Morning caffeine ingestion increases cognitive function and short-term maximal performance in footballer players after partial sleep deprivation

The aim of the present study was to evaluate the effects of caffeine ingestion and partial sleep deprivation at the end of night on cognitive and physical performance. In randomised order, fourteen football players (age: 23.57 ± 1.98 years; body weight: 59.57 ± 4.29 kg; height: 174.35 ± 5.07 cm) completed four test sessions at 08:00 h: after placebo or 3 mg·kg^?1 of caffeine ingestion during a reference night, RN (bed time: from 22:30 h to 07:00 h) or a night of partial sleep deprivation, PSD (bed time: from 22:30 h to 03:00 h). During each test session, participants assessed vigilance and reaction times and performed a series of tests: cancelation test, squat jumps (SJ), and the 30-s Wingate test (for the measurement of peak power, PP, and mean power, PM). During RN, results showed that PP, PM, SJ, and vigilance increased after caffeine ingestion in comparison with placebo (p < 0.001). Moreover, both simple and choice reactions were significantly better after caffeine ingestion in comparison with placebo ingestion (p < 0.05 and p < 0.001, respectively). Results showed that reaction time, vigilance, and SJ were affected by PSD, even though PP, PM, and SJ were not affected, the following day at 08:00 h. During the PSD condition, PP, PM, SJ, and vigilance were significantly higher after caffeine ingestion in comparison with placebo ingestion (p < 0.001). However, both simple and choice reaction times were significantly poorer during PSD in comparison with RN (p < 0.05 and p < 0.001, respectively). Therefore, ingesting caffeine is an effective strategy to maintain physical and cognitive performances after PSD.     

Patch use, apprehension, and vigilance behavior of Nubian Ibex under perceived risk of predation

Foraging theory predicts that animals will sacrifice feedingeffort in order to reduce predation risk. Once a forager choosesa habitat, it must decide how to allocate its foraging effort.Nubian Ibex are diurnal, social, cliff-dwelling herbivores.Many of their characteristics seem to have evolved as responsesto predation risk. In order to assess the effects that perceivedrisk of predation might have on foraging behavior of free-rangingNubian Ibex in the Negev Desert, Israel, we measured giving-updensities (GUDs) in artificial food patches and used them togauge apprehension level. (Apprehension can be defined as areduction in attention devoted to performing an activity asa consequence of reallocating attention to detecting or respondingto predation risk. A forager can also be vigilant. Vigilanceis often defined as time spent scanning the surroundings withthe head up.) We also quantified time budgeting using focalobservation of individual Nubian Ibex. Habitat preferences andpatch selectivity as a measure of apprehension were considered.In particular, we tested the effect of distance from refugeon GUDs, the effect of micropatch structure on selectivity,and the effect of distance from the refuge and group size onNubian Ibex vigilance level and apprehension. Nubian Ibex allocatetheir foraging effort more toward patches closer to the escapeterrain. At the same time, Nubian Ibex are more apprehensiveat intermediate distances from the cliff edge than nearer thecliff, and their use of vigilance increases with distance fromthe cliff edge. These results suggest that Nubian Ibex may switchfrom apprehension to a more extreme behavior of vigilance atgreater distances from the refuge. This study demonstrated theuse of antipredatory behaviors, apprehension, and vigilanceby a forager. Estimating apprehension and vigilance levels ofa forager simultaneously gives a more complete and accuratepicture of how the habitat is perceived by them and combinedwith measurements of GUD allow a more accurate assessment ofhabitat quality.     

Contagious fear: Escape behavior increases with flock size in European gregarious birds

Flight initiation distance (FID), the distance at which individuals take flight when approached by a potential (human) predator, is a tool for understanding predator–prey interactions. Among the factors affecting FID, tests of effects of group size (i.e., number of potential prey) on FID have yielded contrasting results. Group size or flock size could either affect FID negatively (i.e., the dilution effect caused by the presence of many individuals) or positively (i.e., increased vigilance due to more eyes scanning for predators). These effects may be associated with gregarious species, because such species should be better adapted to exploiting information from other individuals in the group than nongregarious species. Sociality may explain why earlier findings on group size versus FID have yielded different conclusions. Here, we analyzed how flock size affected bird FID in eight European countries. A phylogenetic generalized least square regression model was used to investigate changes in escape behavior of bird species in relation to number of individuals in the flock, starting distance, diet, latitude, and type of habitat. Flock size of different bird species influenced how species responded to perceived threats. We found that gregarious birds reacted to a potential predator earlier (longer FID) when aggregated in large flocks. These results support a higher vigilance arising from many eyes scanning in birds, suggesting that sociality may be a key factor in the evolution of antipredator behavior both in urban and rural areas. Finally, future studies comparing FID must pay explicit attention to the number of individuals in flocks of gregarious species.     

“Ecology of fear” in ungulates: Opportunities for improving conservation

Because ungulates are important contributors to ecosystem function, understanding the “ecology of fear” could be important to the conservation of ecosystems. Although studying ungulate ecology of fear is common, knowledge from ungulate systems is highly contested among ecologists. Here, we review the available literature on the ecology of fear in ungulates to generalize our current knowledge and how we can leverage it for conservation. Four general focus areas emerged from the 275 papers included in our literature search (and some papers were included in multiple categories): behavioral responses to predation risk (79%), physiological responses to predation risk (15%), trophic cascades resulting from ungulate responses to predation risk (20%), and manipulation of predation risk (1%). Of papers focused on behavior, 75% were about movement and habitat selection. Studies were biased toward North America (53%), tended to be focused on elk (Cervus canadensis; 29%), and were dominated by gray wolves (40%) or humans (39%) as predators of interest. Emerging literature suggests that we can utilize predation risk for conservation with top‐down (i.e., increasing predation risk) and bottom‐up (i.e., manipulating landscape characteristics to increase risk or risk perception) approaches. It is less clear whether fear‐related changes in physiology have population‐level fitness consequences or cascading effects, which could be fruitful avenues for future research. Conflicting evidence of trait‐mediated trophic cascades might be improved with better replication across systems and accounting for confounding effects of ungulate density. Improving our understanding of mechanisms modulating the nature of trophic cascades likely is most important to ensure desirable conservation outcomes. We recommend future work embrace the complexity of natural systems by attempting to link together the focal areas of study identified herein.     

Number of neighbors instead of group size significantly affects individual vigilance levels in large animal aggregations

The group size effect states that animals living in groups gain anti‐predator benefits through reducing vigilance levels as group size increases. A basic assumption of group size effect is that all individuals are equally important for a focal individual, who may adjust its vigilance levels according to social information acquired from them. However, some studies have indicated that neighbors pose greater influences on an individual's vigilance decisions than other group members, especially in large aggregations. Vigilance has also been found to be directed to both predators (anti‐predation vigilance) and conspecifics (social vigilance). Central individuals might rely more on social vigilance than peripheral individuals. To test these hypotheses, we examined the effects of flock size, number of neighbors and position within a flock on vigilance and competition of greater white‐fronted goose Anser albifrons that form large foraging flocks in winter, controlling the effects of other variables (group identity, winter period and site). We found that individual vigilance levels were significantly affected by number of neighbors and position within a flock, whereas flock size showed no effect. Individuals devoted a large component of vigilance to nearby flock mates. Central individuals directed a relatively larger proportion of vigilance to monitor neighbors than peripheral ones, indicating that central individuals more relied on social information acquired from neighbors, possibly caused by the more blocked visual field of central individuals. Moreover, some social vigilance may function as conducting or preventing agonistic interactions since competition intensity was positively correlated with number of neighbors. Our study therefore demonstrate that the number of neighbors is more important than group size in determining individual vigilance in large animal groups. Further studies are still needed to unravel which neighbors pose greater influence on individual vigilance, and the factors that influence individuals to acquire information from their neighbors to adjust vigilance behaviors.     

Driven to distraction: detecting the hidden costs of flea parasitism through foraging behaviour in gerbils

Gerbilline rodents such as Allenby's gerbils (Gerbillus andersoni allenbyi), when parasitized by fleas such as Synosternus cleopatrae pyramidis, devote long hours of grooming to remove the ectoparasites. Yet no detrimental energetic or immunological effects of the ectoparasites have been found in adult Allenby's gerbil. Why should gerbils go to such trouble? We tested for the various ways that fleas can negatively affect gerbils by manipulating flea infestation on gerbils and the presence of a fox. We demonstrate that gerbils responded to fleas by leaving resource patches at higher giving-up densities. Furthermore, they stayed in those resource patches less time and left them at higher quitting harvest rates so long as a fox was also present. When flea-ridden, gerbils also abandoned using vigilance to manage risk and relied mainly on time allocation. Thus, having fleas imposed a foraging cost similar in nature to that arising from the risk of predation from foxes and may be even larger in magnitude. More than that, the presence of fleas acted as a magnifier of foraging costs, especially those arising from the risk of predation. The fleas reduced the gerbils' foraging aptitude and altered how they went about managing risk of predation. We hypothesize that fleas reduce the attention that gerbils otherwise have for foraging and predator detection. We suggest that this is the major cost of ectoparasitism.