Sunday Primate: Lesser Galagos

The Lesser Galago


Galago is the name given to a primate family which consists of the Greater Galago (Otolemur), Lesser Galago (Galago) and the Needle-clawed Galago (Eutocius). The three genera live throughout sub Saharan Africa. Galagos are arboreal and inhabit various types of forests, i.e. rainforests, deciduous woodlands, valleys, and riverine bush. In fact there is hardly a large forest within Africa that does not contain a population of lesser galagos. It’s easy to see why the are the most abundant primate in Africa.

Like all galagos the Lesser galago is a nocturnal Strepsirhine primate. They have large eyes with tapedum lucidium (a reflective tissue layer in the eye which helps trap light and enhances night vision). As mentioned above they spend the majority of their life in the trees and as such have highly developed vertical clinging and leaping skills. Not only are they fast but also quite small weighing only about 150 to 200 grams.

Lesser galagos are omnivorous, eating fruits, tree gum and small animals. But they also serve as food for other primates such as blue monkeys (Cercopithecus mitis). While extremely populous lesser galagos have a lot predators such as jackals, owls, and snakes. The common chimpanzee is another feared enemy of the Galago, which makes it somewhat surprising that the Galago thomasi often make nests out of abandoned chimp nests.

But the nesting habits of lesser galagos vary between species. Many species aren’t particularly fond of the aforementioned expired chimp nests and instead prefer to sleep in tree hollows. Some species such as Galago senegalensis and Galago moholi live a quite nomadic life, inhabiting over a dozen different sleeping sites annually.

While the exact social structures of different species vary they often consist of a male, multiple females and offspring. Most prefer to sleep in large groups, probably for protective purposes, but some species will only sleep in pairs. It appears that females often show preferential favour to specific males but they will also mate with multiple partners. This creates conflict between males and it comes as no surprise that larger males tend to have more offspring.

Galagos are a very communicative primate and have a range of different vocalizations which have been categorized into the distinct types; social contact calls, threat and distress calls, and attention and alarm calls. They demonstrate reciprocal altruism by warning others of potential predators. As it is in the interest of individuals to avoid predators it serves to protect the group. When the Galago sends an alarm he temporarily puts himself at a greater risk of being caught, so one might ask if this is a completely selfless act.

To answer such a question one can imagine a hypothetical situation in which a sneaky galago doesn’t warn the group about an owl he saw fly overhead. Instead making the normal alarm call our sneaky galago has chosen to hide in the bushes while the other galagos remain in the open, perhaps foraging for food. Quickly the owl swoops down and grabs off an unsuspecting Galago. Initially the behaviour of the sneaky Galago might seem intelligent: he got himself out a bad situation while another galago (perhaps even a potential male competitor) was devoured. But this sort of survival strategy would not work out over a longer period of time. If such a behavior spread throughout the group eventually it would be every galago for themselves and this would drastically reduce protection on an individual level. Even if other galagos didn’t behave in such a manner, the sneaky galago would by his acting of hiding be separated from the group. Although his sneaky actions may have temporarily protected him from a potential predator he now finds himself at a greater risk of being caught than ever before.

This kind of survival strategy provides an interesting insight to see how the evolutionary force of natural selection can shape behaviour. Reciprocal altruism is an interesting topic to explore and I highly recommend the chapter Nice Guys Finish First in Richard Dawkins’ The Selfish Gene as a great place to explore these ideas further and in greater depth.

While galagos are currently extremely populous they are threatene by loss habitat just like nearly all other primates (with exception to humans). The Galago rondoensis, for example, is nearly extinct. They are often accidently caught in bird traps because of their small size. Some galagos are still hunted by humans for meat as well.