Neighbourly behaviour

7 June 2013 by Malcolm Campbell, posted in Biology

And the question comes immediately to mind, for which I haven’ any answer — what power do wild animals have, to melt our strong, hard human hearts, in the faintest stirring of an eyelid?" from Encounters with Mrs. Raccoon by Raymond Souster (1921-2012)

Our cities are curious constructs.

Designed by a species that is very much of Nature, cities seem deliberately at odds with Nature. The concrete, bricks, and asphalt of the built environment push the natural environment to the margins, or constrain it within defined boundaries. The natural world is permitted to manifest itself in a manicured, idealised fashion within gardens and yards, or given opportunity to flourish in a more unrestrained fashion within carefully delimited parks. Domestic companion animals are welcome to reside within urban borders, but this same lenience is sometimes not afforded to their wild counterparts. In some instances, wild animals are deemed pests, and therefore poisoned, trapped, or relocated beyond the reaches of the city.

The presence of Nature in cities doesn’t seem so much a peaceful coexistence as it does a reluctant tolerance on the part of city dwellers. And yet, Nature finds a way to insinuate itself even within the relative intolerance of the urban landscape.

Plants burst forth and bloom from cracks in pavements. Insects occupy nooks and crannies. Birds soar in urban canyons. A handful of mammals seem to flourish amongst their city-building primate hosts.

Of the mammals that flourish in an urban environment, the raccoon is worthy of special recognition.

The raccoon, Procyon lotor, is a North American native, readily recognised by its iconic masked face and striped tail.  Raccoons have the size and appearance of a small dog. In keeping with this, their scientific name is neo-Latin for “before-dog washer”.

The English name “raccoon” owes its origins to the first nations’ Powhatan language, which derived the name from the proto-Algonquin root ahrah-koon-em, which means "the one who rubs, scrubs and scratches with its hands". The name points to a readily identifiable raccoon behaviour, that of incredible dexterity with its paws. In fact, the Aztec name for raccoon translates to "the one who takes everything in its hands". When it comes to city living, it is certainly true that the raccoon has taken the matter in hand.

Raccoons seem uniquely suited to city life. Like humans, raccoons possess the physical and behavioural traits of a generalist – they are great opportunists, able to take up residence whatever space is accessible, with an appetite for whatever is available. Their silver-grey fur has an undercoat that insulates against the cold of winter and the heat of summer. A nocturnal lifestyle enables them to sift through the spoils of urban refuse, without coming into conflict with their human cohabitants. Surprising strength and persistence, combined with great climbing skills and dexterity provides raccoons with access to both preferred nesting sites and food sources that might otherwise be unavailable.

Evolution appears to have provisioned raccoons with a suite of traits honed for an urban niche. Indeed, in urban environments, the leading cause of raccoon mortality is neither predation nor automobile-related, but rather old age and disease. In fact, raccoons have a greater chance of being killed by an automobile in a surburban setting, as well as being beset by disease in this environment. The urban environment is so conducive to raccoon life that they can achieve remarkable densities. It is not uncommon for urban environments to host 50-100 individuals per km2, and there are reports of 160 individuals per km2 in some locales.

Like their cohabitating human denizens, raccoons live in extended social groups. It is not uncommon for female raccoons to give birth to three kits at a time, and these will join a relatively tight knit grouping, consisting of up to 5 or 6 individuals. They range over defined territories, located near nesting sites. Individuals within groups work cooperatively, enabling access resources that might be unobtainable by an individual.

In the neighbourhood in which I live, the collective work of raccoons is evident on almost a daily basis. One night, a group (or posse, as we call them) of raccoons rolled up the newly laid turf grass of a neighbour’s lawn to access the grubs beneath. Another neighbour noticed the internet cable in his home office moving. When he peered into the hole in the floorboards where the cable emerged, a masked eye peered back at him – a raccoon posse had lifted a corner of his roofing, and made their way into the inner recesses between the floors of his house. Indeed, raccoon posses act like night crews, setting about their business at dusk, such that an evening dog walk isn’t really complete without at least one raccoon sighting.

So successful are raccoons in their night work that it has changed human behaviour. Every week, compostable waste is collected from each house using “green bins” – medium-sized plastic refuse containers. Bins are placed curbside on the evening before pickup. As such, they present an attractive, potential all-night diner for enterprising raccoons. The challenge for the raccoons is that the lids of the green bins have been manufactured in such a way that it is meant to be “raccoon proof”. Except it isn’t.

In some regions of the city, raccoons seem to have “solved” the “raccoon proof” green bin lids. Appropriate, directional tipping over of the bins will crack some lids open, liberating the desired contents within. Casual observation reveals that neighbourhoods tend to be either “non-tipped” or “tipped”, as though the raccoons in one group have figured out the lids; whereas, others have not. It’s a striking, albeit anecdotal, observation – well worthy of further investigation.

In neighbourhoods where raccoons have solved the lid problem, they have shifted human behaviour to compensate – so that walkways and streets are not littered with compostable waste. In these neighbourhoods, humans have rigged “anti-tipping” mechanisms. These vary from elaborate, bungee-cord-based tie-downs to merely keeping the bin in an inaccessible location until the human pick-up crew arrives. It’s intriguing that human behaviour here has been modified by the raccoons – score one for Nature.

What is truly remarkable about the coexistence of humans and raccoons is our relatively poor understanding of raccoon behaviour. Concerns about transmission of non-human-animal-borne diseases, zoonoses, has led us to develop a good understanding of raccoon demographics in cities.  We have good knowledge of raccoon population structure, mortality, and disease-carrying capacity. In fact, the latter is major driver in viewing raccoons as pests.

As potential reservoirs of diseases such as leptospirosis, canine distemper, rabies, and avian influenza, raccoons are generally viewed by local authorities as a public health concern, if not an outright pest. This is intriguing in light of the fact that domestic and feral companion animals, which can similarly serve as hosts for these diseases, and which occur in at least as high population densities, seem much less a concern – perhaps because they are more amenable to vaccination and other disease-control strategies. Be that what it may, our focus has been much more on pest-related issues of raccoons’ shared residence in our cities, than on intriguing aspects of their biology and behaviour. This is unfortunate, because it has driven some abhorrent human “animal control” behaviours, and caused to neglect Nature in our midst.

While recognition of raccoon “intelligence” is prevalent today, it is a general impression as opposed to one based on a broad foundation of knowledge. Just over a century ago, there was a call to focus on raccoon behaviour. At this time, studies explored multiple aspects of raccoon behaviour, including problem solving skills and memory. Raccoons were observed solving locks, and retaining this ability for up to three years after discovering the solution.

Intriguingly, in one study, with individual raccoons given names such as Jim and Dolly, raccoons were found to not derive knowledge by watching the actions of others. It is difficult to know what to make of this in light of observations like the neighbourhood-specific nature of green-bin tipping – perhaps this reflects the inability of a learned behaviour to spread between groups. Alternatively, it could be that the observations or experimental methods employed to observe the handful of individuals in the study in question did not accurately test or sample the raccoon population. This underscores the fact that much remains to be known about raccoon behaviour. Since the studies in the early part of the last century, little has been done to better understand raccoon behaviour.

But why bother focusing on raccoons and their behaviour?

Raccoons provide resident natural history. They are fascinating to observe, and provide readily available insights into the non-human animal mind. As such, raccoons might function as excellent conduits through which city-dwelling humans could better connect with nature.

Raccoons provide an ideal opportunity for citizen science – engaging non-scientists in the discovery process. Citizen scientists could shade in details around raccoon behaviour, based on observation-based “field work” in the urban environment.  As such, raccoons could function as a link to both the scientific enterprise, and the natural world.

And raccoons are merely a starting point. There are other city-resident animals the world over that could yield similar benefits.

Beyond this, raccoons, like us, share an evolutionary history that has favoured inquisitiveness and dexterity. These traits have made us excellent co-habitants in our built environment. We share the same air, water, and, indeed, food in this environment. We might learn something about ourselves, and about our place in this environment, by better understanding our nimble neighbours.

Images: All photographs by Malcolm M Campbell.

References:

Broadfoot JD et al. (2001) Raccoon and skunk population models for urban disease control planning in Ontario, Canada. Ecological Applications 11: 295-303

Cole LW (1907) Concerning the intelligence of raccoons. The Journal of Comparative Neurology and Psychology 17: 211–261

Cole LW & Long FM (1909) Visual discrimination in raccoons. Journal of Comparative Neurology and Psychology 19: 657-683

Davis HB (1907) The raccoon: A study in animal intelligence. The American Journal of Psychology 18: 447–489

Davis H (1984) Discrimination of the number three by a raccoon (Procyon lotor). Animal Learning & Behavior 12: 409-413

Duncan C et al. (2012) Leptospirosis and tularaemia in raccoons (Procyon lotor) of Larimer Country, Colorado. Zoonoses and Public health 59: 29-34

Graser WH et al. (2012) Variation in demographic patterns and population structure of raccoons across an urban landscape. The Journal of Wildlife Management 76: 976-986

Gross J et al. (2012) Raccoon use of the urban matrix in the Baltimore Metropolitan Area, Maryland. Urban Ecosystems 15: 667-682

Hunter WS (1913) The delayed reaction in animals and children. Behavior Monographs 2: 1–86

Jardine C et al. (2011) Longitudinal study on the seroprevalence of avian influenza, Leptospirosis, and Tularemia in an urban population of raccoons (Procyon lotor) in Ontario, Canada. Vector-Borne and Zoonotic Diseases 11: 37-42

Luther E (2013) Tales of cruelty and belonging: In search of an ethic for urban human-wildlife relations. Animal Studies Journal 2: 35-54

Pettit M (2010) The problem of raccoon intelligence in behaviourist America. British Journal for the History of Science 43: 391–421

Prange S et al. (2003) Demographic factors contributing to high raccoon densities in urban landscapes. The Journal of Wildlife Management 67: 324-333

Raghavan R et al. (2011) Evaluations of land cover risk factors for canine leptospirosis: 94 cases (2002–2009). Preventive Veterinary Medicine 101: 241-249

Shepherd WT (1911) Imitation in raccoons. The American Journal of Psychology 22: 583-585

Smith HT & Engeman RM (2002) An extraordinary raccoon, Procyon lotor, density at an urban park. Canadian Field Naturalist 2002

Zeveloff SI (2002) Raccoons: a natural history. UBC Press.

Images: All photographs by Malcolm M. Campbell.

****


One Response to “Neighbourly behaviour”

  1. textyourexbackreviewed.Tumblr.com Reply | Permalink

    It's a pity you don't have a donate button! I'd without a doubt donate to this brilliant blog!
    I guess for now i'll settle for book-marking
    and adding your RSS feed to my Google account. I look forward to fresh updates and will share this blog with my Facebook group.
    Talk soon!

Leave a Reply


2 − = one