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Author Clarke, J.A.
Title Moonlight's influence on predator/prey interactions between short-eared owls (Asio flammeus) and deermice (Peromyscus maniculatus) Type Journal Article
Year 1983 Publication Behavioral Ecology and Sociobiology Abbreviated Journal Behav Ecol Sociobiol
Volume 13 Issue 3 Pages 205-209
Keywords Animals
Abstract This study examines the effect of moonlight intensity on deermouse (Peromyscus maniculatus) vulnerability to predation by short-eared owls (Asio flammeus).

Three nocturnal light intensities, labeled new moon, quarter moon, and full moon, were simulated in a flight chamber. Deermouse activity was observed and measured by an index of tracking intensity in the chamber's sand floor. The mice were then exposed to predation by a short-eared owl in each light intensity and search time, chase time, capture time, and the number of escapes/chase were measured.

The results reveal the adaptive significance of deermouse activity suppression in full moon light as an anti-predator response. The deermice reduced activity significantly in bright moonlight during the activity phases. During the predation phases, the owls' hunting effectiveness increased as moonlight waxed. The owls required significantly less time to search for and capture the mice as illumination increased.

The costs and benefits to both species are discussed relative to the prey's variation of activity with moonlight intensity.
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ISSN 0340-5443 ISBN Medium
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Notes Approved no
Call Number LoNNe @ christopher.kyba @ Serial 421
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Author Haim, A.; Heth, G.; Pratt, H.; Nevo, E.
Title Photoperiodic effects on thermoregulation in a 'blind' subterranean mammal Type Journal Article
Year 1983 Publication J Exp Biol Abbreviated Journal
Volume 107 Issue Pages 59-64
Keywords Animals
Abstract Thermoregulatory responses to changes in photoperiod were studied in the ‘blind’ mole rat Spalax ehrenbergi (Nehring). Acclimation of cold-sensitive individuals to short photoperiod (8L:16D) at an ambient temperature (Ta) of 22 degrees C increased their thermoregulatory capacity in cold conditions, when compared to individuals which were acclimated to a photoperiod of 12L:12D at the same Ta. Acclimation of cold-resistant individuals to Ta = 17 degrees C but with a photoperiod of 16L:8D caused a decrease in thermoregulatory capacity. Evaluation of the visual pathway through the visual-evoked potentials showed that the mole rat does not respond to flash stimuli and can thus be considered to be effectively blind.
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Call Number LoNNe @ christopher.kyba @ Serial 422
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Author Alldredge, A.L.; King, J.M.
Title Effects of moonlight on the vertical migration patterns of demersal zooplankton Type Journal Article
Year 1980 Publication Journal of Experimental Marine Biology and Ecology Abbreviated Journal Journal of Experimental Marine Biology and Ecology
Volume 44 Issue 2 Pages 133-156
Keywords Animals
Abstract The diel vertical migration patterns of demersal zooplankton, those organisms which habit bottom substrates but periodically emerge to swim freely in the water column, water determined throughout the lunar cycle. Demersal zooplankton were quantitatively sampled on a subtidal sand flat in the Gulf of California every 2 h for 24-h periods at new, full, first, and last-quarter moons, both as they emerged into the water column and as they returned to the benthos. Demersal zooplankton rarely migrated during daylight. Three general patterns of migration were observed. (1) Polychaetes and cumaceans emerged from the benthos at dusk, regardless of the phase of the moon. Polychaetes returned to the benthos throughout the night while cumaceans returned near dawn. (2) Species of amphipods and isopods exhibited significant avoidance of moonlight, delaying emergence until moonset or returning to the benthos at moonrise. (3) Species of copepods, mysids, shrimp, Branchiostoma (cephalochordate), and tanaids emerged into the water column throughout the night. The timing of migration was highly variable and did not correlate with the presence or absence of moonlight. Large zooplankton migrated less frequently into the water column during moonlit periods than small forms, suggesting that nocturnal predation by visually oriented planktivorous fish may be an important selective pressure.

Demersal zooplankton emerged into artificially darkened emergence traps in significantly higher numbers during daylight and during full and quarter moons than into undarkened control traps, demonstrating that absence of light is a major cue stimulating migration. Reentry traps resting on the bottom captured higher densities of demersal zooplankton than either emergence traps or reentry traps suspended off the bottom. Thus, many demersal zooplankton remain near the bottom, rarely swimming far into the water column. Some trap avoidance was observed and current methods for collecting demersal zooplankton are evaluated. Since most demersal zooplankton remained in the water column only a short time, dispersal, particularly over short distances, may be a major advantage of migratory behavior. Migration facilitates rapid recolonization of disturbed or defaunated sites, disrupts and mixes bottom sediments, and results in daily variation in the microdistribution, patchiness, and species composition of the benthic fauna.
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ISSN 0022-0981 ISBN Medium
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Notes Approved no
Call Number LoNNe @ christopher.kyba @ Serial 423
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Author Hoffmann, K.
Title Photoperiod, Pineal, Melatonin and Reproduction in Hamsters Type Journal Article
Year 1979 Publication Progress in Brain Research Abbreviated Journal
Volume 52 Issue Pages 397–415
Keywords Animals
Abstract This chapter discusses the experiments done on male hamsters. It should be noted, however, that corresponding results have been obtained in females in nearly all cases, regardless of whether photoperiodic effects, the results after pineal manipulations or after application of melatonin are considered. Many mammalian species show a marked annual cycle of gonadal and other functions. In a number of cases it has been shown that the photoperiod, that is, the length of the daily light cycle and its changes, are involved in the regulation of this cycle. The pineal has been shown to participate in the transduction of photoperiodic effects of short photoperiods leading to regression and also of long photoperiods stimulating recrudescence. The latter effect is not only a suppression of antigonadotrophic effects from the pineal, but a positive stimulation. The exact role of melatonin in the photoperiodic mechanism and its site of action are still unclear. Strong effects of melatonin application have been found in photoperiodic mammals. Recent experiments suggest that not only the amount of melatonin, but its pattern of synthesis and release may be important in the conveyance of photoperiodic effects. No support for the assumption that the site of action of melatonin is the pineal itself has been found in experiments with pinealectomized animals.
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Call Number LoNNe @ christopher.kyba @ Serial 424
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Author Hoffmann, K.
Title Photoperiodic effects in the Djungarian hamster: one minute of light during darktime mimics influence of long photoperiods on testicular recrudescence, body weight and pelage colour Type Journal Article
Year 1979 Publication Experientia Abbreviated Journal Experientia
Volume 35 Issue 11 Pages 1529-1530
Keywords Animals
Abstract In male Djungarian hamsters (Phodopus sungorus) short photoperiods (L/D 8/16) with additional 1- or 5-min light-pulses 8 h after light-off were as effective as long photoperiods (L/D 16/8) in stimulating testicular recrudescence, increase in body weight and moult into summer pelage. The results are discussed with regard to the hypothesis that the pattern of melatonin release from the pineal gland is important in mediating photoperiodic effects in mammals.
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ISSN 0014-4754 ISBN Medium
Area Expedition Conference
Notes Approved no
Call Number LoNNe @ christopher.kyba @ Serial 425
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