Chances are good that readers of this column maintain a bird feeder.\u00a0 The U. S. Fish and Wildlife Service estimates nearly a quarter of Americans feed the birds, a practice which has increased greatly in the past 20 years.\u00a0 We feed the birds to attract these creatures to us for our enjoyment and study.\u00a0 With all the bird feeders in the United States, it is logical to ask what effect all of these feeders are having on the birds.<\/p>\n
One effect of bird feeding is to allow birds to expand their ranges.\u00a0 Over the past 30 years, several species have expanded their range north into Maine.\u00a0 These species include Tufted Titmouse, Northern Mockingbird and House Finch.\u00a0 Mourning Doves have become a lot more common in Maine.\u00a0 The provision of supplemental food at feeders has been used to explain these range extensions.\u00a0 Particularly in the winter, few individuals of these species are found far from a feeder.<\/p>\n
Another effect of bird feeding is to increase the survivorship of birds.\u00a0 Members of the chickadee family have been the most-studied species in this regard because they tend to spend their entire lives in a restricted area.\u00a0 Failure to find a banded bird usually means that bird has died rather than moved to a different area.<\/p>\n
The first experimental demonstration of bird feeders improving survivorship was done in Wisconsin by two ornithologists, Margaret Brittingham and Stanley Temple.\u00a0 Brittingham and Stanley had some sites with sunflower seed feeders and others without.\u00a0 In each site, Black-capped Chickadees were captured and banded with unique combinations of color bands.\u00a0 The two workers would regularly census their areas to see which chickadees they could find.\u00a0 Missing chickadees were presumed to be dead.\u00a0 Chickadees had higher survivorship in areas where bird feeders were present.\u00a0 Greater mortality occurred during extended periods of very cold temperature.<\/p>\n
Brittingham and Erica Egan repeated this experiment in northwestern Pennsylvania.\u00a0 In addition to forested sites with and without feeders, these workers also monitored chickadees in suburban areas where there were many feeders.\u00a0 As in the earlier study, feeders had a substantial effect on winter survival.\u00a0 In forested areas without feeders, 16% of the chickadees died each month during the winter.\u00a0 In the forested area with feeders, only 7% of the chickadees died each month.\u00a0 In suburban areas with many feeders available, only 6% of the chickadees died each month.<\/p>\n
We can all attest to the effectiveness of bird feeders in attracting birds to our yards.\u00a0 People often fret when they are away from their feeders on trips and can\u2019t keep their feeders filled.\u00a0 Are their local birds in trouble when the feeders become empty?\u00a0 In other words, do birds become dependent on bird feeders for their food, particularly in the winter?<\/p>\n
The answer to these questions appears to be no.\u00a0 Birds seem to know that they cannot count on even very rich food sources for long periods of time.\u00a0 Birds will not feed solely from a continuously stocked feeder.\u00a0 One study has shown that Black-capped Chickadees only take about 25% of their daily food requirements from\u00a0 well-stocked feeders.\u00a0 The birds are hedging their bets, looking for other sources of food in case a well-stocked feeder should become empty.<\/p>\n
A definitive study to test for feeder dependency in Black-capped Chickadees was done in Wisconsin by Brittingham and Temple.\u00a0 These scientists studied two large populations of chickadees, banding most of the chickadees so that their survival could be monitored.\u00a0 For two years, one population was provided with sunflower seeds continuously.\u00a0 The other population was never given any food.\u00a0 In the third fall of the study, the feeders were removed from the first study area.\u00a0 Therefore, during the third winter of the study, neither population had access to supplemental food.\u00a0 If the chickadees in the first population had become feeder-dependent, we would expect them to have lower survival than the population that never had the benefit of supplemental food.\u00a0 Brittingham and Temple found that there were no significant differences in winter survivorship.\u00a0 The monthly winter survival rate was 84%\u00a0 (with an uncertainty of plus or minus 1%) for the population with feeders in the past and 85% (plus or minus 1%) for the population that never had access to feeders.<\/p>\n
Remember that bird feeding is known to improve winter survival of a number of birds so keeping your feeder stocked will maximize this benefit.\u00a0 However, if your feeder empties while you are away, your local birds will not be at a disadvantage to other birds that never have the benefits of bird feeders.<\/p>\n
[First published on November 28, 2010]<\/p>\n\n
Chances are good that readers of this column maintain a bird feeder.\u00a0 The U. S. Fish and Wildlife Service estimates nearly a quarter of Americans feed the birds, a practice which has increased greatly in the past 20 years.\u00a0 We feed the birds to attract these creatures to us for our enjoyment and study.\u00a0 With […]<\/p>\n","protected":false},"author":146,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_s2mail":"","ngg_post_thumbnail":0,"footnotes":""},"categories":[430],"tags":[],"builder_content":"","_links":{"self":[{"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/posts\/353"}],"collection":[{"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/users\/146"}],"replies":[{"embeddable":true,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/comments?post=353"}],"version-history":[{"count":2,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/posts\/353\/revisions"}],"predecessor-version":[{"id":355,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/posts\/353\/revisions\/355"}],"wp:attachment":[{"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/media?parent=353"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/categories?post=353"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/web.colby.edu\/mainebirds\/wp-json\/wp\/v2\/tags?post=353"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}