The penduline tits (Remiz pendulinus) construct amazingly ingenious nests. The name ‘penduline’ refers to the hanging bag nests that the bird builds for its eggs. While the shape and form of the nest are impressive on their own, it also features a very unique and important defense mechanism: a hidden entrance.

Penduline tits’ nest has an important defense mechanism: a hidden entrance.

Penduline tits primarily inhabit Eurasia, Africa, and North America. They typically measure between 3 to 4.3 inches (7.5 to 11 centimeters) in length and are characterized by a brown back, gray head, and a distinctive black mask. The markings of some subspecies may also include additional colors. For instance, the European penduline tit exhibits black and chestnut markings.

They construct pear-shaped nests on the branches of willow or birch trees. Initially, the male initiates nest construction by attaching plant fibers and fluffy seeds to the twigs and branches. Subsequently, aided by the female, they weave other materials such as spiderwebs, wool, animal hair, and soft plant material to complete the pouch-like nest. The end result is an elaborate nest suspended from the tree.

Their nests incorporate a fake entrance right above the real opening

Thanks to this clever design, penduline tits protect their eggs and themselves. The false entrance leads to an empty chamber, while the real nesting chamber is accessed through a hidden door. This door, partly composed of sticky spider webs, allows the birds to easily close it from the inside after entering or leaving the nest. When a predator attempts to enter the penduline tit’s nest, it will find itself in an empty pouch.