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'Monster' bird reveals dark side

Shoebill chick is filmed attacking its younger sibling

Aggressive bullying between bizarre-looking shoebill

chicks has been filmed for the first time.

The encounter was captured at Bangweulu wetlands, near Kasanka, in northern

Zambia for the BBC One series Africa.

Wildlife filmmakers were surprised to witness an older chick attacking its

younger sibling while their mother was foraging away from the nest.

The birds are rare subjects for study because their swamp breeding grounds

are very difficult to access.

The team's aim was to shed light on the species by documenting intimate

behaviour of shoebill parents and young at the nest.

Siblicide, the phenomenon of offspring killing their siblings, is common

among many larger birds.

"This behaviour had previously been recorded in

shoebills (Balaeniceps rex) but we hadn't planned on seeing it,"

explained director Alex Lanchester, who describes the shoebill as

"prehistoric-looking".

The film, which is at times disturbing, provides intimate footage taken using

three mini-cameras fitted to the nest.

The shoebill chicks were approximately three weeks old at the time of

filming, with one chick a few days older than the other.

The elder chick can be seen viciously attacking its younger sibling while

their parents are absent. It gouges the younger chick with its beak, wounding it

and removing clumps of feathers.

The younger chick is also rejected by its parents in favour of its aggressor.

Mr Lanchester describes the scene as "very hard to watch... Especially

watching the smaller chick trying to fend for itself, for example trying to

shade under the grass and going to get water itself".

 
The shoebill chick was undeterred by the cameras surrounding its nest
Eventually the younger chick succumbed to its circumstances. "It took about

five days for the smaller chick to die," Mr Lanchester told BBC Nature.

"I think it was probably from exhaustion, hunger and thirst rather than a

physical injury by the bigger chick."

The shoebill is an unusual-looking bird that grows up to 1.5m tall with a

wingspan over 2m. Its habitat is restricted to Zambia, Sudan, eastern Democratic Republic of Congo,

Rwanda, Uganda and western Tanzania.

Research suggest the reason for behaviours such as siblicide and offspring

rejection is likely to be energy efficiency.

"It must make sense from a survival point of view, as

this huge bird needs to be fully grown within a few months, and the adults

probably would not manage to supply enough food for more than one," says Frank

Willems, a local ornithologist and ecologist who assisted the filming team.

The shoebill female always lays two eggs but only one ever survives.

Mr Willems commented: "It seems the second egg is just a back-up in case

something is wrong with the first one."

"Normally the first to hatch is the one to survive, unless health or growth

issues make the second become stronger."

The world population of shoebills is estimated to be between 3,300 and 5,300

according to 2012 statistics from conservation partnership Birdlife

International.

Because they live in vast, inaccessible wetlands, there is little knowledge

about exact numbers.

 
Shoebills are only able to rear one chick each year
"The fact that only one chick can fledge per year indicates how sensitive the

species is," commented Mr Willems.

"The low reproduction is compensated by very high survival of the adults. A

few people removing chicks or shooting adults will make all the difference."

The shoebill is listed as "Vulnerable" on the International Union for

Conservation of Nature's global list of threatened plants and animals.

Factors currently threatening the shoebill's future include destruction and

quality reduction of its flooded marsh habitat, illegal capture for trade, as

well as disturbance or destruction of nests and young.