Red, roe and fallow deer are present in the general area and all three species have been seen on Cashel. Red deer frequent the higher ground and are thought to move through the site between the FC forests to the north and east and Montrose Estates land (Buchanan Castle) to the southeast.

The most recent open-ground count by the Deer Commission of the Balquidder/Trossachs count area was in 1988 when seven red deer were found on Cashel and 439 on Buchanan Castle land a short distance to the south. Since red deer were not counted in the adjoining plantation forests these counts are of limited value.

Casual observations suggest that red deer numbers within the Cashel boundary are relatively low during the summer but can be much higher in the winter. Roe deer are common all year round in the adjoining FC plantations and in the privately owned plantation along the Cashel Burn. As the new native woodland develops it is inevitable that numbers of resident deer will increase.