The line graph illustrates how many breeding pairs of four different types of wild bird in Canada from 1992 to 2006.
Overall, the populations of breeding pairs of mallard and Canada goose both increased dramatically while the numbers of American black duck and blue-winged teal remained relatively stable over the period. In addition, the number of mallard species were the most popular.
In 1992, the population of breeding pairs of mallards stood at around 80 thousand and by 2006, it fluctuated at nearly 90 thousand, making it the species with the highest number of breeding pairs among the four types of bird. In addition, the population of Canada goose was only 20 thousand in 1992, but by 2006 it was increased steadily to 60 thousand. This indicates that the number of mallards remained higher than that of goose throughout the period.
While the numbers of mallards and Canada goose experienced growth, the populations of American black duck and blue-winged teal declined instead. In 1992, the number of ducks stood at around 18 thousand, which was higher than the figure for blue-winged teals at only about 10 thousand. By 2006, the numbers for both species decreased slightly and remained stable at approximately 5 thousand.