There are several possible reasons for this behavior.

1. Yes, if there was something in the chemicals that caused the water to taste or smell differently, possibly. However, there are probably other reasons:

2. If the swan was sickened by the chemicals, it may have tried to find another area to go, but once it got out on the roadway found no other area to go and just sat down to get its bearings. It may not have wanted to go too far away from its normal surroundings or may have been disoriented if it was sickened.

3. The weed control chemicals could have cause predators to leave the area. Since we are not sure where you reside, we would suggest that you may still have alligators or snakes, etc. If a predator was caused to move out of a certain area and into the swan's area of the lake or pond, that might be an issue.

4. If a predator attacked the swan, i.e., alligator nipped at it without killing it (and it can happen if it is a small alligator) or if a snake bit the bird (water moccasin), the bird could be sick (as infection or affected by a venomous bite) and could have roamed due to its condition.

5. If the bird was a juvenile bird that was dispatched from the pond by its parents because it is 8-12 months of age and the parents are now viewing it as a rival, this might be the reason that the bird left the area.

6. If the swan was able to fly and was clipped by a car and injured so that it could not walk or move due to an injury or if it mistook the roadway for a waterway and tried to land and got injured (this happens quite often especially during rain because roadways appear slick), then it might have been too injured or sore to move.

Did the swan ever return back to the lake? If so, then just keep and eye on it to see if it is staying and whatever it was that caused it to leave probably dissipated or left the area.

If it is still sitting by the road, please try to contact a local wildlife sanctuary or carefully try to capture the swan and get it to an avian veterinarian or a veterinarian with some bird or waterfowl experience to ensure that it is not sick or injured. We hope this information is of benefit. Please let us know an update. The Regal Swan