Table 1.

Summary of strengths, weaknesses, primary and previous applications of radio frequency identification and radio signal strength systems used in laying hens.

	Radio Frequency Identification	Radio Signal Strength
Primary application differences	Detects presence or absence of individual at location of antennae	Detects movement of individual through time and space and possibly location
Strengths	Possibility to couple with other systems Can detect multiple individuals simultaneously No external power source or battery needed (for bird-mounted component) Relatively easy installation and mobile Sensor can be placed at several points on the body	Ability to couple with various other observations including: accelerometry (described in this article), light, temperature, humidity
Weaknesses	Water or metal can dampen signal strength Quickly moving (or immobile) animals difficult to detect Requires multiple antennae to detect direction of movement Expensive, though depends on system Mainly in high frequency systems (>13.56 MHz), conspecifics can block signal causing missed readings	Stationary receivers ≥1 meter apart Overlapping detection fields Short battery life Metal can obstruct detection causing data loss Sensor must be placed on back of hen for best signal capture
Previous applications	Passage through a pop hole Egg laying in a nest box	Location relative to other sensors (both stationary and mobile) Individual behavior and movement in large groups, including within 3 dimensions