Many animals make homes for themselves, rather than rely solely on natural cover to evade predators or raise a family.
Some of these homes are used all year round and for the inhabitants’ entire lifespans, some are temporary for the purposes of mating or rearing young. Here are a few of the fascinating constructions that can be found across the world.
World's most fascinating animal homes
Sociable Weaverbirds
In their South African homeland, this species of weaver constructs the most elaborate nesting system of any known bird. Throughout the Kalahari Desert these permanent structures drip from acacia, shepherd and quiver trees. The high-rise woven grass apartment complexes are sometimes also found hanging from telegraph poles, each housing hundreds of birds.
The nests are built with dozens of separate chambers. Large twigs are used for the top surfaces of the nest and grasses are woven together to form the separate chambers. Spiky plant stalks are used to protect the entrances from predators, while nesting chambers are lined with soft leaves, animal hairs, cotton seeds and other scavenged fluff.
A pair of birds has its own space for nesting, but the chambers are also used communally for roosting. The centrally placed ones hold the day’s heat and are occupied in night-time roosting. The outer rooms provide shade in the daytime when the temperatures soar. The nature of the weaving provides both insulation and ventilation and scientists have found that temperatures inside the chambers stay remarkably steady, regardless of the outside weather conditions, varying by only a few degrees.
Sociable weavers create an ecosystem within their avian colony. Apart from many different types of insects that inhabit the woven grasses, several other bird species, some reptiles and the Kalahari tree skink find places to shelter and breed within the nests. Scarab beetles and other scavengers thrive on the bird droppings under the trees.
Bowerbirds
The males of the 27 species of bowerbirds from Australia and Papua New Guinea make a home for only one purpose: to attract a mate. They show off their building and interior design skills by first constructing a cosy niche, or bower, from carefully placed sticks. They then decorate it with highly coloured and textured objects they have scavenged.
The house-building arrangement can take the form of a tepee of sticks gathered around a sapling tree trunk or an avenue of sticks stretching back into undergrowth. Sometimes a roof is constructed, sometimes the bower is just left open on top.
Depending on the geographic location of the birds, the meticulously arranged objects in front of the bower can consist of flowers and leaves, feathers, pebbles, shells and berries. Often the bird will focus on one particular colour scheme for the display.
In this modern age a male bowerbird can hit the jackpot in terms of impressive decorations if it finds pieces of brightly coloured plastic or glass, bottle tops, sweetie wrappers and shiny bits of metal, such as coins or discarded screws and nails.
Once collected, the bowerbird spends much time arranging and rearranging his treasures, hoping that a passing female will find his bower attractive and acknowledge his skills as a home builder by allowing him to mate with her.
Prairie dogs
These North American Great Plains rodents have a problem: they’re a tasty meal for a huge range of predators. Coyotes, American badgers, bobcats, bull snakes, wolves, foxes, rattlesnakes, golden eagles, red-tailed and ferruginous hawks, they all love a prairie dog. The solution? Live in large groups in an elaborate maze of tunnels and chambers.
Prairie dog burrows form conurbations covering many acres, with five to 35 dogs per acre. The underground rooms are dug at different depths in the soil to serve varying functions and they are arranged in what are called ‘coteries’, with plenty of space for each family group.
There are chambers close to the surface where the adults can listen out for predators or scuttle into if they detect danger, and there are food stores and deeply dug nurseries to protect the younger prairie dogs in the family. Mounds at the entrance to each burrow keep out rainwater and provide vantage points for lookout dogs.
Loss of wild habitat for their extensive ‘towns’ has become an additional problem for prairie dog survival in the 21st century. A hundred years ago the rodents luxuriated in enormous urban sprawls. One burrow complex, discovered in Texas in 1900, covered 25,000 square miles and housed an estimated 400 million prairie dogs. Today they have to share living space with man and his roads, towns, industries and agriculture covering much of the land they used to occupy.
Trap door spiders
The global family of trap-door spiders, relatives of tarantulas, are also fond of burrowing. They have a special row of teeth that are adapted to help them dig holes to make a home even in very dry soil and sturdy legs to assist with the excavation.
They construct a tunnel, around 15cm (6in) in length, which sometimes includes a branch tunnel, and line it with the silk other spiders extrude to make webs.
They then fashion a ‘door’ to cover the entrances to one or both of the tunnels. This door has a hinge made of the same silk.
Some species of trap-door spider make a lid for their tunnel that resembles a cork in a bottle, formed from soil and plant material mixed with spider silk. Others make do with just the silk, but weave it into a delicate circular flap that works just as well as a seal.
Radiating from the woven tunnel lining, the spider lays thin strands of silk that act like trip wires. As it lurks behind the door a twitch on the wire alerts it to the fact that something which might make a tasty meal has just walked past. The spider then flings back the door, pounces on the prey and drags it back into the tunnel to consume. Female trap doors stay in their tunnel for most of their lives. Males venture outside to search for a mate.
Termites and ants
When it comes to building extensive tunnel complexes, ants and termites have prairie dogs beaten hands down, but in miniature. Ant colonies are called formicaries and they consist of multiple levels and chambers where hundreds of millions of ants all work to a common goal – looking after the queen. So far, so not unusual.
However, it is the mound-building termites of Africa, Australia and South America that have elevated the art of colony construction to fantastic heights – literally.
Using saliva, soil and their own faeces, they build an air conditioning system above ground to aerate their subterranean nests. These fantastic structures regulate the nest’s internal temperatures and humidity in regions where the air outside is scorching.
They take the form of tall conical shapes that can stand up to 10m (30ft) and are full of tunnels and conduits that allow air to circulate in the underground chambers via vertical shafts. Often, a number of termite colonies are situated in a ‘neighbourhood’, with mounds separated from each other by about 20m (66ft).
Scientists have discovered that these termite mounds can be of great age. In Brazil, tests on a series of mounds made by the Syntermes dirus termite concluded that the youngest mound in the group was around 700 years old while the oldest was possibly constructed 4,000 or more years ago.
Hermit crabs
You particularly need a close-fitting home to protect yourself if you have a vulnerable body. Hermit crabs are unusual in the world of crustaceans because they don’t grow their own hard shell to provide protection against predators.
They do have an exoskeleton, like other shellfish, but this is relatively soft. Their long, unprotected abdomens are curled up into a spiral that partially safeguards their vital organs, but they need more than that in the rough and tumble of ocean life.
When they mature beyond the larval stage, hermit crabs find an appropriate-sized discarded shell of a mollusc into which to snuggle. Their head, legs and claws remain outside the shell so that they can move around, feed and defend themselves, while their more delicate parts are safely tucked inside their acquired armour.
The downside of this rental lifestyle is that, as they grow, hermit crabs have to find new and larger shells and there are limited chances of coming across empty, unbroken ones of the right size on the ocean floor or the beach. Many predated molluscs are broken apart by their attackers or their shells are damaged by wave action.
Sometimes a crab will find a good shell but it will be too big for it, which would make carrying it around tricky. In that case it will often secret itself nearby and wait for another, bigger crab to come along in search of a replacement shell. When the incoming crab swaps into the new, larger home, the first hermit quickly appropriates its vacated old one.
It’s not unknown in this scenario for a string of hermit crabs in descending sizes to line up behind a large, vacant shell, each waiting for the crab in front to give up their outgrown home so they can move into it. Nor is it unusual to see a hermit crab sporting an empty tin can, the top of a fabric conditioner bottle, or any other man-made shell-like container, in lieu of a proper shell.
Tailorbirds
As the name implies, this little bird that lives in tropical Asia uses plant fibres, fine grasses, caterpillar cocoons, silk from cobwebs and even threads borrowed from discarded human fabric or carpets to ‘sew’ leaves together and make a nest for itself and its young.
The female bird chooses a tree with large leaves in a safe location, in the middle of dense foliage and at least a metre above ground. She selects a leaf and wraps it around herself to try it for size. If it isn’t big enough, she chooses two leaves growing close together.
First, she pierces each leaf along the edge with her long, needle-like beak. Then, using her feet to hold together the leaves, she carefully pulls each strand of plant material through a hole in the first leaf and loops it over to a hole in the second leaf and pulls it tight before repeating the action along the length of the leaves. While she is doing the needlework, the male brings the threads. Little by little she laces up the leaves to form them into a cup using dozens of stitches.
Into that cup the pair stuffs nesting material – fine grasses, animal hair and fluffy seed down. The female then lays between three and five eggs and the chicks are hatched and grow up safely in their secure and camouflaged home.
Octopus
These cephalopods have long been known for their intelligence and ability at problem solving. But it is only relatively recently that scientists have discovered that one species of octopus don’t just find temporary shelter in crevices in rocks and coral blocks, but actually make artificial homes for themselves. The siting of these homes seems to be dictated by the available materials, empty coconuts, bits of scrap metal and scallop shells, which can all be employed in building.
The species that does this is called tetricus, the strangely nicknamed ‘gloomy octopus’, and it resides in coastal Australian waters around Sydney. To make its home it digs hollows in the sandy bottom and covers them in scallop shells after it has eaten the contents.
Previously, it was thought to live a largely solitary life, in common with other octopus species. However, in 2009, a biologist diving south of the city came across an octopus dwelling complex built around a large piece of scrap metal, augmented by hundreds of scallop shells.
It was 2-3m (6.5-10ft) in diameter and appeared to house around 14 octopuses. It was the first time such a purpose-built multi-occupancy habitat had been observed and it was given the name Octopolis. Seven years later, in 2016, a similar, second tetricus settlement was found nearby and christened Octlantis.
It was also observed that the gloomy octopus’ habits not only benefit members of its kind. These conurbations also result in the creation of entire ecosystems, just like the sociable weaver birds that you read about earlier. In the octopus’ case, the accumulation of shells and other materials provide hiding places for crustaceans and juvenile fish. These small fish and crabs are prey that attract larger fish. Vegetation grows using the shells as anchorage, and micro-organisms thrive. Eventually, given these conditions, a new, multi-occupancy habitat evolves.
Clownfish
These colourful little fish don’t construct anything for their homes. Instead they form a relationship with a home provider – a poisonous sea anemone. The deal is mutually beneficial, and the bond lasts for life as far as the clownfish is concerned.
Each species of clownfish buddies up with a particular species of anemone and lives within its waving fronds. It’s thought that a mucus coating on their scales protects them from the poison on the anemones’ stinging tentacles. The anemone protects the fish from predators by providing a safe haven inside its fronds, and it provides leftover particles of food from its own meals that save the fish from always having to venture out to feed.
The clownfish, in return, defends its anemone from predators, sometimes tackling head-on fish that are much larger than itself. Clownfish will frequently even try to see off a passing diver who takes too close an interest in their landlord.
Clownfish also keep the anemone free from parasites and their bright colours are thought to attract smaller fish that the anemone can catch and consume. In addition, the host benefits from nutrients produced by the clownfish’s faeces, and from nitrogen derived from the same source that promotes the algae that lives on its tentacles, which helps the anemone grow more tissue.
Clownfish activity, as it darts in and out of the anemone, increased water circulation around the host, which speeds up its metabolism. With both those elements working in its favour, the anemone grows larger, which in turn means the clownfish has a more extensive home. A winning combination all round.
Beavers
The beaver is the natural world’s ultimate and most productive architect. These animals shape their environment to suit themselves, but in the process they improve conditions for a myriad of different species. This has earned them the status of being a keystone species in their environment.
Beavers are specially adapted to construction. They have powerful jaw muscles and four chisel-shaped incisor teeth with long, sturdy roots that grow continually throughout the beavers’ lives. The thick enamel coatings on the teeth contains iron compounds that give them extra strength but also turn them orange. Their molars are ridged to provide a good grinding surface to cope with breaking down woody fibres.
With these teeth and the power of their bite they can gnaw and fell quite large trees, strip bark and divide branches. They use these to build dams across streams that create ponds in which their aquatic plant food grows. They also construct cavern-like lodges at the edge of the ponds out of piles of interwoven branches. These are accessed only by diving under the water and they provide shelter from predators and a place to raise young and keep warm in winter.
In addition, beavers’ front feet are dexterous, which means they can grasp and haul branches around and manoeuvre them into position with ease. They also use their paws to collect mud and stones to reinforce their dams, tucking the material under their chins to carry it to the construction site. The urge to build is triggered by the sound of running water so every trickle that indicates a gap in the dam is quickly dealt with.
All this activity leaves the area surrounding the stream and beaver pond saturated and clear of oppressive vegetation, which forms perfect wetland conditions for many other species of insects, birds and mammals.
