| Records |
| Author |
Wiltschko, W.; Munro, U.; Ford, H.; Wiltschko, R. |
| Title |
Red light disrupts magnetic orientation of migratory birds |
Type |
Journal Article |
| Year |
1993 |
Publication |
Nature |
Abbreviated Journal |
Nature |
| Volume |
364 |
Issue |
6437 |
Pages |
525-527 |
| Keywords |
magnetoreception; birds; animals |
| Abstract |
The transduction mechanisms and the neurophysiological basis of magnetoreception in birds are still largely unexplained, even though the role of the magnetic compass in the orientation of birds is fairly well understood. The discussion on magnetoreception in birds and terrestrial vertebrates focuses mainly on two mechanisms: small particles of magnetite and biochemical bi-radical reactions of excited macromolecules. When the bi-radical hypothesis was first proposed, magnetic resonance phenomena in the retina were suggested as the primary processes, which led to the question of whether magnetoreception was light-dependent. Homing experiments and electrophysiological evidence from pigeons have produced evidence consistent with such a mechanism. An effect of the spectral composition of light on magnetic compass orientation in amphibians has recently been described: under blue light of 450 nm and below, newts oriented as they did under the full spectrum, whereas they showed a roughly 90° counterclockwise shift when tested under wavelengths at or above 500 nm. Here we report the first orientation tests on migratory birds under light of different wavelengths; the results suggest a light-dependent process that appears to differ from that reported in newts. |
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0028-0836 |
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IDA @ john @ |
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58 |
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| Author |
Smit, B.; Boyles, J.G.; Brigham, R.M.; McKechnie, A.E. |
| Title |
Torpor in dark times: patterns of heterothermy are associated with the lunar cycle in a nocturnal bird |
Type |
Journal Article |
| Year |
2011 |
Publication |
Journal of Biological Rhythms |
Abbreviated Journal |
J Biol Rhythms |
| Volume |
26 |
Issue |
3 |
Pages |
241-248 |
| Keywords |
Animals; *Biological Clocks; Birds/*physiology; *Body Temperature Regulation; Ecosystem; *Feeding Behavior; Insects; *Moon; Seasons; South Africa |
| Abstract |
Many studies have shown that endotherms become more heterothermic when the costs of thermoregulation are high and/or when limited energy availability constrains thermoregulatory capacity. However, the roles of many ecological variables, including constraints on foraging opportunities and/or success, remain largely unknown. To test the prediction that thermoregulatory patterns should be related to foraging opportunities in a heterothermic endotherm, we examined the relationship between the lunar cycle and heterothermy in Freckled Nightjars (Caprimulgus tristigma), which are visually orienting, nocturnal insectivores that are dependent on ambient light to forage. This model system provides an opportunity to assess whether variation in foraging opportunities influences the expression of heterothermy. The nightjars were active and foraged for insects when moonlight was available but became inactive and heterothermic in the absence of moonlight. Lunar illumination was a much stronger predictor of the magnitude of heterothermic responses than was air temperature (T(a)). Our data suggest that heterothermy was strongly related to variation in foraging opportunities associated with the lunar cycle, even though food abundance appeared to remain relatively high throughout the study period. Patterns of thermoregulation in this population of Freckled Nightjars provide novel insights into the environmental and ecological determinants of heterothermy, with the lunar cycle, and not T(a), being the strongest predictor of torpor use. |
| Address |
DST/NRF Centre of Excellence at the Percy FitzPatrick Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, South Africa. smitbe@gmail.com |
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English |
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0748-7304 |
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PMID:21628551 |
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no |
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IDA @ john @ |
Serial |
59 |
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| Author |
Troy, J.R.; Holmes, N.D.; Green, M.C. |
| Title |
Modeling artificial light viewed by fledgling seabirds |
Type |
Journal Article |
| Year |
2011 |
Publication |
Ecosphere |
Abbreviated Journal |
Ecosphere |
| Volume |
2 |
Issue |
10 |
Pages |
art109 |
| Keywords |
artificial light; fallout; Hydrobatidae; modeling; Newell's Shearwater; Procellariidae; Puffinus newelli; birds |
| Abstract |
Artificial light is increasing in coverage across the surface of our planet, impacting the behavioral ecology of many organisms. Attraction to sources of artificial light is a significant threat to certain fledgling shearwaters, petrels (Procellariidae), and storm-petrels (Hydrobatidae) on their first nocturnal flights to the sea. Disorientation by light can cause these birds to crash into vegetation or manmade structures, potentially resulting in death from physical injury, starvation, dehydration, predation by introduced predators, or collisions with vehicles. We developed a GIS-based method to model the intensity of artificial light that fledgling procellariids and hydrobatids could view en route to the ocean (to estimate the degree of threat that artificial light poses to these birds) and present two models for the island of Kauai as examples. These models are particularly relevant to the federally threatened Newell's Shearwater, or `A`o (Puffinus newelli), of which >30,000 fledglings have been collected in response to disorientation by lights on Kauai during the past 30 years. Our models suggest that there are few to no portions of Kauai from which young birds could fledge and not view light on their post-natal nocturnal flights, which is concerning given evidence of a Newell's Shearwater population decline. In future work using this technique, night light intensity layers could be altered to model the effects of modified coastal light conditions on known and potential procellariid and hydrobatid breeding locations. Furthermore, certain methods presented herein may be applicable to other seabirds and additional taxa in which attraction to anthropogenic light poses a serious threat, including migratory passerines and hatchling marine turtles. Components of this modeling approach could potentially be used to spatially estimate effects of other point-source threats to ecological systems, including sound and air pollution. |
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2150-8925 |
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no |
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IDA @ john @ |
Serial |
60 |
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| Author |
Canário, F.; Hespanhol Leitão, A.; Tomé, R. |
| Title |
Predation Attempts by Short-eared and Long-eared Owls on Migrating Songbirds Attracted to Artificial Lights |
Type |
Journal Article |
| Year |
2012 |
Publication |
Journal of Raptor Research |
Abbreviated Journal |
Journal of Raptor Research |
| Volume |
46 |
Issue |
2 |
Pages |
232-234 |
| Keywords |
Asio otus; Long-eared Owl; birds; Asio flammeus; Short-eared Owl; artificial light; migration; predation |
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0892-1016 |
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no |
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IDA @ john @ |
Serial |
61 |
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| Author |
Woods, C.P.; Brigham, R.M. |
| Title |
Common Poorwill activity and calling behavior in relation to moonlight and predation |
Type |
Journal Article |
| Year |
2008 |
Publication |
The Wilson Journal of Ornithology |
Abbreviated Journal |
The Wilson Journal of Ornithology |
| Volume |
120 |
Issue |
3 |
Pages |
505-512 |
| Keywords |
birds; poorwills; Common Poorwill; Phalaenoptilus nuttallii; Arizona; moonlight |
| Abstract |
We investigated the influence of lunar and environmental factors on behavior of Common Poorwills (Phalaenoptilus nuttallii) in southern Arizona under a diverse set of natural and artificial conditions. Radio-marked poorwills were most active shortly after sunset during the new moon. Movements declined as evening progressed. Activity remained high for several hours after sunset when the moon was full. Poorwills were heard calling from March through October, but most calling occurred between early May and September. Only ambient light was correlated with number of poorwills heard calling. More poorwills responded to playbacks of conspecifics when the moon was full than when it was new. Poorwills did not change their response to conspecifics during full moon when playback of poorwill calls followed playback of Great Horned Owl (Bubo virginianus) calls but, during the new moon, fewer birds responded following the owl call. Poorwill behavior is strongly influenced by lunar conditions; their ability to detect and evade predators is important when calling advertises their location. |
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1559-4491 |
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no |
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IDA @ john @ |
Serial |
62 |
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