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Patterns of nest predation and nest predator abundance in a fragmented englemann spruce/subalpine fir forest Campbell, Victoria Elizabeth Anne
Abstract
In a fragmented Englemann Spruce/Subalpine Fir (ESSF) forest, I used artificial nests to test the hypothesis that nest predation is greater at the forest edge and in clearcuts, than in the forest interior. In this forest type, nests in clearcuts had a lower frequency of predation than nests in the forest, yet there was no consistent difference in the frequency of predation at the forest edge or in the forest interior, a pattern opposite to that previously documented. However, in previous studies the landscape was fragmented by agricultural development, where populations of potential nest predators may be elevated as a result of anthropogenic food sources. I found no evidence that the decrease in the frequency of predation on nests in clearcuts was the result of a concomitant shift in the identity (from plasticine eggs) and/or number of predators (from predator surveys) in these locations. Rather, in habitats fragmented by logging activities, many nest predators may avoid foraging in the clearcut because of the increased predation risk to themselves in these locations. In addition to the effect of nest location on predation rate, there was marked temporal variation in the frequency of nest predation. I documented an increase in nest predation both within and between trials; and this may have been a result of predators learning to exploit artificial nests. Studies which can identify individual predators, and record their foraging activity in response to artificial nests, may shed light on the mechanisms behind this temporal variation in nest predation. While artificial nests provide an index of predation risk, future use of this method must be cautioned against until the biases can be clearly identified. Further study of the patterns of nest predation in fragmented habitats should instead focus on the patterns of nest predation on natural nests, the distribution and abundance of potential nest predators in fragmented and undisturbed forest habitats, and on how nest predators forage within clearcut, forest edge, and in forest interior habitats.
Item Metadata
Title |
Patterns of nest predation and nest predator abundance in a fragmented englemann spruce/subalpine fir forest
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
1995
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Description |
In a fragmented Englemann Spruce/Subalpine Fir (ESSF) forest, I used artificial
nests to test the hypothesis that nest predation is greater at the forest edge and in
clearcuts, than in the forest interior. In this forest type, nests in clearcuts had a
lower frequency of predation than nests in the forest, yet there was no consistent
difference in the frequency of predation at the forest edge or in the forest interior, a
pattern opposite to that previously documented. However, in previous studies the
landscape was fragmented by agricultural development, where populations of
potential nest predators may be elevated as a result of anthropogenic food sources. I
found no evidence that the decrease in the frequency of predation on nests in
clearcuts was the result of a concomitant shift in the identity (from plasticine eggs)
and/or number of predators (from predator surveys) in these locations. Rather, in
habitats fragmented by logging activities, many nest predators may avoid foraging in
the clearcut because of the increased predation risk to themselves in these locations.
In addition to the effect of nest location on predation rate, there was marked
temporal variation in the frequency of nest predation. I documented an increase in
nest predation both within and between trials; and this may have been a result of
predators learning to exploit artificial nests. Studies which can identify individual
predators, and record their foraging activity in response to artificial nests, may shed
light on the mechanisms behind this temporal variation in nest predation.
While artificial nests provide an index of predation risk, future use of this
method must be cautioned against until the biases can be clearly identified. Further
study of the patterns of nest predation in fragmented habitats should instead focus
on the patterns of nest predation on natural nests, the distribution and abundance of
potential nest predators in fragmented and undisturbed forest habitats, and on how
nest predators forage within clearcut, forest edge, and in forest interior habitats.
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Extent |
2351715 bytes
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Genre | |
Type | |
File Format |
application/pdf
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Language |
eng
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Date Available |
2009-01-18
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Provider |
Vancouver : University of British Columbia Library
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Rights |
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.
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DOI |
10.14288/1.0086821
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
1995-11
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Campus | |
Scholarly Level |
Graduate
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Aggregated Source Repository |
DSpace
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Item Media
Item Citations and Data
Rights
For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use.