Ask the Swan Specialist

Re: Mute swan sharing a nest with a Toulouse goose
By:The Regal Swan
Date: 4 April 2014

Hi Sheryl

Interesting question. We’re not sure that we can be accurate in our answer, but we are going to try some deductive reasoning.

First, let’s talk about swan nesting/egg laying/incubation behavior. A male swan will build the nest. The female will provide some guidance as to where she wants the nest built, but ultimately, the male will build the nest and butt scoot inside the nesting material to form the bowl. Then, the female will assist in gathering some materials and help to tidy the nest prior to laying the eggs.

If you have a male swan, even though males help build the nest, they are not likely to sit on the nest. Certain species of swans will have the males incubating the eggs, but most will sit beside the nest and not sit on the eggs. However, this is also an individual swan attribute. Obviously, if you have a male swan, he will not be laying any eggs.

Female swans paired with another female swan will have both swans building the nest. One or both may lay eggs, although the eggs are obviously infertile. We have even heard of lone female swans actually laying non-fertile eggs due to the hormone changes. Females will sit on eggs for incubation purposes.
Now, that we have the nesting, egg laying and incubation behavior outlined for both sexes, we now need to discuss the size of the nest and eggs. This may provide you with another clue as to which species built the nest and produced the eggs.

Swan nests can typically reach 5 feet in diameter, however, the nests can be as small as 2-3 feet in diameter depending on swan species. So, what is the typical size of a Toulouse Goose nest?

Swan eggs are typically 4 inches in length and 3 inches in diameter weighing approximately 9 ounces. The eggs are white with a greenish gray tint which will darken slightly with age. What is the size and color of normal Toulouse Goose eggs? Are there different sizes of eggs in the nest? Could one species have started the nest and the other species overtaken the nest, but both species still sharing some nesting material?

Most swans will NOT tolerate anyone or anything near their eggs or nests. So, in this instance, we would surmise the following (again, we cannot be absolutely sure without actually sexing the birds because behavior from individual swans or geese can and will go against norms):

You probably have a female swan. She is wanting to sit on the nest and is not as stressed about having other species around the nests. Usually, males will be absolutely belligerent toward anything or anyone around their nests and are not going to typically sit on their own nests for any great length of time, much less someone else’s nest. Males will usually sit only long enough so that the female swan can take a break for a quick swim and something to eat before returning to the nest.

Usually, different species cannot physically mate or produce offspring. So, we would find this highly improbably that your swan mated with the goose. We would also seriously doubt that the swan will incubate the eggs if they are not her own. Conversely, we doubt that the goose will incubate another species’ eggs. What we think is occurring is that the nest may be in a prime habitat area (are you feeding near the nest, safe from predators, flooding, etc?). If so, they all may want to have that particular spot and are just sharing a nest with infertile eggs. Having said this, it will be interesting to see who actually ends up on the nest if the eggs hatch. Then, we would love to see the photos. If you have a goose/swan mating, it will be a very rare occurrence and the offspring will be even more interesting than this scenario!! The Regal Swan

Messages In This Thread

Mute swan sharing a nest with a Toulouse goose -- Sheryl -- 4 April 2014
Re: Mute swan sharing a nest with a Toulouse goose -- The Regal Swan -- 4 April 2014