The powerful snake-stomping Secretary Bird
This captivating killer is now at risk...here's why
By Annette J Beveridge
A RAPTOR that stalks and delivers a powerful blow to even the most venomous of snakes is facing real threat due to indiscriminate poisoning, habitat loss and habitat connectivity.
Reaching heights of up to 1.5 metres, (more than 4ft) and with a wingspan of up to 2.1 metres, (6 feet) Secretary Birds are tall, distinctive birds like no others. They can be found stalking the grasslands and savannahs of Africa. A single kick delivers an impressive 195 newtons (43 lbs) of force at the head of targeted prey - snakes, rodents and other small animals.
Secretary birds are terrestrial. Although the birds can fly, it is a laborious and energy-draining process so when they take to the air, they often soar and make use of thermal columns lifting them up to 3, 800m (12,500 feet).
Protection
Secretary birds have very short stubby toes and thick claws limiting its ability to grasp its prey. Once the killer blow has been delivered, food is consumed whole or carried away in its beak.
A mis-timed or misplaced kick could be deadly for the birds even with the tough scales on the lower legs protecting them from potential bites. When attacking, Secretary Birds opt for distraction techniques by flapping their wings and then, delivering a fast, accurate foot strike which will usually stun or kill prey. Depending on the prey, the Secretary Bird may need to continuously stamp until it is certain that the prey is dead.
This ability requires a high level of coordination between the visual and neuromuscular systems.
The legs are long….twice as long as another athletic ground bird with an equivalent body mass. There are long tibiotarsus and tarsometatarsus bones which enables the rapid foot speeds needed when striking prey.
These raptors were once considered related to bustards and storks although molecular analysis now suggests the species could be closely related to the Osprey.
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Territories
Secretary Birds spend most of the day hunting for food and leave the roost a few hours after dawn, returning only at dusk.
The birds hunt fairly close to breeding partners or in small family groups but individuals will spread out from each other and can cover distances of more than 20 miles (32 kilometres) per day.
Breeding
Secretary birds are monogamists. They mate with a single partner for life and pairs defend territories up to 19 square miles (50 square kilometres).
Breeding is most common in the late dry season but can occur throughout the year. The birds indulge in a soaring display high above the ground making a loud creaking sound while flying in an undulating pattern.
A ground display where they chase each other with wings up and back often occurs too and this is similar to how the bird defends its territory. It can take the pair up to six months to build a nest which will usually be built on top of a thorny Acacia tree anywhere up to 40 feet (13 metres) above the ground. The birds make the nest with twigs, leaves, grasses, and dung but will also use animal fur.
The nest can extend to 2.52m wide (8 feet) and is often reused for several years.
Eggs
Up to three pale blue to green or white eggs are laid and both birds spend time incubating them. The female will spend most of the time on the nest especially at night. Chicks hatch approximately 45 days later in the order they were laid and both parents will provide food for the chicks for at least 40 days following hatching. Chicks leave the nest between 75 and 80 days after emerging from the eggs.
If there is sufficient food, the birds will often raise more than one chick successfully.
What’s in a name?
French naturalist Johann Hermann created a separate genus for the birds giving the name Sagittarius – the Latin name for Archer. The species name serpentarius is from the Latin word Serpens which means serpent or snake and is a reflection of the bird’s diet.
One explanation for the name Secretary Bird was suggested by Georges Louis Leclerc who stated in 1780 that the name secretary was based upon its facial features and that the long quill-like feathers sitting at the top of the bird's neck resembled a quill pen.
Alan C Kemp gave a different explanation in 1995 when he said that the name was derived from the Arabic Saqr at-lair which translates as hunter bird, or Falcon of the hunt.
A declining population
In the last decade, secretary birds have suffered a dramatic decline.
A species which is highly nomadic, there is a need to cross environments modified by people.
Research in the last few years has demonstrated that approximately 50% of Secretary Bird sightings in South Africa had been recorded in an environment that was transformed in some way and that the birds have adapted to change.
However in other countries, urbanisation, agriculture, habitat loss and loss of habitat connectivity had resulted in a considerable reduction in the bird populations.
In 2016, Secretary Birds were listed as ‘vulnerable’ by the International Union for Conservation of Nature (IUCN) and then, listed as ‘endangered’ in 2020.
Habitat loss is key and while the species might benefit from deforestation, the negative impact of urbanisation and cultivation outweighs any benefits. The burning of grasslands can also have a detrimental impact on prey species populations along with intensive grazing of livestock.
Secretary Birds have been captured and traded and although in relatively small numbers, it is unknown how many birds die in transit or in captivity. Hunting and nest raiding along with indiscriminate poisoning at water holes all impact the species population.
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