GAP analyses are tools used to inform us about the short-comings of a scientific area or necessities in social-economic problems. In the last 20 years, environmental enrichment as an area of scientific investigation has come of age; this can be clearly seen by the number of publications produced in this area. For example, a search on the database The Web of Science (c) using the keywords "environmental enrichment", from 1985 to 2004 produced 744 articles. In this study we analysed these 744 articles and classified them by year into: type of environment (e.g., zoo, farm and laboratory); taxonomic classification (e.g., mammal, bird, etc.); type of enrichment (e.g., food, sensory, etc.); subject area (e.g., neurosciences and agriculture); country of publication; and gathered data on experimental design (e.g., sample sizes). Furthermore, we collected similar data on animal well-being and animal conservation for comparative purposes (keywords: "animal well-being" and "animal conservation"). The results from this study show that the number of environmental enrichment studies has been steadily increasing from a low level in the 1980s until 1999, when there was a noticeable acceleration in the number of articles published. Largely, this acceleration was a response to the growing interest in environmental enrichment by neuroscientists. The data also show a relative lack of, and recent decline in, publications in the area of agriculture. Thus, the data suggest a need for more research on enriching the lives of farm animals. Environmental enrichment publications over the 20 years of the study corresponded to 27% of all animal well-being publications in the period. One interesting comparison between enrichment and animal well-being revealed the virtual absence of research in animal well-being by neuroscientists. The detailed results of this study will help in identifying gaps in our knowledge about environmental enrichment, and how experimental designs might be improved. (c) 2006 Elsevier B.V. All rights reserved.
