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Fuller, G. (Ed.). (2013). The Night Shift: Lighting and Nocturnal Strepsirrhine Care in Zoos. Ph.D. thesis, , .
Abstract: Over billions of years of evolution, light from the sun, moon, and stars has provided
organisms with reliable information about the passage of time. Photic cues entrain
the circadian system, allowing animals to perform behaviors critical for survival and
reproduction at optimal times. Modern artificial lighting has drastically altered
environmental light cues. Evidence is accumulating that exposure to light at night
(particularly blue wavelengths) from computer screens, urban light pollution, or as
an occupational hazard of night-shift work has major implications for human health.
Nocturnal animals are the shift workers of zoos; they are generally housed on
reversed light cycles so that daytime visitors can observe their active behaviors. As a
result, they are exposed to artificial light throughout their subjective night. The goal
of this investigation was to examine critically the care of nocturnal strepsirrhine
primates in North American zoos, focusing on lorises (Loris and Nycticebus spp.) and pottos (Perodicticus potto). The general hypothesis was that exhibit lighting design affects activity patterns and circadian physiology in nocturnal strepsirrhines. The
first specific aim was to assess the status of these populations. A multi-institutional husbandry survey revealed little consensus among zoos in lighting design, with both red and blue light commonly used for nocturnal illumination. A review of medical records also revealed high rates of neonate mortality. The second aim was to
develop methods for measuring the effects of exhibit lighting on behavior and
health. The use of actigraphy for automated activity monitoring was explored.
Methods were also developed for measuring salivary melatonin and cortisol as
indicators of circadian disruption. Finally, a multi-institutional study was conducted
comparing behavioral and endocrine responses to red and blue dark phase lighting.
These results showed greater activity levels in strepsirrhines housed under red light than blue. Salivary melatonin concentrations in pottos suggested that blue light
suppressed nocturnal melatonin production at higher intensities, but evidence for
circadian disruption was equivocal. These results add to the growing body of
evidence on the detrimental effects of blue light at night and are a step towards
empirical recommendations for nocturnal lighting design in zoos.
Le Tallec, T., Théry, M., & Perret, M. (2016). Melatonin concentrations and timing of seasonal reproduction in male mouse lemurs (Microcebus murinus) exposed to light pollution. J of Mammalogy, 97(3), 753–760.
Abstract: Adverse effects of light at night are associated with human health problems and with changes in seasonal reproduction in several species. Owing to its role in the circadian timing system, melatonin production is suspected to mediate excess nocturnal light. To test this hypothesis, we examined the effect of light pollution on the timing of seasonal reproduction on a strict Malagasy long-day breeder, the nocturnal mouse lemur (Microcebus murinus). We randomly exposed 12 males in wintering sexual rest to moonlight or to a light-mimicking nocturnal streetlight for 5 weeks. We monitored urinary 6-sulfatoxymelatonin concentrations (aMT6s), plasma testosterone concentrations, and testis size, and we recorded daily rhythms of core temperature and locomotor activity. In males exposed to light pollution, we observed a significant decrease in urinary aMT6s concentrations associated with changes in daily rhythm profiles and with activation of reproductive function. These results showed that males entered spontaneous sexual recrudescence leading to a summer acclimatization state, which suggests that light at night disrupts perception of day length cues, leading to an inappropriate photoentrainment of seasonal rhythms.
Romano, M. C., Rodas, A. Z., Valdez, R. A., Hernandez, S. E., Galindo, F., Canales, D., et al. (2010). Stress in wildlife species: noninvasive monitoring of glucocorticoids. Neuroimmunomodulation, 17(3), 209–212.
Abstract: Depression and stress are related pathologies extensively studied in humans. However, this relationship is not well known in animals kept in zoos and even less known in wild animals. In zoo animals, acute and chronic stress caused by difficulties in coping with stressors such as public presence and noise, among others, can induce the appearance of repetitive pathological behaviors such as stereotypies, many times associated with organic pathologies that deeply affect their health and welfare. In the wild, factors such as deforestation, habitat fragmentation, lack of food and water, and human disturbances are potential causes of acute and chronic stress for the resident fauna. Glucocorticoids (GC) have been extensively used as stress indicators in many species including humans. Since chase and handling of wild animals immediately raise their GC serum levels, noninvasive methods have been developed to assess stress without interference caused by sample collection. The hormones and their metabolites can be measured in various body fluids and excreta and detect basal feedback free hormone concentrations as well as the response to ACTH and handling. In order to study the influence of disturbing factors we have measured GC as stress indicators by noninvasive techniques in dolphins and felids (ocelots, jaguarundis and margays) and cortisol and testosterone in spider monkeys.