Ch10 - Nest
Most birds build nests to lay eggs and raise their young. Nests can have various structures, but the cup-shaped ones are the most common. They are built with diverse materials: twigs, blades of grass, moss, spider webs, sand or feathers. A growing number of birds also use trash – plastic bags, strings, rags.
Some bird species use toxic plants to build their nests. They contain substances that lower the number of parasites; consequently, it makes the hatchlings healthier and less endangered.
Nests are constructed by the male or the female bird, sometimes by both of them at once. The final outcome, however, is always a hallmark of a particular species of birds. There are many different nest types and places for building one. Birds build their nests hidden, often in tree hollows or burrows; we also find woven hanging nests, or round ones placed on tops of the highest trees.
Not only birds build nests. Frogs, fish, arthropods (like bees) and reptiles also do it. Interestingly, nests serving as egg incubators were also built by dinosaurs, nowadays extinct.
Nest is synonymous with a safe place. In reality, it does not always work like this. If a bird builds its nest in an unfitting place, visible or easily reachable, the nestlings can well become a target for predators. Therefore, adult birds must not only be extremely careful when choosing a safe spot for a nest, but also cautious when approaching it while the young are inside. Some species use clever tricks to minimize the danger.
Eurasian skylarks are very skillful in the art of deception. They do not land directly in their nests, but some distance away. Then, they sneak through the grass on foot, in order to minimize any potential threats.
Another interesting trick is used by plovers. When the bird spots a fox near its nest, it cleverly starts singing loudly to distract the predator. What is more, the bird pretends to have a broken wing, which would make it an easy target. When the predator is no longer near the nest, the bird finishes its act and flies away.
Small birds usually build a new nest every season. It takes them around 4 or 5 days, not too long. Big birds, such as storks, developed a different strategy. They create big, solid nests that can last for years. Storks' nests are 90 to 200 cm in diameter and up to 200 cm in height. The nests of several years weigh about 500 kg, but the biggest found attained weight of 2 tons.
Most birds living in the built-up areas nest in buildings. Some species are really dependent on urban structures – they won’t build their nests anywhere else, so the availability of buildings may decide their fate. Among such birds we count jackdaws, swifts, sparrows and pigeons. Other birds living in cities are not so heavily dependent on buildings: they may nest in buildings, but can also choose from a variety of other nesting places. This group includes starlings, tawny owls, chickadees and even mallards.
Swallows' nests are quite common and easy to spot. They are built with the use of clay and mud held together by spit, twigs and hay. Swallows are very systematic when it comes to building their nests – they work for 10 minutes every day, and bring building materials even from afar. Such a construction can be used for several years. Some species of swallows build their nests unsealed at the top; it creates an opportunity to leave an egg in the nest by a cuckoo.
Build
To build this model, you will need LEGO Education WeDo 2.0
Explore
The bird nest model represents a bird feeding its nestlings.
When the parent bird is nowhere near the nest, the chicks chirp and jump.
1. The giraffe model is propelled by a motor installed on its back.
2. Next to the giraffe you can see a hub, which powers the construction, reads the program commands and controls the motor appropriately.
1. The nest is placed high on long Technic beams, which resemble a tree trunk.
2. Just like in case of a real nest, the chicks can hide inside.
The construction uses one motor, but moves two nestlings. It is possible thanks to the transmission gear, which splits the drive.
1. The red short axle transfers the drive from the motor to the small cog, which propels the whole mechanism.
2. The long axle connects two identical transmission gears on the opposite parts of the base.
3. The large gray cogwheels are set on axles, which directly move the nestlings.
Each of the nestlings is moving because of a crank gear.
1. The motor propels the axles on both sides. At the end of each axle there is a crank installed, which is also connected with a beam and a nestling at its end.
2. Since the cranks are set conversely to one another, the chicks jump out of the nest in turns.
1. The big bird has colorful feathers and a characteristic, yellow tip of the head. You can tilt its wings as you wish.
2. The bird is not fixed to the nest. It has its place: a shelf with an axle. The bird stands on a plate with a hole, which fits perfectly onto the shelf. There is a distance sensor hidden in the shelf, which can detect when the bird is in the nest.
3. The bird's long beak lands right before the sensor, so its presence is easy to spot.
Program
Let's begin the program for the bird nest with the starting block.
