Sources

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Audubon Society. “American Goldfinch.” Audubon Society, 13 Nov. 2014, https://www.audubon.org/field-guide/bird/american-goldfinch.

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---. “Eastern Bluebird.” Audubon Society, 13 Nov. 2014, https://www.audubon.org/field-guide/bird/eastern-bluebird.

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---. “Northern Cardinal.” Audubon Society, 13 Nov. 2014, https://www.audubon.org/field-guide/bird/northern-cardinal.

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---. “Red-Bellied Woodpecker.” Audubon Society, 13 Nov. 2014, https://www.audubon.org/field-guide/bird/red-bellied-woodpecker.

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---. “Ruby-Throated Hummingbird.” Audubon Society, 13 Nov. 2014, https://www.audubon.org/field-guide/bird/ruby-throated-hummingbird.

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Avery, Julian. “Top Tips for Feeding Wild Birds | EarthSky.Org.” Earth Sky, 2 Sept. 2020, https://earthsky.org/earth/top-tips-feeding-wild-birds.

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Hamilton, Bill. “Why Do We Feed Birds?” Audubon Society of Western Pennsylvania, 2 Sept. 2020, http://www.aswp.org/pages/audubon-blog-why-do-we-feed-birds.

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Kosack, Joe. “Eastern Bluebirds.” Pennsylvania Game Commission, 2 Sept. 2020, https://www.pgc.pa.gov:443/Wildlife/WildlifeSpecies/EasternBluebirds/Pages/default.aspx.

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Mayntz, Melissa. “How to Recognize a Sick or Dying Bird.” The Spruce, 21 Mar. 2020, https://www.thespruce.com/how-to-recognize-sick-birds-387344.

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---. “Not All Birds Migrate - Learn Why.” The Spruce, 2 Sept. 2020, https://www.thespruce.com/why-birds-dont-migrate-4151247.

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Nelson, S. H., et al. “The Efficacy of Collar-Mounted Devices in Reducing the Rate of Predation of Wildlife by Domestic Cats.” Applied Animal Behaviour Science, vol. 94, no. 3, 3, Oct. 2005, pp. 273–85. ScienceDirect, doi:10.1016/j.applanim.2005.04.003.

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Pennsylvania Game Commission. “Backyard Birdfeeding.” Pennsylvania Game Commission, 2 Sept. 2020, https://www.pgc.pa.gov:443/Wildlife/Birding/Pages/BackyardBirdfeeding.aspx.

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Wilson, Sam. “Feeding Birds.” Project Feeder Watch, 2 Sept. 2020, https://feederwatch.org/learn/feeding-birds/.