Cette plage destimations est fonde sur des relevs indiquant que les Canadiens possdent 8,5 millions de chats domestiques environ, une approximation grossire du nombre de chats sauvages se situant entre 1,4 et 4,2 millions et des taux de prdation tirs dautres recherches menes ailleurs quau Canada.

Estimates of total bird kills were calculated using a Monte Carlo approach, selecting a value at random for each parameter from within ranges listed in Table 1, and then applying the formulae.

All ranges of values were treated as continuous distributions between low and high values, except that number of pet cats (n PC) was treated as a normal distribution, and birds returned per urban outdoor pet per yr (Bp U) was treated as a continuous distribution with 50% of values between the low value and midpoint, and 50% between the midpoint and high value.

Many species of birds are potentially vulnerable to at least local population impacts in southern Canada, by virtue of nesting or feeding on or near ground level, and habitat choices that bring them into contact with human-dominated landscapes where cats are abundant.

Because cat predation is likely to remain a primary source of bird mortality in Canada for some time, this issue needs more scientific attention in Canada.

The objectives of this study were to provide plausible estimates for the number of birds killed by house cats in Canada, identify information that would help improve those estimates, and identify species potentially vulnerable to population impacts.

In total, cats are estimated to kill between 100 and 350 million birds per year in Canada ( 95% of estimates were in this range), with the majority likely to be killed by feral cats. The specific formulae used were: where n PC is the number of pet cats in Canada, p RP is the proportion of pet cats that are rural, p Od is the proportion of pet cats with at least some access to the outdoors, Bp U (or Bp R) is the average number of birds returned to owners per outdoor urban (or rural) pet cat, Adjust is a multiplier to convert birds returned and detected by owners to birds killed by pets, n FC is the number of feral cats in Canada, and Kp F is the average number of birds killed per feral cat. Based on existing data and rationale provided below, a plausible range of values was established (Table 1) for each parameter in the formulae above. The main objective in this paper is to provide a plausible range of estimates for the number of birds killed annually by house cats in Canada, based on a review of data and literature available in Canada and other temperate-zone countries, so that this source of bird mortality can be compared to other anthropogenic sources. A secondary objective is to examine the sensitivity of mortality estimates to values used for each parameter included in the calculations, to identify data that would most improve precision of future estimates of birds killed by cats in Canada. La prdation par les chats domestiques (Felis catus) est une des causes de mortalit lies aux humains les plus importantes chez les oiseaux sauvages aux tats-Unis et ailleurs; elle a galement t mise en cause dans lextinction et le dclin de populations de plusieurs espces.