Radio Frequency Identification (RFID) technology has been broadly applied in the biological sciences to yield new insights into behavior, cognition, population biology, and distributions. RFID systems entail wireless communication between small tags that, when stimulated by an appropriate radio frequency transmission, emit a weak, short-range wireless signal that conveys a unique ID number. These tags, which often operate without a battery, can be attached to animals such that their presence at a particular location can be detected by an RFID reader. This paper describes an RFID data-logging system that can serve as the core for a wide variety of field and laboratory applications for monitoring the activities of individual animals. The core electronics are modeled on an Arduino circuit board, which is a hobbyist electronics system. Users can customize the hardware and software to accommodate their needs. We demonstrate the utility of the system with cursory descriptions of three real-world research applications. The first is a large-scale deployment that was used to examine individual breeding behaviors across four local populations of Wood Ducks. The second application employed an array of RFID-enabled bird feeders that allowed for tests of spatial cognition. Third, we describe a nest-box monitoring system that both records visits from breeding birds and administers experimental treatments, such as increasing temperature or playing audio recordings, in accordance to the presence/absence of individual birds. With these examples we do not attempt to relate details with regard to research findings; rather our intent is to demonstrate some of the possibilities enabled by our low-cost RFID system. Detailed descriptions, design files, and code are made available by means of the Open Science Framework.

Probability of detection and accuracy of distance estimates in aural avian surveys may be affected by the presence of anthropogenic noise, and this may lead to inaccurate evaluations of the effects of noisy infrastructure on wildlife. We used arrays of speakers broadcasting recordings of grassland bird songs and pure tones to assess the probability of detection, and localization accuracy, by observers at sites with and without noisy oil and gas infrastructure in south‐central Alberta from 2012 to 2014. Probability of detection varied with species and with speaker distance from transect line, but there were few effects of noisy infrastructure. Accuracy of distance estimates for songs and tones decreased as distance to observer increased, and distance estimation error was higher for tones at sites with infrastructure noise. Our results suggest that quiet to moderately loud anthropogenic noise may not mask detection of bird songs; however, errors in distance estimates during aural surveys may lead to inaccurate estimates of avian densities calculated using distance sampling. We recommend caution when applying distance sampling if most birds are unseen, and where ambient noise varies among treatments.

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SUMMARYBecause of their reliance on temporally predictable resources across large spatial scales, migratory birds may be especially vulnerable to anthropogenic climate and land-use changes. Although some long-distance migrants appear unable to adjust to phenological shifts on their wintering grounds, several short-and medium-distance migrants appear to have altered the timing and/or distance of their yearly movements to compensate for the environmental effects of global warming. Which environmental cues are responsible for stimulating these adjustments is an unanswered question, although most studies have focused on weather conditions. Here, we present a novel field experiment that demonstrates that an alternative cue, food availability, may be a crucial link between local conditions on the wintering grounds and the timing of spring departure. When we provided dark-eyed juncos (Junco hyemalis) with an abundant food supply in early spring, we observed an advance in migration, especially among individuals that increased their mass and fat stores in response to the treatment. This finding indicates a simple mechanism by which short-distance migrants may calibrate their migration behavior such that arrival on the breeding grounds and initiation of reproduction are in sync with resource availability. Supplementary material available online at