by Darryl Jones
But what about winter? Obviously food is seriously limited when it is cold, and the birds that don’t migrate away clearly find it hard to survive. Providing relief for the suffering seems to be where all this began, and it remains the most pronounced motive for feeding in the Northern Hemisphere. Yes, these birds do need food in winter and people tend to respond. This is an entirely different scenario, however, involving assisting individuals for welfare reasons rather than whole populations for conservation. Survival through the winter can be significantly enhanced by having access to supplementary food, so more of these birds are likely to make it through to the following spring. These survivors will include some that are sick, maimed, infectious, and impaired in some way. Nor-mally, the natural process of winter’s demands would have removed these individuals from the population, leaving only the strong and tough to survive. With access to food, however, birds that would normally have expired may get to breed. Feeding may, therefore, be canceling out what was a “natural” (in the sense of natural selection) process, with potential evolutionary implications for the species. See what a simple feeder can do!
2.The bird food industry is relatively new and extremely influential.
People have always fed wildlife spontaneously, and even systematic, planned, organized feeding has been around for quite a while. Traditions of suet balls, feeding tables, and peanut hangers, for example, go back centuries. Virtually all the food and apparatus used was homemade or derived from existing supplies: food scraps from the kitchen, grain from farm supplies placed on simple feeding platforms whipped up for nothing in the home workshop. The arrival of mass-produced, ready-made, packaged bird-food mixes and feeders utterly transformed a private domestic activity with negligible monetary cost into a gigantic industry based on unbe-lievable amounts of money being paid for seed and associated hardware. This has happened remarkably quickly, with much of the growth occurring since the 1980s.3
The influence of the big corporations involved in the bird food industry is not simply strong and pervasive. In many ways, these commercial enti-ties run the show from top to bottom. From the beginning, their entirely legitimate financial objective of selling products and enhancing demand has driven every aspect of the bird-feeding movement. Industry marketing has always been extremely effective in recognizing the motivations and meeting the needs of the feeding public—well ahead of the researchers—and in the process has built an extraordinarily successful marketplace where consumers and producers interact with mutual satisfaction. Provided that nutritional standards are preserved, quality is rigidly maintained, and their products are rigorously assessed (that they don’t add pesticide would be nice), it is hard to fault it as a successful model for business. Those are major caveats, however, and there are some very big and conspicuous exceptions. Nonetheless, the suppliers appear to be meeting (as well as ma-nipulating) the demand of eager customers in innovative and imaginative ways. And let’s face it, visiting a bird-feeding outlet can be a real pleasure, full of motivated people sharing stories of their latest visitation. Perhaps the industry’s greatest triumph has been in convincing the buying public that they are actually interested in birds rather just selling things.
3.The move from feeding only in winter to year round is profoundly important.
Winters are tough, and small nonmigratory birds are unlikely to make it through unless they have access to a reliable food supply. Away from the city, this might be fat from a dead animal, insect pupa, the last fruit and seeds, or the suet balls in a farmer’s garden. These days, the suburbs are full of feeders, topped up regularly right through winter by caring people. In many places, however, these supplies end when the warm weather returns. Indeed, feeding birds was traditionally a winter-only activity, humane assistance to struggling birds in times of trouble. Feeding in summer was thoroughly discouraged.
This traditional culture of feeding seasons is changing, however, dramatically and rapidly, especially in Europe. In many countries, feeding now occurs year round and is actively promoted, not only by the people selling the seed but also by the bird and conservation groups. Of course, feeding also occurs in places without serious winters, generally in the Southern Hemisphere where the reasons for feeding have always been different. In general, the size of the industry in such countries is far smaller. Throughout the Northern Hemisphere, increasingly, the feeders are full all year round. This is both an unparalleled cultural shift as well as a monumental ecological alteration. It’s too soon to know what is going to happen next, but I think we can expect fundamental changes to entire bird communities and possibly even ecosystems.
4.Even a little supplementary food leads to change.
While research into the implications of bird feeding in suburban environments is still fairly limited, scientists do know an awful lot about the effects of what adding food can mean for birds in natural areas. Hundreds of careful experiments have shown conclusively that even small amounts of additional food usually lead to some sort of change in the lives of birds.4 Although many alterations in activities and behavior have been noted in a wide selection of species, typical changes include starting breeding earlier, breeding more often, and producing more young. When you include an increased likelihood of surviving through to the next spring, one rather obvious conclusion drawn from these short-term, small-scale, strictly controlled experiments is, quite simply, that more food means more birds. Sometimes a lot more birds.
More birds might sound like an excellent outcome, especially if a species is struggling. This is just what the numerous conservation programs that employ supplementary feeding hope to see, after all. In the suburbs, however, the recipients are almost always regular garden birds, and these are not being supplied with, say, 30 grams of sunflowers every second day for the two weeks leading up to nest construction, or whatever the protocol being followed in a carefully monitored experiment. No, indeed, these birds are likely to have unlimited access to as many feeders as they like, every day of their lives! Let me say it again: the wild bird–feeding phenomenon we are engaged in is a gigantic supplementary feeding experiment on a continental scale.5 But without carefully devised protocols or careful monitoring. And no end point. And because this experiment started decades ago, we have no way of knowing what the outcome has been or will be.
5.Feeding changes entire ecosystems.
Big call? I don’t think so, not any more. It doesn’t take much to link the logic of the preceding statements to the suspicion that all that food must be having a fundamental influence at the ecosystem level. Several important studies on the relationship between the amount of supplementary food and the abundance of local birds have demonstrated clearly that there are many more birds in places with lots of feeders.6 The density of birds is closely correlated with the density of feeders. Interestingly, because the number of feeders is often related to the level of affluence of human communities, poorer areas are also likely to have a lot less birds; there is less cash to spend on feeding. This is important because less well-off neighborhoods already tend to have less access to the benefits associated with contact with nature (see below), such as green space. Mind you, in the UK at least, the lowest levels of feeding have been found to be in the richest areas.7 But while not really unexpected—birds are more likely to hang around in areas with plenty of easily accessed food—this relationship between feeders and bird abundance does again confirm the profound, landscape-level influence that is possible due to a simple, private action. It’s just another feeder, but it may be one more rather commonplace illustration of the cumulative impact that the individual decisions of many people can have over vast areas. (Google “Anthropocene.”)8
Birds have always moved around in response to the availability of resources, of course. It’s the same with feeders. Although plenty of people fill their feeders daily, most do not, and many are irregular suppliers at best. With their survival contingent on the waxing and waning of seed crops, berry production, and beech masting, and on the occasional fort
uitous bonanza (an overturned grain truck or a dead moose, for instance), birds everywhere have survived by being opportunistic. They take advantage of what is on offer, then move on when it’s gone. Or maybe not if the supply is predictable and reliable, like a feeder that is topped up daily. But even regular sources can suddenly dry up or shut down. People with feeders eventually stop, leave, retire, die. When that happens, the birds usually just move on. If they don’t, they would starve, but the well-publicized concern that birds may become dependent on our supplies have largely proved to be baseless. Apart from times when conditions are obviously challenging—prolonged snow, excessive heat, drought—the birds almost certainly don’t rely on our feeders. Several decisive experiments, involving shutting down the food supply after a long period of use (in the most famous case, after 26 years), found no evidence of impact on the birds that had been using the feeders, even in winter.9 The birds simply moved on. (Remind me again about that golden rule . . .)
It has taken a while to convince some people, but cities really are a rather special form of ecosystem. Admittedly, there are some dramatic differences between urban ecosystems and the natural sort, but they can be studied in much the same way. Apart from the obvious feature of being utterly dominated by the presence and activities of one particular species, urban ecologists are starting to reveal that, far from being nature-free zones, many cities actually support remarkably high levels of biodiversity. In part, this is because the original settlements were usually sited on fairly productive land, places were food could be grown to supply the growing community. And although the process of urbanization inevitably wipes out much of the local biodiversity, once gardens are planted, parklands established, and reserves of the original landscape declared, animals of all kinds move in, from outside the township or from the reserves within. They will find a very different type of environment, however: noisier, smellier, and full of people and their supposedly tame companion predators. Only species with certain characteristics are going to prosper—tolerance, clev-erness, cunning, and aggression are all advantageous qualities—but urban environments also offer some definite advantages for those game to try.10 Food is fundamental, and because people tend to like gardens, the associated fruits, berries, seeds, and, of course, insects, are all there for the taking. It is not always appreciated, but well-established suburbs typically have far higher numbers and species of plants than the surrounding forests or woodlands. Add to these “natural” resources the huge amount of food provided by feeders, and it is hardly a surprise that urban environments support plenty of birds.
Plenty of birds but not necessarily plenty of species. Studies that found that the density of feeders predicted the abundance of birds also found that there was no similar relationship with the number of different species. In other words, all that food had little effect on diversity. In natural ecosystems, complex food webs can be constructed showing all the ways that myriad species interact (read “consume”) with their food types: granivores, fructivores, carnivores, scavengers, and so on. The most stable ecosystems are also the most complex, and the most resilient to distur-bance. We have always known that urban ecosystems are quite different, obviously, but recent detailed investigations of some urban bird communities found them to be extremely “unbalanced” and therefore potentially susceptible to sudden change.11 Such systems, theoretically, have low resil-ience. The reason: an unusually large proportion of the species are associated with a single food source: bird food.
6.Feeders attract feeder birds.
You may be lucky and have a lot of different species visiting your feeders. I recall walking around a large snowy garden in Ithaca, New York, and counting more than 20 different species on the numerous feeders. When I asked why there were so many species in one place, my host, Natalie, explained. “If you want diversity, provide diversity. Here we have nyger, black sunflowers, sunflower hearts, safflower, white millet, suet . . .” Each feeder was attracting a different clientele and there were enough feeders for the visiting birds to be able to avoid one another. I think it was the greatest diversity of feeder birds I have seen, though I have been told of gardens where you can see even more.
These numbers are notable because they are extreme exceptions. Generally, a typical feeder attracts relatively few species, depending on its location and the current climatic conditions. It will be news to no one but does need to be said: our feeders are utilized only by species that are attracted to the type of food being offered. In most parts of the world, this will be seeds of various kinds, although just a few—black sunflowers being the leader—have dominated the market for quite a while. Seeds, as singles but even more so as mixes, are sold in vast amounts simply because many local garden bird species are granivorous. There are plenty of other sorts of food on offer as well, including suet, sugar mixes, and mealworms, for example, although these may been highly seasonal (such as suet) or species specific (the sweet solutions loved by hummingbirds, for example). In terms of the overall food supply across the landscape, however, it really is dominated by seeds.
The visitors that attend our feeders are certainly not a representative sample of the much more diverse community of local birds. That is not necessarily a problem; we all realize that there are species just too shy or specialized to be attracted to a feeder. Insectivorous species rarely visit feeders, even when mealworms are on offer (in many cases, the seed eaters tend to eat them first anyway). It does mean, however, that all the different feeders in the world cannot pretend to benefit the whole local bird community, as is sometimes claimed. And this can be a problem if some of the feeder species actually drive others away. Certain birds are naturally belligerent and will often roughly displace other, less pushy species. Usually, these victims tend to wait nearby for the bullies to leave before resuming their feeding (assuming anything is left). Sometimes, however, some species, typically those that are highly social, may occupy the vicinity of the feeder or an entire garden for long periods of time, effectively keeping all other species away. And sometimes the species attracted are not wanted at all. In a recent New Zealand study, for example, feeders were found to significantly increase the local abundance of introduced species such as House Sparrows and Spotted Doves, while some native species that didn’t even use feeders declined.12
7.Most feeder birds eat mostly nonfeeder food.
Sometimes we seem to be convinced that our well-supplied feeders are almost solely responsible for keeping a lot of the local birds alive. After all, think of the time, money, energy and care we have invested in seed, feeders, and the like. I am sorry to have to break it to you, but this is extremely unlikely. Indeed, you may not want to hear it, but most of “your” birds also visit twelve other feeders around your area. Perhaps even more disturbing news is that, apart from some critical periods of physiological stress (such as when females produce eggs and during severe cold), or when certain key natural foods are extremely limited (late summer can be dire), the diet of most birds most of the time is not obtained from feeders at all. Sensibly, almost all birds, including the apparently more specialized, seem to have a rather diverse diet where possible, with a sizeable proportion of insects typically being included. The very few studies of the overall diet of several small bird species indicate that a wide range of different food types is necessary in order to cover all their nutritional bases.13 These requirements change continuously through the seasons and with the various stages of reproduction. Sometimes they need more protein, sometimes calcium, sometimes some obscure micromineral found only in thistle heads. Even a good supply of Premium WildBird PowerMix will never provide all the nutrition that is needed.
This is important news with a humbling conclusion: our birds almost certainly don't need us as much as we need them.
8.Feeders do spread disease.
I have learned an enormous amount during this project but nothing as disturbing as the spread of horrifying bird diseases described in Chapter 6. There is no shying away from this undeniable fact: fee
ders have been directly involved in the rapid dissemination of House Finch conjunctivitis in the United States, trichomoniasis in the UK, and almost certainly other major epidemics among feeder birds. Feeders represent a textbook example of a perfect model of rapid and sustained contagion: highly infectious individuals are able to mix closely with concentrations of potential recipients with continuous mobility among many other similar locations. Once this process gets going it is virtually impossible to stop. With no effective treatment, House Finch disease simply burned its way through the popula- tion, resulting in the deaths of millions of birds. Trichomoniasis in Great Britain reduced the national population of Greenfinch by around a third over just a few years.14 Wildlife disease experts frequently note that it is astonishing that there have not been many more similar epidemics. Future catastrophes are almost inevitable.
Unless we all take this component of our role as feeders extremely seriously. Everyone knows that they should be diligent about cleaning their feeders. Besides, we never see any sick birds at our place. And that is the normal, daily experience. Even during serious outbreaks, most sick or dying birds disappear fast; the lingering House Finches or the conspicu-ously pox-encrusted Greenfinches are notable exceptions. One of the paramount impressions I hope that feeders will take away from this book is that their garden—or balcony or window ledge—and its feeder are part of a vast, interconnected network of dozens or hundreds, maybe more, across the landscape, with birds moving endlessly between these points. Feeders are points of bird-to-bird contact, as well as sources of food, and therefore they are ideal places for picking up infection. We can’t see this web of exchange or imagine the complexity of the bird traffic involved, but we do need to stop and appreciate both the extraordinary invisible network of contact all our feeders have brought to the world. Such a network simply did not exist before we invented it. The World Wide Wings Web, almost. And, a lot like the Internet, interchange is now possible on a truly grand scale, and with that, so are genuine risks.