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Bird-borne video-cameras show that seabird movement patterns relate to previously unrevealed proximate environment, not prey.

Tremblay Y, Thiebault A, Mullers R, Pistorius P - PLoS ONE (2014)

Bottom Line: We found that movement patterns were related to specific stimuli which were mostly other predators such as gannets, dolphins or fishing boats.We demonstrate that movement patterns of foraging seabirds can be heavily driven by processes unobservable with conventional methodology.Except perhaps for large scale processes, local-enhancement seems to be the only ruling mechanism; this has profounds implications for ecosystem-based management of marine areas.

View Article: PubMed Central - PubMed

Affiliation: Centre de Recherche Halieutique Méditerrannéenne et Tropicale, Institut pour la Recherche et le Développement, Unité Mixte de Recherche 212: IRD-IFREMER-UM2 : Expoited Marine Ecosystems, Sète, France.

ABSTRACT
The study of ecological and behavioral processes has been revolutionized in the last two decades with the rapid development of biologging-science. Recently, using image-capturing devices, some pilot studies demonstrated the potential of understanding marine vertebrate movement patterns in relation to their proximate, as opposed to remote sensed environmental contexts. Here, using miniaturized video cameras and GPS tracking recorders simultaneously, we show for the first time that information on the immediate visual surroundings of a foraging seabird, the Cape gannet, is fundamental in understanding the origins of its movement patterns. We found that movement patterns were related to specific stimuli which were mostly other predators such as gannets, dolphins or fishing boats. Contrary to a widely accepted idea, our data suggest that foraging seabirds are not directly looking for prey. Instead, they search for indicators of the presence of prey, the latter being targeted at the very last moment and at a very small scale. We demonstrate that movement patterns of foraging seabirds can be heavily driven by processes unobservable with conventional methodology. Except perhaps for large scale processes, local-enhancement seems to be the only ruling mechanism; this has profounds implications for ecosystem-based management of marine areas.

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Related in: MedlinePlus

Portions of GPS tracks and video-camera images recorded concurrently, in Cape Gannets.Dots represent events seen in the images. For each track, the wind speed and direction (clockwise from true North) is given. a) b) c) Zoom in each of the tracks. Arrows indicate dives, blue = other gannets, red = prey, green = dolphins, magenta = boat.
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pone-0088424-g001: Portions of GPS tracks and video-camera images recorded concurrently, in Cape Gannets.Dots represent events seen in the images. For each track, the wind speed and direction (clockwise from true North) is given. a) b) c) Zoom in each of the tracks. Arrows indicate dives, blue = other gannets, red = prey, green = dolphins, magenta = boat.

Mentions: Out of the 35 deployments that provided usable data (additional table S1), particularly sinuous movement patterns (visually determined, Figure 1) were recorded in 10 birds (always in the context of group foraging) and only three birds seemed to have foraged alone during the camera running-time. All others had joined other predators, con-specific or not. Therefore, over 90% of birds were associated with other predators. Despite the fact that only the first 1.5 hours (∼10%) of the foraging trips were recorded (additional table S1), diving was observed from 14 instrument-carrying birds, with gannet, dolphin and trawler-associated feeding occurred in 79%, 36% and 7% of these birds, respectively. Diving was generally not associated with directional movement. However, images showed that during these relatively straight-trajectories the birds reacted to the presence of other birds, by joining them and/or orientating in an opposite direction. Given the challenge of quantifying coupled video and GPS data, we chose to qualitatively describe three out of the 35 records in order to exemplify how combined video and tracking data allows for an understanding of stimuli that drive the birds' trajectories (Figure 1). These three records were selected to represent all foraging situations observed.


Bird-borne video-cameras show that seabird movement patterns relate to previously unrevealed proximate environment, not prey.

Tremblay Y, Thiebault A, Mullers R, Pistorius P - PLoS ONE (2014)

Portions of GPS tracks and video-camera images recorded concurrently, in Cape Gannets.Dots represent events seen in the images. For each track, the wind speed and direction (clockwise from true North) is given. a) b) c) Zoom in each of the tracks. Arrows indicate dives, blue = other gannets, red = prey, green = dolphins, magenta = boat.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3921161&req=5

pone-0088424-g001: Portions of GPS tracks and video-camera images recorded concurrently, in Cape Gannets.Dots represent events seen in the images. For each track, the wind speed and direction (clockwise from true North) is given. a) b) c) Zoom in each of the tracks. Arrows indicate dives, blue = other gannets, red = prey, green = dolphins, magenta = boat.
Mentions: Out of the 35 deployments that provided usable data (additional table S1), particularly sinuous movement patterns (visually determined, Figure 1) were recorded in 10 birds (always in the context of group foraging) and only three birds seemed to have foraged alone during the camera running-time. All others had joined other predators, con-specific or not. Therefore, over 90% of birds were associated with other predators. Despite the fact that only the first 1.5 hours (∼10%) of the foraging trips were recorded (additional table S1), diving was observed from 14 instrument-carrying birds, with gannet, dolphin and trawler-associated feeding occurred in 79%, 36% and 7% of these birds, respectively. Diving was generally not associated with directional movement. However, images showed that during these relatively straight-trajectories the birds reacted to the presence of other birds, by joining them and/or orientating in an opposite direction. Given the challenge of quantifying coupled video and GPS data, we chose to qualitatively describe three out of the 35 records in order to exemplify how combined video and tracking data allows for an understanding of stimuli that drive the birds' trajectories (Figure 1). These three records were selected to represent all foraging situations observed.

Bottom Line: We found that movement patterns were related to specific stimuli which were mostly other predators such as gannets, dolphins or fishing boats.We demonstrate that movement patterns of foraging seabirds can be heavily driven by processes unobservable with conventional methodology.Except perhaps for large scale processes, local-enhancement seems to be the only ruling mechanism; this has profounds implications for ecosystem-based management of marine areas.

View Article: PubMed Central - PubMed

Affiliation: Centre de Recherche Halieutique Méditerrannéenne et Tropicale, Institut pour la Recherche et le Développement, Unité Mixte de Recherche 212: IRD-IFREMER-UM2 : Expoited Marine Ecosystems, Sète, France.

ABSTRACT
The study of ecological and behavioral processes has been revolutionized in the last two decades with the rapid development of biologging-science. Recently, using image-capturing devices, some pilot studies demonstrated the potential of understanding marine vertebrate movement patterns in relation to their proximate, as opposed to remote sensed environmental contexts. Here, using miniaturized video cameras and GPS tracking recorders simultaneously, we show for the first time that information on the immediate visual surroundings of a foraging seabird, the Cape gannet, is fundamental in understanding the origins of its movement patterns. We found that movement patterns were related to specific stimuli which were mostly other predators such as gannets, dolphins or fishing boats. Contrary to a widely accepted idea, our data suggest that foraging seabirds are not directly looking for prey. Instead, they search for indicators of the presence of prey, the latter being targeted at the very last moment and at a very small scale. We demonstrate that movement patterns of foraging seabirds can be heavily driven by processes unobservable with conventional methodology. Except perhaps for large scale processes, local-enhancement seems to be the only ruling mechanism; this has profounds implications for ecosystem-based management of marine areas.

Show MeSH
Related in: MedlinePlus