Direct and indirect effects of anthropogenic bird food on population dynamics of a songbird

Jason D. Fischer, James R. Miller

Research output: Research - peer-reviewArticle

Abstract

Anthropogenic bird foods are frequently credited with affecting avian population dynamics, but few studies have tested this assertion over broad spatial scales. Human-derived foods could directly impact population sizes or indirectly affect them by mediating the influence of another factor, such as disease. In 1994, a novel disease outbreak (mycoplasmal conjunctivitis) substantially reduced populations of the house finch (Haemorhous mexicanus) in the eastern United States, creating an opportunity to test whether bird feeding indirectly exacerbated or ameliorated the impacts of the disease. We assessed the effects of bird food availability on house finch populations using data from the National Survey on Fishing, Hunting, and Wildlife-associated Recreation and the Christmas Bird Count. House finch densities were positively related to the density of people providing food for birds prior to the spread of mycoplasmal conjunctivitis, suggesting that the availability of bird seed can limit the size of finch populations. Following the disease epidemic, house finch declines were greatest where the density of people feeding birds also fell dramatically. This pattern suggests that bird food could have a positive indirect effect on disease-related mortality. Our findings suggest that the collective actions of individual people have the potential to influence resource availability and population dynamics of wildlife in human-modified landscapes.

LanguageEnglish (US)
Pages46-51
Number of pages6
JournalActa Oecologica
Volume69
DOIs
StatePublished - Nov 1 2015
Externally publishedYes

Fingerprint

songbird
population dynamics
bird
food
effect
songbirds
anthropogenic activities
birds
Carpodacus mexicanus
wildlife
conjunctivitis
collective action
resource availability
food availability
hunting
population size
fishing
seed
mortality
test

Keywords

  • Anthropogenic food
  • Bird feeding
  • Bottom-up regulation
  • House finch
  • Indirect effects
  • Mycoplasmal conjunctivitis

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Nature and Landscape Conservation

Cite this

Direct and indirect effects of anthropogenic bird food on population dynamics of a songbird. / Fischer, Jason D.; Miller, James R.

In: Acta Oecologica, Vol. 69, 01.11.2015, p. 46-51.

Research output: Research - peer-reviewArticle

@article{1ed9b26dc34d40cf9afb678641902dcd,
title = "Direct and indirect effects of anthropogenic bird food on population dynamics of a songbird",
abstract = "Anthropogenic bird foods are frequently credited with affecting avian population dynamics, but few studies have tested this assertion over broad spatial scales. Human-derived foods could directly impact population sizes or indirectly affect them by mediating the influence of another factor, such as disease. In 1994, a novel disease outbreak (mycoplasmal conjunctivitis) substantially reduced populations of the house finch (Haemorhous mexicanus) in the eastern United States, creating an opportunity to test whether bird feeding indirectly exacerbated or ameliorated the impacts of the disease. We assessed the effects of bird food availability on house finch populations using data from the National Survey on Fishing, Hunting, and Wildlife-associated Recreation and the Christmas Bird Count. House finch densities were positively related to the density of people providing food for birds prior to the spread of mycoplasmal conjunctivitis, suggesting that the availability of bird seed can limit the size of finch populations. Following the disease epidemic, house finch declines were greatest where the density of people feeding birds also fell dramatically. This pattern suggests that bird food could have a positive indirect effect on disease-related mortality. Our findings suggest that the collective actions of individual people have the potential to influence resource availability and population dynamics of wildlife in human-modified landscapes.",
keywords = "Anthropogenic food, Bird feeding, Bottom-up regulation, House finch, Indirect effects, Mycoplasmal conjunctivitis",
author = "Fischer, {Jason D.} and Miller, {James R.}",
year = "2015",
month = "11",
doi = "10.1016/j.actao.2015.08.006",
volume = "69",
pages = "46--51",
journal = "Acta Oecologica",
issn = "1146-609X",
publisher = "Elsevier",

}

TY - JOUR

T1 - Direct and indirect effects of anthropogenic bird food on population dynamics of a songbird

AU - Fischer,Jason D.

AU - Miller,James R.

PY - 2015/11/1

Y1 - 2015/11/1

N2 - Anthropogenic bird foods are frequently credited with affecting avian population dynamics, but few studies have tested this assertion over broad spatial scales. Human-derived foods could directly impact population sizes or indirectly affect them by mediating the influence of another factor, such as disease. In 1994, a novel disease outbreak (mycoplasmal conjunctivitis) substantially reduced populations of the house finch (Haemorhous mexicanus) in the eastern United States, creating an opportunity to test whether bird feeding indirectly exacerbated or ameliorated the impacts of the disease. We assessed the effects of bird food availability on house finch populations using data from the National Survey on Fishing, Hunting, and Wildlife-associated Recreation and the Christmas Bird Count. House finch densities were positively related to the density of people providing food for birds prior to the spread of mycoplasmal conjunctivitis, suggesting that the availability of bird seed can limit the size of finch populations. Following the disease epidemic, house finch declines were greatest where the density of people feeding birds also fell dramatically. This pattern suggests that bird food could have a positive indirect effect on disease-related mortality. Our findings suggest that the collective actions of individual people have the potential to influence resource availability and population dynamics of wildlife in human-modified landscapes.

AB - Anthropogenic bird foods are frequently credited with affecting avian population dynamics, but few studies have tested this assertion over broad spatial scales. Human-derived foods could directly impact population sizes or indirectly affect them by mediating the influence of another factor, such as disease. In 1994, a novel disease outbreak (mycoplasmal conjunctivitis) substantially reduced populations of the house finch (Haemorhous mexicanus) in the eastern United States, creating an opportunity to test whether bird feeding indirectly exacerbated or ameliorated the impacts of the disease. We assessed the effects of bird food availability on house finch populations using data from the National Survey on Fishing, Hunting, and Wildlife-associated Recreation and the Christmas Bird Count. House finch densities were positively related to the density of people providing food for birds prior to the spread of mycoplasmal conjunctivitis, suggesting that the availability of bird seed can limit the size of finch populations. Following the disease epidemic, house finch declines were greatest where the density of people feeding birds also fell dramatically. This pattern suggests that bird food could have a positive indirect effect on disease-related mortality. Our findings suggest that the collective actions of individual people have the potential to influence resource availability and population dynamics of wildlife in human-modified landscapes.

KW - Anthropogenic food

KW - Bird feeding

KW - Bottom-up regulation

KW - House finch

KW - Indirect effects

KW - Mycoplasmal conjunctivitis

UR - http://www.scopus.com/inward/record.url?scp=84940977941&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84940977941&partnerID=8YFLogxK

U2 - 10.1016/j.actao.2015.08.006

DO - 10.1016/j.actao.2015.08.006

M3 - Article

VL - 69

SP - 46

EP - 51

JO - Acta Oecologica

T2 - Acta Oecologica

JF - Acta Oecologica

SN - 1146-609X

ER -