Looking at what the cat dragged in will supply Sheffield University researchers with a key chunk of raw data for their investigation into the impact of domestic cats on urban wildlife.
A number of reports in recent years have suggested that hunting by cats has had a devastating impact on garden birds. But most of the evidence has come from rural areas and has involved semi-wild cats that do much more hunting than the average well-fed town moggie.
Sheffield's cat owners are being recruited to fill in detailed questionnaires about their cats' habits and the "presents" they bring home.
About 120 owners have so far agreed to take part but more are required.
Victoria Sims, a graduate in conservation management who is conducting the survey as part of her PhD, said: "The kind of things we want to find out are whether there's a link between what a cat is fed and how much it hunts - and whether, for instance, its colour or a collar and bell hinder its hunting ability."
Kevin Gaston of the university's department of animal and plant sciences, who is leading the project, said: "We are going to try to look for ways in which owners can minimise cats' effectiveness as predators, as well as looking at characteristics that may make them less effective.
"For example, does a ginger cat hunt as well as a tabby? Does the level of feeding have an effect on a cat's hunting ability or inclinations? Are cats let out at night more likely to hunt successfully?
"This important piece of work will give us the first independent research into the way that cats affect urban ecosystems, whether wildlife figures will change over the years as a result of hunting by cats - or whether the numbers they kill are largely insignificant to overall population levels.