scholarly journals Does Moonlight Increase Predation Risk for Elusive Mammals in Costa Rica?

2020 ◽  
Vol 13 ◽  
pp. 194008292095240
Author(s):  
Ryan T. Botts ◽  
Amy A. Eppert ◽  
Timothy J. Wiegman ◽  
Steven R. Blankenship ◽  
Abner Rodriguez ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Costa Rica ◽  
Predation Risk ◽  
Activity Patterns ◽  
Night Vision ◽  
Lunar Phase ◽  
Nocturnal Activity ◽  
Related Activity ◽  
Risk Of Predation ◽  
Increased Risk

An increasing body of evidence indicates that moonlight influences the nocturnal activity patterns of tropical mammals, both predators and prey. One explanation is that brighter moonlight is associated with increased risk of predation (Predation Risk hypothesis), but it has also been proposed that nocturnal activity may be influenced by the sensory ecology of a species, with species that rely on visual detection of food and danger predicted to increase their activity during bright moonlight, while species relying on non-visual senses should decrease activity (Visual Acuity hypothesis). Lack of an objective measure of “visual acuity” has made this second hypothesis difficult to test, therefore we employed a novel approach to better understand the role of lunar illumination in driving activity patterns by using the tapetum lucidum as a proxy for “night vision” acuity. To test the alternative predictions, we analyzed a large dataset from our long-term camera trap study in Costa Rica using activity overlap, relative abundance, and circular statistical techniques. Mixed models explored the influence of illumination factors (moonrise/set, cloud cover, season) and night vision acuity (tapetum type) on nocturnal and lunar phase-related activity patterns. Our results support the underlying assumptions of the predation risk and visual acuity models, but indicate that neither can fully predict lunar-related activity patterns. With diurnal human “super predators” forcing a global increase in activity during the night by mammals, our findings can contribute to a better understanding of nocturnal activity patterns and the development of conservation approaches to mitigate forced temporal niche shifts.

The effects of moonlight on nocturnal activity in bushy-tailed wood rats (Neotoma cinerea)

1999 ◽  
Vol 77 (3) ◽  
pp. 480-485 ◽  
Author(s):  
Michael G Topping ◽  
John S Millar ◽  
James A Goddard
Keyword(s):  
Light Level ◽  
Intermediate Level ◽  
Nocturnal Activity ◽  
Risk Of Predation ◽  
Increased Risk ◽  
Neotoma Cinerea ◽  
Two Measures ◽  
Males And Females ◽  
Rocky Outcrops ◽  
Breeding Seasons

The nocturnal activity of bushy-tailed wood rats (Neotoma cinerea) was monitored for two breeding seasons (1993 and 1994) in the Canadian Rockies. Radiotelemetry was used under three levels of moonlight to assess two measures of nocturnal activity: (i) the proportion of animals crossing rocky outcrops and entering the surrounding forest to forage, search for mates, or both, and (ii) the distance moved from the den site while in the forest. Males and females exhibited significant differences among moonlight levels, with greater activity on nights of intermediate-level moonlight and less activity on nights with bright or dark moonlight. There was no difference in the proportions of males and females active at any moonlight level. The distances moved from the den did not differ among moonlight levels for either males or females. Having traversed the rocks and entered the forest, individuals moved similar distances regardless of light level. These results suggest that wood rats respond to moonlight only when making the decision to cross rocks and enter the forest. This behaviour presumably serves to counteract the increased risk of predation on bright nights.

Moonlight Avoidance Behavior in Leach's Storm-Petrels as a Defense against Slaty-Backed Gulls

The Auk ◽  
1986 ◽  
Vol 103 (1) ◽  
pp. 14-22 ◽  
Author(s):  
Yutaka Watanuki
Keyword(s):  
Predator Avoidance ◽  
Full Moon ◽  
Activity Patterns ◽  
Predation Rate ◽  
Activity Levels ◽  
Nocturnal Activity ◽  
Oceanodroma Leucorhoa ◽  
Risk Of Predation ◽  
Reduced Activity ◽  
Moonlight Avoidance

Abstract Diurnal activity patterns of Leach's Storm-Petrels (Oceanodroma leucorhoa) and Slaty-backed Gulls (Larus schistisagus) were investigated. The petrels reduced activity in moonlight in May and June when the predation rate by gulls was relatively high. Petrel activity levels were inversely correlated with light intensities and the corresponding risk of predation by the gull. This suggests that nocturnal activity and moonlight avoidance by the petrel in its colony are an effective defense against diurnal predators. Activity synchronization of the petrel was most marked during the full moon, further supporting the predator-avoidance hypothesis.

scholarly journals Widespread nocturnality of living birds stemming from their common ancestor

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Yonghua Wu
Keyword(s):  
Positive Selection ◽  
Common Ancestor ◽  
Activity Patterns ◽  
Bright Light ◽  
Night Vision ◽  
Diel Activity ◽  
Divergent Evolution ◽  
Nocturnal Activity ◽  
Evolutionary Origins ◽  
Diel Activity Patterns

Abstract Background Many living birds exhibit some nocturnal activity, but the genetic basis and evolutionary origins of their nocturnality remain unknown. Results Here, we used a molecular phyloecological approach to analyze the adaptive evolution of 33 phototransduction genes in diverse bird lineages. Our results suggest that functional enhancement of two night-vision genes, namely, GRK1 and SLC24A1, underlies the nocturnal adaption of living birds. Further analyses showed that the diel activity patterns of birds have remained relatively unchanged since their common ancestor, suggesting that the widespread nocturnal activity of many living birds may largely stem from their common ancestor rather than independent evolution. Despite this evolutionary conservation of diel activity patterns in birds, photoresponse recovery genes were found to be frequently subjected to positive selection in diverse bird lineages, suggesting that birds generally have evolved an increased capacity for motion detection. Moreover, we detected positive selection on both dim-light vision genes and bright-light vision genes in the class Aves, suggesting divergent evolution of the vision of birds from that of reptiles and that different bird lineages have evolved certain visual adaptions to their specific light conditions. Conclusions This study suggests that the widespread nocturnality of extant birds has a deep evolutionary origin tracing back to their common ancestor.

Incubation time as an important influence on egg production and distribution into clutches for sauropod dinosaurs

Paleobiology ◽  
10.1666/13028 ◽  
2014 ◽  
Vol 40 (3) ◽  
pp. 323-330 ◽  
Author(s):  
Graeme D. Ruxton ◽  
Geoffrey F. Birchard ◽  
D. Charles Deeming
Keyword(s):  
Predation Risk ◽  
Incubation Time ◽  
Egg Production ◽  
Adaptive Strategy ◽  
Finite Limit ◽  
Small Individual ◽  
Risk Of Predation ◽  
Increased Risk ◽  
Production And Distribution ◽  
Long Time

Individual egg size and clutch size of the largest of the dinosaurs (the sauropods) are both smaller than might be expected for such large oviparous organisms. We suggest that these effects can be understood in the light of likely incubation times of sauropod eggs. Using allometric relationships from extant birds and crocodilians, we estimate that time from laying to hatching was likely to have been 65–82 days. If total predation risk varies with length of incubation time, there may be egg sizes above which the advantages of larger initial hatchling size are outweighed by the increased risk of predation during the egg stage. Also, in seasonal environments there will often be a finite limit to the period over which environmental temperatures are high enough for egg development. Thus incubation time may have been an important constraint explaining the small individual size of sauropod eggs. We further suggest that for sauropods spatial dispersal of eggs in small clutches was an adaptive strategy to mitigate this high predation risk associated with long time of exposure in the egg stage. Such a dispersive strategy brings several benefits. Thus, incubation time may also be key to explaining the surprisingly small clutch sizes.

Increased risk of predation increases mobbing intensity in tropical birds of French Guiana

2015 ◽  
Vol 31 (3) ◽  
pp. 243-250 ◽  
Author(s):  
Vallo Tilgar ◽  
Kadri Moks
Keyword(s):  
Predation Risk ◽  
French Guiana ◽  
Empirical Studies ◽  
Predator Species ◽  
Acoustic Stimuli ◽  
Risk Of Predation ◽  
Increased Risk ◽  
In The Wild ◽  
The Common ◽  
Animal Communities

Abstract:Stressful environments have been suggested to enhance cooperative behaviours in animal communities. Prey animals living in risky environments can also increase long-term benefits by cooperating with neighbours, such as collectively harassing predators. However, empirical studies have rarely tested this prediction in the wild. In this experimental study we explored whether the perceived predation risk influences cooperative mobbing behaviour in tropical forest birds in French Guiana. The predation risk was increased by 5-d-long presentation of visual and acoustic stimuli of pygmy-owls in 24 locations. In order to examine whether mobbing response can vary in relation to the abundance of local predators, we used the Amazonian pygmy-owl (Glaucidium hardyi) as a common predator and the ferruginous pygmy-owl (Glaucidium brasilianum) as a rare predator in the study area. Our results showed that repeated predator-presentations increased mobbing response over time for the rarer owl species, while this effect was not significant for the common owl species. No effect of repeated presentations of either pygmy-owl species was found on the latency of mobbing. Moreover, mobbing latency was shorter and mobbing response was stronger for the common predator species, the Amazonian pygmy-owl. This study provides experimental evidence that birds exhibit stronger mobbing responses when the predator is locally abundant, while repeated encounters can be perceived as more dangerous when the predator is rare.

Reproducibility of Night Vision Goggle Visual Acuity Measurements Using Landolt C's

1999 ◽  
Author(s):  
Alan Pinkus ◽  
H. L. Task ◽  
Sharon Dixon ◽  
Charles Goodyear
Keyword(s):  
Visual Acuity ◽  
Night Vision

The population dynamics of bite-sized predators: prey dependence, territoriality, and mobility

2018 ◽  
Author(s):  
Xavier Lambin
Keyword(s):  
Prey Species ◽  
Top Down ◽  
Predator Prey ◽  
Biological Barrier ◽  
Reciprocal Interactions ◽  
Demographic Rates ◽  
Risk Of Predation ◽  
Increased Risk ◽  
Rodent Prey ◽  
Small Mustelids

The dependency of mustelid demographic rates on prey abundance has the potential to cause a strong coupling between predator-prey populations. Data on mustelid dynamics show that such strong reciprocal interactions only materialise in some restricted conditions. Bite-size mustelid predators searching for scarce, depleted prey expose themselves to increased risk of predation by larger predators of small mammal that are themselves searching for similar prey species. As voles or muskrats become scarcer, weasels and mink searching for prey over larger areas become increasingly exposed to intra-guild predation, unless they operate in a habitat refuge such as the sub-nivean space. Where larger predators are sufficiently abundant or exert year-round predation pressure on small mustelids, their impact on mustelids may impose biological barrier to dispersal that are sufficient to weaken the coupling between small mustelids and their rodent prey, and thus impose a degree of top down limitation on mustelids.

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