One of our family members is a female whooper swan about 16+ years old. She moved onto our property & lake when we built our home (in S. Florida equestrian community) in the late 1990's. She originally lived with a flock of identical swans (possibly siblings) on a neighboring property; the owner later "evicted" all the swans and they scattered.
Our swan has a pinioned wing and has never had a companion swan. She doesn't seem lonely and is very aggressive to other waterfowl and even wading birds (chases them away or tried to drown them). For the past few weeks our swan has been hard at work building a large nest for herself from vines and weeds. We have never seen her do anything like this in the 13 years she has lived with us. We know she is a female because we had our avian vet do a DNA test. She has no mate and we can't figure out what would be causing this sudden nesting behavior. Any ideas?