American Kestrel Nesting Biology and Long-Term Trends in the Alaskan Arctic: 2002–2021

Abstract

We monitored a population of American Kestrels (Falco sparverius) nesting in boxes at the northern extent of the kestrel range (between 66° and 68°N) in the Alaskan Arctic, 2002–2021. There was no significant trend in occupancy during the study period but yearly variation in occupancy was high (range = 17–70%). Occupancy rate was positively related to the lowest temperature recorded in May (7–20°C). The mean estimated clutch initiation date was 16 May ± 6 d; we observed a slight but significant trend for later clutch initiation (4 d) during the study period. Kestrel clutch size averaged 4.7 ± 1.0 (range = 1–7), brood size averaged 4.6 ± 0.8, and the mean minimum number of young fledged/successful pair was 4.9 ± 0.4. Clutch and brood sizes remained stable from 2002–2021, with no significant trend. Nest failure was low (16%). We report a late nesting and possible double brooding attempt in 2018, suggesting a possible response to the warming trend (2002–2021) in average temperatures at the end of the normal nesting season.

The Full Annual Cycle of the American Kestrel: State of the Knowledge, Information Gaps, and Conservation Needs

“…Also, the absence of starling activity was related to higher breeding success. Finally, Erica Craig and colleagues (2023) report data from a 20-yr study of a kestrel nest box population in the Alaskan Arctic. Overall, this population exhibited excellent reproductive success, low predation rates, and were not affected by a number of hypothesized factors that may potentially adversely affect kestrel populations at lower latitudes.…”

Annual Survivorship and Movement Ecology of Migrant American Kestrels (Falco sparverius) Overwintering in North Texas

“…Kestrels are easily monitored during their summer breeding season due to being nest-site limited and their tendency to utilize man-made nest boxes. Nesting success of kestrels have been studied across North America and have reported an overall high average reproductive success (62-84%; Rohrbaugh and Yahner 1997, Craig et al 2023, though apparently reproductively successful in fecundity, some researchers still have reported continued population declines (E.g., ).…”