The Feeding Response of Hand-reared Red-winged Blackbirds (Agelaius phoeniceus) to a Stinkbug (Euschistus conspersus)

Sixteen red-winged blackbirds hand-reared on an artificial and limited diet were each offered two live stinkbugs in succession. Despite never having seen stinkbugs before the test, the birds generally attacked the bug about as rapidly as familiar prey (mealworms). In addition, they ate most of the first and second bugs they received despite apparently finding the insects distasteful. The failure of the limited rearing diet to influence later food selection by the birds and their relative tolerance of novelty and distastefulness were related to features of the species' ecological niche. A readiness to attack both strange and distasteful prey presumably provides the foundation for a bird's familiarity with a large number of food items and may also increase the probability of a young bird's survival during the stressful post-fledgling period. INTRODUCTION This paper reports the reaction of young hand-reared red-winged blackbirds (Agelaius phoeniceus) to a stinkbug (Euschistus conspersus). At the time of the encounters the birds had had very limited experience with insect prey and none whatsoever with an insect presumed to be distasteful. It is well known that adult birds of several species quickly learn to! avoid distasteful foods (e.g., Tinbergen, 1960; -Prop, 1960; Brower et al., 1963). Less well studied is the tendency of adult birds to prefer familiar, as opposed to novel, food items. However, an aversion to novelty is widespread among animal species (Thorpe, 1963). Coppinger (1969) has shown that wild-caught blue jays (Cyanocitta cristata) tend to be conservative in the selection of prey, preferring those items they had been fed previously while in captivity. The effects of early experience on the response to novel and unpalatable prey have been very little studied. Birds do receive a great deal of potential information about suitable foods in the initial weeks of their development. Altricial species and some precocial ones depend entirely or largely upon their parents for food for substantial periods of time (Nice, 1962). What young birds are fed during this stage could have a formative effect on the diets they choose when older. For example, Rabinowitch (1968) found that 30% of young gulls tested starved to death rather than sample novel foods after having been hand-reared on a severely restricted training diet. Similarly, over half the young hand-reared blue jays, grackles (Quiscalus quiscala) and red-winged blackbirds (Agelaius phoeniceus) tested by Coppinger 1 Present address: Department of Zoology, Arizona State University, Tempe 85281.