In the past 30 years, parrot populations have been increasing in the United States, especially in California and Florida. Most of these species of parrots have small populations that are probably a result of continual accidental and intentional releases, but at least three parrot species are believed to have self-sustaining breeding populations. They are the Monk Parakeet (Myiopsitta monachus), Black-hooded Parakeet (Nandayus nenday and Red-crowned Parrot (Amazona viridigenalis). I gathered data from the Christmas Bird Counts (CBCs) for California, Florida, and the United States since the early 1970s. I then performed linear and curvilinear regression statistics on percentage of birds seen per party-hour versus year, percentage of CBCs containing parrots versus year, and number of parrots seen per CBC circle per year.
Monk Parakeets showed significant curvilinear increases in number seen per party-hour, percentage of CBCs containing parakeets, and numbers seen per CBC circle per year, in both Florida and the United States. Red-crowned Parrot significantly linearly increased per party-hour the entire United States, but the changes in Florida and California were not significant. The percentage of CBCs containing Red-crowned Parrots significantly decreased linearly in Florida, but significant curvilinear increases were seen in both California and the United States. The number of Red-crowned Parrots seen per CBC circle per year showed a significant curvilinear increase in California, but the curvilinear changes in Florida and the United States were not significant. The parrots did show a significant linear increase in population numbers in the United States.
Black-hooded Parakeets seen per party-hour per year significantly linearly declined in the United States, but not significant changes were obtained in Florida and California. The number of parakeets seen per CBC circle per year showed significant linear increases in Florida, California, and the United States. The percentage of parrots found in CBC circles per year (range expansion) statistically significant linearly increased in both Florida and the United States, but range expansion in California was not significant over time.
The reasons for these increases in number of birds might be attributed to the growing human population, changes in land use, increased food availability and nesting locations. Only more study will determine whether any of these exotic species of psittacids will become pests in either California or Florida, or the rest of the United States. Eradication should only be used as a last resort considering there are a growing number of people who admire parrots, and their presence in the wild brings in tourist dollars.
","abstract_html":"<p>In the past 30 years, parrot populations have been increasing in the United States, especially in California and Florida. Most of these species of parrots have small populations that are probably a result of continual accidental and intentional releases, but at least three parrot species are believed to have self-sustaining breeding populations. They are the Monk Parakeet (<em>Myiopsitta monachus</em>), Black-hooded Parakeet (<em>Nandayus nenday</em> and Red-crowned Parrot (<em>Amazona viridigenalis</em>). I gathered data from the Christmas Bird Counts (CBCs) for California, Florida, and the United States since the early 1970s. I then performed linear and curvilinear regression statistics on percentage of birds seen per party-hour versus year, percentage of CBCs containing parrots versus year, and number of parrots seen per CBC circle per year.</p> <p>Monk Parakeets showed significant curvilinear increases in number seen per party-hour, percentage of CBCs containing parakeets, and numbers seen per CBC circle per year, in both Florida and the United States. Red-crowned Parrot significantly linearly increased per party-hour the entire United States, but the changes in Florida and California were not significant. The percentage of CBCs containing Red-crowned Parrots significantly decreased linearly in Florida, but significant curvilinear increases were seen in both California and the United States. The number of Red-crowned Parrots seen per CBC circle per year showed a significant curvilinear increase in California, but the curvilinear changes in Florida and the United States were not significant. The parrots did show a significant linear increase in population numbers in the United States.</p> <p>Black-hooded Parakeets seen per party-hour per year significantly linearly declined in the United States, but not significant changes were obtained in Florida and California. The number of parakeets seen per CBC circle per year showed significant linear increases in Florida, California, and the United States. The percentage of parrots found in CBC circles per year (range expansion) statistically significant linearly increased in both Florida and the United States, but range expansion in California was not significant over time.</p> <p>The reasons for these increases in number of birds might be attributed to the growing human population, changes in land use, increased food availability and nesting locations. Only more study will determine whether any of these exotic species of psittacids will become pests in either California or Florida, or the rest of the United States. Eradication should only be used as a last resort considering there are a growing number of people who admire parrots, and their presence in the wild brings in tourist dollars. </p>","abstract_has_math":false,"creators":["Lovell, Helen W."],"institution":null,"degree_name":"Master of Science","degree_level":"Thesis (restricted to Georgia Southern)","degree_discipline":"Department of Biology","degree_department":null,"school":null,"contributors":["Lissa M. Leege","Steve P. Vives"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2003,"date_issued":"2003-01-01T08:00:00Z","date_published":"2003-01-01T08:00:00Z","updated_at":"2026-07-24T02:28:40Z","subjects":["ETD","Parrot populations","California","Florida","Monk parakeet","Myiopsitta monachus","Black-hooded parakeet","Nandayus nenday","Red-crowned parrot","Amazona viridigenalis","Curvilinear regression","Christmas Bird Counts","Biochemistry, Biophysics, and Structural Biology","Biology"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"https://digitalcommons.georgiasouthern.edu/etd_legacy/1015","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Lissa M. Leege","Steve P. Vives"]},{"key":"dc:creator","label":"Author","values":["Lovell, Helen W."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.available","label":"Dc Date Available","values":["2015-08-28T07:00:00Z"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Department of Biology"]},{"key":"thesis:degree_level","label":"Degree Level","values":["Thesis (restricted to Georgia Southern)"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["ETD","Parrot populations","California","Florida","Monk parakeet","Myiopsitta monachus","Black-hooded parakeet","Nandayus nenday","Red-crowned parrot","Amazona viridigenalis","Curvilinear regression","Christmas Bird Counts","Biochemistry, Biophysics, and Structural Biology","Biology"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["https://digitalcommons.georgiasouthern.edu/etd_legacy/1015"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["In the past 30 years, parrot populations have been increasing in the United States, especially in California and Florida. Most of these species of parrots have small populations that are probably a result of continual accidental and intentional releases, but at least three parrot species are believed to have self-sustaining breeding populations. They are the Monk Parakeet (Myiopsitta monachus), Black-hooded Parakeet (Nandayus nenday and Red-crowned Parrot (Amazona viridigenalis). I gathered data from the Christmas Bird Counts (CBCs) for California, Florida, and the United States since the early 1970s. I then performed linear and curvilinear regression statistics on percentage of birds seen per party-hour versus year, percentage of CBCs containing parrots versus year, and number of parrots seen per CBC circle per year.
Monk Parakeets showed significant curvilinear increases in number seen per party-hour, percentage of CBCs containing parakeets, and numbers seen per CBC circle per year, in both Florida and the United States. Red-crowned Parrot significantly linearly increased per party-hour the entire United States, but the changes in Florida and California were not significant. The percentage of CBCs containing Red-crowned Parrots significantly decreased linearly in Florida, but significant curvilinear increases were seen in both California and the United States. The number of Red-crowned Parrots seen per CBC circle per year showed a significant curvilinear increase in California, but the curvilinear changes in Florida and the United States were not significant. The parrots did show a significant linear increase in population numbers in the United States.
Black-hooded Parakeets seen per party-hour per year significantly linearly declined in the United States, but not significant changes were obtained in Florida and California. The number of parakeets seen per CBC circle per year showed significant linear increases in Florida, California, and the United States. The percentage of parrots found in CBC circles per year (range expansion) statistically significant linearly increased in both Florida and the United States, but range expansion in California was not significant over time.
The reasons for these increases in number of birds might be attributed to the growing human population, changes in land use, increased food availability and nesting locations. Only more study will determine whether any of these exotic species of psittacids will become pests in either California or Florida, or the rest of the United States. Eradication should only be used as a last resort considering there are a growing number of people who admire parrots, and their presence in the wild brings in tourist dollars.
"]},{"key":"dc:title","label":"Title","values":["Population Increase and Range Expansion of Three Psittacids in Florida and California"]}]}],"canonical_facts":{"dc:contributor":["Lissa M. Leege","Steve P. Vives"],"dc:creator":["Lovell, Helen W."],"dc:date.available":["2015-08-28T07:00:00Z"],"dc:description.abstract":["In the past 30 years, parrot populations have been increasing in the United States, especially in California and Florida. Most of these species of parrots have small populations that are probably a result of continual accidental and intentional releases, but at least three parrot species are believed to have self-sustaining breeding populations. They are the Monk Parakeet (Myiopsitta monachus), Black-hooded Parakeet (Nandayus nenday and Red-crowned Parrot (Amazona viridigenalis). I gathered data from the Christmas Bird Counts (CBCs) for California, Florida, and the United States since the early 1970s. I then performed linear and curvilinear regression statistics on percentage of birds seen per party-hour versus year, percentage of CBCs containing parrots versus year, and number of parrots seen per CBC circle per year.
Monk Parakeets showed significant curvilinear increases in number seen per party-hour, percentage of CBCs containing parakeets, and numbers seen per CBC circle per year, in both Florida and the United States. Red-crowned Parrot significantly linearly increased per party-hour the entire United States, but the changes in Florida and California were not significant. The percentage of CBCs containing Red-crowned Parrots significantly decreased linearly in Florida, but significant curvilinear increases were seen in both California and the United States. The number of Red-crowned Parrots seen per CBC circle per year showed a significant curvilinear increase in California, but the curvilinear changes in Florida and the United States were not significant. The parrots did show a significant linear increase in population numbers in the United States.
Black-hooded Parakeets seen per party-hour per year significantly linearly declined in the United States, but not significant changes were obtained in Florida and California. The number of parakeets seen per CBC circle per year showed significant linear increases in Florida, California, and the United States. The percentage of parrots found in CBC circles per year (range expansion) statistically significant linearly increased in both Florida and the United States, but range expansion in California was not significant over time.
The reasons for these increases in number of birds might be attributed to the growing human population, changes in land use, increased food availability and nesting locations. Only more study will determine whether any of these exotic species of psittacids will become pests in either California or Florida, or the rest of the United States. Eradication should only be used as a last resort considering there are a growing number of people who admire parrots, and their presence in the wild brings in tourist dollars.
"],"dc:identifier":["https://digitalcommons.georgiasouthern.edu/etd_legacy/1015"],"dc:subject":["ETD","Parrot populations","California","Florida","Monk parakeet","Myiopsitta monachus","Black-hooded parakeet","Nandayus nenday","Red-crowned parrot","Amazona viridigenalis","Curvilinear regression","Christmas Bird Counts","Biochemistry, Biophysics, and Structural Biology","Biology"],"dc:title":["Population Increase and Range Expansion of Three Psittacids in Florida and California"],"thesis:degree_discipline":["Department of Biology"],"thesis:degree_level":["Thesis (restricted to Georgia Southern)"],"thesis:degree_name":["Master of Science"]},"updated_at":"2026-07-24T02:28:40Z"}