I need some help from 'swanologists.' So do Boston's ducklings. In the middle of Boston's Public Garden, there is a large pond (although for some reason it's called a lagoon, even though it's not a lagoon). Every year, two swans, Romeo and Juliet, are brought to the Lagoon and released to build a nest (it turns out that both swans are female. LESBIAN SWANS!! AAAIEEE!!!).
Last weekend, I happened to be in the Public Garden all three days (long weekend), and every day I saw a swan (no idea if it was Romeo, Juliet, or both) that was chasing after ducklings.
By chasing, I mean that it would see ducklings and their mother 50+ yards away, and light out after them. I don't simply mean fluffing up their wings and swimming towards them. They would pursue them relentlessly--often across the entire pond--rising out of the water to pick up additional speed (and probably scare the duckling), striking at the duckling with their beaks. One day I saw one swan prevent the flock of ducklings from entering the pond: wherever the ducks went to try to jump in, the swan was right there hissing at them. That day, the swan even jumped out of the water and pursued them on land.
It gets even more vicious. The swan (again, no idea which one) will try to isolate a couple ducklings and then pursue those ducklings. The duck's mother then tries the 'broken wing' gambit (squawking loudly and then veering off, in an attempt to draw the swan away). It never works. These swans are on a mission. And I don't think this was a bad weekend, since I saw this same behavior last Thursday evening.
What makes this really weird is that the swans' nest is surrounded by sleeping ducks, often only a few feet away from the nest. It can't be they're trying to shoo birds away from the nest: why would ducklings be more of a threat than fully-grown ducks? (not to mention the occasional cormorant).
Does anyone have an explanation for this behavior? Are these just evil, demented swans? I would like to think not, since the swans also hate geese, which makes them good in my book....
The avian violence is even worse than that. I've seen male ducks chasing female ducks presumably with ill intent. The other day I saw a duck family sitting on the edge of the land and another duckling swam in and hopped up. Well one of the parents went nuts beating at it and even beaking it around the neck at one point.
I've only visited Boston once in my life, about 20 years ago. Some 20 years before that, as a young child, I apparently read (or had read to me) Make Way for Ducklings, which I then promptly forgot (along with The Five Chinese Brothers, so perhaps it was all for the best).
And so, years later, on my one-and-only-visit to Boston, I decided to explore on foot, when I encountered the Make Way for Ducklings sculpture in Boston Common. Alone in a strange city, I began to weep uncontrollably for reasons I could not understand (like a kind of Stendhal Syndrome for children's books). It wasn't until a few hours later, in a touristy gift shop, that I made the connection between the sculpture and the book I'd read as a child.
I can't tell you about swan behavior, though. However, according to Andersen (1843), anseriformes are fucking psychopaths.
Apparently swans are extremely territorial, something I learned about this week when assigning this article about two swans in Melrose who just had kids. The swans have apparently scared away a lot of the Canadian geese:
Don't know about swans, but do know about turkeys and chickens: They are perfectly happy to roost and sleep with their nemeses at night, but during the day will happily exterminate their arch-rivals. I would not go by their night-time behavior to determine territoriality, I have had roosters, siblings from the same hatch, with plenty of hens around, fight each other like crazy things during the day; at night they cuddle next to each other even in a warm barn.
In chickens and turkeys, the following do NOT work:
-Trying to break up the fight or distract the aggressor
-Putting out separate feeders far apart and keeping them full, free-choice of the most expensive poultry food money can buy
-Trimming spurs, they will invent kung fu moves to inflict damage if they are spur-less. Waterfowl don't have spurs to my knowledge, but in case anyone comes up with a similar bright idea, it doesn't work. These things could give Jackie Chan a run for his money with one wing tied behind their backs.
-Sticking to the Storey's Guide requirements for square footage of coop & run space per bird, plus a little extra
What did work was physically separating the offending animals for a few months, adding more birds or otherwise changing up the mix of birds, then re-uniting them. This shifted the flock pecking order in such a way that everyone had to re-negotiate their positions from scratch, and they reached an uneasy peace with fewer skirmishes. You'd think that the different species would realize that they are, you know, different species but if they've been together for a while they appear to think they are the same.
Mute Swans (which are probably the captives/domestics released to "breed" in the park) are extremely aggressive. They have escaped and are breeding in many states in the eastern US, and are actually doing a fair amount of ecological damage. Just as you say, they're attacking native birds and their young, and often disrupting breeding or killing babies.
As for why they would only be interested in ducklings... some ducks and geese will actually try to swipe each others' broods. Mixing broods may reduce your babies chances of being singled out by a predator, but the explanation for this is not clear. If the swans aren't successfully breeding, perhaps they're "jealous"? So hopped up on momma hormones that they see small Anatids and want to help?
You say "pursue". Any idea what would happen if they caught up to the babies?
At my last job I had a good view of our man-made pond. The company stocked it with a pair of swans. We were also on a migratory path for Canada Geese. Over the years I witnessed the swans killing about five large geese. They would attack whenever the geese would enter the pond.
Laura, the swans aren't nesting only at night. I think they're trying to hatch the eggs cause I always see at least one of them sitting on the nest and as mike says there's a whole passel of ducks that are chilling out around the nest. Maybe it's the same thing going on though. Maybe they're okay with the ducks sitting near their nest but get pissed at them wandering around their territory. Or maybe they're just mean.
I will second mike's amazement at this. It's something to watch the swan all of a sudden see the ducks and start going after them. It will make a bee line towards them and the ducks will all scatter. I never noticed it as being about ducklings especially. I kind of imagine the ducks thinking "Oh shit, there's a motherfucking swan on my tail!"
There was an article in the NYTimes last year (I think) about a clashing set of swan pairs in the Brooklyn Botanical Gardens. Same stuff- chasing, attacking, killing of cygnets from the rival family.
It is possible they are defending a food source area that they are sharing with the other ducklings you have mentioned.
Many swans pair up and pick a territory that is good for building nests and has an abundance of foodstuffs.