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 and reproductive success of birds with and without access to feeders. The most thorough studies consider the effects of supplemental food given during the nesting season, and these types of studies tend to find that feeding has a positive effect on reproductive success; in other words, fed birds have more or healthier young. Furthermore, looking at bird populations overall, feeder-birds tend to be doing better than non-feeder birds (see our blog post about population trends in feeder and non-feeder birds). However, there is very little research demonstrating either positive or negative effects of feeding birds during the winter, so we still have much to learn about the effects of winter bird feeding on survival and fitness. This is why it is especially valuable for people who feed their birds to contribute counts to Project FeederWatch. Simultaneously contributing to programs such as NestWatch can help even more, by allowing us to build a database of winter bird feeding practices and local nesting success. These comparisons are complex, so the more data, the better! 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. The benefits include learning more about birds and the joy of connecting with the natural world.