Effect of changing landscape structure on the predator-prey interaction between goshawk and grouse

Abstract I studied the ecology of the goshawk-grouse relationship in Oulu, northern Finland, during and outside the breeding season, by radio-telemetry. This included museum samples of goshawk to obtain a better ecological as well as a better evolutionary understanding of it. The proportion of grous...

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Bibliographic Details
Main Author: Tornberg, R. (Risto)
Format: Doctoral or Postdoctoral Thesis
Language:English
Published: University of Oulu 2000
Subjects:
Online Access:http://urn.fi/urn:isbn:9514256379
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record_format openpolar
spelling ftunivoulu:oai:oulu.fi:isbn951-42-5637-9 2023-07-30T04:04:45+02:00 Effect of changing landscape structure on the predator-prey interaction between goshawk and grouse Tornberg, R. (Risto) 2000-05-03 application/pdf http://urn.fi/urn:isbn:9514256379 eng eng University of Oulu info:eu-repo/semantics/altIdentifier/pissn/0355-3191 info:eu-repo/semantics/altIdentifier/eissn/1796-220X info:eu-repo/semantics/openAccess © University of Oulu, 2000 change goshawk grouse predation regulation info:eu-repo/semantics/doctoralThesis info:eu-repo/semantics/publishedVersion 2000 ftunivoulu 2023-07-08T20:01:13Z Abstract I studied the ecology of the goshawk-grouse relationship in Oulu, northern Finland, during and outside the breeding season, by radio-telemetry. This included museum samples of goshawk to obtain a better ecological as well as a better evolutionary understanding of it. The proportion of grouse in the diet of goshawks has decreased since the 1960’s, in accordance with the decline of grouse populations. The main prey groups replacing the lacking grouse were corvids, squirrels and hares. The proportion of grouse was highest in spring and it decreased towards the end of the nestling phase. The most preferred grouse species were hazel grouse Bonasa bonasia and willow grouse Lagopus lagopus. Preferences for different prey types are not explained by active choices of goshawk, but by changes in the vulnerability of the prey species. The nestling phase, when food demand is highest, is not adjusted to when prey supply is highest, but before it. The size and shape of the goshawks has changed from the 1960’s. Adult males became smaller but females larger. Both became relatively longer winged and tailed. Decrease of male’s size may be a response to the change in the food supply. Prey types replacing grouse are generally smaller, which may cause the change in the male’s morphology. Females being less active during the breeding season may not be affected. For the female to be larger is advantageous in winter when they kill ‘over large’ prey like mountain hares Lepus timidus and capercaillie cocks Tetrao urogallus. Wintering goshawks were mainly females in adult plumage that tended to stay in the study area. However, only one third bred locally. More than one quarter of all hawks died during the study. Although known to be inhabitants of old forests, which this study supports, goshawks are fairly well adapted to mosaic landscape resulting from modern forestry, providing that suitable sized prey is available. Females have less problems, probably because hares, the main winter prey for females, are not affected negatively ... Doctoral or Postdoctoral Thesis Lepus timidus Northern Finland Jultika - University of Oulu repository
institution Open Polar
collection Jultika - University of Oulu repository
op_collection_id ftunivoulu
language English
topic change
goshawk
grouse
predation
regulation
spellingShingle change
goshawk
grouse
predation
regulation
Tornberg, R. (Risto)
Effect of changing landscape structure on the predator-prey interaction between goshawk and grouse
topic_facet change
goshawk
grouse
predation
regulation
description Abstract I studied the ecology of the goshawk-grouse relationship in Oulu, northern Finland, during and outside the breeding season, by radio-telemetry. This included museum samples of goshawk to obtain a better ecological as well as a better evolutionary understanding of it. The proportion of grouse in the diet of goshawks has decreased since the 1960’s, in accordance with the decline of grouse populations. The main prey groups replacing the lacking grouse were corvids, squirrels and hares. The proportion of grouse was highest in spring and it decreased towards the end of the nestling phase. The most preferred grouse species were hazel grouse Bonasa bonasia and willow grouse Lagopus lagopus. Preferences for different prey types are not explained by active choices of goshawk, but by changes in the vulnerability of the prey species. The nestling phase, when food demand is highest, is not adjusted to when prey supply is highest, but before it. The size and shape of the goshawks has changed from the 1960’s. Adult males became smaller but females larger. Both became relatively longer winged and tailed. Decrease of male’s size may be a response to the change in the food supply. Prey types replacing grouse are generally smaller, which may cause the change in the male’s morphology. Females being less active during the breeding season may not be affected. For the female to be larger is advantageous in winter when they kill ‘over large’ prey like mountain hares Lepus timidus and capercaillie cocks Tetrao urogallus. Wintering goshawks were mainly females in adult plumage that tended to stay in the study area. However, only one third bred locally. More than one quarter of all hawks died during the study. Although known to be inhabitants of old forests, which this study supports, goshawks are fairly well adapted to mosaic landscape resulting from modern forestry, providing that suitable sized prey is available. Females have less problems, probably because hares, the main winter prey for females, are not affected negatively ...
format Doctoral or Postdoctoral Thesis
author Tornberg, R. (Risto)
author_facet Tornberg, R. (Risto)
author_sort Tornberg, R. (Risto)
title Effect of changing landscape structure on the predator-prey interaction between goshawk and grouse
title_short Effect of changing landscape structure on the predator-prey interaction between goshawk and grouse
title_full Effect of changing landscape structure on the predator-prey interaction between goshawk and grouse
title_fullStr Effect of changing landscape structure on the predator-prey interaction between goshawk and grouse
title_full_unstemmed Effect of changing landscape structure on the predator-prey interaction between goshawk and grouse
title_sort effect of changing landscape structure on the predator-prey interaction between goshawk and grouse
publisher University of Oulu
publishDate 2000
url http://urn.fi/urn:isbn:9514256379
genre Lepus timidus
Northern Finland
genre_facet Lepus timidus
Northern Finland
op_relation info:eu-repo/semantics/altIdentifier/pissn/0355-3191
info:eu-repo/semantics/altIdentifier/eissn/1796-220X
op_rights info:eu-repo/semantics/openAccess
© University of Oulu, 2000
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