In all walks of life, often the best form of defense is attack. In the bush this is all too true and examples of it can be seen every day in a behavior called ‘mobbing’. Organisms of all sizes exhibit this behavior from time to time: from angry herds of buffalo chasing off marauding lions, to the plucky pint-sized Fork-tailed Drongo dive bombing loitering raptors, this unexpected aggressive behavior is often enough to repel a potential attack before it happens. In birds especially, it is often a true case of David and Goliath but the element of surprise and the will to survive at any cost is a strong motivator!
On a recent birding census on Sabi Sabi’s reserve, we were lucky enough to stumble across a pair of Verreaux Eagle Owls roosting in a large Jackelberry tree. Their huge eyes peered down at us from their perch but their subdued nature gave the impression that they were quite happy to see out the heat of the day without incident. However, it seemed that we were not the only passersby that had noticed their presence…
A small flock of Retz’s Helmet shrikes were busy foraging in the area; their metallic calls penetrating the thick riverine vegetation as they commenced their attack runs on any unsuspecting insects sheltering in the undergrowth. A bird’s skull is almost entirely eye and their keen eyesight soon picked up the slumbering danger in the branches above them. As one, the flock rose high into the tree and launched a frenzied offensive against the unsuspecting owls.
The intensity of the attack was severe and time after time, the fearless under-dogs rained down on the nocturnal predators, dive bombing them and actually striking the head on more than one occasion. The onslaught had the desired effect on one of the owls, who (excuse the pun), after receiving such a feverish blitzkrieg, fled to the safety of a nearby Sycamore Fig tree. The other member of the pair however seemed to have trouble motivating itself to make for safety and resigned itself to a pummeling from its assailants.
The harassment continued for more than 5 minutes as wave after wave of angry aviators plunged towards the owl. Its tolerance of the fearless feathered frenzy was remarkable as the Helmet Shrikes bounced off its head. It was obviously a situation that the owl had encountered before and had decided to just weather the storm and wait for the barrage to peter out and the pint-sized bullies to lose interest. Even in the midst of the maelstrom, the owl gave us a wonderful insight into its routine. It seemed to begin gagging, twisting its head from side to side, a look of gross discomfort visible on its face. After a few seconds of obvious straining, a walnut sized object emerged from its large bill and dropped to the ground. This is known as an owl pellet and contains all of the indigestible material consumed by the hunter during recent meals. Bones and fur make up the majority of its content and is routinely regurgitated by the owl, giving those brave enough to examine it, an insight into its feeding habits.
The passive nature of the owl was finally rewarded as the Helmet shrikes grew bored of the attack, or perhaps felt that their message had been unequivocally delivered, and continued on their own food finding mission. It was a remarkable sighting for all of us present and left us a with a huge feeling of respect for the Helmet shrikes, whose courage and determination to survive and protect prospective young was most certainly not muted due their diminutive stature. These games of chess between predator and prey are happening all around us during all hours of the day and night and this small window to the world of survival was a perfect example.