Circadian activity pattern is important to comprehension and management of wild mammals. Camera trapping may be useful for understand circadian activity pattern of sympatric mammals, because this method is able to survey multiple species at once. The aim of our research is to reveal circadian activity pattern of sympatric forest mammals by camera trapping.

The study was conducted from 2004 to 2011 in 10,000 ha national forest in northwest Gunma prefecture, central Japan. Camera traps located at 56 sites in study area. Mammals taken by camera traps were identified at specie level except Chiroptera and Apodemus, and checked photographed time.

The results of investigation, 21 mammals were identified (including Chiroptera and Apodemus). Circadian activity pattern of mammals could be roughly divided into three groups, nocturnal, diurnal and crepuscular. On the other hand, it was also revealed that mammals had different peaks of activity by species, even if they classified into same group. Circadian activity pattern will become more useful for management of mammals by clarifying seasonality and considering food habits or habitat selection.