Iron filings as magnetically retrievable markers

Iron filings (plain, red-painted and red-fluorescent-painted) in tallow baits were tested as bait acceptance markers for coyotes (Canis latrans). The paint coatings did not survive digestive passage. Based on very small numbers of treated animals, recovery period of iron filings appeared longer than for two types of particle markers examined by others. Iron filings would be simple to use, readily available and inexpensive.