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.

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 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.

Breeding behaviour of ectotherms at high latitudes: the case of the natterjack toad Epidalea calamita at its northern range limit

Behaviour ◽  
2021 ◽  
pp. 1-20
Author(s):  
Linda Saare ◽  
Riinu Rannap
Keyword(s):  
Climatic Conditions ◽  
Energetic Cost ◽  
Breeding Period ◽  
High Latitudes ◽  
Range Limit ◽  
Photo Identification ◽  
Breeding Behaviour ◽  
Risk Of Predation ◽  
Increased Risk ◽  
Northern Range Limit

Abstract We explored the breeding behaviour of a threatened amphibian, the natterjack toad, at its northern range limit in Estonia, to determine the extent to which reproduction is affected by harsh and unstable climatic conditions. Using photo identification of specimens, we found that in optimal weather conditions males formed three breeding cohorts, while in adverse conditions only a single cohort occurred and under extreme conditions reproduction was skipped entirely. During the extended breeding season, larger males participated in reproduction throughout the breeding period, while smaller males appeared in later cohorts. Breeding success was related to the calling effort of a male, where larger males had greater mating success than smaller ones. We found that the natterjack toad males exhibit significant plasticity in reproductive behaviour at the northern range limit, which, given the energetic cost of reproduction and the increased risk of predation, allows them to increase their fitness at high latitudes.

scholarly journals Risk-sensitive mating decisions in a visually compromised environment

2009 ◽  
Vol 5 (5) ◽  
pp. 600-602 ◽  
Author(s):  
Bob B. M. Wong ◽  
Marja Järvenpää ◽  
Kai Lindström
Keyword(s):  
Visual Cues ◽  
Perca Fluviatilis ◽  
Reproductive Decisions ◽  
Sand Goby ◽  
European Perch ◽  
Pomatoschistus Minutus ◽  
Risk Sensitive ◽  
Risk Of Predation ◽  
Males And Females ◽  
Reproductive Activities

Reproductive activities are often conspicuous and can increase the risk of predation. Evidence suggests that individuals are capable of responding to predators in a risk-sensitive manner. However, most studies tend to consider only the predator-mediated responses of males and females in isolation and with little regard to differences in local environmental conditions. Here, we experimentally investigate the effects of environmental visibility (turbidity) and predation risk on reproductive decisions in the sand goby, Pomatoschistus minutus , when exposed to a visually oriented predator, the European perch, Perca fluviatilis . We found that gobies were more reluctant to spawn in the predator's presence, although larger males spawned sooner than smaller males. Interestingly, latency to spawning was unaffected by the visual environment, suggesting that gobies may be relying on non-visual cues under turbid conditions.

scholarly journals Heat, health and hatchlings: associations of in situ nest temperatures with morphological and physiological characteristics of loggerhead sea turtle hatchlings from Florida

2020 ◽  
Vol 8 (1) ◽  
Author(s):  
Kelsey A Fleming ◽  
Justin R Perrault ◽  
Nicole I Stacy ◽  
Christina M Coppenrath ◽  
Alison M Gainsbury
Keyword(s):  
Life Stage ◽  
Sea Turtle ◽  
Additional Stress ◽  
Loggerhead Sea Turtle ◽  
Righting Response ◽  
In Situ Incubation ◽  
Risk Of Predation ◽  
Increased Risk ◽  
Incubation Temperatures

Abstract Incubation temperatures, in addition to an embryo’s genetic makeup, are critical in many aspects of adequate sea turtle embryonic development. The effects of high and low incubation temperatures on hatchling quality have been previously examined; however, many of these studies were conducted on relocated or laboratory-reared nests, which do not accurately reflect natural nest temperature fluctuations. To observe the impacts of varying in situ incubation temperatures on loggerhead sea turtle (Caretta caretta) hatchling morphology, various health variables and locomotor performance, temperature data loggers were deployed in 15 loggerhead nests on Juno Beach, Florida, between May and July 2018. Over the course of the study period, 10 morphological traits were measured, blood analytes and heart rate were assessed for the establishment of reference intervals and the self-righting response in seawater was evaluated. Warmer months were associated with smaller body size and higher body condition index, larger umbilical scar size, slower righting time, lower heart rates and higher packed cell volume, hemoglobin, total solids, total white blood cell count, absolute heterophils and absolute basophils. These findings provide evidence that higher in situ incubation temperatures have the potential to adversely affect hatchlings from warmer nests due to increased risk of predation from smaller body sizes, decreased physical responses and overall fitness, altered hemodynamic balance (e.g. dehydration) and potential inflammation and/or stress. With rising temperatures, we predict sea turtle hatchlings may have increasing risks of developing suboptimal physiological features affecting overall fitness and ultimately survival. These results demonstrate that rising environmental temperatures can negatively impact sea turtle hatchlings, thus representing additional stress on sea turtle populations and contributing to our understanding of potential pathophysiological effects of climate change on the delicate life-stage class of the sea turtle hatchling. This information will be useful for formulating effective future sea turtle management plans.

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 Evidence of breeding activity of subadult Turdus thrushes in Argentina

2019 ◽  
Vol 27 (3) ◽  
pp. 149-152
Author(s):  
Exequiel Barboza ◽  
Patricia Capllonch ◽  
Fernando Diego Ortiz ◽  
Alex E. Jahn
Keyword(s):  
Population Dynamics ◽  
Life History ◽  
Bird Species ◽  
Life History Strategies ◽  
Brood Patch ◽  
Breeding Condition ◽  
Different Populations ◽  
Males And Females ◽  
Breeding Seasons ◽  
Subadult Female

AbstractLittle is known about the age at which many Neotropical bird species first attempt to breed. We evaluated the breeding condition of 515 adult and subadult males and females among four species of Turdus thrushes (T. nigriceps, T. chiguanco, T. amaurochalinus and T. rufiventris) in Tucumán, Argentina during three breeding seasons (2015 to 2018). We registered a total of 126 individuals with brood patches and cloacal protuberances, which accounted for 24.5% of thrushes in breeding condition that we sampled. Forty thrushes had a brood patch (31.7% of those in breeding condition), of which 11 were subadults (8.7%). Eighty-six thrushes (68.3%) had a swollen cloacal protuberance, 18 of which were subadults (14.3%). Only a few of the subadults in breeding condition built nests, incubated eggs or raised nestlings. Of 130 nests we found, only 3 belonged to a subadult thrush (in all cases, a subadult female with an adult social mate), one of which was successful. Further research on these patterns among various Neotropical bird species could lead to important insights into the life history strategies that characterize different populations, and how these ultimately affect their population dynamics.

Observations on the biology of Carcharhinus cautus (Whitley), C. melanopterus (Quoy & Gaimard) and C. fitzroyensis (Whitley) from Northern Australia

1987 ◽  
Vol 38 (6) ◽  
pp. 701 ◽  
Author(s):  
JM Lyle
Keyword(s):  
Reproductive Biology ◽  
Teleost Fish ◽  
Species Range ◽  
Northern Australia ◽  
Males And Females ◽  
Breeding Seasons

The reproductive biology and diets of C. cautus, C. melanopterus and C. fitzroyensis from northern Australia are described. Males and females are usually mature at 84 and 91 cm, respectively, in C. cautus, 95 and 97 cm in C. melanopterus, and 88 and 100 cm in C. fitzroyensis. The species exhibit placental viviparity, have restricted breeding seasons, and individual females appear to breed annually. Breeding seasons for C. cautus and C. melanopterus are very similar: mating occurs between January and March, ovulation in February-March, and parturition in October-November. Individuals of C. fitzroyensis mate between May and July, ovulate between July and September, and give birth the. following February- April. Gestation periods for the three species range from 7 to 9 months. Approximate sizes at birth are 40 cm for C. cautus, 48 cm for C. melanopterus and 50 cm for C. fitzroyensis. Mean litter sizes are 2.9 (range 1-5) for C. cautus, 3.8 (range 3-4) for C. melanopterus and 3.7 (range 1-7) for C. fitzroyensis. Teleost fish are an important component of the diets, with crustaceans and molluscs (mainly cephalopods) of lesser importance. Snakes are eaten by C. melanopterus and C. cautus.

Correlation between Scores on the Beck Depression Inventory and the Zung Self-Rating Depression Scale

1983 ◽  
Vol 53 (3) ◽  
pp. 969-970 ◽  
Author(s):  
Sharla A. Kerner ◽  
Keith W. Jacobs
Keyword(s):  
College Students ◽  
Beck Depression Inventory ◽  
Depression Scale ◽  
Self Rating ◽  
Stratified Sample ◽  
Two Measures ◽  
Males And Females

The Beck Depression Inventory and the Zung Self-rating Depression Scale were administered to a stratified sample of 78 college students. The two measures of depression were significantly correlated .54. In addition, Beck scores were influenced by an interaction of year and college variables, and Zung scores were different for males and females. It is concluded that these two scales offer somewhat different measures of depression.

Diel onshore–offshore migrations in northern redbelly dace, Phoxinus eos (Cope), in relation to prey distribution in a small oligotrophic lake

1988 ◽  
Vol 66 (6) ◽  
pp. 1249-1253 ◽  
Author(s):  
Marc Naud ◽  
Pierre Magnan
Keyword(s):  
Littoral Zone ◽  
Salvelinus Fontinalis ◽  
Oligotrophic Lake ◽  
Pelagic Zone ◽  
Brook Charr ◽  
Significant Preference ◽  
Prey Distribution ◽  
Feeding Efficiency ◽  
Risk Of Predation ◽  
Increased Risk

Northern redbelly dace, Phoxinus eos (Cope), exhibit diel onshore–offshore migrations in a small oligotrophic Quebec lake. The fish swim in shoals in the littoral zone during the day, migrate to the pelagic zone at sunset, where the shoals break up into single fish, and then go back to the littoral zone at sunrise. Dace eat mainly two cladocerans, Daphnia and Holopedium. Zooplankton sampling indicated that Daphnia were significantly more abundant in the pelagic zone than in the littoral zone, and Holopedium were rarely found in the littoral zone. Dace showed a significant preference for a dense cover habitat over a sparse cover habitat in the littoral zone during the day. Our results support the hypothesis that dace migrate to the pelagic zone at sunset to increase their feeding efficiency on zooplankton. The foraging benefits of remaining in the offshore zone may be offset by increased risk of predation by brook charr, Salvelinus fontinalis (Mitchill), during the daylight hours, thus resulting in diel onshore–offshore migrations.

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