To read a conservation table, describe the trend with numbers, calculate the change, and say what the data cannot show. A count is evidence, but it is not proof of recovery.
This lesson is part of environmental sustainability. It follows causes and effects of environmental change.
What does the table show?
The data is invented for practice. A beach project counts turtle nests each year.
| Year | 1 | 2 | 3 | 4 | 5 |
|---|---|---|---|---|---|
| Nests counted | 40 | 46 | 52 | 49 | 58 |
The trend is an overall increase, with a small dip in year 4. The mean is (40 + 46 + 52 + 49 + 58) ÷ 5 = 245 ÷ 5 = 49 nests.
How do you calculate the change?
Percentage change from year 1 to year 5 = (58 − 40) ÷ 40 × 100 = 18 ÷ 40 × 100 = 45%.
A good sentence: “The number of nests rose from 40 to 58, an increase of 45%, although it fell slightly in year 4.”
How do you calculate hatching success?
In one year, 800 eggs were laid and 600 hatched. Hatching success = 600 ÷ 800 × 100 = 75%.
This shows survival to hatching only. It does not tell you how many hatchlings reach the sea or grow to adults.
What can the data not show?
- A nest count is not the total population, since one female may nest more than once.
- A rise may reflect more searching effort.
- Five years is a short run, so a longer record would give stronger support.
Mention at least one limit in your conclusion, because it shows you are judging the evidence.
The mistake that costs marks
The common error is to write “the turtle population is recovering” from the table. The data gives nest counts, not the population.
A safer wording: “Nest counts rose from 40 to 58, which suggests the project may be helping, but more years of data and the search effort are needed to be sure.”
Check yourself
A project records 500 eggs with 360 hatched in one year. Calculate the hatching success, and say what it does not show.
Answer
360 ÷ 500 × 100 = 72%.
It does not show how many hatchlings survive after reaching the sea, or whether the total population is growing. It covers only survival from egg to hatchling.
What to study next
Go on to evaluating a management action against stated criteria. The graph evidence comparison lab gives you more tables to practise on, and the mistake log tracks calculation slips.
If you want a teacher to check which words in your conclusions go beyond the table, see online one-to-one Biology tuition.