Resource 26

Bird counts at the Western Treatment Plant

The Western Treatment Plant in Werribee has long been recognised as an area of high conservation value. In 1921, parts of the plant were declared a sanctuary for the protection of native fauna, including wildfowl such as ducks and quail.

The large area of the plant encompasses a diverse and complex array of landforms, vegetation communities and wildlife. Over 270 species of birds have been recorded in the area. They are attracted by the wetlands habitat and plentiful food supplies.

The spreadsheet 'bird_species.xls' contains data on bird numbers seen at the Western Treatment Plant during the four months from November 2001 to February 2002. For comparison, there is also data on the mean numbers observed during the period 1987 to 1997, as well as for the year 2001.

In this activity, you will analyse and interpret this data.

Look at the November to February data.

  1. What were the most common bird species found at the Western Treatment Plant?
  2. Which species increased their numbers during this period? Can you suggest why this might be the case?
  3. Are there any species whose numbers stayed the same or declined? What might you infer from this data?
  4. Choose one species whose numbers grew over the four months and one whose numbers declined and graph the results.

Now look at the longer-term trends by comparing the mean for 1987 to 1997 with the mean for 2001.

  1. Which species have increased in number over this time?
  2. Are there any species that have declined?
  3. Have bird numbers increased? What reasons can you suggest to explain your findings?

Further research

Choose one of the birds listed on the Birds Australia website (www.birdsaustralia.com.au) and investigate its migratory patterns.