Every animal needs a place to find food, water, shelter and mates. Some find all of this in a few square metres; others need thousands of square kilometres or travel between continents every year. Understanding how animals use space is essential for designing protected areas, corridors and conservation plans.
What you will learn
- What habitat is and how animals choose it
- The difference between home ranges and territories
- Why animals disperse, wander or migrate
- How animals navigate, and how tracking technology reveals their journeys
Habitat and habitat selection
A habitat is the place and conditions where an animal lives: its vegetation, climate, water, shelter and other species. Habitat selection is the process by which animals choose where to live, usually at several scales: the broad region, the home range within it, the patches used within the home range, and the individual sites used for feeding, resting or breeding.
Good habitat provides food, water, cover from predators and weather, and breeding sites. Habitat quality can vary widely. Some habitats that look suitable are actually ecological traps: animals are attracted to them but do poorly there, such as sea turtle hatchlings drawn inland by artificial lights, or birds nesting in hayfields that are mown before chicks fledge.
Home ranges and territories
- A home range is the area an animal normally uses for its daily activities. Home ranges of neighbours can overlap.
- A territory is the part of a home range that an animal actively defends against others, using scent marks, songs, displays or fights.
Home range size depends on body size, diet and habitat quality. Carnivores need much larger areas than herbivores of the same size, because their food is scarcer. Tiger home ranges vary from about 20 km² for females in prey-rich Indian reserves to over 1,000 km² for males in the Russian Far East. This single fact explains why large carnivores are often the first to disappear from small or fragmented reserves.
Researchers estimate home ranges from tracking data using methods such as minimum convex polygons (drawing a boundary around all locations) and kernel density estimates (which map how intensively each area is used).
Dispersal
Dispersal is movement from where an animal was born to where it breeds. It reduces inbreeding and competition with relatives and lets species colonise new areas. In many mammals, young males disperse further than females; in many birds, females disperse further. Dispersal is when animals are most at risk of road deaths and conflict with people, and when corridors between protected areas matter most. A young wolf tracked in Europe travelled more than 1,000 km from Germany to Belarus, and dispersing tigers regularly cross farmland between reserves in India.
Migration and nomadism
Migration is a regular, often seasonal, round-trip movement between separate areas. Animals migrate to follow food, avoid harsh conditions or reach safe breeding sites.
| Migrant | Route | Distance and notes |
|---|---|---|
| Arctic tern | Arctic breeding grounds to Antarctic waters | Tens of thousands of km a year, the longest known migration |
| Bar-tailed godwit | Alaska to New Zealand | Over 11,000 km nonstop in about 9–11 days |
| Wildebeest | Serengeti–Mara loop | About 1.3 million animals following rain |
| Grey whale | Arctic to Baja California | About 16,000–20,000 km round trip |
| Monarch butterfly | Canada and USA to central Mexico | Several generations complete the cycle |
| Bar-headed goose | Central Asia over the Himalaya to South Asia | Flies at high altitude across the mountains |
| Salmon | Ocean to birthplace streams | Return to spawn, often after years at sea |
Nomadic animals move irregularly in response to unpredictable resources rather than on fixed routes. Examples include red kangaroos and many Australian desert birds following rain, and the Mongolian gazelle.
Partial migration, where some individuals in a population migrate and others stay, is common in birds and in species such as elk and red deer.
How animals navigate
Animals use several cues, often in combination:
- The sun, corrected for time of day with an internal clock (monarchs, many birds).
- The stars: night-migrating songbirds learn star patterns around the celestial pole.
- Earth’s magnetic field: sea turtles, salmon and many birds can sense magnetic direction and intensity, helping them return to specific places.
- Landmarks such as coastlines, rivers and mountain ranges.
- Smell: salmon recognise the chemical signature of their home stream; some seabirds navigate partly by smell.
Tracking animal movement
GPS collars, satellite tags and tiny geolocators have transformed our understanding of movement (see Ecology Module 15). Tracking has revealed the nonstop flights of godwits and swifts, elephants moving through narrow corridors at night, and the long foraging trips of albatrosses. The global database Movebank stores billions of animal locations shared by researchers.
Case study: elephant corridors in Kenya
Elephants in Kenya’s Laikipia and Mount Kenya regions once moved freely between the mountain forests and the lowland plains. Farms and fences cut these links. In 2011, a dedicated underpass beneath the Nanyuki–Meru highway opened as part of the Mount Kenya Elephant Corridor. Within days, GPS-collared and camera-trapped elephants were using it, and it has since been used regularly, reconnecting populations and reducing conflict with farmers. The project shows how tracking data can guide practical solutions.
Try it yourself
Use a free app with GPS (for example a hiking app) to record your own movements for a day. Plot the points on a map and draw a boundary around them. How large is your “home range”? Which areas did you use most intensively, and why?
Key terms
- Habitat selection: how animals choose where to live.
- Home range and territory: the area used and the area defended.
- Dispersal: movement from birthplace to breeding place.
- Migration: regular round-trip movement between areas.
- Ecological trap: a habitat that attracts animals but reduces their success.
Quick quiz
Further reading
- Milner-Gulland, E. J., Fryxell, J. M. and Sinclair, A. R. E. (eds.) Animal Migration: A Synthesis.
- Movebank (movebank.org).