The brown snake eagle, scientifically known as Circaetus cinereus, is a large bird of prey that primarily resides in open habitats such as savannahs and grasslands across sub-Saharan Africa. These majestic birds have a unique and captivating life cycle that is worth exploring.
The Breeding Cycle
The breeding cycle of the brown snake eagle is quite extensive, lasting for several months. The female lays a single egg, which hatches after an incubation period of 52 to 59 days, averaging around 55 days. This is one of the longest incubation periods among African raptors.
Hatchling and Early Development
The hatchling is highly altricial, meaning it is born in a helpless state, unable to lift its own heavy head and possessing a deeply wrinkled cere. The young eaglet is initially covered in creamy down with a chocolate-brown patch behind the eye, which matches the rest of the body. As it grows, the down develops a patchy appearance, and by three weeks, it has a downy white head but the down color above is dark brown, with the first brown feathers sprouting on the back of the head, secondaries, and scapulars.
Feather Growth and Appearance
By four weeks, the eaglet no longer has any white down, and brown feathers grow especially on the back and wings; a week later, the feathers continue to emerge, and the secondaries outgrow the primaries. The young eaglet resembles those of snake eagles in appearance and feather growth pattern, particularly the retarded growth of the primary feathers, and its general coloring becomes greyer as it ages.
Behavioral Development
The nestling may first stand at about five weeks and engage in wing-flapping. Pre-independence juveniles may perch or lie in a prone position before they can fly well. The stage at which the young first feeds itself is dictated by what prey is brought; if it is large, the parents will feed the young to 40 days, but small fragments will be eaten unaided by the downy young. Around six weeks is when the eaglet can typically feed itself for the first time.
Nest and Breeding Habits
Image source: Brown snake eagle By Derek Keats
Brown snake eagles tend to build a relatively small but sturdy stick nest in a large tree and lay only a single egg. Despite being a rather aggressive bird in other contexts, bateleurs are easily flushed from their own nest, making them exceptionally vulnerable to nest predators, including humans, and nest failures.
Maturity and Longevity
It may take as long as 7 to 8 years for a brown snake eagle to attain full maturity, perhaps the longest stretch to maturity of any raptor. This species has long been known to be declining rather pronouncedly, likely due to a combination of factors such as habitat loss, persecution, and other threats.
In conclusion, the life cycle of the brown snake eagle is a fascinating and intricate process, marked by a prolonged breeding cycle, unique feather development, and a slow path to full maturity. Understanding the intricacies of this raptor’s life cycle is crucial for conservation efforts and ensuring the continued survival of this remarkable species.
References:
- Avibase. (n.d.). Circaetus cinereus (Brown Snake-Eagle) – Avibase. Retrieved from https://avibase.bsc-eoc.org/species.jsp?avibaseid=6904D83FD07E202F
- Wikipedia. (2023, July 13). Bateleur. Retrieved from https://en.wikipedia.org/wiki/Bateleur
- Earth Life. (2023, July 13). Snake Eagles (Circaetus) Information | Earth Life. Retrieved from https://earthlife.net/snake-eagles/.
