Eur J Wildl Res (2006) 52: 265–270 DOI 10.1007/s10344-006-0049-z ORIGINAL PAPER Christoph Randler Disturbances by dog barking increase vigilance in coots Fulica atra Received: 21 December 2005 / Accepted: 27 May 2006 / Published online: 8 July 2006 # Springer-Verlag 2006 Abstract Animals frequently interrupt their activity to look up and to scan their surrounding environment for potential predators (vigilance). As vigilance and other activities are often mutually exclusive, such behaviours are at the expense of feeding, sleeping or preening. Authors of many wildlife disturbance studies found that people with free-running dogs provoked the most pronounced distur- bances (e.g. greater flushing distances and more birds affected). However, dogs on leash may also negatively affect wild animals, and barking dogs may lead to an increase in vigilance. In this study, I tested this hypothesis in coots (Fulica atra) using three different playback procedures: (1) dog barks, (2) conspecific coot alarm calls and (3) chaffinch song. The trials were conducted in spring and autumn 2005 at three study sites in southwestern Germany. During the dog playbacks, vigilance increased significantly from 17 to 28%. This increase in vigilance is comparable to the presence of a natural predator. As expected, vigilance also increased significantly during conspecific coot alarm calls but not during playbacks of the chaffinch song control. Two main findings result from the study: (1) coots respond to acoustic traits of dogs and may be able to acoustically recognise this predator and (2) this increase in vigilance might have implications for con- servation, especially when considering buffer zones around sensitive areas. Keywords Auditory stimuli . Disturbances by dogs . Human disturbances . Predator recognition . Recreation Introduction During feeding and preening, animals frequently interrupt their activities to look up within different time intervals to detect a given stimulus (Beauchamp 2003). During this vigilance behaviour, the animals scan their surrounding environment for potential predators (for reviews, see Elgar 1989; Roberts 1996; Treves 2000; Beauchamp 2003). As vigilance and other activities are often mutually exclusive (see Lima and Bednekoff 1999, for exception), such vigilance behaviour is at the expense of feeding, sleeping or preening and, therefore, incurs costs. Observational and experimental studies have shown that most wild animals increase their vigilance in the presence of a predator independently whether these predators were detected or experimentally presented via visual (Pöysä 1987), acous- tical (Randler 2006) or chemical traits (Monclús et al. 2005). In domestic animals, the time spent being vigilant is used as a measure of fear towards new stimuli (Welp et al. 2004). Human-caused disturbance stimuli are considered a form of predation risk (Frid and Dill 2002) and these disturbances often negatively affect wildlife (Pomerantz et al. 1988; Skagen et al. 1991; Holmes et al. 1993; Klein 1993; Klein et al. 1995; Hill et al. 1997; Blumstein et al. 2005; but see as an exemption, e.g. wildlife in parks and on islands that do not show a predator-specific reaction towards humans). Apart from other human disturbances, free-ranging or unleashed dogs (Canis familiaris) present a major threat and disturbance factor in many animal species and at different localities during all season (see, for overview, Sime 1999; Miller et al. 2001; for parks in Madrid, see Fernandez-Juricic and Telleria 2000). Dogs are often present in natural, suburban and recreational areas as companions of humans seeking recreation and physical or wildlife-related activities. Therefore, dogs account for a large proportion of disturbances (e.g. Fernandez-Juricic and Telleria 2000; Randler 2003). Authors of many wildlife disturbance studies concluded that people with dogs, dogs on leash or loose dogs provoked the most pronounced disturbances, e.g. greatest flushing distances, longest duration and highest numbers of individuals affected (Sime 1999; Randler 2003). Dogs are canid-like predators, and canids are natural, evolutionary predators of many, if not all, wildlife species (Sime 1999). Concerning birds, the presence of dogs has an impact on incubating birds (Keller C. Randler (*) Institute of Biology I, University of Leipzig, Johannisallee 46, 04103 Leipzig, Germany e-mail: Randler@uni-leipzig.de