The Birds at my Table

by Darryl Jones

  A particularly spectacular example of this relationship between feeders and undesirable urban birds is that of two most unusual invaders: tropical parrots now living in the Northern Hemisphere. Feral populations of both Monk Parakeets and Rose-ringed Parakeets (often called “Ring-necks”) originated from aviary escapees and both are thriving in their extremely different new habitat. The Monk Parakeet, a native of Argentina, now lives in highly social (and noisy!) aggregations in numerous locations in the eastern United States but most famously in the wealthier suburbs of Chicago. A study of their diet in this area found the expectedly broad and opportunistic diet for most the year, but with the coming of winter, these birds relied entirely on local bird feeders for all their food.60 In this location, Monk Parakeets persist only because of feeders, which are definitely not being provisioned with them in mind.

  It’s a similar story for the Rose-ringed Parakeets now spreading across several European countries including Spain, Germany, and Belgium.61 Their numbers in southern England are also rising steadily, and large, conspicuous flocks of these exotic-looking parrots are now regularly spotted around the picturesque parks of inner London. While subsisting on a wide range of foods, like the Monk Parakeet, Ring-necks are frequent users of feeders, even managing to use the hanging tube feeders provided for much smaller species. This raises some obvious concerns about the possible influence that these large and assertive parrots could have on the usual birds coming to feeders. After all, being on average about 400 millimeters (16 inches) in length and 120 grams (4.2 ounces) in weight, Rose-ringed Parakeets are about ten times the size of your typical Blue Tit (12 grams, or 4.2 ounces); there would not be much of a contest if these two species were trying to visit a feeder at the same time. Indeed, in some places, the presence of these big parrots appears to have effectively stopped most typical species from visiting feeders. In the center of Antwerp in Belgium, for example, friends who have been feeding birds for years report that since large numbers of parakeets arrived a few years ago, they simply don’t see tits in their gardens.

  I still vividly remember my first encounter with wild Ring-necked Parakeets. This was not in the dry, hot woodlands of India or Africa where they occur naturally, but one damp, cold May in London’s Regent Park. My bird watcher’s ears detected an unexpectedly loud, harsh screech, and large shapes swooped incongruously among the foggy elms. My companion Jim Reynolds identified them immediately: “They have even been seen in Scotland but are especially abundant around London and the surrounding counties where their numbers are definitely expanding.” We pause to watch a group of about eight scream past, their size impressive even from this distance. “Imagine that lot arriving at your feeder!”

  Such an unlikely scenario is now all too familiar to many people in London. There are plenty of stories of these parakeets taking over the nests of other hole-nesters such as Little Owls and Jackdaws. Some have even used that massive beak to destroy wooden feeders and nest boxes. But do they actually affect feeder visits by the smaller species? While Blue Tits and Great Tits, the typical English feeder visitors, obviously would not attempt to compete, they may simply stay clear of the feeder until the larger bird has left. Plenty of species share common areas, more or less amicably, in the natural world, simply by avoiding one another. On the other hand, the presence of these big, dominating birds may simply be overwhelming for the smaller species.

  These were issues investigated by Hannah Peck and her colleagues in an ingenious series of experiments undertaken in over forty London gardens.62 To simulate the presence of parakeets, a tame (but typically noisy) caged parakeet was placed near existing feeders, and the number and behavior of wild birds visiting was recorded by video camera. The information collected was then compared to feeder visits in gardens without parakeets. The really clever part of this research was determining whether the small birds were reacting to the bird itself or whether being aware that parakeets were apparently present nearby was sufficient to worry them. This was simulated by using recordings of their screeches broadcast from speakers hidden in the gardens. Finally, to ensure than any effects were not simply a general reaction of small birds to big ones, a large species occurring naturally in the area, the Great Spotted Woodpecker, was also presented, again in a cage and as a broadcast call.

  Despite the apparent complexity of all the components of this experiment, the results were remarkably clear: tits really didn’t like coming to feeders if they perceived parakeets to be around. The presence of the parakeet—both the bird itself and also the call alone—led to a consistent and significant reduction in the number of visits to the feeder, and those birds that did visit spent less time actually feeding and more time being vigilant (that is, looking about). The tits did react to the presence of the woodpecker, but far less dramatically. These results are important in being the first to demonstrate clearly that the simple presence of this otherwise nonthreatening invasive species can have a marked influence on the birds coming to feeders.

  But, as usual, that is not the whole story. The experiment may have demonstrated that parakeets disrupt feeder visits by tits, but what about the people involved? What do they think? When I met Hannah Peck to discuss her innovative research, she was quick to point out that, contrary to her own expectations, plenty of people were pleased to see these big birds. “I guess I had assumed that all feeders would be concerned about this aggressive foreign species driving out their nice English ones,” Hannah explained. “But lots of people were really excited to have these remarkable—and very attractive—parrots coming to their gardens. When you are used to a couple of tits and a robin, the arrival of these vibrant, exotic creatures out of the blue can be a great surprise and treat. It did make me realize that we tend to forget about the people in this story.”

  And So?

  This seems a good point to pause, gather our thoughts, and consider whether we have reached any conclusions about the potential way that millions of feeders may be influencing the birds around us. We have covered a lot of territory—from upstate New York to the suburbs of London—and considered a lot of claims and evidence along the way. This has been intriguing and illuminating, but it has also been sobering to admit that there is still so much we can’t be definite about. Certainly, all that birdseed seems to have influenced the behavior of some species, causing them to move to and sometimes stay in places they didn’t use to. But it is hard to disentangle this from other factors, such as a warmer climate and changes in vegetation. Feeders seem to have played a role in allowing some diseases to spread, but also in enabling affected birds to survive. And in certain extreme situations, the day-to-day survival of some birds is obviously entirely tied to access to reliable feeders. Yet probably for most birds on most days, feeders are top-ups rather than essentials. If the natural food supplies are available, our feeders are often forgotten.

  We don’t know what happens when you provide several million tons of sunflower seeds and fat balls every day across entire continents. We can’t be sure that seeing lots of Blue Tits or chickadees—or Silvereyes or magpies—is actually a sign of a healthy and resilient ecosystem, or one propped up by artificial foods. We do need to know these things if we are to be entirely satisfied that our pastime is good for the planet and not simply good for us. To tease these issues apart requires some serious science, well-designed experiments that should provide reliable findings. It’s time to look at studies of supplementary feeding.

  5

  WHAT HAPPENS WHEN WE FEED?

  Insights from Supplementary Feeding Studies

  “Maggie” is the inevitable nickname given to innumerable Australian Magpies, even though many are likely to be males. They are big, bold birds, abundant throughout the country, especially within the suburbs where the landscape of scattered, tall trees and endless well-watered lawns provides ideal habitat. These birds are very well known to Australians for two main reasons: their complex and evocative territorial song (“caroling”), which seems to capture the essence of a
n antipodean spring morn-ing; and, in violent contrast, their aggressive aerial assaults on humans trespassing too close to the nests. It may sound far-fetched, but these attacks are extremely common during the breeding season and lead to lots of injuries and anguish each year.1 Yet somehow this vigorous combination of art and aggression seems to appeal to Australian sensibilities as the species is often declared our favorite bird. Half the sporting teams in the country seem to be called the Magpies.

  Australian Magpies are also well known because they are the most frequent—and favored—visitors to the feeding tables of Australia. This may come as a surprise because while magpies are certainly broad in their dietary tastes (they will eat almost anything), they are primarily insectivores, specializing in worms and grubs gleaned from just below the surface of lawns or grassy fields.2 They have a similar foraging style to that of American Robins and the Common Blackbirds of Europe, although they are about twice the size. Although Australian Magpies will eat seed and bread and many other things, to attract magpies most people place out a much more carnivorous selection: chopped sausage, ham, pieces of bacon, diced heart, and especially beef mince (ground beef) are all commonly used, as well as cheese and pet foods. The contrast with a typical Northern Hemisphere feeding station could hardly be greater: seed and tiny tits or chickadees versus meat and massive magpies.

  The discovery of these veritable butcher’s shop smorgasbords throughout the suburbs was an unexpected and significant event in the development of my interest in bird feeding. For some time I have been interested in the wildlife of urban environments and particularly the features that enabled some species to prosper in this strange contrived landscape while many others could not. I was also fascinated by the interactions between people and the otherwise wild creatures they shared the suburbs with. Magpies were an obvious choice for an urban study species: they were abundant, relatively approachable, and most people liked them. And although they had been well studied, to my great surprise this common and familiar bird had not been investigated in its favored habitat, the suburbs. Despite being filled with people (and their cars, cats, and kids), the suburban environment offers plentiful opportunities to an intelligent and resourceful bird. Vast areas of lawns and garden beds for foraging, tall, well-spaced trees for nests and surveillance, and generally fewer aerial predators; no wonder the density of magpies in the suburbs was far higher than in rural landscapes close by.3 But there was more to the story than simply lawn and trees and fewer hawks.

  Food and space are two essentials for survival, and they are closely linked in the lives of many animals. For species capable of defending an area—a territory—against others, a home patch needs to contain all the resources required for both day-to-day survival and reproduction. For the majority of birds, the effort required in defending a patch against determined trespassers and intruders potentially seeking to pilfer your resources or make off with your partner is so demanding that territoriality is typically limited to a few weeks of the year. The process of finding a suitable area, claiming it as your own (usually through vigorous singing and displays), repelling competitors, attracting a mate, building a nest, producing and incubating eggs, and protecting nestlings from weather and predators, among other duties, is exhausting. Most birds, sensibly, are actively territorial only briefly, ceasing their boundary patrols and moving away from the breeding site once the young are mobile.

  Not so the Australian Magpie. Unlike virtually all other songbirds, these birds are permanently territorial. This means remaining continuously vigilant for potential intruders and patrolling the boundaries of their territories every day of the year. This highly unusual feature of magpie life has numerous implications for the birds, including the reality that finding a life partner means really settling down: remaining in the same patch for the rest of their lives. For such a long-lived species (Australian Magpies frequently live for more than 20 years, much longer than a robin, for example), this makes the resources provided within the territory of critical importance: everything needed for survival and reproduction—and shelter and everything else—must be suitable and sufficient more or less permanently. Although we now know that both males and females do make the occasional furtive and apparently secret sojourns out of their territories,4 these escapades are almost always brief; in general, most mated magpies spend most of their lives in the same patch. Given the obvious necessities required, it is not surprising that magpie territories in the suburbs are relatively small compared to that of an out-of-town magpie.5

  This was the background to one of our first studies of the ecology of suburban magpies. There were plenty of worthy questions to pursue, but we chose to investigate what was fundamental to them all: What was the food supply of an average territory in the suburban landscape? With my colleagues Tom Nealson and Dan Rollinson, we began the usual process of modern wildlife research: the careful capture of birds so as to measure, weigh, and attach colored leg bands to allow us recognize individuals, and the methodical observations of the birds as they went about their normal lives. These are activities familiar to field biologists studying birds anywhere in the world, except for the fact that we were attempting to conduct our research in the urban environment. And “urban” means people. Plenty of folks came over to see what we were up to. From simple curiosity and genuine interest to skepticism and outright alarm at our actual or imagined methods—we spent a lot of time patiently explaining and listening. But we also managed to obtain some important observations of our magpies.

  As has been understood for some time, Australian Magpies (like Common Blackbirds and American Robins) use their ears as much as their eyes to hunt for the grubs and worms that make up the bulk of their diet. Through some remarkable experiments using recordings of these invertebrates moving through soil,6 we now know that those characteristic side-to-side movements of the bird’s head as they concentrate on a spot on the ground immediately in front allow them to accurately locate their prey beneath the surface with pinpoint accuracy. A dramatic pause, a sudden thrust deep into the sward, and the next moment a large worm is thrash-ing at the end of the bill. It’s an approach to foraging that predisposes birds such as magpies to success in a landscape dominated by lawns and grassy fields. Magpies do very well because these well-watered, fertilized, mowed, bright-green landscapes, so characteristic of suburbs throughout the world, are also ideal for the invertebrates they thrive on.

  Our careful observations of the foraging behavior quickly allowed us to form a clear impression of the richness of lawns and sports fields as a food source for magpies. We were able to compare their feeding activities on lawns versus fields, in suburbs versus on farms, at dry times versus wet, and their foraging behavior for their own consumption compared to when they were feeding hungry young. We felt we were beginning to understand the relationship between the availability of natural foods and the success of the species in this human-dominated environment. It was when we started to focus on the chicks in the nest, however, that we began to realize that we were dealing with only part of the story.

  Baby birds still in the nest (“nestlings”) are, obviously, entirely reliant on their parents for all their food. The arrival of an adult magpie at the nest was always accompanied by pandemonium among the chicks, as is entirely normal with most birds. The level of noisy confusion in the magpie nests we watched seemed especially pronounced, although this was probably due simply to the larger size of the species and the offspring’s corresponding loudness. We could often hear the magpie nestlings long before we were close to the nest tree. This vocal onslaught must have been deafening for the adults, and grew ever more cacophonous as the chicks grew. Nonetheless, the parents labored away valiantly, returning again and again to the nest with their bills full of grubs, worms, caterpillars, moths, and skinks for the three or four ravenous craws in the nest. Watch-ing from a safe distance through a powerful telescope, we were able to observe the continuous circuit of foraging on the ground until the bill was stuffed with squirming b
aby food, the direct flight back to the nest, a brief pause to unload into one of the noisy gapes, then a long swoop back to earth to start all over again. Male and female worked at almost the same rate, arriving at the nest in turns, on a punishing schedule that continued almost all day and lasted for about five weeks.

  Breaks in this relentless routine of the adult magpies were infrequent but noticeable because they usually involved the birds flying out of sight from our particular vantage point. We simply assumed that they were somewhere within the territory that we did not have a direct view of. Subsequent investigation, however, revealed an unexpected discovery: these birds were partaking of the hospitality of some of the feeding stations nearby. We soon found that a large proportion of the pairs we were studying in the suburbs had the same arrangements: a conveniently positioned and well-provisioned larder. Not only that, this was a food source replenished daily, and because it was almost always within the boundaries of the territory, it was the exclusive domain of a local pair of magpies. And some pairs had at least three different stations to call on within their patch— although the people didn’t realize that.