What does a female bird want in a mate? The female wren wants a good, sturdy house to raise their children in. But that is not all that she is looking for.
Broadly speaking among birds, as is pretty much true in most species, it is the female who usually makes the choice of a mate. And she usually makes it founded on a set of criteria that humans would recognize all too well.
The most important criteria, of course, is her consideration of the male suitor himself. She has to satisfy to herself that the mate she eventually will choose is well off enough to be able to support the family that she plans on having. The male suitor can demonstrate this in a number of ways. For example, the male wren demonstrates his suitability for marriage by the skill with which he is able to construct a nest.
Therefore as mating season approaches, you will see the male wrens frenetically collecing twigs and leaves to build a nest. The intention, of course, is of attracting females. If it is flimsy, he may construct another one. And he will continually to do this until he has built one that he thinks will pass inspection.
What exactly is the female wren looking for? She is mainly looking for a strong, sturdy home in which to raise her nestlings. As a result, she will carefully inspect the nest that her suitor has built to ensure that it is well built and will not fall out of the tree. If it doesn’t pass her inspection she will pass it up, leaving the suitor for another.
It can get embarrassing if the female birds ignore the nests that he has built. But, if enough females reject his nest, the male may finally get the message and return to the drawing board in an attempt to build a better one. A young male wren, fresh on his own for the first time, may have such difficulty building a proper nest that he fails to attract any female during his first or second mating season. Out of luck, he will simply have to wait until the following year to try for a mate. Hopefully, his nest building skills will have improved by then.
An additional feature that the female wren looks for is location. The location has to be a place good enough to raise her young. If the male wren is smart, he has built his nest in a high end neighborhood. This would be a branch high above the ground and on a tip of a branch where it is difficult for a predator to reach. It is also good if other birds have nested nearby as there is safety in numbers and the neighbors can act as the neighborhood watch by keeping an eye out for neighborhood troublemakers.
Assuming that the male wren manages to pass this first exam, he may very well be on his way to attracting a good mate. To be sure, there will be other tests along the way, but this is the most important.