal article (other academic/artistic)abstract
- Social insects have evolved remarkable physiological adaptations and behavioural strategies that enable them to access new temporal foraging niches (for example [1]). Here we report striking correlations between the timing of foraging bouts and the modification of eye structure in four species of ants belonging to the primitive genus Myrmecia. Most noteworthy, photoreceptor diameters progressively increase from 1.3 μm in strictly day-active species, to 5.9 μm in predominantly night-active species.
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| 3. |
- Ribi, Willi, et al.
(author)
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The organization of honeybee ocelli: Regional specializations and rhabdom arrangements
- 2011
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In: Arthropod Structure & Development. - : Elsevier BV. - 1467-8039. ; 40:6, s. 509-520
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Journal article (peer-reviewed)abstract
- We have re-investigated the organization of ocelli in honeybee workers and drones. Ocellar lenses are divided into a dorsal and a ventral part by a cusp-shaped indentation. The retina is also divided, with a ventral retina looking skywards and a dorsal retina looking at the horizon. The focal plane of lenses lies behind the retina in lateral ocelli, but within the dorsal retina in the median ocellus of both workers and drones. Ventral retinula cells are ca. 25 mu m long with dense screening pigments. Dorsal retinula cells are ca. 60 mu m long with sparse pigmentation mainly restricted to their proximal parts. Pairs of retinula cells form flat, non-twisting rhabdom sheets with elongated, straight, rectangular cross-sections, on average 8.7 mu m long and 1 mu m wide. Honeybee ocellar rhabdoms have shorter and straighter cross-sections than those recently described in the night-active bee Megalopta genalis. Across the retina, rhabdoms form a fan-shaped pattern of orientations. In each ocellus, ventral and dorsal retinula cell axons project into two separate neuropils, converging on few large neurons in the dorsal, and on many small neurons in the ventral neuropil. The divided nature of the ocelli, together with the particular construction and arrangement of rhabdoms, suggest that ocelli are not only involved in attitude control, but might also provide skylight polarization compass information. (C) 2011 Elsevier Ltd. All rights reserved.
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| 4. |
- Wallace, Jesse Rudolf Amenuvegbe, et al.
(author)
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Camera-based automated monitoring of flying insects (Camfi). I. Field and computational methods
- 2023
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In: Frontiers in Insect Science. - 2673-8600. ; 3
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Journal article (peer-reviewed)abstract
- The ability to measure flying insect activity and abundance is important for ecologists, conservationists and agronomists alike. However, existing methods are laborious and produce data with low temporal resolution (e.g. trapping and direct observation), or are expensive, technically complex, and require vehicle access to field sites (e.g. radar and lidar entomology). We propose a method called “Camfi” for long-term non-invasive population monitoring and high-throughput behavioural observation of low-flying insects using images and videos obtained from wildlife cameras, which are inexpensive and simple to operate. To facilitate very large monitoring programs, we have developed and implemented a tool for automatic detection and annotation of flying insect targets in still images or video clips based on the popular Mask R-CNN framework. This tool can be trained to detect and annotate insects in a few hours, taking advantage of transfer learning. Our method will prove invaluable for ongoing efforts to understand the behaviour and ecology of declining insect populations and could also be applied to agronomy. The method is particularly suited to studies of low-flying insects in remote areas, and is suitable for very large-scale monitoring programs, or programs with relatively low budgets.
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| 5. |
- Wallace, Jesse Rudolf Amenuvegbe, et al.
(author)
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Camera-based automated monitoring of flying insects in the wild (Camfi). II. flight behaviour and long-term population monitoring of migratory Bogong moths in Alpine Australia
- 2023
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In: Frontiers in Insect Science. - 2673-8600. ; 3
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Journal article (peer-reviewed)abstract
- Introduction: The Bogong moth Agrotis infusa is well known for its remarkable annual round-trip migration from its breeding grounds across eastern and southern Australia to its aestivation sites in the Australian Alps, to which it provides an important annual influx of nutrients. Over recent years, we have benefited from a growing understanding of the navigational abilities of the Bogong moth. Meanwhile, the population of Bogong moths has been shrinking. Recently, the ecologically and culturally important Bogong moth was listed as endangered by the IUCN Red List, and the establishment of a program for long-term monitoring of its population has been identified as critical for its conservation. Methods: Here, we present the results of two years of monitoring of the Bogong moth population in the Australian Alps using recently developed methods for automated wildlife-camera monitoring of flying insects, named Camfi. While in the Alps, some moths emerge from the caves in the evening to undertake seemingly random flights, filling the air with densities in the dozens per cubic metre. The purpose of these flights is unknown, but they may serve an important role in Bogong moth navigation. Results: We found that these evening flights occur throughout summer and are modulated by daily weather factors. We present a simple heuristic model of the arrival to and departure from aestivation sites by Bogong moths, and confirm results obtained from fox-scat surveys which found that aestivating Bogong moths occupy higher elevations as the summer progresses. Moreover, by placing cameras along two elevational transects below the summit of Mt. Kosciuszko, we found that evening flights were not random, but were systematically oriented in directions relative to the azimuth of the summit of the mountain. Finally, we present the first recorded observations of the impact of bushfire smoke on aestivating Bogong moths – a dramatic reduction in the size of a cluster of aestivating Bogong moths during the fire, and evidence of a large departure from the fire-affected area the day after the fire. Discussion: Our results highlight the challenges of monitoring Bogong moths in the wild and support the continued use of automated camera-based methods for that purpose.
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