Extent of Double-Brooding and Seasonal Movement of Nesting Females in a Northern Population of Wood Thrushes

Nest predation in an anthropogenic landscape

“…N Nest period: whether nest monitoring began before Jun 15 in any year (this date marks the approximate beginning of the start of second nesting attempts by Wood Thrushes in our area (Friesen et al 2000).…”

Multiple Broods and Nest Success in Western Yellow-breasted Chats (Icteria virens auricollis) in the south Okanagan Valley, British Columbia, Canada

“…Double brooding in Wood Thrushes was much higher, at least 74%, but could be as high as 87% if unidentified females were included (Friesen et al 2000). In the south Okanagan Valley at the northern edge of the range for Sagebrush Brewer's Sparrows (Spizella breweri breweri) distribution, 17% of females had double broods and two females had triple broods (Mahony et al 2001).…”

“…We also did not observe another female during any of the territory visits. The location of nests was in close proximity to each other, and timing between broods was short (Friesen et al 2000). This added to our confidence that it was the same female who initiated the three broods.…”

“…Although uncommon, chats occasionally double brood (Table 1). Double brooding is defined here as a female making a second nesting attempt after successfully fledging young from one previous nesting attempt in one breeding season (Friesen et al 2000). and it was therefore often difficult to determine whether females were banded or to observe a complete color band combination.…”

“…Another 32 females (referred to as unidentified females) for which it was unknown whether they were banded appeared to have double broods. As per Friesen et al (2000), in which they included double brooding by unidentified Wood Thrush females based on distance and time from first broods, we surmise this from our observations at territories visited at least every 3 days. We observed the average time between fledging and laying of the first egg for banded females was 7.4 days and the average time for unidentified females nesting in the same study site was 5.8 days.…”