Eastern bluebirds (Sialia sialis) are widespread across eastern North America, but populations appear to be susceptible to extreme winter weather. Declines in population following cold winters in states like Kentucky suggest the need to better understand winter-specific habitat requirements and behavioral responses to inclement weather. My objectives were to 1) describe the size and habitat composition of the home ranges of wintering bluebirds, and 2) examine the effects of weather (i.e., temperature, wind speed, and snow presence) on habitat occupancy, group size, and foraging behavior. My study was conducted at the Blue Grass Army Depot in Madison County, Kentucky. I radio-tracked 19 bluebirds during January and February 2010 and 2011 and recorded their locations, the size and composition (males vs. females) of groups, and foraging behavior. Mean home range size (± SE) was 29.2 ± 2.36 ha (N = 9), which is smaller than previously published estimates for wintering bluebirds. Home ranges consisted of an average (± SE) of 39.6 ± 2.6% wooded habitat and 60.4 ± 2.6% open habitat (N = 9), and edge habitat between these areas was likely an important additional component. Insectivory was the most frequently observed foraging behavior (>65% of all observations, N = 235), although shifts to frugivory were observed during periods of low temperatures, low wind speeds, and the presence of snow. Hackberry (Celtis occidentalis), mistletoe (Phoradendron leucarpum), and red cedar (Juniperus virginiana) were the most commonly consumed fruits, but high winds may restrict their potential as a food resource. High winds, when combined with low temperatures and substantial snow cover, potentially lower the efficiency of both insectivory and frugivory to sub-optimal levels, thus representing especially challenging winter conditions for bluebirds. In addition to changing foraging strategies, bluebirds appeared to respond to weather conditions by adjusting group sizes, a tactic which may enhance foraging efficiency, allow individuals to locate food resources, or both. These responses to weather occurred without an apparent shift in habitat occupancy, thus the ability of bluebirds to survive extreme winter weather may be constrained by available food resources and interacting weather conditions that may restrict foraging options.
","abstract_html":"<p>Eastern bluebirds (<em>Sialia sialis</em>) are widespread across eastern North America, but populations appear to be susceptible to extreme winter weather. Declines in population following cold winters in states like Kentucky suggest the need to better understand winter-specific habitat requirements and behavioral responses to inclement weather. My objectives were to 1) describe the size and habitat composition of the home ranges of wintering bluebirds, and 2) examine the effects of weather (i.e., temperature, wind speed, and snow presence) on habitat occupancy, group size, and foraging behavior. My study was conducted at the Blue Grass Army Depot in Madison County, Kentucky. I radio-tracked 19 bluebirds during January and February 2010 and 2011 and recorded their locations, the size and composition (males vs. females) of groups, and foraging behavior. Mean home range size (± SE) was 29.2 ± 2.36 ha (N = 9), which is smaller than previously published estimates for wintering bluebirds. Home ranges consisted of an average (± SE) of 39.6 ± 2.6% wooded habitat and 60.4 ± 2.6% open habitat (N = 9), and edge habitat between these areas was likely an important additional component. Insectivory was the most frequently observed foraging behavior (>65% of all observations, N = 235), although shifts to frugivory were observed during periods of low temperatures, low wind speeds, and the presence of snow. Hackberry (<em>Celtis occidentalis</em>), mistletoe (<em>Phoradendron leucarpum</em>), and red cedar (<em>Juniperus virginiana</em>) were the most commonly consumed fruits, but high winds may restrict their potential as a food resource. High winds, when combined with low temperatures and substantial snow cover, potentially lower the efficiency of both insectivory and frugivory to sub-optimal levels, thus representing especially challenging winter conditions for bluebirds. In addition to changing foraging strategies, bluebirds appeared to respond to weather conditions by adjusting group sizes, a tactic which may enhance foraging efficiency, allow individuals to locate food resources, or both. These responses to weather occurred without an apparent shift in habitat occupancy, thus the ability of bluebirds to survive extreme winter weather may be constrained by available food resources and interacting weather conditions that may restrict foraging options. </p>","abstract_has_math":false,"creators":["Weinkam, Todd J."],"institution":"Eastern Kentucky University","degree_name":"Master of Science (MS)","degree_level":"Master's","degree_discipline":"Biological Sciences","degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2013,"date_issued":"2013-01-01T08:00:00Z","date_published":"2013-01-01T08:00:00Z","updated_at":"2026-07-24T02:15:19Z","subjects":["bluebird","foraging","fruit","sialia","weather","winter","Ecology and Evolutionary Biology","Ornithology"],"languages":[],"rights":["Copyright 2013 Todd J. Weinkam"],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://encompass.eku.edu/etd/144","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:creator","label":"Author","values":["Weinkam, Todd J."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:publisher","label":"Institution","values":["Encompass Digital Archive, Eastern Kentucky University"]},{"key":"dc:type","label":"Dc Type","values":["Master Thesis"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Biological Sciences"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Master's"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science (MS)"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Eastern Kentucky University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["bluebird","foraging","fruit","sialia","weather","winter","Ecology and Evolutionary Biology","Ornithology"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:rights","label":"Dc Rights","values":["Copyright 2013 Todd J. Weinkam"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://encompass.eku.edu/etd/144"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Eastern bluebirds (Sialia sialis) are widespread across eastern North America, but populations appear to be susceptible to extreme winter weather. Declines in population following cold winters in states like Kentucky suggest the need to better understand winter-specific habitat requirements and behavioral responses to inclement weather. My objectives were to 1) describe the size and habitat composition of the home ranges of wintering bluebirds, and 2) examine the effects of weather (i.e., temperature, wind speed, and snow presence) on habitat occupancy, group size, and foraging behavior. My study was conducted at the Blue Grass Army Depot in Madison County, Kentucky. I radio-tracked 19 bluebirds during January and February 2010 and 2011 and recorded their locations, the size and composition (males vs. females) of groups, and foraging behavior. Mean home range size (± SE) was 29.2 ± 2.36 ha (N = 9), which is smaller than previously published estimates for wintering bluebirds. Home ranges consisted of an average (± SE) of 39.6 ± 2.6% wooded habitat and 60.4 ± 2.6% open habitat (N = 9), and edge habitat between these areas was likely an important additional component. Insectivory was the most frequently observed foraging behavior (>65% of all observations, N = 235), although shifts to frugivory were observed during periods of low temperatures, low wind speeds, and the presence of snow. Hackberry (Celtis occidentalis), mistletoe (Phoradendron leucarpum), and red cedar (Juniperus virginiana) were the most commonly consumed fruits, but high winds may restrict their potential as a food resource. High winds, when combined with low temperatures and substantial snow cover, potentially lower the efficiency of both insectivory and frugivory to sub-optimal levels, thus representing especially challenging winter conditions for bluebirds. In addition to changing foraging strategies, bluebirds appeared to respond to weather conditions by adjusting group sizes, a tactic which may enhance foraging efficiency, allow individuals to locate food resources, or both. These responses to weather occurred without an apparent shift in habitat occupancy, thus the ability of bluebirds to survive extreme winter weather may be constrained by available food resources and interacting weather conditions that may restrict foraging options.
"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf"]},{"key":"dc:source","label":"Dc Source","values":["Encompass Digital Archive: Online Theses and Dissertations"]},{"key":"dc:title","label":"Title","values":["Winter Behavior and Ecology of Eastern Bluebirds (Sialia sialis): Home Ranges, Habitat Use, and Effect of Weather on Foraging Behavior"]}]}],"canonical_facts":{"dc:creator":["Weinkam, Todd J."],"dc:description.abstract":["Eastern bluebirds (Sialia sialis) are widespread across eastern North America, but populations appear to be susceptible to extreme winter weather. Declines in population following cold winters in states like Kentucky suggest the need to better understand winter-specific habitat requirements and behavioral responses to inclement weather. My objectives were to 1) describe the size and habitat composition of the home ranges of wintering bluebirds, and 2) examine the effects of weather (i.e., temperature, wind speed, and snow presence) on habitat occupancy, group size, and foraging behavior. My study was conducted at the Blue Grass Army Depot in Madison County, Kentucky. I radio-tracked 19 bluebirds during January and February 2010 and 2011 and recorded their locations, the size and composition (males vs. females) of groups, and foraging behavior. Mean home range size (± SE) was 29.2 ± 2.36 ha (N = 9), which is smaller than previously published estimates for wintering bluebirds. Home ranges consisted of an average (± SE) of 39.6 ± 2.6% wooded habitat and 60.4 ± 2.6% open habitat (N = 9), and edge habitat between these areas was likely an important additional component. Insectivory was the most frequently observed foraging behavior (>65% of all observations, N = 235), although shifts to frugivory were observed during periods of low temperatures, low wind speeds, and the presence of snow. Hackberry (Celtis occidentalis), mistletoe (Phoradendron leucarpum), and red cedar (Juniperus virginiana) were the most commonly consumed fruits, but high winds may restrict their potential as a food resource. High winds, when combined with low temperatures and substantial snow cover, potentially lower the efficiency of both insectivory and frugivory to sub-optimal levels, thus representing especially challenging winter conditions for bluebirds. In addition to changing foraging strategies, bluebirds appeared to respond to weather conditions by adjusting group sizes, a tactic which may enhance foraging efficiency, allow individuals to locate food resources, or both. These responses to weather occurred without an apparent shift in habitat occupancy, thus the ability of bluebirds to survive extreme winter weather may be constrained by available food resources and interacting weather conditions that may restrict foraging options.
"],"dc:format":["application/pdf"],"dc:identifier":["https://encompass.eku.edu/etd/144"],"dc:publisher":["Encompass Digital Archive, Eastern Kentucky University"],"dc:rights":["Copyright 2013 Todd J. Weinkam"],"dc:source":["Encompass Digital Archive: Online Theses and Dissertations"],"dc:subject":["bluebird","foraging","fruit","sialia","weather","winter","Ecology and Evolutionary Biology","Ornithology"],"dc:title":["Winter Behavior and Ecology of Eastern Bluebirds (Sialia sialis): Home Ranges, Habitat Use, and Effect of Weather on Foraging Behavior"],"dc:type":["Master Thesis"],"thesis:degree_discipline":["Biological Sciences"],"thesis:degree_level":["Master's"],"thesis:degree_name":["Master of Science (MS)"],"thesis:institution_name":["Eastern Kentucky University"]},"updated_at":"2026-07-24T02:15:19Z"}