Predator Defense

In the Dwarf mongoose, predation risk is high and group size is small enough that this does not really provide adequate protection in itself from the threat of predation. The mongoose has many many predators, including both land and avian predators. These predators include the slender mongooses, banded mongooses, great grey mongooses, blackbacked and golden jackals, serval, caracal, wild dog, cheetah, tawny eagle, martial eagle, bateleur, snake eagle, secretary bird, dark chanting goshawk, python, spitting cobra, and puff adder (Rood, 1990).

As a response to these harsh conditions in the desert of the Serengeti and the wide variety of predators that inhabit it, the Dwarf mongoose has developed an elaborate system of calling which resembles a language, and constant vigilance. The advantages to this system for are that the members of the foraging group can devote their constant attention to looking for prey on the ground and thus forage more efficiently while one or more individuals located on a higher spot of ground, scan the surrounding area for danger (Rasa, 1986). An average of 1.7 guards are present for every 10 individuals in the group.

The mongooses that watch over the group during foraging is usually a subordinate male (Rasa, 1977). Subordinate males account for approximately 89.1% of all guarding bouts, while the alpha male and/or alpha female account for the other 10% (Rasa, 1986). Thus, the subordinate males who may or may not be related to the group place themselves at a considerable risk to predation because of their relative exposure and sacrifices feeding time while performing this "altruistic?" behavior (Rasa, 1977). During bouts of vigilance or guarding, the guard constantly emits a "contact call" distinctive in pitch for all the mongooses which signifies to the group that a guard is present and actively watching and also which individual is guarding, despite a possible loss of visual contact due to the high grasses that are prevalent in the mongooses environment (Rasa, 1986). The guard varies the volume of the call as the group moves farther away.

In most animal species without a complex vocalization, the immediate response to a predator sighting regardless of the predator's intentions, is to immediately run for cover. In other species, such as the dwarf mongoose, the sighting of a predator invokes a changing of the contact call to specify its location relative to the group and its future danger based on species type, and does not immediately result in hiding (Beynon, 1989). In studies conducted in the Serengeti over 782 foraging hours, the groups were disturbed by the sighting of a potentially dangerous predator 1325 times and received 102 actual attacks. This is an average of 1.69 disturbances/hr. 0.13 attacks/hr (Rasa, 1989). Thus, the relative danger of being attacked is less than 1 time per 10 disturbances. In this situation, it would probably be maladaptive to run for cover upon first sight of a predator. In species with a high predation risk, like the dwarf mongoose, it would be adaptive to develop a system whereby the group could avoid predation without significantly altering their feeding efficiency.

This system of guarding is apparently very efficient in disrupting attacks specifically by avian predators. Accipiters such as the shikra, gabar goshawk, pale chanting goshawk that hide in trees and bushes before attacking are successful in catching prey in only 12.2% of attacks, and eagles, buzzards, and falcons which attack from high in the air are successful about 10% of the time. Thus, once a raptor has been seen and the group has been warned of its presence, an attack is not attempted (Rasa, 1989).