White-Tailed Eagles on the Isle of Mull

From Start to Finish

Early Breeders

Clutches of two or three eggs are normal and are laid asyncronously at intervals of between two and five days from early March onwards. Incubation takes place after the first egg is laid and lasts for an average of 38 days. The first chick to hatch is always the largest and strongest and, during periods of food scarcity due to inclement weather, the older bird may be forced to eat its sibling in order to survive. Unlike the Golden Eagle, both sexes share responsibility for sitting on the eggs, although the bulk of the incubation duty is carried out by the female.

This can be a frustrating time for would-be White-tailed Eagle watchers on the Isle of Mull and a greater degree of patience and good fortune can be required to secure good sightings. Incubating birds may sit tight for hours at a time, while the off-duty partner forages away from the nest or roosts in a favoured location nearby Birds can provide impressively close views at such times, but loafing birds may simply appear to sit around doing very little until it is time for a change-over to take place. During the five-six weeks of incubation, the luckiest eagle watchers may be fortunate to witness one of these changeovers, when both adults may be present at the nest for a short time. However, despite their enormous size (especially when in flight) it is possible for changeovers to take place unbeknown to the would-be observer!

Keeping Warm

For the first two - four weeks after hatching, the female remains in close proximity of the nest and may be seen actively brooding the young eaglets at this critical stage in their early development. White-tailed Eagle hatchlings are unable to regulate their own body temperature at this time and require to be sheltered from the vagaries of the Isle of Mull climate in order to prevent excessive heat loss and potential mortality. The nest of a White-tailed Eagle can become saturated or blown out of its location during wind and rain in Spring. The male provides all the food required by its partner and the chicks at this time, with the female not usually commencing hunting duties until after the third week. The Eaglets may now be left unattended at the nest for long periods as both parents extend their hunting forays in search of food to satisfy the appetites of the chicks.

Sea (Eagle) Cadets

Young White-tailed Eagle chicks start to feed themselves in the nest when they are about 6 weeks of age and begin to explore their nest surroundings during the following weeks. As fledging approaches, the adults will encourage the eaglets to exercise and will attempt to get the chicks to fly short distances from the safety of the nest in order to receive food. At 10 – 12 weeks, the young eagles are ready to leave the sanctuary of the nest but will often stay in the vicinity for several months while they remain dependent on their parents for food and learn to fend for themselves.

From the time of the first egg being laid in March until the year’s fledglings are successfully weaned from their parents in Autumn, the breeding season for White-tailed Eagles on the Isle of Mull may last in the region of seven months.