Post-fledging parental care in the female great grey owl (Strix nebulosa) : a trade-off between provisioning and guarding
Post-fledging parental care is generally little studied in birds. By use of radio telemetry, I studied the post-fledging parental behaviour of female great grey owls (Strix nebulosa), measured as number of prey deliveries from males and females and female aggressiveness and brood defence. I also obs...
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Norwegian University of Life Sciences, Ås
2018
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Online Access: | http://hdl.handle.net/11250/2565476 |
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ftunivmob:oai:nmbu.brage.unit.no:11250/2565476 2023-06-11T04:12:00+02:00 Post-fledging parental care in the female great grey owl (Strix nebulosa) : a trade-off between provisioning and guarding Hegtun, Kari Sonerud, Geir A. 2018 application/pdf http://hdl.handle.net/11250/2565476 eng eng Norwegian University of Life Sciences, Ås http://hdl.handle.net/11250/2565476 Attribution-NonCommercial-NoDerivatives 4.0 Internasjonal http://creativecommons.org/licenses/by-nc-nd/4.0/deed.no Parental care Behavioural ecology Ornithology Atferdsøkologi Lappugler VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Økologi: 488 Master thesis 2018 ftunivmob 2023-05-17T22:46:54Z Post-fledging parental care is generally little studied in birds. By use of radio telemetry, I studied the post-fledging parental behaviour of female great grey owls (Strix nebulosa), measured as number of prey deliveries from males and females and female aggressiveness and brood defence. I also observed the behaviour and movement patterns of the dependent fledged juveniles. The females provided care by staying near the young to guard them and assisting the males with food provisioning. No female deserted the male and offspring before the study was terminated. The males provided more than twice as many prey items for the offspring than the females did in the post-fledging dependence period, and the probability of a female delivering a prey tended to increase with brood size. Females also delivered more prey items when the ambient temperature was low. When a male had captured a prey, he delivered it directly to the fledglings in 83% of the cases, and if he delivered it to the female instead, it was usually under stressful situations. The female spent much time near the fledglings, but the probability of her being absent increased with increased fledgling age and brood size. When intruders were approaching the fledglings, the female could show an extremely aggressive behaviour, and female aggressiveness depended on observer behaviour and decreased with increasing fledgling age. An alternative defence strategy of the female was to perform distraction displays, and the probability of her doing so decreased with brood size. The fledglings moved away from the nest as they aged, and the distance from the nest significantly increased with increasing fledgling age. However, the siblings stayed close to each other during the entire post-fledging dependence period. The juvenile mortality rate from fledging until the fledglings could fly and escape predators was 38%, and the highest mortality rate occurred the first time after fledging. Increasing perching height, staying near siblings and moving towards the parent’s ... Master Thesis great grey owl Strix nebulosa Open archive Norwegian University of Life Sciences: Brage NMBU |
institution |
Open Polar |
collection |
Open archive Norwegian University of Life Sciences: Brage NMBU |
op_collection_id |
ftunivmob |
language |
English |
topic |
Parental care Behavioural ecology Ornithology Atferdsøkologi Lappugler VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Økologi: 488 |
spellingShingle |
Parental care Behavioural ecology Ornithology Atferdsøkologi Lappugler VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Økologi: 488 Hegtun, Kari Post-fledging parental care in the female great grey owl (Strix nebulosa) : a trade-off between provisioning and guarding |
topic_facet |
Parental care Behavioural ecology Ornithology Atferdsøkologi Lappugler VDP::Matematikk og Naturvitenskap: 400::Zoologiske og botaniske fag: 480::Økologi: 488 |
description |
Post-fledging parental care is generally little studied in birds. By use of radio telemetry, I studied the post-fledging parental behaviour of female great grey owls (Strix nebulosa), measured as number of prey deliveries from males and females and female aggressiveness and brood defence. I also observed the behaviour and movement patterns of the dependent fledged juveniles. The females provided care by staying near the young to guard them and assisting the males with food provisioning. No female deserted the male and offspring before the study was terminated. The males provided more than twice as many prey items for the offspring than the females did in the post-fledging dependence period, and the probability of a female delivering a prey tended to increase with brood size. Females also delivered more prey items when the ambient temperature was low. When a male had captured a prey, he delivered it directly to the fledglings in 83% of the cases, and if he delivered it to the female instead, it was usually under stressful situations. The female spent much time near the fledglings, but the probability of her being absent increased with increased fledgling age and brood size. When intruders were approaching the fledglings, the female could show an extremely aggressive behaviour, and female aggressiveness depended on observer behaviour and decreased with increasing fledgling age. An alternative defence strategy of the female was to perform distraction displays, and the probability of her doing so decreased with brood size. The fledglings moved away from the nest as they aged, and the distance from the nest significantly increased with increasing fledgling age. However, the siblings stayed close to each other during the entire post-fledging dependence period. The juvenile mortality rate from fledging until the fledglings could fly and escape predators was 38%, and the highest mortality rate occurred the first time after fledging. Increasing perching height, staying near siblings and moving towards the parent’s ... |
author2 |
Sonerud, Geir A. |
format |
Master Thesis |
author |
Hegtun, Kari |
author_facet |
Hegtun, Kari |
author_sort |
Hegtun, Kari |
title |
Post-fledging parental care in the female great grey owl (Strix nebulosa) : a trade-off between provisioning and guarding |
title_short |
Post-fledging parental care in the female great grey owl (Strix nebulosa) : a trade-off between provisioning and guarding |
title_full |
Post-fledging parental care in the female great grey owl (Strix nebulosa) : a trade-off between provisioning and guarding |
title_fullStr |
Post-fledging parental care in the female great grey owl (Strix nebulosa) : a trade-off between provisioning and guarding |
title_full_unstemmed |
Post-fledging parental care in the female great grey owl (Strix nebulosa) : a trade-off between provisioning and guarding |
title_sort |
post-fledging parental care in the female great grey owl (strix nebulosa) : a trade-off between provisioning and guarding |
publisher |
Norwegian University of Life Sciences, Ås |
publishDate |
2018 |
url |
http://hdl.handle.net/11250/2565476 |
genre |
great grey owl Strix nebulosa |
genre_facet |
great grey owl Strix nebulosa |
op_relation |
http://hdl.handle.net/11250/2565476 |
op_rights |
Attribution-NonCommercial-NoDerivatives 4.0 Internasjonal http://creativecommons.org/licenses/by-nc-nd/4.0/deed.no |
_version_ |
1768387541889712128 |