Comparing reproductive success of a colonial seabird, the Magellanic Penguin, estimated by coarse- and fine-scale temporal sampling

Abstract Background Fine-scale data on animal position are increasingly enabling us to understand the details of animal movement ecology and dead-reckoning, a technique integrating motion sensor-derived information on heading and speed, can be used to reconstruct fine-scale movement paths at sub-second resolution, irrespective of the environment. On its own however, the dead-reckoning process is prone to cumulative errors, so that position estimates quickly become uncoupled from true location. Periodic ground-truthing with aligned location data (e.g., from global positioning technology) can correct for this drift between Verified Positions (VPs). Yet relatively few bio-logging studies have adopted this approach due to an apparent inaccessibility of the complex analytical processes involved. We present step-by-step instructions for implementing Verified Position Correction (VPC) dead-reckoning in R using the tilt-compensated compass method, accompanied by the mathematical protocols underlying the code and improvements and extensions of this technique to reduce the trade-off between VPC rate and dead-reckoning accuracy. These protocols are all built into a user-friendly, fully-annotated VPC dead-reckoning R function; Gundog.Tracks, with multi-functionality to reconstruct animal movement paths across terrestrial, aquatic, and aerial systems, provided within the supplementary information as well as online (GitHub). Results The Gundog.Tracks function is demonstrated on three contrasting model species (the African lion Panthera leo, the Magellanic penguin Spheniscus magellanicus, and the Imperial cormorant Leucocarbo atriceps) moving on land, in water and in air, respectively. We show the effect of uncorrected errors in speed estimations, heading inaccuracies and infrequent VPC rate and demonstrate how these issues can be addressed. Conclusions The function provided will allow anyone familiar with R to dead-reckon animal tracks readily and accurately, as the key complex issues are dealt with by Gundog.Tracks. This will help the community to consider and implement a valuable, but often overlooked method of reconstructing high-resolution animal movement paths across diverse species and systems without requiring a bespoke application.

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Landfast ice: a major driver of reproductive success in a polar seabird

Biology Letters ◽

10.1098/rsbl.2021.0097 ◽

2021 ◽

Vol 17 (6) ◽

pp. 20210097

Author(s):

Sara Labrousse ◽

Alexander D. Fraser ◽

Michael Sumner ◽

Frédéric Le Manach ◽

Christophe Sauser ◽

...

Keyword(s):

Reproductive Success ◽

Nonlinear Effects ◽

Weather Conditions ◽

Breeding Habitat ◽

Emperor Penguin ◽

Fine Scale ◽

Breeding Parameters ◽

Polar Species ◽

Top Predators ◽

Landfast Ice

In a fast-changing world, polar ecosystems are threatened by climate variability. Understanding the roles of fine-scale processes, and linear and nonlinear effects of climate factors on the demography of polar species is crucial for anticipating the future state of these fragile ecosystems. While the effects of sea ice on polar marine top predators are increasingly being studied, little is known about the impacts of landfast ice (LFI) on this species community. Based on a unique 39-year time series of satellite imagery and in situ meteorological conditions and on the world's longest dataset of emperor penguin ( Aptenodytes forsteri ) breeding parameters, we studied the effects of fine-scale variability of LFI and weather conditions on this species' reproductive success. We found that longer distances to the LFI edge (i.e. foraging areas) negatively affected the overall breeding success but also the fledging success. Climate window analyses suggested that chick mortality was particularly sensitive to LFI variability between August and November. Snowfall in May also affected hatching success. Given the sensitivity of LFI to storms and changes in wind direction, important future repercussions on the breeding habitat of emperor penguins are to be expected in the context of climate change.

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Fine-scale Weather Patterns Drive Reproductive Success in the Brown Pelican

Waterbirds ◽

10.1675/063.044.0202 ◽

2021 ◽

Vol 44 (2) ◽

Author(s):

Rochelle A. Streker ◽

Juliet S. Lamb ◽

John Dindo ◽

Patrick G. R. Jodice

Keyword(s):

Reproductive Success ◽

Fine Scale ◽

Weather Patterns

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Status and conservation of Magellanic PenguinsSpheniscus magellanicusin Patagonia, Argentina

Bird Conservation International ◽

10.1017/s0959270900001787 ◽

1996 ◽

Vol 6 (4) ◽

pp. 307-316 ◽

Cited By ~ 37

Author(s):

Patricia Gandini ◽

Esteban Frere ◽

P. Dee Boersma

Keyword(s):

Reproductive Success ◽

Human Activities ◽

Human Impacts ◽

Breeding Population ◽

Adult Mortality ◽

Breeding Habitat ◽

Breeding Period ◽

Santa Cruz ◽

Magellanic Penguin ◽

Spheniscus Magellanicus

SummaryThere are 36 breeding colonies of Magellanic PenguinsSpheniscus magellanicusalong the coast of mainland Argentina. During the breeding period we counted the number of active nests and estimated the breeding population was approximately 652,000 pairs. Development of coastal areas is diminishing the quality of Magellanic Penguin breeding habitat and reducing penguin reproductive success. Adult mortality rates are increasing because of human activities. Maritime petroleum traffic and petroleum operations are known to cause mortality. Fishing activities cause incidental mortality and may negatively affect penguin foraging and reproductive success. In some areas, offal is increasing gull populations with a corresponding increase in predation on penguin eggs and chicks, thereby lowering reproductive success. These sources of mortality are relatively recent and are human caused. We found three areas where human activities are of particular concern: Península Valdés, Golfo San Jorge and Estrecho de Magallanes. Human impacts on Magellanic Penguin populations could be reduced, benefiting the tourist industry where yearly tens of thousands of people come to the provinces of Chubut and Santa Cruz to visit penguin colonies.Existen 36 colonias de pingüino de MagallanesSpheniscus magellanicusa lo largo de la costa Argentina. La población reproductiva se estimó en 652,000 parejas realizando un conteo de nidos activos durante la estación reproductiva. El desarrollo de las áreas costeras está reduciendo la calidad del hábitat de reproducción y el éxito reproductivo del pingüino de Magallanes. El tráfico de petróleo y las actividades relacionadas son conocidas causas de mortalidad. Las actividades pesqueras están causando mortalidad incidental y pueden estar afectando negativamente el éxito de alimentatión y reproductivo. En algunas áreas la basura está contribuyendo al aumento de la población de gaviotas, incrementándose la predación sobre huevos y pichones de pingüino reduciendo su éxito reproductivo. Estas fuentes de mortalidad son relativamente recientes y provocadas por el hombre. Hemos detectado tres áreas donde la mortalidad relacionada con actividades humanas es preocupante: Península Valdés, Golfo San Jorge y Estrecho de Magallanes. El impacto humano sobre la población de pingüino de Magallanes podría reducirse y beneficiar la industria turística de las provincias de Chubut y Santa Cruz, donde anualmente decenas de miles de personas visitan las colonias reproductivas del pingüino.

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Dead-reckoning animal movements in R: a reappraisal using Gundog.Tracks

Animal Biotelemetry ◽

10.1186/s40317-021-00245-z ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Richard M. Gunner ◽

Mark D. Holton ◽

Mike D. Scantlebury ◽

O. Louis van Schalkwyk ◽

Holly M. English ◽

...

Keyword(s):

Animal Movement ◽

Movement Ecology ◽

Dead Reckoning ◽

Fine Scale ◽

Magellanic Penguin ◽

True Location ◽

Position Correction ◽

Ground Truthing ◽

User Friendly ◽

Aerial Systems

Abstract Background Fine-scale data on animal position are increasingly enabling us to understand the details of animal movement ecology and dead-reckoning, a technique integrating motion sensor-derived information on heading and speed, can be used to reconstruct fine-scale movement paths at sub-second resolution, irrespective of the environment. On its own however, the dead-reckoning process is prone to cumulative errors, so that position estimates quickly become uncoupled from true location. Periodic ground-truthing with aligned location data (e.g., from global positioning technology) can correct for this drift between Verified Positions (VPs). We present step-by-step instructions for implementing Verified Position Correction (VPC) dead-reckoning in R using the tilt-compensated compass method, accompanied by the mathematical protocols underlying the code and improvements and extensions of this technique to reduce the trade-off between VPC rate and dead-reckoning accuracy. These protocols are all built into a user-friendly, fully annotated VPC dead-reckoning R function; Gundog.Tracks, with multi-functionality to reconstruct animal movement paths across terrestrial, aquatic, and aerial systems, provided within the Additional file 4 as well as online (GitHub). Results The Gundog.Tracks function is demonstrated on three contrasting model species (the African lion Panthera leo, the Magellanic penguin Spheniscus magellanicus, and the Imperial cormorant Leucocarbo atriceps) moving on land, in water and in air. We show the effect of uncorrected errors in speed estimations, heading inaccuracies and infrequent VPC rate and demonstrate how these issues can be addressed. Conclusions The function provided will allow anyone familiar with R to dead-reckon animal tracks readily and accurately, as the key complex issues are dealt with by Gundog.Tracks. This will help the community to consider and implement a valuable, but often overlooked method of reconstructing high-resolution animal movement paths across diverse species and systems without requiring a bespoke application.

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High Resolution Stereography of Complementary Freeze-Fracture Replicas Reveals the Presence of Depressions Opposite Membrane Associated Particles of Split Membranes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100066267 ◽

1971 ◽

Vol 29 ◽

pp. 442-443

Author(s):

Russell L. Steere

Keyword(s):

High Resolution ◽

Cardiac Muscle ◽

Electron Micrographs ◽

Chromic Acid ◽

Freeze Fracture ◽

Distilled Water ◽

Fine Scale ◽

Acid Cleaning ◽

Cleaning Solution

Complementary replicas have revealed the fact that the two common faces observed in electron micrographs of freeze-fracture and freeze-etch specimens are complementary to each other and are thus the new faces of a split membrane rather than the original inner and outer surfaces (1, 2 and personal observations). The big question raised by published electron micrographs is why do we not see depressions in the complementary face opposite membrane-associated particles? Reports have appeared indicating that some depressions do appear but complementarity on such a fine scale has yet to be shown.Dog cardiac muscle was perfused with glutaraldehyde, washed in distilled water, then transferred to 30% glycerol (material furnished by Dr. Joaquim Sommer, Duke Univ., and VA Hospital, Durham, N.C.). Small strips were freeze-fractured in a Denton Vacuum DFE-2 Freeze-Etch Unit with complementary replica tooling. Replicas were cleaned in chromic acid cleaning solution, then washed in 4 changes of distilled water and mounted on opposite sides of the center wire of a Formvar-coated grid.

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