By Amanda Ramsing-Lund (University of Vermont)
If you visit Africa or Madagascar, you have a chance of seeing a bird called the Hamerkop (Scopus umbretta), which is the Afrikaans name meaning “hammer head.” Before coming to Africa, I thought the only animal strange enough to have a hammer-shaped head is the Hammerhead shark. Within my first three days in Botswana I saw otherwise: the Hamerkop has a thick, pointed beak and an almost equally sized, pointed crest of feathers on the back of its head, creating an asymmetrical hammer profile. I’m not sure if this backwards-facing, feathered crest has a specific purpose- does it benefit the bird in some way? Is it used in a mating display? Nonetheless, it is quite a striking, unique feature that characterizes this very unique bird.
The Hamerkop is actually the only member of its scientific family, called a monotypic family, so there are no other birds quite like these¹. They weigh between 400 and 600 grams, and can be about half a meter long from head to tail (50-60 cm). The males and females are not sexually dimorphic (distinguishable by physical differences in coloration, tail length, etc), so individual Hamerkops of each sex have largely the same physical appearance. They both have a fairly uniform brown coloration, in a range of shades, with dark-colored beaks, eyes, and legs.
Hamerkops are monogamous- they mate for life and construct several nests within their territory that they reuse year to year. I have only seen one pair of Hamerkops together, as usually I observe the birds foraging or flying alone, but this pair seemed quite bonded: they were huddled close to one another on a dead tree branch, feathers touching, looking out at a river early one morning.
Hamerkops are typically found in territories near bodies of water, especially rivers. I’ve observed this firsthand, as all of the nests I have seen (about 10 total) have been well within one or two kilometers of an active river, including the Thamalakane, Khwai, Linyanti, and even Zambezi rivers. I was even fortunate enough to see one Hamerkop collecting damp grasses and vegetation from a floodplain area across from a river, then carrying clumps back to its nest in a Rain Tree (Philenoptera violacea) approximately 85 meters away. I did not see it use these grasses in any particular way, but it appeared to be actively building the nest. I’ve included a few pictures of this situation.
Hammerkop collecting twigs for its nest
Hammerkop on its nest
Hammerkop nest
Hamerkops construct their nests out of numerous sticks as well as anything else they can find, even human objects and debris. In the picture (above) you might be able to see that there is a knee-high sock hanging from the left side of the nest. There’s so much material incorporated into Hamerkop nests that they appear to just be massive mounds shaped like upside-down pyramids, wedged precariously in the crooks of thick tree trunks. I have seen one that was about 2.5 meters deep and at least 2 meters wide, much larger than the Hamerkops themselves. Something that I did not realize about these nests is that Hamerkops don’t sit on top of them, but construct a side entrance and nest inside the maze of sticks.
I really enjoy every chance I get to see a Hamerkop, with their soaring style of flight and their quirky way of trotting through the reeds searching for fish in the rivers. Hopefully I keep seeing them do interesting things and interacting with other species in the next month that we’re here, I’ll be writing a final report on what I observed about their behaviors and role in the ecosystem!
¹Information courtesy of Birds of Southern Africa, Fourth Edition by Ian Sinclair, Phil Hockey, Warwick Tarboton and Peter Ryan.