Air Date: Week of February 12, 2010

(Photo: FLICKR/Mozzercork)

Divorce has become common in our society but when swans go their separate ways, scientists take notice. This winter, a pair of Bewick Swans returned to the Wildfowl and Wetlands Centre in Slimbridge, England, with new mates, raising questions about the typically monogamous birds. Host Jeff Young talks with wildlife research officer Julia Newth about the surprising split.

Transcript

YOUNG: Images of canoodling swans are common around Valentine’s Day – those graceful birds that mate for life are living symbols of lasting love. Right? Well, it is with mixed emotions that we bring you a story about a bit of a flap on a certain swan lake.

[SOUND OF SWANS HONKING]

YOUNG: Those are Bewick swans, recorded on Valentine’s Day 1966 at the Wildfowl and Wetlands Trust Centre in Slimbridge, England. Each year the birds return to Slimbridge in their life-mated pairs from nesting grounds in the far north. But this year, naturalists like Julia Newth noticed something that has ruffled a few feathers. Ms. Newth is a wildlife health research officer at the center, welcome to Living on Earth!

NEWTH: Hello, hello!

YOUNG: So what’s going on with these swans?

NEWTH: Well, it seems that we’ve witnessed a divorce, a swan divorce this winter. A faithful pair called Sarindi and Saruni have been returning a few years as a couple. Sarindi flew in with a new partner in December and you know we kind of thought perhaps something untoward had happened to her old mate, Saruni. So, we were therefore very surprised when Saruni rocked up a few weeks later also with a new partner.

YOUNG: Scandalous!

NEWTH: It is! It’s very unusual in the swan world, certainly, for this to happen.

YOUNG: How unusual? I mean, does this happen from time to time? Is this a first of its kind?

NEWTH: This is actually the second time that we’ve witnessed this at Slimbridge, but bearing in mind this is almost 40 year of studying the swans intensively at Slimbridge, and that includes the studying of over 4,000 pairs. So, this really is quite an unusual event.

YOUNG: Before we seem too judgmental about this certain swan couple, I guess we should point out that over 40 years just two examples of splits, that’s a darned better marriage success rate than we humans can claim.

NEWTH: [Laughs] It seems to be, yes.

YOUNG: Any ideas about why they split up?

NEWTH: One possible scenario could be – I mean, Saruni and Sarindi never brought cygnets back to Slimbridge and they were never known to have bred before, so this failure to breed could be a possible reason as to why they’ve split. Certainly in the case of divorce previous to this, it was a similar pattern; the pair had never brought cygnets back to Slimbridge. So, we can really only speculate, but this could be possible reason.

YOUNG: Do we know yet if the new pairings might be more successful in producing cygnets?

NEWTH: Well, this is what’s going to be fascinating actually next winter; the Bewick Swans will be leaving on migration to Russia towards the end of February. They’ll hopefully return again in October. So, hopefully we’ll be able to kind of gather a bit more meat to the story. It will be very interesting to see whether either pair brings back cygnets next year.

YOUNG: Is this an opportunity to learn more about what happens when monogamous pairing breaks down?

NEWTH: We’re certainly watching very closely. I mean at Slimbridge we’re able to identify all the individual swans that come winter here by their distinct bill pattern, which is a little bit like a unique thumbprint that us humans might have. So, we know exactly who’s paired with who, and we’ve got both pairs back on the same lake now, so we’re certainly watching very closely.

YOUNG: So, what’s that interaction like? This is, you know, anthropomorphizing the whole affair, but it’s got to be a little awkward for them, isn’t it?

NEWTH: Well, it’s been very interesting because we haven’t actually seen all that much interaction between Saruni and Sarindi – the old pair, the divorced pair – I mean, they no doubt recognize each other, they’re very sociable creatures, they’d been together for a number of years, and they recognize each other through particularly their calls to each other.

We’ve actually seen them in very close proximity of each other, within meters. Given that, we’re kind of surprised that we haven’t seen any kind of display of any kind, whether it’s aggression or affection. So, we’re kind of looking for telltale signs of some kind of interaction. I’m sure they’ve communicated, but nothing too obvious as of yet.

YOUNG: And what’s the reaction been among people who come to see the swans there?

NEWTH: Every Bewick Swan assemblage is recognized and named as an individual, so I think people kind of have an empathy with them because of that. And this kind of case of divorce is almost kind of a very modern quality, if you like. Some people have said it’s a sign of the times. So, I think people feel very connected to this kind of behavior in a way, and they can – well, some people can relate to it. So, it’s generated a lot of interest back at Slimbridge.

YOUNG: Why is it that swans mate for life, anyway? I mean, we project virtue on this, but there’s real biology going on here – why do they do it this way?

NEWTH: Well, particularly for the Bewick Swans they’re migrating from their summer breeding grounds in Arctic Russia, that’s 3,000 kilometers away. And when they arrive back up to breed on the tundra in May, they’ve only got a very short window in which to reproduce, rear the young so that they can fly back to their wintering grounds in September in northwest Europe. So, they really only have a very short turnaround there, so we think monogamy kind of benefits them. If they have the same partner it cuts out time they have to spend otherwise looking for a new mate.

YOUNG: And has this at all shaken your belief in the swan as a symbol of undying love?

NEWTH: It hasn’t really. At the moment at Slimbridge we have a number of pairs and a number of long standing pairs. You know, just a few years ago we had a pair called Lemonia and Laburnum and they had been returning together for 21 years, so there’s plenty of birds out on the lake at the moment that are really showing the characteristics of monogamy.

YOUNG: So, no signs here that the honeymoon’s over, as it were, with the swans and mating for life? That’s still the norm here?

NEWTH: Absolutely, absolutely. Yes. It’s just such a rare occurrence here. It’s a very fascinating thing to be observing, but I have every faith the Bewick Swans particularly will continue to show their usual displays of monogamy.

YOUNG: Julia Newth with the Wildfowl and Wetlands Trust Center in Slimbridge, England. Thanks very much.

NEWTH: Thank you.