What are the costs and benefits of bird feeding?
It is difficult to assess the costs and benefits of bird feeding because it is difficult to compare the health of birds without access to feeders with birds that frequent feeders. Only one study was able to obtain some sound results. That study found that any benefits of feeding only appear to occur sporadically under extreme climactic conditions. No research has been able to demonstrate a cost. Aside from costs and benefits to birds, there is a cost and benefit to humanity. The costs are obvious–the expense of bird feeding supplies.
