The ability of predators to kill prey depends on the ease of capture and handling, and therefore the issue of prey vulnerability becomes paramount. Temple (1987) revealed a direct relationship between the difficulty of prey capture and the proportion of “substandard individuals” in the predator’s diet. Ullrich (1971) found that such individuals were more common in the diet when shrikes fed on birds than when they ate mice. Small avian predators such as jays and shrikes tend to ignore healthy adult birds under ordinary conditions because of the challenge of capture. However, predatory behavior appears to be stimulated by circumstances that render such birds vulnerable to attack (e.g., Balda 1965). A recent field incident I witnessed, in conjunction with a survey of similar published observations, shed further light on predation by jays and shrikes on adult birds.