Factors associated with occupancy and survival in Barn Owl nest boxes in Illinois

Barn Owl (Tyto alba) populations have decreased in the Midwestern U.S. in recent years, and they are listed as endangered in several states, including Illinois. This is largely due to the loss of grassland habitat to increased row cropping and development, as well as a potential decrease in suitable nesting substrates. To deal with the problem of nest site scarcity, many states, including Illinois, have initiated nest-box programs. In Illinois, > 300 nest boxes have been installed since 1990. However, monitoring of these nest boxes has been intermittent. We set out to examine factors associated with nest box use, estimate the number of occupied nest boxes in Illinois, and examine survival of nests in these boxes. We monitored 235 previously installed nest boxes located throughout Illinois, and examined landscape composition and structure at Barn Owl nest sites and unoccupied boxes. Although most boxes were unoccupied, we found that a number of factors, including crop cover and grassland cover in the surrounding landscape, were associated with nest box use. At active nests sites, nest box type and grassland cover affected daily survival rates. In addition to improving our understanding of Barn Owl ecology, this information will aid in the placement of future nest boxes and will contribute to efforts to conserve this species in Illinois and elsewhere in the Midwestern U.S.