Stephen Leaver, MSc candidate
email: sleaver@uvic.ca

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Behavioural implications of tail docking in Canis familiaris

The canid tail is important for intraspecific communication. Changes in height and motion reflect the motivational state of the signaller and provide important cues for approaching conspecifics. The tail may be intentionally docked in up to one third of recognized dog breeds. Some of these breeds, such as Dobermanns and Rottweilers, have higher probability of aggressive behaviour and we suspect that this may be facilitated by the loss of the major signalling capacity of the tail.

Unfortunately, differences in breed, size, and social history make it very difficult to elucidate the behavioural effects of one variable - tail length – in social interactions. As a solution, Dr. Reimchen and I completed a project using an artificial and remotely-controlled model to provide a standard stimulus with which only tail height and motion varied. During the summer of 2006, I videotaped and quantified the approach of 496 off leash dogs to the model when the model had one of four tail conditions: short/still tail, short/wagging tail, long/still tail, and a long/wagging tail.

We found that dogs responded to differences in tail motion of the model, not surprising given the respective meanings of an upright still tail versus a wagging tail, but only when the tail was long. Dogs responded similarly to the still tail model and the wagging tail model when the model’s tail was short. We interpret this as evidence that the different visual signals conveyed by the tail, in this case tail motion, are best interpreted when the tail is long. While not directly demonstrating behavioural consequences of tail docking, this work does provide evidence that docking a tail may impair intraspecific communication in canids.

Leaver, S.D.A. & Reimchen, T.E. (2008). Behavioural responses of Canis familiaris to different tail lengths of a remotely-controlled life-size dog replica. – Behaviour 145: 377-390. Pdf

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Behavioural ecology of Haida Gwaii Threespine Stickleback, Gasterosteus aculeatus

My Master’s research will focus on (1) behavioural and (2) morphological comparisons of Gasterosteus aculeatus from habitats differing in a variety of biophysical factors, most specifically predation pressure.

My work began in July 2007 with the collection of Stickleback adults and eggs from five different Haida Gwaii lakes. I have been successful in maintaining the adults and rearing the fry at the University of Victoria Aquatic facility and currently have over 200 fish with which I have started behavioural experiments. My research will focus on behavioral differences between populations. Specifically, I have been examining differences in response to potential predatory cues (olfactory, visual, pressure stimuli). As many of the lakes are darkly stained and the fish may live in scotopic/aphotic conditions, I will include the influence of light level on behavioural responses. My work may also examine behavioural plasticity and learning capacity in relation to ecological background.

For my morphological comparisons, I will use stickleback previously collected by Dr. Reimchen combined with high resolution digital imaging. The lab has demonstrated population level morphological changes in response predation pressure (see publications). My work will specifically compare the morphology of several Haida Gwaii populations that differ in many biophysical features, including predation pressure. One of these, the Mayer Pond population, was started twenty years ago by transplanting stickleback from the dystrophic Mayer Lake habitat into a eutrophic barren pond lacking vertebrate predators. I will investigate the potential morphological (and behavioral) divergence of these fish from their ancestors during shift in selective pressures imposed by the new habitat.

Beach near Tlell, Haida Gwaii

For my non-stickleback photographs, please see my flickr website.