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Author  |
Eriksen, A.; Wabakken, P. |
| Title |
Activity patterns at the Arctic Circle: nocturnal eagle owls and interspecific interactions during continuous midsummer daylight |
Type |
Journal Article |
| Year |
2018 |
Publication |
Journal of Avian Biology |
Abbreviated Journal |
J Avian Biol |
| Volume |
49 |
Issue |
7 |
Pages |
e01781 |
| Keywords |
Animals |
| Abstract |
Circadian rhythms result from adaptations to biotic and abiotic environmental conditions that cycle through the day, such as light, temperature, or temporal overlap between interacting species. At high latitudes, close to or beyond the polar circles, uninterrupted midsummer daylight may pose a challenge to the circadian rhythms of otherwise nocturnal species, such as eagle owls Bubo bubo. By non‐invasive field methods, we studied eagle owl activity in light of their interactions with their main prey the water vole Arvicola amphibius, and their competitor the white‐tailed eagle Haliaeetus albicilla during continuous midsummer daylight on open, treeless islands in coastal Northern Norway. We evaluated circadian rhythms, temporal overlap, exposure, and spatial distribution. The owls maintained a nocturnal activity pattern, possibly because slightly dimmer light around midnight offered favourable hunting conditions. The eagles were active throughout the 24‐hour period as opposed to the strictly diurnal rhythm reported elsewhere, thus increasing temporal overlap and the potential for interference competition between the two avian predators. This may indicate an asymmetry, with the owls facing the highest cost of interference competition. The presence of eagles combined with constant daylight in this open landscape may make the owls vulnerable to interspecific aggression, and contrary to the available literature, eagle owls rarely exposed themselves visually during territorial calls, possibly to avoid detection by eagles. We found indications of spatial segregation between owls and eagles reflecting differences in main prey, possibly in combination with habitat‐mediated avoidance. Eagle owl vocal activity peaked in the evening before a nocturnal peak in visual observations, when owls were active hunting, consistent with the hypothesis of a dusk chorus in nocturnal bird species. The owls may have had to trade‐off between calling and foraging during the few hours around midnight when slightly dimmer light reduced the detection risk while also providing better hunting conditions. |
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0908-8857 |
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GFZ @ kyba @ |
Serial |
1881 |
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Holveck, M.-J.; Grégoire, A.; Doutrelant, C.; Lambrechts, M.M. |
| Title |
Nest height is affected by lamppost lighting proximity in addition to nestbox size in urban great tits |
Type |
Journal Article |
| Year |
2018 |
Publication |
Journal of Avian Biology |
Abbreviated Journal |
J Avian Biol |
| Volume |
in press |
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Animals |
| Abstract |
Both natural and artificial light have proximate influences on many aspects of avian biology, physiology and behaviour. To date artificial light at night is mostly considered as being a nuisance disrupting for instance sleep and reproduction of diurnal species. Here, we investigate if lamppost night lighting affects cavity‐nesting bird species inside their breeding cavity. Nest height in secondary cavity‐nesting species is the result of trade‐offs between several selective forces. Predation is the prevailing force leading birds to build thin nests to increase the distance towards the entrance hole. A thin nest may also limit artificial light exposure at night. Yet, a minimum level of daylight inside nesting cavities is necessary for adequate visual communication and/or offspring development. Against this background, we hypothesised that avian nest‐building behaviour varies in response to a change in night lighting. We monitored nest height of urban great tits (Parus major) during six years and found that it varied with artificial light proximity. The birds built thinner nests inside nestboxes of various sizes in response to increasing lamppost night light availability at the nest. In large nestboxes, the nests were also thinner when a lamppost was present in the territory. Whether this relationship between artificial night lighting and nest height reflects a positive or negative effect of urbanisation is discussed in the light of recent experimental studies conducted in rural populations by other research groups. |
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0908-8857 |
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GFZ @ kyba @ |
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2062 |
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Lee, J.G.-H.; MacGregor-Fors, I.; Yeh, P.J. |
| Title |
Sunrise in the city: disentangling drivers of the avian dawn chorus onset in urban greenspaces |
Type |
Journal Article |
| Year |
2017 |
Publication |
Journal of Avian Biology |
Abbreviated Journal |
J Avian Biol |
| Volume |
48 |
Issue |
7 |
Pages |
955-964 |
| Keywords |
Animals |
| Abstract |
Urban systems are known to have a number of effects on avian diversity, density, and morphological and behavioral traits. However, no study to date has simultaneously examined the wide range of urban variables in relation to the avian dawn chorus, a complex behavioral phenomenon. Previous studies investigating adjustments of the dawn chorus onset in urban settings have mainly been confined to relationships with noise and light levels. In addition to noise and light levels, in this study we included other potentially related environmental characteristics describing vegetation structure, urban infrastructure, and human activity, all of which have been shown to be drivers of bird diversity in urban areas. We conducted dawn chorus surveys at 38 Los Angeles urban greenspaces and used a classification and regression tree analysis to identify specific urban scenarios that best explained timing differences in the dawn chorus onset. Our results show that light level was the most important determinant of the dawn chorus onset time, in which, counter-intuitively, bird communities in greenspaces with higher light levels had later onsets. In addition, noise was an important factor for the chorus onset in greenspaces with higher light levels. Although our results differ from those of previous studies, these findings highlight the importance of noise and light levels in explaining dawn chorus onset variation, indicating the need for further research in untangling this complex and ecologically important phenomenon. |
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0908-8857 |
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LoNNe @ kyba @ |
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1623 |
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Pajot, A.; Corbeau, A.; Jambon, A.; Weimerskirch, H. |
| Title |
Diel at‐sea activity of two species of great albatrosses: the ontogeny of foraging and movement behaviour |
Type |
Journal Article |
| Year |
2021 |
Publication |
Journal of Avian Biology |
Abbreviated Journal |
J Avian Biol |
| Volume |
52 |
Issue |
2 |
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| Keywords |
Moonlight; Animals |
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The first year of life is a period of high mortality in animals. Reduced foraging capacities of naive individuals might be the primary cause of their mortality. These capacities are supposed to be progressively acquired during the first months of life. In this study, we investigate the ontogeny of flight capacities, by day and night, of first‐year individuals, and compare it with adults from two closely related species of great albatrosses: Amsterdam Diomedea amsterdamensis and wandering Diomedea exulans albatrosses which forage in different environmental conditions. We used 71 tracks of 71 juvenile birds and 141 of 116 incubating adults to compare both age categories. In order to explore the effect of moon light on night activity, we elaborated a new formula which improves the precision of the proxy of moon illumination. By day, we found that juveniles of both species reach some adult foraging capacities in less than two months. By night, albatrosses have reduced activity increasing during the first weeks at sea for juveniles and changing in accordance with moon illumination for both juveniles and adults. A peak of flight activity at dawn and dusk was apparent for both species. Interspecific comparison underlined that Amsterdam albatrosses were more active than wandering albatrosses, suggesting a difference in food and foraging strategy. Overall, we highlighted how life history traits, environmental conditions and time of the day affect the foraging activity of two related species of seabirds. |
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GFZ @ kyba @ |
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3431 |
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Silva, A.D.; Diez‐Méndez, D.; Kempenaers, B. |
| Title |
Effects of experimental night lighting on the daily timing of winter foraging in common European songbirds |
Type |
Journal Article |
| Year |
2017 |
Publication |
Journal of Avian Biology |
Abbreviated Journal |
J Avian Biol |
| Volume |
48 |
Issue |
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Pages |
862-871 |
| Keywords |
Animals |
| Abstract |
The ecological effects of light pollution are becoming better understood, especially in birds. Recent studies have shown that several bird species can use street lighting to extend activity into the night during the breeding season. However, most of these studies are correlational and little is known about the effects of artificial night lighting on the timing of activities outside the breeding season. During winter, low temperatures and short days may limit foraging opportunities and can negatively affect survival of resident birds. However, night lighting may allow them to expand the time niche available for foraging. Here, we report on a study where we repeatedly manipulated the amount of night lighting during early winter at automated feeding stations in a natural forest. We used video-recordings at the feeders to determine the time of the first (at dawn) and last (at dusk) foraging visits for six songbird species. We predicted that all species, and in particular the naturally early-foraging species, would advance their daily onset of foraging during the mornings with night lighting, but would show minimal or no delays in their daily cessation of foraging during the lighted evenings. We found that two early-foraging species, the blue tit and the great tit, started foraging earlier during the experimentally lighted mornings. However, in great tits, this effect was weak and restricted to nights with inclement weather. The light treatment did not have any effect on the start of foraging in the willow/marsh tit, the nuthatch, the European jay, and the blackbird. Artificial night lighting did not cause later foraging at dusk in any of the six species. Overall, our results suggest that artificial light during winter has only small effects on timing of foraging. We discuss these findings and the importance of temperature and winter weather in shaping the observed foraging patterns. |
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0908-8857 |
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LoNNe @ kyba @ |
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1627 |
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