  Radio-frequency identification (RFID) is an increasingly popular wireless
technology that allows researchers to monitor wild bird populations from fixed
locations in the field. Our lab has developed an RFID-equipped birdfeeder based
on the Raspberry Pi Zero W, a low-cost single-board computer, that collects
continuous visitation data from birds tagged with passive integrated
transponder (PIT) tags. Each birdfeeder has a perch antenna connected to an
RFID reader board on a Raspberry Pi powered by a portable battery. When a
tagged bird lands on the perch to eat from the feeder, its unique code is
stored with the date and time on the Raspberry Pi. These birdfeeders require
only basic soldering and coding skills to assemble, and can be easily outfitted
with additional hardware like video cameras and microphones. We outline the
process of assembling the hardware and setting up the operating system for the
birdfeeders. Then, we describe an example implementation of the birdfeeders to
track house finches (Haemorhous mexicanus) on the campus of Queens College in
New York City.
