Cues Used in Searching for Food By Red-Winged Blackbirds (Agelaius Phoeniceus)

Abstract

AbstractSixteen red-winged blackbirds (Agelaius phoeniceus) were given an opportunity on each of four consecutive days to search for food items partly hidden in a wooden "food maze". The birds were divided equally into four groups. Each group on Days 1 and 2 of the experiment hunted for one of two baits placed on one of two separate rows of holes in the food maze (either sunflower seed bits in the lower row or seeds in the upper row or mealworm halves in the lower row or mealworms in the upper row). On the second day of the experiment the birds' foraging efficiency had usually improved with the redwings requiring less time to find ten baits. This improvement was linked to the adoption of a long distance scanning strategy which replaced the birds' initial tendency to inspect each hole at close range. On the third day of the experiment the birds were offered the same food item as on Days 1 and 2 but this time equally distributed in the upper and lower rows instead of entirely in one or the other. The redwings' previous experience affected their searching pattern. Birds that had been hunting and finding food only in the upper row continued to concentrate their efforts there. Birds that had been offered food in the lower row of holes initially took several baits there before switching to the upper row baits. On the fourth day of the experiment birds were offered two baits instead of just one. Again previous experience biased the searching behavior of the birds. Redwings that had on earlier days been hunting solely for mealworms usually removed many larvae before finding their first sunflower seed bit. Birds that had been searching for seeds quickly took several before switching to mealworms. It appears likely that redwings are sensitive to both locational and visual cues associated with prey and learn to use them while foraging. These results were discussed in the context of L. TINBERGENS search image hypothesis.