Animals as Neighbors: The Past and Present of Commensal Animals

Chapter 2 - Sources of Evidence

25 2 sources of evidence Up to this point, we have considered commensalism rather in theory or principle, as a life strategy adopted by some species. Another way of approaching the topic is to ask how we recognize commensalism: how do we decide that the term applies to this or that population of animals, either today or in the past? This may seem self-evident, but we shall see that there are many often subtly different ways of using human living space for food and shelter, necessitating criteria that can be applied in a wide range of circumstances. Furthermore , our concern here is with the past and present of this strategy, so we need criteria that can enable us to recognize commensal behavior in the past beyond direct observation. other country that it is, the past presents further challenges. We have contemporary documents and recorded observations for the more recent centuries, but even here we have to take care to understand what people may have chosen to record or not to record, and the motivation or agenda that may have influenced the making of that record.1 For much of the human past, of course, we have no contemporary documentation, and the archaeological record, the surviving scraps of material evidence, is all that we have. material evidence—most of it garbage in at least one sense—has biases of its own, though it is perhaps less susceptible to deliberate “storytelling” than are most historical documents. For times such as the medieval period where the two sources of evidence overlap, we should not assume that they will concur, or be concerned if they do not.2 The ConTemPorArY reCorD The whole point of drawing attention to our commensal neighbors is that they are the familiar everyday animals that live around us, so we hardly need criteria for recognizing them: we know them when we see them around our homes and gardens or hear them rustling through the attic. rats, pigeons, and urban foxes are clearly subject matter for this book. some other familiar species may need more consideration. starlings Sturnus vulgaris, for example, are abundant enough around our towns and cities. Are they commensal animals? The abundance of starlings in some english towns, especially in winter, can be quite striking. The species has an evident taste for Victorian buildings, developing huge roosts on municipal stone buildings and on seaside piers.3 however, although starlings will take advantage of food handouts in parks and gardens, they are by no means specialist garbage feeders. many of the birds in those huge winter roosts will fly out of the town center by day in order to feed on nearby farmland, 26| Chapter 2 or on the grasslands provided by our sports grounds and recreation spaces. This is almost the inverse of the strategy applied by some foxes that live on the leafy edge of town by day, then venture into the urban mean streets by night in order to raid garbage bins. both species are commensal for the purposes of this study, however. The foxes benefit directly from food and other debris around human settlements, while starlings make direct use of our built environment for shelter while gaining feeding benefit from the adjacent modified environment. by colonizing buildings, starlings are simply adapting, or exapting, a behavior that is typical of the species.4 in rural areas, starlings develop similarly huge winter roosts in reed beds, swirling like great clouds of chattering smoke before descending to pass the night in the relative warmth and safety that comes with sheer numbers. That same behavior readily adapts to a municipal building or to a seaside pier. even present-day observational evidence has to be used with due care. in the internet age, informal, anecdotal records are quickly spread and proliferated, and it can be remarkably difficult to trace the original factual observation on which one charitably assumes they were originally based. Do urban foxes actually prey on household cats? or has a fear that they might do so elided into “knowing” that they do? or did one fox, once, get the better of an unfortunate cat, and therefore it is assumed that “foxes eat cats”? Perhaps all of the above? similar questions attend the predation of cats by coyotes in north American towns, and we return to this topic in a later chapter. The point here is the care that has to be exercised when using informal records of animals raiding garbage bins, living in roof spaces...