Bird Feeding has had one clearly established impact:? the northward range expansion of Cardinals.? Much of this range expansion took place during the recent period of global cooling -- roughly 1940-1970.? Since the climate was cooling in that time period, bird feeding is widely accepted as the only clear explanation. ? See Dow, D.D., and D.M. Scott. 1971. Dispersal and range expansion by the
cardinal: An analysis of banding records. Canadian Journal of Zoology
49:185-198 and Beddall, B.G. 1963. Range expansion of the cardinal and other birds in
the northeastern states. Wilson Bulletin 75:140-158, for example.?

No one has even hypothesized, much less established, any negative impact from the range expansion of these lovely birds.???

An excellent summary of this issue is in: Food for thought: supplementary feeding as a driver of ecological change in avian populations. Gillian N Robb1, Robbie A McDonald2, Dan E Chamberlain3,

You can get a free copy of this by googling it.? I have the pdf if you have trouble.

RCC

Richard Carlson

Full-time Birder, Biker and Rotarian

Part-time Economist

Tucson, AZ, Lake Tahoe, CA, & Kirkland, WA

rccarl at pacbell.net

Tucson 520-760-4935

Tahoe 530-581-0624

Kirkland 425-828-3819

Cell 650-280-2965

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