White-bellied Sea Eagle feeding behaviour

posted in: Feeding chicks, Raptors | 4

“I have several pictures of a pair of White-bellied Sea Eagles (Haliaeetus leucogaster) feeding their chick at Changi on Wed 27th April 2011. The nest has been recycled over the years and it grew quite big. The nest is sitting on top of a tree trunk that had an almost flat top with branches spreading like a star-fish, similar to the trunk on its left (above). With such a strong base and a thick layer of interlocking branches tempered over time, I wonder if the nest is strong enough to support an adult man? This tree has been marked as a heritage tree.

“The series starts with an adult (I assumed it is a male as it was smaller in size, but stand corrected) flying in with the catch (above). Before this happened, the chick stayed hidden from view by remaining low in the nest but prop its head up immediately when it sensed the male bird flying in. The female bird joined in the feast with the chick (below left). Strangely, the male bird immediately moved aside when the female came over (below right). The male bird then flew to a higher branch. It’s interesting to note that the adult birds don’t fight over the food but are quite gracious with each other.

“The hunt for food can take more than an hour. I observed this three days earlier. During the wait, the female got restless and flew off on two occasions but came back without any food and resumed the wait for the male bird. While waiting for the male to return, I also noticed other smaller birds hovering near the nest and never seemed afraid of the bigger birds. These birds were mynahs, bee-eaters and pigeons. Some perched at the same level as the nest while others perched a few meters below. Interesting to note that these birds could co-exist with a raptor.

“My pictures were taken next to some white colonial houses built on the slopes along Cramwell Road. They have such a good view of the nest, I bet they have watched many cycles of life over the years.”

Thong Chow Ngian
Singapore
27th April 2011

4 Responses

  1. Lee Chiu San

    Dear Chow Ngian,

    You have confirmed another case of the suppression of the hunting instinct in the proximity of the home territory. I believe that this observation was publicised many years ago by ethologist Konrad Lorenz. Since then, other examples have been noted in mammals, birds and fish.

    This phenomenon is expressed in two ways – firstly, refusal to hunt in close proximity to the home base and secondly, non-recognition of creatures below a certain size as threats.

    In the first case it has been postulated that if predators with fearsome talons, claws or fangs continue to hunt close to home, they may accidentally injure their mates or their offspring. So the hunting instinct is switched off at home base. A classic example can be seen in domestic dogs and cats. Some large and savage dogs can live with cats in the same home. But let them meet the same cats some distance away from home, and their hunting instincts take over.

    In the second case, larger and fiercer creatures simply do not recognise creatures below a certain size as threats worthy of taking action against. Lorenz has noted that in Europe, songbirds do nest in close proximity to eagles. In my own experience, I have a large sucker catfish (Hypostomus) of about 30 cm. These catfish, though vegetarian, are known to be aggressive. He was about 5 cm when he came, and over the years, eliminated one after another of his tankmates. Attempts to introduce some more fish of close to his size almost ended in disaster.

    I moved him to another tank containing a breeding colony of milk-and-ink moons/platies (Xiphophorus maculatus), the excess of which supply my kingfisher feeding stations. An adult milk-and-ink moon measures about 4 cm. There are dozens in this tank. The catfish does not bother any of them, and they do not bother him.

  2. Thong Chow Ngian

    Chiu San
    You explained the behaviour and phenomenon very well! Wasn’t aware of this in other creatures until now. Interesting.
    Thanks for your comment
    Chow Ngian

  3. Dear Chow Ngian,
    Good day!
    May I use one of your pictures in my forthcoming book? The second one with the male flying in towards the nest. I am writing a book on wildlife.
    Your response will be highly appreciated.

  4. Thong Chow Ngian

    Dear Patrick
    Yes you have my permission.

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