Data from: Individual variation and seasonality drive bird feeder use during winter in a Mediterranean climate

Purposeful provisioning of food to wild animals is a widespread and
growing activity that has the potential to impact populations and
communities. Nevertheless, studies assessing use of recreational feeders
by free-living birds during winter are surprisingly rare and largely
limited to regions with continental climates characterized by freezing
temperatures and snow cover. In contrast, there is little information
available regarding bird use of feeders within warmer climates during
winter, despite widespread recreational feeding in these areas. In this
study we quantified visitation patterns to bird feeders in a Mediterranean
climate to evaluate the relationship between feeder use and several
environmental variables known to influence supplemental feeder use in
continental climates. We established a network of bird feeders in
Corvallis, Oregon, USA that were filled with black oil sunflower
(Helianthus annuus) seeds and equipped with radio frequency identification
(RFID) data loggers that recorded >315,000 visits by 70 individual
Black-capped Chickadees (Poecile atricapillus) across a 5-month period
(October 2016 – March 2017). We found extensive variation in feeder use,
with individuals averaging 1 – 406 feeder visits/day and using 1 – 9 of
the 21 feeders that were available; individual variability was largely
consistent during the course of our study. At the population level, we
found that feeder use decreased from the start of our study, and this
decline continued through the period when foraging was most limited by
daylight, including the winter solstice. In contrast to theoretical
predictions and empirical work in continental climates, we found that
weather variables did not drive feeder use and that feeder visits peaked
at mid-day and gradually decreased until sunset. Our study indicates that
individual-level differences combined with seasonality to drive feeder use
patterns, and we conclude that how birds use supplemental feeders during
winter in Mediterranean climates appears to differ notably from feeder use
in continental climates.