Human Disturbance Influences Behaviour and Local Density of Juvenile Frogs Trenton W. J. Garner*, , Deise Nishimura , Josephine Antwi & Nyakunga Oliver  * Institute of Zoology, Zoological Society of London, London, UK  Tropical Biology Association, Department of Zoology, Cambridge, UK Introduction It is well accepted that the activities of humans are the current primary cause of biodiversity loss (Stuart et al. 2004). Much of this loss can be attributed to the direct impact humans have on habitat quality, but human activity need not substantially alter the physical structure of a habitat to render it less suit- able. Instead, the periodic or persistent presence of humans, referred to as human disturbance, can modify animal species behaviour and disturb pat- terns of habitat use. Under these circumstances, physically unmodified areas also exhibit decreased animal abundance and species richness (Griffiths & van Schaik 1993; Carney & Sydeman 1999; Bejder et al. 2006). The means by which human distur- bance influences animals are many: disturbance can cause reproductive failure; abandonment of part of a home range; the adoption of more costly habitat-use patterns; and incurring of physiological costs that affect condition, immune response and presumably survival (Kerley et al. 2002; Beale & Monaghan 2004; Rodrı´guez-Prieto & Ferna ´ ndez-Juricic 2005; Amo et al. 2006; Ellenberg et al. 2006; Williams et al. 2006). However, the primary mechanism through which human disturbance operates is through the modification of behaviour (Frid & Dill 2002). Amphibians as a group are declining globally (Houlahan et al. 2000; Blaustein & Kiesecker 2002; Relyea 2003). Direct modification and loss of amphibian habitat are certainly recognized as the primary threats to amphibian species and popula- tions (Gallant et al. 2007), but human disturbance is also implicated in species declines (http:// www.globalamphibians.org/threats.htm). A search of the 2007 Red List restricted to the Amphibia and human disturbance as the threat returns over 360 records (http://www.iucnredlist.org/search). Human disturbance correlates negatively with adult frog presence (Rodrı´guez-Prieto & Ferna ´ ndez-Juricic 2005), suggesting that sufficient levels of disturbance may cause amphibians to abandon otherwise amena- ble habitat. Human presence certainly elicits anti- predator behaviours (Gregory 1979; Martı´n et al. 2005; Rodrı´guez-Prieto & Ferna ´ ndez-Juricic 2005), behaviours which incur physiological costs in exo- thermic vertebrates (Amo et al. 2006). Although current research examining the effects of human disturbance on amphibians has focused on adults Correspondence Trenton W. J. Garner, Institute of Zoology, Zoological Society of London, Regent’s Park, London NW1 4RY, UK. E-mail: trent.garner@ioz.ac.uk Received: April 21, 2008 Initial acceptance: May 30, 2008 Final acceptance: May 30, 2008 (K. Reinhold) doi: 10.1111/j.1439-0310.2008.01540.x Abstract Habitat can be rendered less suitable because of numerous factors, including the presence of humans. Human disturbance is implicated as a threat for hundreds of amphibian species, but there is a dearth of peer- reviewed literature addressing this topic, and what little is available focuses on adults. Here we present the results of a study examining the effects human disturbance may have on the distribution and behaviour of juvenile Eastern African leaf litter frogs of the genus Arthroleptis. Our findings show that human activity affects the local density of juveniles and strongly influences escape behaviour. These results indicate that costs of human disturbance to juvenile frogs may be severe and that human disturbance may play a role in fragmenting local frog populations. Ethology Ethology 114 (2008) 1006–1013 ª 2008 The Authors 1006 Journal compilation ª 2008 Blackwell Verlag, Berlin