The effects of domestic cat (Felis catus) density on urban bird abundance and richness

Cat predation is considered the greatest causes of bird mortality worldwide. I predict the effect of cats should be greatest on birds that are less than 150 grams on average, nest or feed on or low to the ground, feed at bird feeders, or are migrants. I tested these predictions using OBC bird surveys and cat density estimates across residential Ottawa. I compared bird abundance and species richness with cat density for all birds and those hypothesized to have a strong or weak effect of cats for each trait. I found cat density had little effect on bird abundance or species richness. Migrants were the only group that showed a significant effect of cats. My results suggest cats have little impact on urban bird abundance and richness, at least in urban regions where cat density is low and cats spend a large part of the year indoors.