A couple of things come to mind. First, if the cause was some kind of parasite, bacteria, fungal infection, etc., it would readily be seen at the time of necropsy, although tissue tests would need to confirm. If there is a hemorrhage caused by parasites, fungus, etc., usually it is systemic which would mean that upon opening the carcass, you would usually see this throughout various organs and tissue.

If the bleeding is contained in one area, then usually blunt force trauma would be suspected. An example would be if you ran into a bed post with your leg. The resulting bruise (hemorrhage) would be from the bursting of small blood vessels in that localized area, not systemic (throughout the body). This is blunt force trauma.

Blunt force trauma can be from any cause. Yes, an idiot could hit a swan with a baseball bat or other object if the swan goes up to the individual with the enticement of food. Do the deaths occur at night? If so, there is a possibility someone is doing this and a quiet stake out around the pond would be warranted.

However, there are also other possibilities. If there are several different family pairs or the parents are chasing the cygnets due to the new mating season, internal injuries can be sustained if other swans beat the younger swans. Are there soft shelled or snapping turtles or other predators that might be able to reach the swans (this would be our least likely account as the predator will eat portions of the carcass).

Blunt force trauma can be caused by running into objects in the pond. Have you had a drought recently which could allow objects to come up from the bottom of the pond and be accessible to the birds as they swim in the pond? Are there any new objects that were placed in the pond recently?

Finally, have you had a large amount of rain? If the banks which were usually visible are no longer visible and submerged by water, the birds may be swimming toward the edge of the bank that they see out of the water, but may run into the actual bank that is submerged. We have seen this type of injury numerous times which usually results in leg injuries as the birds run into the submerged bank as they exit the water.

We would suggest that you still get a tissue sample conducted from the dead birds to ensure that nothing else may be occurring as far as fungal, bacterial, viral or parasitic infection. We hope that this information is beneficial. The Regal Swan