We are so sorry for your loss. The coyote issue is actually the easier to solve. You would need to enclose the pond with a 6 foot fence with a barrier at the top of the fence bending outward so nothing could use the fence to climb over and into the pond. The bottom of the fence would need to be sunk into the ground aporoximately 2 feet with chicken wire placed under the fence, extending 2 feet inside and 3 feet outside the fence, covered with dirt. The chicken wire must be used around the entire perimeter of the fence so nothing can dig under the fence.
Snapping turtles are a difficult issue as you would have to find and remove any large turtles. You would probably need some wildlife permit for removal and would need to hire a licensed wildlife trapper for assistance.
Venomous snakes are the most difficult because they can enter, exit and habitate an area and you may not be aware of their presence.
We are not sure where you are located, but,$2250 a pair seems rather expensive. We know Bob Knox deals in swans and a pair are not that expensive 847-875-3947.
Now, having said this, your male swan is fine with or without another swan. Do Not place another male swan in the pond because they will fight, seriously injure each other to the point one or both could be killed. Male swans usually, not always, but usually do not re-pair with another female once something happens to their old mate. This is an individual attribute, but you would have to build a pen, (again enclosed top to bottom, no steep entrance to the pond, half in water and half on ground) with feeder inside. The female needs to stay in the pen for approximately 2 weeks to see if the male is going to accept her. Any signs of defensiveness towards her will mean you will need to see if the seller will take her back or you will need to find her a new home.
The best thing to do is to leave the male alone. Introducing another swan(s) that are not familiar to your pond, increases the chance of coyote/snapping turtle encounter. Introduce some other waterfowl such as small geese or ducks to the pond. Even though he does not have a mate, during nesting season, he will become more defensive of his territory due to hormones and may chase the other waterfowl, especially if they have young and try to protect their family.
Finally, if you live in the U.S., you will be responsible for any offspring of a Mute Swan that may be produced by a mating pair. You must have the cygnets pinioned (rendered unable to fly) at 1-3 weeks of age. If the parents chase them from your pond for the next breeding season, you will be responsible for finding them a good home. Selling them or giving them back to just any breeder would not be an acceptable good home, but may become necessary. Just make sure your breeder(seller) is reputable. Once you have a mating pair on your property, you may be considered as a breeder under some state laws and you will need to have a breeder’s permit. A pair of Mute Swans can produce 1-8 cygnets a year. If the parents begin chasing them, do you have an alternative plan for cygnet placement elsewhere? Now, you see why we maintain that you and your male swan are better with no other swan being introduced to your habitat.
Federal and state U.S. wildlife officials wrongly assess Mute Swans as non-native and invasive (which research shows they are a Sentinel species and native). These wildlife officials have the intent of killing Mute Swans in the U.S., so they can free habitats for introduction of the larger Trumpeter Swans for Trophy Waterfowl Hunting purposes. Trophy Waterfowl hunting permits are more expensive and increase revenue for wildlife budgets. So, you must be careful in maintaining your swan(s) to prevent wildlife officials from placing undue hardships on you for possession and maintenance. We hope this information is of benefit. The Regal Swan