Watching behaviour is at the heart of wildlife biology and of every great wildlife encounter. Why do meerkats take turns on guard? Why do lions live in prides while tigers live alone? Why do some birds sing at dawn? The science of animal behaviour, or ethology, answers these questions and gives field workers the skills to interpret what they see.
What you will learn
- Tinbergen’s four questions for explaining behaviour
- How animals decide what and where to eat
- Why some animals live in groups and others alone
- Mating systems, communication, learning and culture
Tinbergen’s four questions
In 1963, the Dutch ethologist Niko Tinbergen, who shared a Nobel Prize in 1973 with Konrad Lorenz and Karl von Frisch, argued that any behaviour can be explained at four levels:
- Mechanism: what triggers it and how does the body produce it? (A robin sings because rising day length changes its hormones.)
- Development: how does it develop during an animal’s life? (Young songbirds learn their song by listening to adults.)
- Function: how does it help survival and reproduction? (Song attracts mates and defends territory.)
- Evolution: how did it evolve over generations? (Song evolved from simpler calls in ancestors.)
A complete explanation needs all four, and confusing them leads to muddled answers.
Foraging: how animals find food
Optimal foraging theory predicts that natural selection favours animals that maximise the energy they gain relative to the time and risk involved. For example:
- Predators should prefer prey that give the most energy per unit of handling time, and add less profitable prey only when good prey are scarce.
- An animal feeding in patches should leave a patch when its rate of gain falls below the average for the whole habitat (the marginal value theorem).
Real animals also trade food against danger. Elk in Yellowstone feed differently where wolves are active, and gazelles spend more time watching and less time feeding at the edges of herds. Ecologists call this the “landscape of fear”.
Living alone or in groups
Group living has costs and benefits.
| Benefits | Costs |
|---|---|
| More eyes to spot predators (meerkats, antelope herds) | More competition for food |
| Dilution: each individual’s risk is lower | Easier spread of parasites and disease |
| Cooperative hunting (lions, wild dogs, orcas) | Conspicuousness to predators |
| Shared care of young (elephants, meerkats) | Competition for mates |
| Information sharing about food (bats, bees) | Conflict and aggression |
Whether group living pays off depends on food and predators. Tigers hunt large prey alone in dense forest, where a single cat can ambush effectively and prey is dispersed. Lions on open savannas benefit from cooperation to bring down large prey, defend kills from hyenas and protect cubs from rival males.
Social systems
- Solitary: tigers, leopards, orangutans, most bears.
- Pair-living: gibbons, many birds, beavers.
- Family groups: wolves, elephants (matriarchal families), meerkats.
- Fission–fusion societies: chimpanzees, spotted hyenas, dolphins and elephants form groups that split and merge.
- Eusocial colonies: ants, termites, honey bees and naked mole-rats, with reproductive division of labour.
Cooperation and kinship
Why help others at a cost to yourself? The biologist W. D. Hamilton showed in 1964 that helping relatives can spread shared genes (kin selection). This explains helpers at the nest in many birds and non-breeding meerkats babysitting pups. Cooperation between non-relatives can evolve through reciprocity; vampire bats share blood meals with roost-mates that have shared with them before.
Mating systems
- Monogamy: one male and one female pair, often for a season or for life (albatrosses, swans, gibbons).
- Polygyny: one male mates with several females (elephant seals, red deer, gorillas).
- Polyandry: one female mates with several males (jacanas, phalaropes, where males incubate the eggs).
- Promiscuity and leks: males gather at display grounds called leks, and females choose among them (sage grouse, some antelope, birds-of-paradise, Bengal floricans).
Competition for mates drives sexual selection: large antlers, bright plumage, elaborate songs and displays.
Communication
Animals communicate with:
- Sound: birdsong, whale song, the infrasound rumbles of elephants, the alarm calls of vervet monkeys, which have different calls for leopards, eagles and snakes.
- Sight: displays, colours and postures, from the peacock’s train to a wolf’s raised tail.
- Scent: urine marking by big cats, dung middens by rhinos, pheromone trails by ants.
- Touch: grooming in primates, which strengthens social bonds.
- Vibration and electricity: elephants may detect ground vibrations; some fish communicate with electric signals.
Learning and culture
Many animals learn from experience and from each other. Chimpanzee communities have different tool-use traditions; bottlenose dolphins in Shark Bay pass sponge-carrying techniques from mother to daughter; humpback whale songs spread across ocean basins; and New Caledonian crows make hooked tools. When behaviours differ between populations because of social learning, scientists describe them as animal cultures, and some conservationists argue that cultures themselves are worth conserving.
Case study: meerkat sentinels
Meerkats in South Africa’s Kalahari live in groups of up to about 50. While the group forages, one adult climbs to a high point and watches for eagles and jackals, giving different alarm calls for aerial and ground predators. Research at the Kalahari Meerkat Project, running since 1993, found that sentinels tend to go on guard when they have fed well, and that individuals gain safety by being first to spot a threat. Watch for sentinel behaviour next time you see meerkats, mongooses or even crows.
Try it yourself
Watch a group of birds, squirrels or other animals for 20 minutes. Every 30 seconds, write down what one chosen individual is doing (feeding, vigilant, moving, resting, social). This is called focal sampling. What percentage of time did it spend on each activity?
Key terms
- Ethology: the scientific study of animal behaviour.
- Optimal foraging theory: the idea that selection favours efficient foraging.
- Kin selection: helping relatives who share your genes.
- Lek: a gathering of males displaying to attract females.
- Animal culture: behaviour passed on by social learning that differs between populations.
Quick quiz
Further reading
- Davies, N. B., Krebs, J. R. and West, S. A. An Introduction to Behavioural Ecology.
- Tinbergen, N. (1963). “On aims and methods of ethology.” Zeitschrift für Tierpsychologie.