Belling the cat

After reviewing the available articles considering the effect of bells on feline hunting behaviour, we found a big difference between results of surveys considering cats wearing bells previously to the study and studies where cats were experimentally provided with bells.

Surveys show that bells have little effect on predatory behaviour. After one study, 33% of pet cats wore a bell in UK. Cats wearing a bell hunted fewer mammals than un-belled ones, but there was no difference for birds and herps; probably birds rely more on visual cues than mammals, but maybe skilled cats wear bells more frequently than the rest (Woods et al. 2003). Paton (1991) relying on respondents' memory, found that belling cats has no incidence in the number of preys brought home. In Australia, Reark (1994) found that belled cats hunted more than un-belled ones, but there were not data on how much did they use to hunt before wearing a bell. Barrat (1998) did not find any difference between cats wearing bells or not. In New Zealand, Morgan et al. (2009) got similar results. Hansen (2010) also found no evidence of effect of bells on predation. Comparing sites where belling is compulsory and sites without obligation, no positive correlation was found between small mammal abundance and regulations (Lilith et al., 2010).

Experimental studies where cats were equipped with bells show a decrease between 30 and 50% in the number of preys (Ruxton et al., 2002; Nelson et al., 2005; Gordon et al., 2010). Nevertheless, those studies were, probably, too short (4-8 weeks) to allow cats to learn how to silently stalk their prey. Electronic devices tend to be more effective than bells anone, but are no exempt of problems (Clark & Burton, 1998; Clark, 1999; Nelson et al., 2005). Other devices were more effective, reducing up to 80% the number of preys, but the period was also short (3 weeks) (Calver et al., 2007).

Bright coloured collars seem to be very effective to warn birds on the approaching cat: collared cats kill as much as 19 times less than uncollared animals (Willson et al., 2015), and this could be independent of the cat's skills.

There is a need of longer term studies to better understand the whether

- the effect observed in experimental studies is due to the lack of training, and cats wearing a bell for a longer time will improve their chances

- the lack of effect in surveys is due to a potential bias towards skilled cats wearing bells more frequently that less capable ones.