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

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 ten 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 magnitude and
frequency of drought and declining owl population trends.