Audubon Blog: Why Do We Feed Birds?

Audubon Blog: Why do we feed wild birds?

Contributed by Bill Hamilton

In the New York Times Magazine (January 6, 2016), Helen MacDonald (the author of H is For Hawk) wrote an article entitled “Why do we feed wild animals?” MacDonald stated that 20 to 30% of all households in Europe, Australia and the United States put out seed for wild birds and that the cost of all of this wild bird feeding amounts to over three billion dollars a year. There are many of us, then, who put out seed and lay down a substantial amount of money to do it.

According to MacDonald we really don’t know if bird feeding benefits bird populations. We do have, though, observations that clearly show that feeding birds has an impact on their behaviors.

For example, In the United States, Northern Cardinals and American Goldfinches have, in recent decades, expanded their year-round ranges northward in response to the abundance of feeder seed.  In Europe, a sub-population of the Eurasian Blackcap, a warbler that eats insects during its summer breeding season throughout northern Europe, now overwinters in the south of England, a land rich in bird feeders laden with suet, fruit, bread and peanuts, instead of making the energetically expensive migration to northern Africa.

These England-overwintering Eurasian Blackcaps are even starting to show morphological differences from their south-migrating counterparts. The “English birds” have rounder wings and longer, narrower bills. In the thirty generations that these birds have been studied, a measurable, evolutionary change has been observed!

So, bird feeding can change bird behaviors and stimulate evolution, but are these changes for the “better” or for the “worse”?

Bird feeders can lead to very high concentrations of birds, and this may cause pathogens or parasites to be very freely exchanged between individuals. The recent case in the United States of house finches and the explosive epidemic of mycoplasmal conjunctivitis seems to support that fear.

Also, feeding birds may cause populations to overestimate the quality of a particular habitat possibly leading to early seasonal reproduction (perhaps before the essential natural food that the species requires to nurture its young are available) or to excessively high nesting densities in areas that cannot support the birds if artificial feeding is interrupted or suspended.

In Wisconsin, Black-capped Chickadees that had been given access to winter bird feeders had a much higher winter survival rate (69%) compared to control populations (only a 37% survival rate). These chickadees with access to winter seed also made their nests earlier than controls and had larger clutches. Their reproductive success rate (raising nestlings to fledge) was also higher. Most studies, in fact, show these beneficial impacts of feeding on survival and breeding success.

There have been a number of other studies, though, that show the opposite. In England, the Blue Tit both exhibited poorer reproduction statistics (fewer eggs, fewer fledges) after a winter diet of bird feeder seed. This negative impact was possibly due to the lower nutritional quality of the feeder seed (too much fat and not enough protein) compared to the natural foods that their winter habitats could provide.

So why do we spend so much time and money feeding birds and so many types of other animals? Maybe, and this was the conclusion that Helen MacDonald so beautifully articulated in her article, “it surrounds us with creatures that know us, are able to forge bonds with us, have come to regard us as part of their world.”

It is, indeed, a pleasure to feel a part of the natural world! We all must strive, though, to give our birds as healthy a diet as possible and a safe and clean a place to enjoy it!              

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