Bivouacs are living nests constructed by army ants only because they do not make permanent shelters and keep moving at different locations. They have an unusual lifestyle and are known for recurrent migrations, unlike other ants that create a permanent nest.
How Do Army Ants Make Bivouacs? Army ants make bivouacs or temporary nests with their bodies as they cling to each other’s feet to make a large mass. Almost 100,000 to 500,000 ants make bivouacs that are less dense from the middle. It helps capture prey, kill predators, and protect the queen. They take a few hours to group and form a big structure that usually disintegrates every 15 to 20 days.
Building a compact structure or bivouac takes effort and energy; these ants move speedily and become part of the interconnected structure. The queens and male drones do not cling to each other and get surrounded by these worker ants.
This way, they are protected from predators and cold weather when the exposed surface area of their body reduces.
How do army ants build bivouacs?
Army ants are known for their distinct behavior of making bivouacs, as they do not stay in one place for longer periods. They do not cause permanent nests like other species and build temporary shelters.
This species uses a body or particularly legs to make these living nests during the stationary phase. The worker ants cling to each other’s legs and build a large structure.
In addition, these living nests are heterogeneous structures because they do not have the same thickness from their outer edge to the center.
Its thickness decreases significantly in the internal region, and queens are present in the less dense central region. The newly produced eggs and larvae fill this space when queens reproduce.
In addition, the internal region is less dense because worker ants leave some space for predators and prey so that they are surrounded by a big swarm.
They have tiny hooks on their feet that are present on the tips and support the clinging behavior. They form an interconnected structure to make bivouacs between their migration episodes.
Furthermore, the army ants become a part of this living shelter by clinging to the legs of other fellows who are already part of this structure. The live nest disintegrates after some time when they try to move to a new location.
Why do army ants make bivouacs?
They make bivouacs for different reasons, including protecting queens and eggs during the egg production phase, capturing prey, and targeting predators by swarming around them.
They have two phases of activity: nomadic and stationary. The nomadic phase involves wandering around the trees, grasses, and plants in search of food when the colonies move to another location.
The stationary phase involves the formation of temporary nests when they stop moving for a few days and rest. They usually stop when the pregnant queens need to lay eggs and increase the population.
After that, the cycle continues, and the nomadic phase starts again, but this phase initiates after 10 to 12 days of the egg-laying process by queens.
In addition, they make bivouacs when they target a prey organism, like small birds and frogs. They capture prey from all sides to restrict their movement and attack them easily.
It is also termed colonial or mass raiding in army ants when a large population moves across the forests and collectively hunts for prey.
Similarly, they swarm around predators, usually Tetradonia beetles, which are known for killing them. It is a strategy to kill their predators by restricting them to one location when a swarm of army ants covers its body from all directions.
How long do army ants take to make bivouacs?
The time to make bivouacs depends on several factors, like their colony size and environmental conditions.
Their colonies have at least 100,000 army ants, while they can have 200,000 to 500,000 members at maximum. It takes more time when the colony is larger.
Moreover, they can construct an interconnected structure in a few hours, as they are known for their remarkable ability to cling to each other’s legs.
This time period can increase to several hours when millions of ants are a part of the colony that need more time to make an interconnected structure.
However, environmental conditions also play a crucial role as their efficiency and speed decrease when the external conditions are not favorable for them.
High humidity and temperature affect their ability to move and make a bivouac during migratory phases. Accordingly, they spend more than a few hours if the conditions are not favorable for them.
Where do army ants make bivouacs?
They make bivouacs in the wild while navigating through the forest floor to hunt for prey organisms. They swarm around the predator and prey after encountering it on the ground.
In addition, the worker ants also make such living nests on the tree branches by maintaining a firm grip. They hold on tightly using hooks on their feet and build an interlocked structure.
They can also fall on the floor if hundreds or thousands of workers try to become a part of this hanging structure. They also swarm inside the tree trunk cavities and enter a stationary phase.
A fallen tree log also provides a suitable place for swarming army ants to stay inside the log for almost 15 to 20 days until the queens lay eggs.
They also get inside the burrows and soil chambers made by other insects and live inside the structure for a long time period.
Furthermore, their colonies are usually present above ground, while others generally hide within underground chambers in the soil.
How big bivouacs do army ants make?
The size of bivouacs is dynamic because it depends on the number of army ants that are a part of the living nest. Thousands of worker ants build a living structure and spread on the ground.
Their temporary nests spread to a larger surface area, covering a few meters apart. Their size also varies depending on the density as highly dense structures spread over a small area.
Moreover, they cover a surface area of around 30 to 35 meters around a single point where millions of ants are part of it. They are observed to cover almost 1500 to 1800 square yards of area.
In addition, environmental factors also affect the size of bivouacs because the colony size increases in the summer when the weather is mild or favorable for them.
All of their colony members participate in the swarming behavior and become a part of the living nest when they need to rest for a while.
How do army ants build bridges?
Army ants are known for deadly raids and killing potential but have fascinating behavioral features. They are primarily known for forming bivouacs, but they also build bridges and highways.
These bridges help maintain traffic flow or the swarm of army ants from the gaps and barriers in their way. They do not have to stop and return if they encounter hurdles or barriers.
In addition, each ant steps over the other and moves ahead to build a bridge. This way, a large number of these ants firmly grasp one another and make a stable structure to facilitate others.
This way, they can easily cross the gap and move ahead without getting stopped after encountering such challenges.
Furthermore, they are unstoppable and find a way to overcome the challenges efficiently and fill the gap.