scholarly journals Social foraging and individual consistency in following behaviour: testing the information centre hypothesis in free-ranging vultures

2017 ◽  
Vol 284 (1852) ◽  
pp. 20162654 ◽  
Author(s):  
Roi Harel ◽  
Orr Spiegel ◽  
Wayne M. Getz ◽  
Ran Nathan
Keyword(s):  
Spatial Scales ◽  
Social Foraging ◽  
Foraging Efficiency ◽  
Information Centre ◽  
Gyps Fulvus ◽  
Declining Populations ◽  
Tracking Movements ◽  
Communal Roosting ◽  
Individual Consistency ◽  
Free Ranging

Uncertainties regarding food location and quality are among the greatest challenges faced by foragers and communal roosting may facilitate success through social foraging. The information centre hypothesis (ICH) suggests that uninformed individuals at shared roosts benefit from following informed individuals to previously visited resources. We tested several key prerequisites of the ICH in a social obligate scavenger, the Eurasian griffon vulture ( Gyps fulvus ), by tracking movements and behaviour of sympatric individuals over extended periods and across relatively large spatial scales, thereby precluding alternative explanations such as local enhancement. In agreement with the ICH, we found that ‘informed’ individuals returning to previously visited carcasses were followed by ‘uninformed’ vultures that consequently got access to these resources. When a dyad (two individuals that depart from the same roost within 2 min of each other) included an informed individual, they spent a higher proportion of the flight time close to each other at a shorter distance between them than otherwise. Although all individuals occasionally profited from following others, they differed in their tendencies to be informed or uninformed. This study provides evidence for ‘following behaviour’ in natural conditions and demonstrates differential roles and information states among foragers within a population. Moreover, demonstrating the possible reliance of vultures on following behaviour emphasizes that individuals in declining populations may suffer from reduced foraging efficiency.

scholarly journals Behavioral repeatability and foraging performance in wild free-flying nectarivorous bats (Glossophaga commissarisi)

2018 ◽  
Author(s):  
Vladislav Nachev ◽  
York Winter
Keyword(s):  
Individual Differences ◽  
Mixed Model ◽  
Linear Mixed Model ◽  
Field Investigation ◽  
Foraging Efficiency ◽  
Behavioral Measures ◽  
Foraging Performance ◽  
Patterns Of Behavior ◽  
Artificial Flowers ◽  
Free Ranging

ABSTRACTAnimal individuals show patterns of behavior that are stable within individuals but different among individuals. Such individual differences are potentially associated with differences in foraging efficiency and in fitness. Furthermore, behavioral responses may be correlated in specific suites of so called behavioral syndromes that are consistent across different contexts and with time. Here we present a field investigation on individual differences between wild, free-flying nectarivorous bats (Glossophaga commissarisi) in the foraging context. We further investigated how individual differences effect foraging performance, and we examined their interdependence within hypothesized behavioral syndrome structures. Free-ranging bats were individually identified as they visited an array of 24 artificial flowers with nectar of high or low sugar concentration. We found that three behavioral measures of foraging behavior were individually stable over the two-month observation period. We investigated the link between individual behavioral measures and measures of foraging performance using generalized linear mixed models. Individual measures of foraging performance showed significant repeatability, and we found evidence that bats making more visits per bout tend to be slower in learning to avoid unprofitable flowers. We used a multi-response generalized linear mixed model to estimate between-individual correlations and compare hypothesized syndrome structures. There were no clear patterns of between-individual correlations among the behavioral measures in our study, despite the measures exhibiting significant repeatability. This may indicate that foraging performance depends on multiple individual behavior dimensions that are not adequately described by simple models of behavior syndromes.

scholarly journals Decision-making by a soaring bird: time, energy and risk considerations at different spatio-temporal scales

2016 ◽  
Vol 371 (1704) ◽  
pp. 20150397 ◽  
Author(s):  
Roi Harel ◽  
Olivier Duriez ◽  
Orr Spiegel ◽  
Julie Fluhr ◽  
Nir Horvitz ◽  
...  
Keyword(s):  
Decision Making ◽  
Long Range ◽  
Spatial Scales ◽  
Movement Ecology ◽  
Accelerometer Data ◽  
Temporal Scales ◽  
Gyps Fulvus ◽  
Trade Offs ◽  
Gliding Flight ◽  
Spatio Temporal

Natural selection theory suggests that mobile animals trade off time, energy and risk costs with food, safety and other pay-offs obtained by movement. We examined how birds make movement decisions by integrating aspects of flight biomechanics, movement ecology and behaviour in a hierarchical framework investigating flight track variation across several spatio-temporal scales. Using extensive global positioning system and accelerometer data from Eurasian griffon vultures ( Gyps fulvus ) in Israel and France, we examined soaring–gliding decision-making by comparing inbound versus outbound flights (to or from a central roost, respectively), and these (and other) home-range foraging movements (up to 300 km) versus long-range movements (longer than 300 km). We found that long-range movements and inbound flights have similar features compared with their counterparts: individuals reduced journey time by performing more efficient soaring–gliding flight, reduced energy expenditure by flapping less and were more risk-prone by gliding more steeply between thermals. Age, breeding status, wind conditions and flight altitude (but not sex) affected time and energy prioritization during flights. We therefore suggest that individuals facing time, energy and risk trade-offs during movements make similar decisions across a broad range of ecological contexts and spatial scales, presumably owing to similarity in the uncertainty about movement outcomes. This article is part of the themed issue ‘Moving in a moving medium: new perspectives on flight’.

Foraging efficiency: energy expenditure versus energy gain in free-ranging black-tailed deer

1996 ◽  
Vol 74 (3) ◽  
pp. 442-450 ◽  
Author(s):  
Katherine L. Parker ◽  
Michael P. Gillingham ◽  
Thomas A. Hanley ◽  
Charles T. Robbins
Keyword(s):  
Energy Expenditure ◽  
Energy Intake ◽  
Body Mass ◽  
Dry Matter ◽  
Energy Content ◽  
Metabolizable Energy ◽  
Foraging Efficiency ◽  
Dry Matter Digestibility ◽  
Metabolizable Energy Intake ◽  
Free Ranging

Foraging efficiency (metabolizable energy intake/energy expenditure when foraging) was determined over a 2-year period in nine free-ranging Sitka black-tailed deer (Odocoileus hemionus sitkensis) in Alaska, and related to foraging-bout duration, distances travelled, and average speeds of travel. We calculated the energy-intake component from seasonal dry matter and energy content, dry matter digestibility, and a metabolizable energy coefficient for each plant species ingested. We estimated energy expenditures when foraging as the sum of energy costs of standing, horizontal and vertical locomotion, sinking depths in snow, and supplementary expenditures associated with temperatures outside thermoneutrality. Energy intake per minute averaged 4.0 times more in summer than winter; energy expenditure was 1.2 times greater in summer. Animals obtained higher amounts of metabolizable energy with higher amounts of energy invested. Energy intake during foraging bouts in summer was 2.5 times the energy invested; in contrast, energy intake during winter was only 0.7 times the energy expended. Changes in body mass of deer throughout the year increased asymptotically with foraging efficiency, driven primarily by the rate of metabolizable energy intake. Within a season, summer intake rates and winter rates of energy expediture had the greatest effects on the relation between foraging efficiency and mass status. Seasonal changes in foraging efficiency result in seasonal cycles in body mass and condition in black-tailed deer. Body reserves accumulated during summer, however, are essential for over-winter survival of north-temperate ungulates because energy demands cannot be met by foraging alone.

scholarly journals Switching spatial scale reveals dominance-dependent social foraging tactics in a wild primate

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3462 ◽  
Author(s):  
Alexander E.G. Lee ◽  
Guy Cowlishaw
Keyword(s):  
Evolutionary Dynamics ◽  
Spatial Scales ◽  
Social Rank ◽  
Group Living ◽  
Social Foraging ◽  
Potential Cost ◽  
Papio Ursinus ◽  
Theoretical Predictions ◽  
Lower Ranking ◽  
Foraging Tactics

When foraging in a social group, individuals are faced with the choice of sampling their environment directly or exploiting the discoveries of others. The evolutionary dynamics of this trade-off have been explored mathematically through the producer-scrounger game, which has highlighted socially exploitative behaviours as a major potential cost of group living. However, our understanding of the tight interplay that can exist between social dominance and scrounging behaviour is limited. To date, only two theoretical studies have explored this relationship systematically, demonstrating that because scrounging requires joining a competitor at a resource, it should become exclusive to high-ranking individuals when resources are monopolisable. In this study, we explore the predictions of this model through observations of the natural social foraging behaviour of a wild population of chacma baboons (Papio ursinus). We collected data through over 800 h of focal follows of 101 adults and juveniles across two troops over two 3-month periods. By recording over 7,900 social foraging decisions at two spatial scales we show that, when resources are large and economically indefensible, the joining behaviour required for scrounging can occur across all social ranks. When, in contrast, dominant individuals can aggressively appropriate a resource, such joining behaviour becomes increasingly difficult to employ with decreasing social rank because adult individuals can only join others lower ranking than themselves. Our study supports theoretical predictions and highlights potentially important individual constraints on the ability of individuals of low social rank to use social information, driven by competition with dominant conspecifics over monopolisable resources.

Lead poisoning in a free ranging griffon vulture (Gyps fulvus)

1997 ◽  
Vol 140 (2) ◽  
pp. 47-48 ◽  
Author(s):  
R. Mateo ◽  
R. Molina ◽  
J. Grifols ◽  
R. Guitart
Keyword(s):  
Lead Poisoning ◽  
Griffon Vulture ◽  
Gyps Fulvus ◽  
Free Ranging

scholarly journals The role of elephantLoxodonta africanapathways as a spatial variable in crop-raiding location

Oryx ◽  
2014 ◽  
Vol 48 (3) ◽  
pp. 436-444 ◽  
Author(s):  
K. Von Gerhardt ◽  
A. Van Niekerk ◽  
M. Kidd ◽  
M. Samways ◽  
J. Hanks
Keyword(s):  
Land Use Planning ◽  
Spatial Scales ◽  
Spatial Variable ◽  
Foraging Efficiency ◽  
Crop Raiding ◽  
Crop Fields ◽  
The Matrix ◽  
Remnant Forest ◽  
Species Specific ◽  
The Impact

AbstractShort-range elephantLoxodonta africanamovements were examined in a heterogeneous landscape mosaic of settlements, crop fields and remnant forest in the Caprivi Strip, Namibia. We explored the penetration of the landscape through the use of permanent pathways and determined the impact of pathway use on crop-raiding location. Pathways were linear, devoid of vegetation and maintained by repeated movement. Functional connectivity of pathways was not species-specific, and pathways were used by various species. Elephants travelled in single file at night and we recorded selective pathway use: females selected pathways away from settlements to access water, whereas males used pathways among settlements to launch crop raids. Proximity of raided fields to the nearest pathway was the only significant spatial variable explaining crop-raiding location. Bulls were responsible for all crop-raiding incidents. We conclude that (1) pathways were the most significant spatial variable influencing which fields were raided, (2) crop-raiding from pathways may maximize foraging efficiency by reducing time spent and distance travelled while foraging, (3) pathways may facilitate penetration of the matrix by connecting predictable resources (crops) with preferred shelter areas, crossing points at roads and preferred drinking spots, and (4) access to the Kwandu River is restricted by settlements, predictably resulting in human–elephant conflict. By highlighting the relevance of pathways for movement of elephants we show that an understanding of the use of pathways is important for land-use planning in conservation landscapes, specifically with regard to human–elephant conflict. We also argue for the need to more fully explore pathway occurrence and use at larger spatial scales.

scholarly journals Take-off and landing kinetics of a free-ranging gliding mammal, the Malayan colugo ( Galeopterus variegatus )

2008 ◽  
Vol 275 (1638) ◽  
pp. 1007-1013 ◽  
Author(s):  
Greg Byrnes ◽  
Norman T.-L Lim ◽  
Andrew J Spence
Keyword(s):  
Forest Floor ◽  
Spatial Scales ◽  
Three Dimensional ◽  
The Body ◽  
Aerodynamic Forces ◽  
Distributed Resources ◽  
Risk Of Injury ◽  
Free Ranging ◽  
Kinetics Of ◽  
Reduced Risk

Arboreal animals negotiate a highly three-dimensional world that is discontinuous on many spatial scales. As the scale of substrate discontinuity increases, many arboreal animals rely on leaping or gliding locomotion between distant supports. In order to successfully move through their habitat, gliding animals must actively modulate both propulsive and aerodynamic forces. Here we examined the take-off and landing kinetics of a free-ranging gliding mammal, the Malayan colugo ( Galeopterus variegatus ) using a custom-designed three-dimensional accelerometry system. We found that colugos increase the propulsive impulse to affect longer glides. However, we also found that landing forces are negatively associated with glide distance. Landing forces decrease rapidly as glide distance increases from the shortest glides, then level off, suggesting that the ability to reorient the aerodynamic forces prior to landing is an important mechanism to reduce velocity and thus landing forces. This ability to substantially alter the aerodynamic forces acting on the patagial wing in order to reorient the body is a key to the transition between leaping and gliding and allows gliding mammals to travel long distances between trees with reduced risk of injury. Longer glides may increase the access to distributed resources and reduce the exposure to predators in the canopy or on the forest floor.

scholarly journals Phenotypic and environmental correlates of natal dispersal in a long-lived territorial vulture

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
David Serrano ◽  
Ainara Cortés-Avizanda ◽  
Iñigo Zuberogoitia ◽  
Guillermo Blanco ◽  
José Ramón Benítez ◽  
...  
Keyword(s):  
Linear Models ◽  
Spatial Scales ◽  
Breeding Site ◽  
Adult Mortality ◽  
Dispersal Distance ◽  
Natal Dispersal ◽  
Environmental Correlates ◽  
Individual Traits ◽  
Declining Populations ◽  
Dispersal Distances

AbstractNatal dispersal, the movement between the birth and the first breeding site, has been rarely studied in long-lived territorial birds with a long-lasting pre-breeding stage. Here we benefited from the long-term monitoring programs of six populations of Egyptian vultures (Neophron percnopterus) from Spain and France to study how the rearing environment determines dispersal. For 124 vultures, we recorded a median dispersal distance of 48 km (range 0–656 km). Linear models were used to assess the effect of population and individual traits on dispersal distance at two spatial scales. Dispersal distances were inversely related to vulture density in the natal population, suggesting that birds perceive the abundance of conspecifics as a signal of habitat quality. This was particularly true for declining populations, so increasing levels of opportunistic philopatry seemed to arise in high density contexts as a consequence of vacancies created by human-induced adult mortality. Females dispersed further than males, but males were more sensitive to the social environment, indicating different dispersal tactics. Both sexes were affected by different individual attributes simultaneously and interactively with this social context. These results highlight that complex phenotype-by-environment interactions should be considered for advancing our understanding of dispersal dynamics in long-lived organisms.

scholarly journals Hot days are associated with short-term adrenocortical responses in a Southern African arid-zone passerine bird

2021 ◽  
Author(s):  
Lesedi L. Moagi ◽  
Amanda R. Bourne ◽  
Susan J. Cunningham ◽  
Ray Jansen ◽  
Celiwe A. Ngcamphalala ◽  
...  
Keyword(s):  
Stress Responses ◽  
Physiological Stress ◽  
Arid Zone ◽  
Biological Effects ◽  
Physiological Mechanism ◽  
Dry Weight ◽  
Foraging Efficiency ◽  
Daily Maximum ◽  
Hot Days ◽  
Free Ranging

AbstractNon-invasive methods for investigating the biological effects of environmental variables are invaluable for understanding potential impacts of climate change on behavioural and physiological stress responses of free-ranging animals. Foraging efficiency, body mass maintenance and breeding success are compromised in Southern pied babblers Turdoides bicolor exposed to air temperatures between ~35°C and ~40°C. We tested the hypothesis that these very hot days are acute stressors for free-ranging babblers by quantifying the relationship between daily maximum air temperature (Tmax) and faecal glucocorticoid metabolite (fGCM) levels. We collected naturally-excreted droppings from free-ranging pied babblers and analysed fGCM levels. Levels of fGCMs in droppings collected after 3pm were independent of same-day Tmax < 38 °C and averaged 140.25 ng g−1 Dry Weight ± 56.92 ng g−1 DW (mean ± SD) over this range. Above an inflection Tmax = 38 °C, however, fGCM levels increased linearly with same-day Tmax and averaged 190.79 ng g−1 DW ± 70.13 ng g−1 DW. There was no relationship between Tmax on the previous day and fGCM levels in droppings collected the following morning. Group size, breeding stage, sex and rank did not predict variation in fGCM levels. These results suggest that very high Tmax may be linked to acute, but not chronic, heat stress responses. The fGCM levels we measured are likely to represent a biologically meaningful response to an environmental stressor (high Tmax), suggesting a physiological mechanism underlying observed changes in behaviour and reproductive success at high temperatures in this species.

scholarly journals Comparison of Patterns of Genetic Variation and Demographic History in the Greater Sage-Grouse (Centrocercus urophasianus): Relevance for Conservation

2014 ◽  
Vol 7 (1) ◽  
pp. 19-29 ◽  
Author(s):  
Robert M. Zink
Keyword(s):  
Genetic Variation ◽  
Spatial Scales ◽  
Demographic History ◽  
Local Population ◽  
Centrocercus Urophasianus ◽  
Columbia Basin ◽  
Population Declines ◽  
Microsatellite Data ◽  
Sage Grouse ◽  
Declining Populations

The greater sage-grouse (Centrocercus urophasianus) was once widespread in western North America but its range has contracted by an uncertain degree owing to anthropogenic and natural causes. Concern over population declines has led to its proposed listing as threatened under the U.S. Endangered Species Act. Detailed genetic and demographic analyses of this species throughout its range are available but heretofore have not been compared. Reduced genetic variability is often taken as a proxy for declining populations, but rarely are there quantitative population estimates with which to compare. I compared published mitochondrial DNA (mtDNA) control region sequences, microsatellite allele frequencies at seven loci, and estimates of numbers of males per lek, number of active leks, percent decline in the best population models, and the probability (P) of Ne < 50 in 30 years and P(Ne < 500) in 100 years, at two spatial scales, 45 local population samples and 16 larger aggregates of samples. When excluding the populations from the Columbia Basin, which show little genetic diversity and are statistical outliers, there were no consistent relationships between estimates of genetic variation and demographic trends across the remainder of the range at either spatial scale. A measure of inbreeding derived from microsatellite data was also not related to population trends. Thus, despite habitat reduction and range fragmentation, the greater sage-grouse does not exhibit expected genetic signatures of declining populations. Possibly, the mtDNA and microsatellite data are insufficiently sensitive to detect population declines that have occurred over the span of a half century. Alternatively, only when populations are reduced to the levels seen in the Columbia Basin will genetic effects be seen, suggesting that the bulk of the range of the greater sage-grouse is not currently in genetic peril.

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