Burrowing Owl (Athene cunicularia) nest phenology influenced by drought on nonbreeding grounds

Abstract

Migratory birds are demonstrating changes in phenology linked to climate change. Understanding these changes requires connecting events that occur over the multiple regions occupied during their annual cycle. The Burrowing Owl (Athene cunicularia) is a species of concern in North America, with pronounced declines in regions of the Great Plains. Using a dataset that spanned 10 breeding sites from South Dakota to northern Mexico in various years during 1989–2017, we observed both advances and delays in nesting along with increasing variation in nest initiation dates. We examined the effects of a large-scale climate system (El Niño Southern Oscillation), drought, and local weather patterns throughout the annual cycle as potential predictors of early and late nesting. Moisture conditions during the winter and spring migratory period had the greatest influence on nest phenology. Years with more intense drought on winter and migratory grounds increased the probability of nests initiating late relative to early. Correspondingly, wet conditions were associated with an increased probability of early nest initiation. Drought likely has cascading ecological effects that negatively influence food abundance for Burrowing Owls, resulting in delays in the ability of individuals to meet energetic demands required for migration. How climate change will impact Burrowing Owl phenology is important considering a projected increase in the magnitude and frequency of drought and declining owl population trends.

Breeding Phenology of Red-Shouldered Hawks (Buteo lineatus) Is Related to Snow Cover and Air Temperature During the Pre-Laying Period

“…Delayed egg-laying of Rough-legged Hawks (Buteo lagopus; Terraube et al, 2015), Tengmalm's Owls (Aegolius funereus; Kouba et al, 2020), Tawny Owls (Strix aluco; Solenen, 2014), and Ural Owls (Strix uralensis; Lehikoinen et al, 2011) is linked to increased winter/spring snow cover, which reduces the prey availability of some species of voles. However, delayed egg-laying of Burrowing Owls (Athene cunicularia) in several populations in the western United States is linked to winter drought conditions, which likely reduce prey abundance (Porro et al, 2020).…”

“…The effects of weather conditions on raptor breeding phenology are often attributed to indirect effects on prey abundance or availability, which influences the physiological condition of the female, which in turn influences laying date (Newton, 1986;Steenhof et al, 1997;Dunn, 2019;Porro et al, 2020;Bangerter et al, 2021). However, other causal relationships have been described; for example, advancing hatching dates of American Kestrels (Falco sparverius) are likely related to changes in the wintering locations of the birds (nearer the breeding sites; Heath et al, 2012).…”

“…However, weather conditions during the pre-laying period can also influence breeding phenology of raptors (e.g., Newton, 1986;Lehikoinen et al, 2010Lehikoinen et al, , 2013Kreiderits et al, 2016). The effects of weather variables on breeding phenology are typically explained by indirect effects on prey availability: higher prey availability results in better physiological condition of the female, which leads to an earlier laying date (Newton, 1986;Steenhof et al, 1997;Porro et al, 2020;Bangerter et al, 2021). The specific weather conditions that influence prey availability vary depending on ecoregion, but in temperate or more-northern regions warmer winter or spring weather is generally associated with greater prey abundance and earlier laying dates (Lehikoinen et al, 2013;Bangerter et al, 2021).…”

Nest survival and productivity of translocated and resident burrowing owls in Arizona

“…We used nest initiation dates to evaluate differences in the timing of reproduction among translocation histories, years, and study sites. We estimated nest initiation date (date first egg was laid) by backdating from the hatch date using an incubation period of 31 days, which included the egg laying stage (Garcia and Conway 2009 a , Lantz and Conway 2009, Porro et al 2020). We recorded fledge dates as the date when juveniles reached 42 days old.…”

“…We recorded fledge dates as the date when juveniles reached 42 days old. When we estimated nest initiation date based on fledge date, we used 42 days to backdate from fledge date to hatch date (Porro et al 2020).…”