Signs of Winter 11: Why Do We Feed Wild Birds?

Photo by D. Sillman

In the January 6, 2016 New York Times Magazine, Helen MacDonald (the author of the wonderful and highly acclaimed book, H is For Hawk) wrote a piece entitled “Why do we feed wild animals?” She cited a number of statistics in her second paragraph: 20 to 30% of all households in Europe, Australia and the United States put out seed for wild birds (although I have read elsewhere that 75% of households in Great Britain and 40% of households in the United States feed 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!

I started adding up my own expenditures on bird (and assorted mammal) seed and feed. I buy fifty pounds of black oil sunflower seeds every two or three weeks. That price fluctuates between $25 and $35 depending on the quality of the harvest up in the Dakotas and Minnesota. I also buy twenty-five pounds of shelled corn every four weeks or so. That usually costs around $6. I also buy ten pounds of peanuts in the shell every four weeks or so for about $11. So, if I break all that down to a cost per week, I come up with just about $15 a week as my base seed cost. Dangerously, I then multiplied that by 52 to get my annual bird (and associated mammal) feed and seed costs: $780 a year.

I’ll come back to that later.

I also have to factor in the time I put in to filling, cleaning, and repairing the bird feeders. I have to put out a small amount of seed at a time because of the neighborhood deer herd. They come in (usually in the late afternoon or early evening, but occasionally bright and early in the morning) and can clean out whatever seed is in the hopper feeders. So, to minimize losses, I only put out one scoop (about a pound) in each feeder every morning filling the feeders to about a quarter of their capacity. If the feeders are empty when I get home from work, I put out a little more seed for the evening fill-up.

This all comes up to only fifteen minutes or so a day. So, multiplying fifteen minutes times 365 days, and dividing that by 60 minutes in an hour, I come up with 91 ½ hours a year spent doing bird feeder tasks.

So for all of this money and time, there has to be a big benefit for the birds, right?

Maybe not.

According to MacDonald we really don’t have the critical data on whether backyard bird feeding benefits bird populations. We do have, though, data that clearly shows that feeding birds has an impact on their behaviors and maybe even their ongoing evolution!

Photo by D. Brensinski, USFWS

For example, In the United States northern cardinals (Cardinalis cardinalis) and American goldfinches (Spinus tristis) have in recent decades expanded their year-round ranges northward in response to the year-round abundance of feeder seed. In Europe, a small sub-population of the Eurasian blackcap (Sylvia atricapilla) a warbler that eats insects during its summer breeding season throughout northern Europe, has taken to migrate for the winter not to distant Mediterranean countries of southern Europe and northern Africa but instead to the much closer counties in the south of England, a land rich in bird feeders and attentive human care givers. These overwintering insectivores feed on fruit, suet, bread and peanuts and are able to return to their summer breeding ranges more quickly and with less metabolic energy cost than their far-south migrating counterparts. They arrive in the breeding ranges first, and extremely well fed and ready to procreate.

Photo by R. Knight, Wikimedia Commons

These England-overwintering blackcaps (picture to the left) are even starting to show distinct, morphological changes compared to 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! And, this is all due to bird feeding providing these initially off-course migrators with emergency winter rations.

So bird feeding can change bird behaviors, but is this for the “better” or for the “worse?”

Photo by nigel, Wikimedia Commons

There are concerns that bird feeders lead to excessively high concentrations of birds and may cause pathogens or parasites to be too freely exchanged between individuals. The recent case in the United States of house finches (Haemorhous mexicanus) and the explosive epidemic of mycoplasmal conjunctivitis seems to support that fear. Further, feeding birds may cause whole populations to overestimate the quality of a particular habitat possibly leading to excessively early reproduction (perhaps even 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.

Photo by A. Wolf, Wikimedia Commons

In Wisconsin, black-capped chickadees (Poecile atricapillus) 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 control populations, laid their eggs earlier, and had larger clutches. Their reproductive success rate (raising nestlings to fledge) was also higher. Winter feeding these Northern Midwest chickadees, then, did seem to benefit the species, and most studies do show this beneficial impact of stress-season feeding on survival and breeding success.

Eurasian blue tit, Photo by F.C.Franklin, Wikimedia Commons

There have been a number of other studies, though, that show the opposite. In England the blue tit (Cyanistes caeruleus) and the great tit (Parus major) (two European relatives of the chickadee) both exhibited poorer reproduction statistics (fewer eggs, fewer fledges) after a winter diet of bird feeder seed. It has been suggested that this negative impact was due to the lower nutritional quality of the bird feeder seed (too much fat and not enough protein and essential nutrients) compared to the natural foods that their winter habitats could provide. Are these birds be exhibiting some type of “metabolic syndrome” similar to that plaguing the fast food and junk food eating humans in our society?

There are laws against certain types of bird feeding. Scattering seed or bread crumbs for feral pigeons (Columbia livia domestica) can subject you to a hefty fine. There are, apparently, certain birds that are deemed to be worth feeding and other that are not. I have heard that mixed blackbird flocks can swoop in on fields of ripening sunflower seeds in the Northern Midwest and wipe out the entire crop. Methods of poisoning these blackbirds are outlined on Cooperative Exchange flyers and websites from many states. The irony of killing some birds in one place so that other birds can be fed in another place is never developed in these documents.

So why do we feed birds (and all of the other animals (the squirrels, the rabbits, the chipmunks, and, yes, even the deer))? Why do we spend so much time and money in this task? 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 be part of the natural world! It’s feeling worth much more than the cost of $780 and 91 1/2 hours of work a year! We should all strive, though, to give our birds as healthy a diet as we can and also as a clean and as predictable a feeding place for them as possible!