Juvenile White-tailed sea Eagle feeding. (c) Arthur Ellis
The diet of the White-tailed Eagle is extremely varied and includes fish, birds, carrion and small mammals. Many birds exist as scavengers especially during the winter months. Studies of food remains collected from nests after young have fledged, reveal that over forty different species of bird, mammal and fish regularly contribute to the diet of White-tailed Eagles in the breeding season.
Whilst they will scavenge in leaner times, White-tailed Eagles are nonetheless powerful and effective hunters and show a marked preference for fresh food. They snatch fish from the surface of both freshwater and the sea employing a spectacular shallow, feet-first dive. They have small spikes called spicules on the underside of their feet which helps prevent slippery prey from escaping. Somewhat incongruously, White-tailed Eagles have even been known to wade into shallow water to fish like a Grey Heron although we have yet to see this on Lough Derg.
The White-tailed Eagle is a less active hunter than other raptors such as the Golden Eagle and may be seen perched in a tree or on a rock for hours on end. This has given first time eagle watchers great opportunities to see the birds as they perch for long periods on favorite trees on Bushy and Crilly Island on Lough Derg. The daily food requirement of a White-tailed Eagle is in the region of 500 – 700g (two large fish) and equates to about 1/10th of their body weight. A variety of sea birds and waterfowl are eaten with ducks being particular favorites where fish are less plentiful.
Carrion (dead animals)
- Ungulate remains: sheep, deer
- Pinnipeds: dead seals on coast
- Fish: spent/dead salmon, other fish washed up on shore
- Also fish stolen/left over from Otters, gulls
- Seabirds: Fulmar, diving duck
- Fish: Saithe, Pollack, Lumpsucker
- Mammals: rabbit, hare, rarely lamb
Throughout their range, individual White-tailed Eagles are accomplished thieves robbing other birds and animals of their prey. White-tailed Eagles can often be encountered actively harassing sea mammals in the hope that that for instance an otter may relinquish its catch. They can be seen hounding and robbing birds of their hard earned dinners and are often far from welcome guests in the territory of large gulls and cormorants.
White-tailed Eagles have a swelling in their oesophagus called a crop which allows them to store excess food without discomfort. The diet of White-tailed Eagles can be varied and includes fish, birds (normally ducks and gulls) and mammals, including rabbits . The indigestible parts of their meals (bones, feathers, fur and hair) is formed into a pellet in the muscular part of the bird’s stomach called the gizzard and regurgitated through its mouth.
White-tailed Eagle pellets may be cast anywhere that the bird may be resting or roosting, near the nest or in the vicinity of a favourite place that an individual bird may use to eat the prey it has caught. The pellets of a White-tailed Eagle can be very large (up to 5 inches) and consist predominantly of feathers and fur. Eagles, unlike owls, do not swallow their prey whole. Instead, they use their beaks to tear at the flesh of their prey, which means that very few bones will ever be swallowed. Consequently, bones should rarely appear in their pellets. By comparison, the pelleted remains of an owl’s meal will reveal a high proportion of vole, mice and bird skeletons.