- Library Home /
- Search Collections /
- Open Collections /
- Browse Collections /
- UBC Theses and Dissertations /
- Resource availability and limitation for a cavity-nesting...
Open Collections
UBC Theses and Dissertations
UBC Theses and Dissertations
Resource availability and limitation for a cavity-nesting community in mature conifer forests and aspen groves in interior British Columbia Aitken, Kathryn Elizabeth Helen
Abstract
Nest-site availability limits cavity-nesting populations in harvested forests, and woodpeckers are often considered keystone species because they influence the abundance of other cavity-nesters in the community. However, little is known about the relative importance of excavated versus non-excavated holes for cavity-nesters, and the extent of nest-site limitation in mature forests. I analyzed data from 1371 holes used by 29 bird and mammal species between 1995-2006. Excavated cavities were more abundant than non-excavated and were smaller and higher above ground, but were used in proportion to their availability. To test the hypothesis that nest-site availability limited cavity-nester abundance in mature forests, I conducted two multiyear, replicated before-after/control-impact (BACI) experiments in which I altered nest-site availability. In coniferous forests, which had low cavity densities (1.9/ha) and low occupation rates (9%) prior to treatment, I added nest boxes within the size ranges of the most common excavators (northern flicker Colaptes auratus and red-naped sapsucker Sphyrapicus nuchalis). Densities of mountain chickadees (Poecile gambeli), red squirrels (Tamiasciurus hudsonicus), and northern flying squirrels (Glaucomys sabrinus) increased following box addition and returned to pre-treatment levels following box removal. In aspen groves, which had high cavity densities (16/ha) and relatively high occupancy rates (44%) prior to my experiment, I blocked the entrances of high quality cavities (those with a high probability of occupancy). Total nest abundance declined by 49% on treatment sites following cavity blocking and returned to pretreatment levels once cavities were reopened. Nest abundance of European starlings (Sturnus vulgaris), a dominant secondary cavity-nester, declined by 89% and failed to recover posttreatment. Conversely, nest abundance of mountain bluebirds (Sialia currucoides; a subordinate secondary cavity-nester) increased following cavity blocking and remained high following reopening. While woodpeckers provide an abundant supply of cavities in some mature forests, non-excavated holes may release secondary cavity-nesters from the constraints of excavator nest-site preferences. Additionally, while nest-sites may appear to be abundant and potentially non-limiting at the community level, individual species preferences, as well as interspecific interactions, may influence true nest-site availability, particularly for mountain chickadees, starlings, and small mammals.
Item Metadata
Title |
Resource availability and limitation for a cavity-nesting community in mature conifer forests and aspen groves in interior British Columbia
|
Creator | |
Publisher |
University of British Columbia
|
Date Issued |
2007
|
Description |
Nest-site availability limits cavity-nesting populations in harvested forests, and woodpeckers are often considered keystone species because they influence the abundance of other cavity-nesters in the community. However, little is known about the relative importance of excavated versus non-excavated holes for cavity-nesters, and the extent of nest-site limitation in mature forests. I analyzed data from 1371 holes used by 29 bird and mammal species between 1995-2006. Excavated cavities were more abundant than non-excavated and were smaller and higher above ground, but were used in proportion to their availability. To test the hypothesis that nest-site availability limited cavity-nester abundance in mature forests, I conducted two multiyear, replicated before-after/control-impact (BACI) experiments in which I altered nest-site availability. In coniferous forests, which had low cavity densities (1.9/ha) and low occupation rates (9%) prior to treatment, I added nest boxes within the size ranges of the most common excavators (northern flicker Colaptes auratus and red-naped sapsucker Sphyrapicus nuchalis). Densities of mountain chickadees (Poecile gambeli), red squirrels (Tamiasciurus hudsonicus), and northern flying squirrels (Glaucomys sabrinus) increased following box addition and returned to pre-treatment levels following box removal. In aspen groves, which had high cavity densities (16/ha) and relatively high occupancy rates (44%) prior to my experiment, I blocked the entrances of high quality cavities (those with a high probability of occupancy). Total nest abundance declined by 49% on treatment sites following cavity blocking and returned to pretreatment levels once cavities were reopened. Nest abundance of European starlings (Sturnus vulgaris), a dominant secondary cavity-nester, declined by 89% and failed to recover posttreatment. Conversely, nest abundance of mountain bluebirds (Sialia currucoides; a subordinate secondary cavity-nester) increased following cavity blocking and remained high following reopening. While woodpeckers provide an abundant supply of cavities in some mature forests, non-excavated holes may release secondary cavity-nesters from the constraints of excavator nest-site preferences. Additionally, while nest-sites may appear to be abundant and potentially non-limiting at the community level, individual species preferences, as well as interspecific interactions, may influence true nest-site availability, particularly for mountain chickadees, starlings, and small mammals.
|
Genre | |
Type | |
Language |
eng
|
Date Available |
2011-02-11
|
Provider |
Vancouver : University of British Columbia Library
|
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.
|
DOI |
10.14288/1.0074957
|
URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
|
Campus | |
Scholarly Level |
Graduate
|
Aggregated Source Repository |
DSpace
|
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.