Documenting Bluebird Copulation

In order to tell the story of the complete nesting-cycle of bluebirds in Bluebird Man, one of the critical scenes we needed to capture was bluebird copulation. At this early stage in the breeding cycle, male and female bluebirds pair up together and occupy a territory that contains a nest box or natural cavity. It is here that they begin to build their nest, and that instinctual hormonal drive tells the male he needs to begin reproduction. Yesterday, we were able to capture this crucial life-history stage in the Mountain Bluebird.

The female we were observing was perched atop a stunted Juniper tree, and as the male made passes overhead, she began to shake her wings, presumably as an invitation for the male to proceed. This series of still images from our video documents what happened next. The male flew in and landed directly on female’s back, and in that split second copulated with her. It only takes songbirds a very short amount of time to do this.

Male Mountain Bluebird landing on the females back. Still images from video by Neil Paprocki. Click on the image for a larger view.

But, if you look closely enough, it appears as if the male passes off a piece of food to the female while copulating with her! It is unclear if the male actually gives the piece of food to the female, or if he is just using this as a tactic to mate with her. In animal behavior circles, this is called a “nuptial gift” or “courtship feeding”, and occurs when a male passes along a piece of food or other ‘gift’ to the female just prior to, or during, copulation. Presumably, the gift entices the female to mate with the male, and also may provide the female with a measure of how fit and strong her male is.

Male Mountain Bluebird passing along a ‘Nuptial Gift’. Still images from video by Neil Paprocki.

The reason I say it is unclear if the male actually gives the female food while copulating is because just after the male hops off the female’s back, she takes a piece of food from his mouth. Did the male provide the female with two small pieces of food? Or did he bait the female into copulating first, and then gave her the food? It appeared to me as if the latter happened. Either way, it was extremely fun to capture, and we were excited to document this behavior for the film. Doesn’t it appear as if the male and female are “kissing” in the picture below?

Male passing along a piece of food after copulation. Still image from video by Neil Paprocki.

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