An investigation was carried out to monitor the populations of red squirrels (Sciurus vulgaris) and grey squirrels (Sciurus carolinensis) in a 15 km² wooded area - Scottish Highers Biology - Question 6 - 2018

In September 2011, the average number of breeding pairs of red squirrels was recorded at 33 pairs/km². Therefore, the total number in a 15 km² area would be:

$ext{Total red squirrels} = 33 ext{ pairs/km}^2 \times 15 \text{ km}^2 = 495 \text{ pairs}$

In June 2012, the number of grey squirrels was observed at 1.6 pairs/km² and red squirrels at 0.4 pairs/km². The ratio of grey squirrels to red squirrels can be calculated as follows:

$\text{Ratio} = \frac{1.6}{0.4} = 4:1$.

The method may lead to inaccuracies because the same pine marten may be counted more than once if it passes by multiple cameras. Additionally, not all animals might trigger the cameras, leading to potential underestimation.

Evidence from the table shows that in wooded area 1, there are 45 estimated pine martens, while there are significantly more red squirrels (645) compared to grey squirrels (88). This suggests that pine martens predate more on grey squirrels, given their relative numbers.

The table indicates that there are 645 estimated red squirrels versus 88 grey squirrels in wooded area 1, suggesting that grey squirrels are outcompeting red squirrels, as indicated by their lower numbers indicating less successful foraging.

Invasive species.