The line graph illustrates the changes in the population of different types of wild birds in the United Kingdom between 1970 and 2004.
Overall, there were significant differences among the four categories. While the total number of all species remained relatively stable with minor fluctuations, coastal species showed a clear upward trend. In contrast, both woodland and farmland species experienced an overall decline, with farmland birds falling most dramatically.
In 1970, all four groups started at approximately the same level. However, coastal species began to increase steadily and continued this upward trend until the late 1980s. Although there were some slight fluctuations after this period, their population remained the highest throughout the entire timeframe.
By comparison, farmland species showed a small increase in the early years, but after 1977 their numbers declined sharply. This downward trend continued for the rest of the period, making them the least numerous group by 2004. Similarly, woodland species experienced fluctuations, with minor rises around 1977 and 1981. However, their overall trend was also downward. Meanwhile, the total number of all species remained relatively stable, with only slight variations over time.