Environmental enrichment affects the fear and exploratory responses to novelty of young Amazon parrots

Abstract

The development of techniques to reduce fear responses of captive animals is important because fear is generally considered an undesirable emotional state that is related to increased risk of injury and decreased biological functioning. We tested the effects of environmental enrichments designed to increase the physical complexity of the cage and to provide opportunities for foraging behaviors on responses to novelty of young Orange-winged Amazon parrots ( Amazona amazonica). Parrots ( n=16) were housed in either barren or enriched conditions for 1 year and responses to novel objects and human handlers were tested periodically. Parrots in the enriched condition had significantly shorter latencies to approach novel objects placed in their home cages than parrots from the control group (repeated measures GLM: F 1,13=8.00; P=0.014). In addition, parrots from the enriched condition had shorter bouts of interaction ( F 1,14=27.93; P<0.0005) and spent significantly less time interacting with novel objects overall ( F 1,14=27.93; P<0.0005). Taken together, these results suggest that enrichment reduced both the fear response to novel objects and the motivation to explore and interact with those objects. When tested with a familiar handler, the control parrots had significantly higher response scores (i.e. they were less aggressive and more interactive) than the parrots from the enriched group ( t-test; P<0.005). This suggests that parrots housed in barren conditions may be more motivated to interact with familiar humans as a source of environmental stimulation. All parrots showed higher response scores to familiar than unfamiliar handlers, but in the control group there was a significant drop in score from the familiar to the unfamiliar handler ( t-test; P<0.0005) while in the enriched group the scores with familiar and unfamiliar handlers were similar. Thus, environmental enrichment reduced fear responses to both novel objects and unfamiliar human handlers. Factor analysis revealed that the responses to the novel object and novel human tests were independent, which implies that they did not measure the same underlying factor. Similarly, the factor analysis showed that enrichment independently decreased motivation to interact with novel objects and humans. Our results indicate that the enrichment protocol we employed can successfully modify both fear responses and motivation for environmental interaction in parrots and sheds light on the multi-factorial nature of both of these behavioral systems.