The behavior of many birds flying around noisily and chasing after a snake can appear quite chaotic. However, in many yards and wetlands, this kind of behavior happens during the mating and breeding seasons, when bird nests contain eggs and chicks. Based on findings made by animal experts, this does not necessarily mean that the birds are exhibiting a panic response.
Instead, what is happening is called 'mobbing,' where birds use this technique to protect their eggs and young ones from any predators that might attack their nest, especially snakes. It appears that the reactions of birds increase greatly depending on the presence of chicks in the nests, and it increases during the breeding season.
Why do snakes make birds do this?
Birds do not react to all predators with such intensity. Studies about the behavior of the Japanese tit, presented in the Proceedings of the Royal Society B journal, show that birds make different kinds of calls based on their threats. Upon hearing alarm calls concerning a snake threat, birds instantly engaged in search behavior and assembled themselves around the threat region.
This kind of discovery confirms that these birds do not produce sounds out of fear, but rather they are trying to exchange some information among themselves. The vocal communication system of the Japanese tit reveals that animal communication abilities to send certain information about their enemy through an alarm call. It is necessary to admit that snakes represent additional danger, especially when located close to a nest, because in this way, they have an opportunity to consume eggs as well as offspring.
In other words, the appearance of a snake in the given area represents reproductive danger, not only danger in general. On the other hand, scientists analyze different reactions in response to the appearances of snakes. In particular, it is possible to claim that a snake in the vicinity of a bird's nest is likely to cause a mobbing behavior whereas observing the snake far away from the nest will have a different reaction from the birds.
The breeding season causes increased aggressiveness regarding defense of nests
The study of barn swallows, which was conducted in the Journal of Animal Behavior, proved that during the breeding season, birds mob much more than usual, especially with nestlings. For the birds, the investment is actively involved and needs protection because laying eggs and nurturing chicks takes several weeks, which makes losses of nests quite damaging biologically.
Ecological studies conducted recently and published on the website of PubMed in 2023 found out that snakes could be predators for the nests of birds, and they had a big impact on bird populations. Researchers believe that frequent attacks by snakes might have played a significant role in the evolution of the behavior concerning the defense of nests. It becomes quite clear that birds confront much bigger animals right there in front of their nests.
