Spiders in space-orb-web-related behaviour in zero gravity.

Gravity is very important for many organisms, including web-building spiders. Probably the best approach to study the relevance of gravity on organisms is to bring them to the International Space Station. Here, we describe the results of such an experiment where two juvenile Trichonephila clavipes (L.) (Araneae, Nephilidae) spiders were observed over a 2-month period in zero gravity and two control spiders under otherwise identical conditions on Earth. During that time, the spiders and their webs were photographed every 5 min. Under natural conditions, Trichonephila spiders build asymmetric webs with the hub near the upper edge of the web, and they always orient themselves downwards when sitting on the hub whilst waiting for prey. As these asymmetries are considered to be linked to gravity, we expected the spiders experiencing no gravity to build symmetric webs and to show a random orientation when sitting on the hub. We found that most, but not all, webs built in zero gravity were indeed quite symmetric. Closer analysis revealed that webs built when the lights were on were more asymmetric (with the hub near the lights) than webs built when the lights were off. In addition, spiders showed a random orientation when the lights were off but faced away from the lights when they were on. We conclude that in the absence of gravity, the direction of light can serve as an orientation guide for spiders during web building and when waiting for prey on the hub.

Sensory pollutants alter bird phenology and fitness across a continent.

Expansion of anthropogenic noise and night lighting across our planet1,2 is of increasing conservation concern3-6. Despite growing knowledge of physiological and behavioural responses to these stimuli from single-species and local-scale studies, whether these pollutants affect fitness is less clear, as is how and why species vary in their sensitivity to these anthropic stressors. Here we leverage a large citizen science dataset paired with high-resolution noise and light data from across the contiguous United States to assess how these stimuli affect reproductive success in 142 bird species. We find responses to both sensory pollutants linked to the functional traits and habitat affiliations of species. For example, overall nest success was negatively correlated with noise among birds in closed environments. Species-specific changes in reproductive timing and hatching success in response to noise exposure were explained by vocalization frequency, nesting location and diet. Additionally, increased light-gathering ability of species' eyes was associated with stronger advancements in reproductive timing in response to light exposure, potentially creating phenological mismatches7. Unexpectedly, better light-gathering ability was linked to reduced clutch failure and increased overall nest success in response to light exposure, raising important questions about how responses to sensory pollutants counteract or exacerbate responses to other aspects of global change, such as climate warming. These findings demonstrate that anthropogenic noise and light can substantially affect breeding bird phenology and fitness, and underscore the need to consider sensory pollutants alongside traditional dimensions of the environment that typically inform biodiversity conservation.

Effects of different light durations during incubation on hatching, subsequent growth, welfare, and meat quality traits among three broiler strains.

Present study was aimed to evaluate the hatching traits and subsequent performance of broilers strains under the intermittent and continuous light regime during incubation. In total, 2250 eggs from Hubbard classic, Cobb-500, and Ross-308 strains (750 eggs from each of same age breeders) were incubated under three different light durations. First treatment was the incubation totally under darkness where no light was able to penetrate in the assigned section of machine. In the second treatment, eggs were incubated at 12 h of lightness and 12 h of darkness. In the third treatment, the eggs received lightning of 24 h. Data were collected for hatching traits and hatch window, growth performance, welfare aspects, and meat quality. A two-way factorial analysis was performed using SAS software applying Duncan's multiple range test. The results showed that hatching traits were improved when Hubbard breeder eggs were provided with light period of 12 h. However, gait score was non-significantly different among the treatment. The meat quality was better in Hubbard broilers obtained after 12 h of intermittent light during incubation. Blood biochemistry was also improved in Hubbard broilers of 12 h of light duration. It was concluded that 12 h of light period during incubation is beneficial for getting better hatchability and subsequent performance of Hubbard broilers.

Effects of chronic exposure to a mixed field of neutrons and photons on behavioral and cognitive performance in mice.

To simulate the space radiation environment astronauts are exposed to, most studies involve acute exposures but during a space mission there will be chronic (long-lasting) exposures. To address this knowledge gap, a neutron irradiator using a 252Cf (252Californium) source was used to generate a mixed field of neutrons and photons to simulate chronic, low dose rate exposures to high LET radiation. In the present study, we assessed the effects chronic neutron exposure starting at 60 days of age on behavioral and cognitive performance of BALB/c female and C3H male mice at 600 and 700 days of age as part of an opportunistic study that took advantage of the availability of neutron and sham-irradiated mice from a radiation carcinogenesis experiment. There were profound dose- and time point-dependent effects of chronic neutron exposure. At the 600-day time point, irradiated BALB/c female mice showed improved nest building at all three doses. At the 700-day, but not 600-day, time point slightly but significantly increased body weights were seen in C3H male mice exposed to 0.118 Gy. At the 600-day time point BALB/c female mice irradiated with 0.2 Gy did, like sham-irradiated, not show preferential exploration of the novel object that was seen in mice irradiated with 0.118 or 0.4 Gy. In C3H male mice exposed to 0.4 Gy and at the 600-day time point, increased measures of anxiety were observed on days 1 and 2 in the open field. Thus, different outcome measures show distinct dose-response relationships, with some anticipated to worsen performance during space missions, like increased measures of anxiety, while other anticipated to enhance performance, such as increased nest building and object recognition.

Penguin colony attendance under artificial lights for ecotourism.

Wildlife watching is an emerging ecotourism activity around the world. In Australia and New Zealand, night viewing of little penguins attracts hundreds of thousands of visitors per year. As penguins start coming ashore after sunset, artificial lighting is essential to allow visitors to view them in the dark. This alteration of the nightscape warrants investigation for any potential effects of artificial lighting on penguin behavior. We experimentally tested how penguins respond to different light wavelengths (colors) and intensities to examine effects on the colony attendance behavior at two sites on Phillip Island, Australia. At one site, nocturnal artificial illumination has been used for penguin viewing for decades, whereas at the other site, the only light is from the natural night sky. Light intensity did not affect colony attendance behaviors of penguins at the artificially lit site, probably due to penguin habituation to lights. At the not previously lit site, penguins preferred lit paths over dark paths to reach their nests. Thus, artificial light might enhance penguin vision at night and consequently it might reduce predation risk and energetic costs of locomotion through obstacle and path detection. Although penguins are faithful to their path, they can be drawn to artificial lights at small spatial scale, so light pollution could attract penguins to undesirable lit areas. When artificial lighting is required, we recommend keeping lighting as dim and time-restricted as possible to mitigate any negative effects on the behavior of penguins and their natural habitat.

Light pollution affects nesting behavior of loggerhead turtles and predation risk of nests and hatchlings.

The introduction of artificial light into wildlife habitats is a rapidly expanding aspect of global change, which has many negative impacts on a wide range of taxa. In this experimental study, which took place on a beach located on the island of Boa Vista (Cabo Verde), three types of artificial light were tested on nesting loggerhead sea turtles as well as on ghost crabs, which intensively predate on nests and hatchlings, to determine the effects they would produce on the behavior of both species. Over the course of 36days, female loggerheads and ghost crabs were studied under yellow, orange and red lights, with observations also being made on dark nights that served as a control treatment. During this period, the frequencies of nesting attempts, the time taken by turtles to complete each phase of the nesting process, and ghost crab abundance and behaviors were carefully recorded. 1146 loggerhead nesting attempts were observed and recorded during the experiments, and results showed a decrease in nesting attempts of at least 20% when artificial lighting was present. A significant decline in successful attempts was also observed within the central sections of the beach, which corresponded to those that received more light. This artificial lighting significantly increased the time that turtles spent on the nesting process and forced them to do more extensive beach crawls. Despite this, the presence of light had no apparent effect on the final selection of the nesting site. Yellow and orange lights significantly disrupted the sea finding behavior and turtles were often unable to orient themselves seaward under these color lights. Disoriented turtles were observed crawling in circuitous paths in front of the light source for several minutes. In addition, artificial lights had the potential to increase the number of ghost crabs present within the illuminated stretches of the beach. However, only yellow lighting produced a significant change on aggressive and prey searching behaviors. These changes in abundance and behavior could cause a greater predation on loggerhead turtle nests. Red light had no significant impact on the behavior of either species. It should be a priority to enforce preventive measures and light mitigation strategies to ensure the conservation of important loggerhead rookeries.

Early life exposure to artificial light at night affects the physiological condition: An experimental study on the ecophysiology of free-living nestling songbirds.

Light pollution or artificial light at night (ALAN) is increasingly recognised to be an important anthropogenic environmental pressure on wildlife, affecting animal behaviour and physiology. Early life experiences are extremely important for the development, physiological status and health of organisms, and as such, early exposure to artificial light may have detrimental consequences for organism fitness. We experimentally manipulated the light environment of free-living great tit nestlings (Parus major), an important model species in evolutionary and environmental research. Haptoglobin (Hp) and nitric oxide (NOx), as important indicators of immunity, health, and physiological condition, were quantified in nestlings at baseline (13 days after hatching) and after a two night exposure to ALAN. We found that ALAN increased Hp and decreased NOx. ALAN may increase stress and oxidative stress and reduce melatonin which could subsequently lead to increased Hp and decreased NOx. Haptoglobin is part of the immune response and mounting an immune response is costly in energy and resources and, trade-offs are likely to occur with other energetically demanding tasks, such as survival or reproduction. Acute inhibition of NOx may have a cascading effect as it also affects other physiological aspects and may negatively affect immunocompetence. The consequences of the observed effects on Hp and NOx remain to be examined. Our study provides experimental field evidence that ALAN affects nestlings' physiology during development and early life exposure to ALAN could therefore have long lasting effects throughout adulthood.

Effects of LED lighting during incubation on layer and broiler hatchability, chick quality, stress susceptibility and post-hatch growth.

Providing light during incubation has been shown to affect hatchability, but the use of LED lights has not been evaluated. This experiment evaluated the effects of LED lighting during embryogenesis on White Leghorn and commercial broiler eggs. To determine this, two experiments were conducted, the first using White Leghorn eggs (N=3456) and the second using commercial broiler eggs (N=3456) where eggs were incubated 12 h of light and 12 h of darkness (LED) or complete darkness (DARK); the light level was 250 lux. Hatchability, embryo mortality, and chick quality were measured in both studies, and a subset of one of the broiler egg trials were grown out to investigate fear and stress parameters. There was no effect (P>0.05) on hatchability of layer eggs; however, there was a difference (P=0.02) observed in chick quality, with the LED group having more chicks (75.34%) with no defects than the DARK group (56.53%). Broiler eggs exposed to LED light showed an increase in hatchability (90.12%, P=0.03) and an increase in no-defect chick percentage (86.12%, P=0.04) at hatch compared to the DARK chicks (85.76% and 69.43%, respectively). Differences were observed between treatments during the 14 d grow-out. The LED birds had lower (P<0.05) physical asymmetry (0.90±0.05 mm) and heterophil/lymphocyte ratios (0.279±0.021), indicating that they were less susceptible to stress than the DARK birds (1.16±0.07 mm and 0.347±0.021, respectively). There was no difference (P>0.05) observed between treatments in growth, FCR, or fear measures at 14 d. These results indicate that providing LED light during incubation can improve chick quality in both white layer and broiler eggs; however, it only appears to improve hatchability in broilers, which could be related to shell pigmentation. It was also demonstrated that providing LED light during incubation can reduce the stress susceptibility of broilers post-hatch. Utilizing light during incubation may be useful tool for the poultry industry.

A radiation-induced adaptive response prolongs the survival of prion-infected mice.

Previously, it has been demonstrated that an "adaptive response" that includes the prevention, repair, and removal of oxidative damage can be evoked by radiation at dose rates substantially lower than those at which risks have been observed. The exact pathogenic mechanism of prion diseases is unknown, but circumstantial evidence suggests that oxidative stress plays a central role. Exposure of prion-infected mice to four 500 mGy/fraction doses of (60)Co γ-radiation administered every other day at a low dose rate (0.5 mGy/min) starting at 2 days before infection, 7 days postinfection (dpi), or 50 dpi significantly prolonged the survival of infected mice. The 500-mGy radiation treatments started at 50 dpi also significantly prolonged the symptom-free period of the disease and caused a significant delay in the rise of the 8-hydroxydeoxyguanosine concentration observed in the urine of nonirradiated infected mice at 98 dpi. The duration of the reduction in oxidative stress achieved by the radiation treatments was similar in length to the prolonged survival of the irradiated mice. This suggests that the adaptive response induced by low-dose whole-body radiation treatments prolongs the survival of prion-infected mice by reducing oxidative stress.

Behavioral effect of terahertz waves in male mice.

We studied the effect of terahertz waves (3.6 THz, 81.5 micro, 15 mW) on the behavior of mice. The mice perceived terahertz waves even after short-term exposure (15 min). The effect of terahertz waves was maximum in direct contact of the mice with the laser. Increased anxiety of experimental animals was observed on the next day after 30-min irradiation.

Birds prefer to breed in sites with low radioactivity in Chernobyl.

Low-level radioactive contamination may affect choice of breeding site and life-history decisions if (i) radioactivity directly affects body condition or (ii) it affects resource abundance that then secondarily influences reproductive decisions. We tested the effects of radioactive contamination on nest-site choice and reproduction in a community of hole nesting birds by putting up nest boxes in areas differing in levels of background radiation. Great tit Parus major and pied flycatcher Ficedula hypoleuca significantly avoided nest boxes in heavily contaminated areas, with a stronger effect in flycatchers than in tits. These preferences could not be attributed to variation in habitat quality or resource abundance, as determined by analyses of habitat use and the relationship between radiation and life-history characters. Likewise, none of these effects could be attributed to individuals of a specific age breeding in the most contaminated areas. Laying date and clutch size were not significantly related to dose rate in either species. Hatching success was depressed by elevated radioactive contamination, interacting with habitat in the great tit and with laying date in the pied flycatcher. Interspecific differences in effects of radiation on nest-site choice suggest that species respond in a species-specific manner to radiation, perhaps related to differences in migratory habits. We suggest that individual body condition rather than secondary effects of radiation on resource abundance account for the effects on nest box use and hatching success.

Ecology: ultraviolet reflectance by the skin of nestlings.

Birds can perceive the reflectance of ultraviolet light by biological structures. Here we show that the skin of the mouth and body of starling nestlings substantially reflects light in the ultraviolet range and that young in which this reflectance is reduced will gain less mass than controls, despite low background levels of ultraviolet and visible light in the nest. We suggest that this ultraviolet reflectance from starling nestlings and its contrast with surrounding surfaces are important for parental decisions about food allocation.

Hornet peak flight activity is correlated with solar UV radiation: a multi-annual survey.

This study deals with the effect which solar irradiation of short wavelength, particularly ultraviolet (UV), exerts on the activities of hornets. The findings are based on multi-annual observations carried out during the years 1985, 1989 and 1998 on hornet nests in the field. At the peak of UV radiation, which occurs at noon, hornet activity is greater by 1-2 orders of magnitude than that during the morning or evening hours. The main visible hornet activity appears to be the removal of soil particles from the nest so as to enlarge its volume, enable the building of additional combs and also increase the size of existing combs. Hornet flight during peak insolation hours is characterized by its briefness (5-20 seconds only) and brevity (to distances of 5-10 meters only) as compared to flights at other hours of the day. These prolonged, multi-annual observations lead to the conclusion that hornets are capable of converting the energy of UV radiation into a form amenable to metabolic usage. In this respect the hornet cuticle behaves as a thermophotovoltaic device, i.e., a semiconductor diode that converts photons radiating from the sunlight into electrical energy.

External factors affecting the duration of broody behavior in the ring dove (Streptopelia risoria).

The object of this study was to investigate factors which determine the duration of sitting in ring doves. This normally lasts ca. 19 days from laying, with very small variation. The period is made up of 15 days incubating eggs and 4-5 days brooding squabs. The duration of sitting is unaffected by substituting fresh or sterile eggs, and can only be slightly influenced by substituting foster squabs or new eggs just before or after hatching. The sitting period appears to be predetermined to run for 19 days following laying. The maintenance of sitting, however, requires the presence of the nest and eggs, and can be drastically varied by keeping subjects in continuous daylight or on a day of 6 hr light:6 hr dark (6 L:6 D). Birds kept on ahemeral cycles (11 L: 10 D; 13 L:14 D) displayed significantly different periods of incubation on infertile eggs and recycling, indicative of an endogenous circadian basis to the timing mechanism.

Photopollution: artificial light optic spatial control systems fail to cope with. Incidents, causation, remedies.

The term photopollution is proposed for artificial light having adverse effects on wildlife. The differences between natural and artificial light are discussed in relation to the concepts of orientation, disorientation, misorientation and abnormal orientation. The ways in which optic orientation systems are attuned to natural illumination conditions are analysed, and it is shown why they therefore may fail to cope with artificial light. It is concluded that for many nocturnally active animals a natural light-field between sunset and sunrise is a requirement for survival. A review is given of data on a) bird kills at man-made lighted obstacles, and b) the interference of artificial light with nest site selection by female sea turtles and water-finding by hatchlings at nesting beaches. Conventional remedies against the hazards of photopollution are critically reviewed and new ones are suggested. It is emphasized that measures should aim not only at reducing threats to a species or population but also at preventing suffering in individual animals.