Glenesk has a rich natural history. Many bird species are to be seen, from the humble Meadow Pipit and the Red Grouse and the Ptarmigan, Golden Plover and the rare Ring Ousel; also many birds of prey, Golden Eagle, Sea Eagle (White-Tailed Eagle) , Peregrine Falcon, Merlin, Kestrel and Hen Harrier and increasing rapidly the Common Buzzard. Many mammals are also present. Red deer are to be seen in herds numbering many hundreds, mountain hares, wildcat, fox, otter, red squirrel.
The red grouse is the main reason for employing gamekeepers in the Glen, and although numbers have declined in recent years, they are still the most important bird to the estates. On the higher hills, there are a number of ptarmigan, while pheasants and partridges inhabit the low ground. There are golden eagles, buzzards, peregrine falcons, hen harriers, sparrowhawks and kestrels to be found in various parts of the Glen. There are also increasing numbers of crows and gulls which may be one reason for the decline in the numbers of lapwings, curlews, oyster catchers and other ground nesting birds.
Thrushes and mistle thrushes also seem to be in decline, although there are plenty of blackbirds. Most of the usual birds appear in the Glen, along with occasional visits from osprey. Red deer are numerous on the hills and roe deer are common on the lower ground. Stalking plays an important role in the commercial viability of the estates, and venison is a much under-rated meat which is low in fat and very tasty.