Using Transmitters to Track Feeder Visits
FeederWatch researchers and students at Cornell University gained an unprecedented amount of information about the feeding behaviors of our favorite backyard birds by fitting wild birds in the Ithaca, New York, area with small transmitters called PIT (passive integrated transponder) tags.
Watch a short video about the project.
PIT tags and RFID technology
PIT tags are attached to leg bands–one tag per bird. These lightweight tags weigh less than 0.1 gram (for comparison, a Black-capped Chickadee averages approximately 11 grams). Each tag transmits a unique identification number to a reading device that is built into a specially “wired” bird feeder containing an RFID circuit board and antenna. Every time a bird with a tag visits the RFID feeder, the bird’s identity is recorded along with the date and time of the visit.
Since initiating a pilot study of the technology in November of 2009, more than 120 Black-capped Chickadees, White-breasted Nuthatches, House Finches, and Tufted Titmice have been tagged and more than 2.5 million visits to the wired feeders have been recorded!
What is RFID?
Radio Frequency Identification (RFID) is the technology used to read the PIT tags and automatically record the feeding behavior of the birds in our study. RFID is a widespread technology that is used for a variety of commercial purposes. It is used to track boxes in warehouses and is even used in passports! You may be most familiar with PIT tags as the “microchips” that veterinarians implant in pets so that lost animals may be identified and returned to their owners.
Dr. Eli Bridge of the University of Oklahoma is the engineering guru behind the development of the low-cost RFID readers. Learn more about Eli’s inexpensive RFID readers on his web site.
What can we learn about bird behavior through the use of RFID?
RFID is providing incredibly detailed information about the behaviors of our tagged birds. We are using the technology to answer a variety of questions:
When do birds feed during the day?
How is feeding behavior affected by weather or competitors?
What influence does feeder location (edge vs. interior of a forest) have on feeding behavior?
How are feeding patterns influenced by gender and dominance status?
And over time, we can track survival in our study populations.
Survival and feeding behavior.
Many aspects of the daily lives of our common feeder birds remain a mystery. RFID technology is allowing us to better understand relationships among birds and between birds and their environment. In a five-month pilot study in 2011, David Bonter, Ben Zuckerberg, and a team of Cornell University students put tags on 129 Black-capped Chickadees, White-breasted Nuthatches, Tufted Titmice, and House Finches. When the birds visited feeders equipped with tag readers placed in nearby woods, the data started pouring in—8,000 hours of continuous observations at a cost of just 6 hours of feeder upkeep per week. Some of the results were surprising:
- Individual birds took up to 203 seeds in a single day (some of these they almost certainly cached for later in the season).
- Most chickadees had favorite feeders—one or two locations they habitually visited even though several other feeders were available within the typical home-range area of a chickadee.
- Over three months, a single Tufted Titmouse drifted through the woods, frequenting three feeders one after another across a distance of more than half a mile.
- A Black-capped Chickadee spent two months visiting a feeder daily, then abruptly moved nearly a half-mile away to a different feeder.
- The feeder/readers were very accurate—garbled identifications happened less than one percent of the time. By comparison, humans recording color bands make mistakes five percent of the time or more.
House Finch eye disease.
Jon DeCoste examined various aspects of how the bacterium Mycoplasma gallisepticum infects wild finches, often leading to the House Finch eye disease while he was a graduate student in Cornell’s Ecology and Evolutionary Biology program. Jon used a network of RFID feeders in the Ithaca, New York, area to study movements in both sick and healthy House Finches and to quantify where and how long birds feed. Jon predicted that sick birds would be less likely to move large distances and would spend more time at supplemental feeders than healthy birds.
Special thanks to Wild Birds Unlimited
How can I help?
We designed and built our own RFID readers, which greatly reduced the financial barriers limiting this kind of research. But our projects still require funds to purchase PIT tags, batteries, and other equipment. To support this research, please donate to FeederWatch and type “RFID” in the Comments box under “Additional Information.” Donations labeled “RFID” will only be used to support the RFID research.
RFID information, news, and updates
The inexpensive RFID readers used in our research were detailed in the March 2011 issue of the Journal of Field Ornithology along with a review article of how RFID can and has been used in ornithological research.