Why Evolution is True is a blog written by Jerry Coyne, centered on evolution and biology but also dealing with diverse topics like politics, culture, and cats.
No Republicans or ultra-Conservative Christian groups are going to be worried terribly much about this case though. However it seems that at least one other mammalian species is “redefining traditional relationships”.
There’s an interesting article by Colin Barras in New Scientist on mixed-species dolphin groups in the Bahamas. Although interaction between dolphin species is not unknown (Jerry’s written about this before), apparently this level of interaction is “unprecedented“.
Atlantic bottlenose (Tursiops truncatus) and spotted (Stenella frontalis) dolphins play, forage, babysit, fight common foes and even engage in cross-species sex.
The research is being done at the Wild Dolphin Project and you can read or download the publication by Denise Herzing and Cindy Elliser on the subject here.
It’s not always harmony and cooperation though. Barras notes:
Bottlenose males are about twice as long as spotted males and sometimes exploit this to force their way into groups of spotted dolphins and mate with females. Elliser and Herzing found that male spotted dolphins can fend them off, but only by cooperating in very large groups (Marine Mammal Science, doi.org/583).
There is some more bird news today, and this is at once fascinating and heartwarming. The BBC News reports that an eight-year-old girl in Seattle, Gabi Mann, is in a reciprocal trade relationship—one might call it “affection”—with a bunch of local crows. And it’s been going on for four years, since Gabi was four. I can’t help reproducing a lot of the tale. The BBC report starts like this:
Eight-year-old Gabi Mann sets a bead storage container on the dining room table, and clicks the lid open. This is her most precious collection.
“You may take a few close looks,” she says, “but don’t touch.” It’s a warning she’s most likely practised on her younger brother. She laughs after saying it though. She is happy for the audience.
Inside the box are rows of small objects in clear plastic bags. One label reads: “Black table by feeder. 2:30 p.m. 09 Nov 2014.” Inside is a broken light bulb. Another bag contains small pieces of brown glass worn smooth by the sea. “Beer coloured glass,” as Gabi describes it.
Each item is individually wrapped and categorised. Gabi pulls a black zip out of a labelled bag and holds it up. “We keep it in as good condition as we can,” she says, before explaining this object is one of her favourites.
There’s a miniature silver ball, a black button, a blue paper clip, a yellow bead, a faded black piece of foam, a blue Lego piece, and the list goes on. Many of them are scuffed and dirty. It is an odd assortment of objects for a little girl to treasure, but to Gabi these things are more valuable than gold.
She didn’t gather this collection. Each item was a gift – given to her by crows.
She holds up a pearl coloured heart. It is her most-prized present. “It’s showing me how much they love me.”
Here are the crow gifts sorted and arranged. The heart is at upper right:
How it began:
Gabi’s relationship with the neighbourhood crows began accidentally in 2011. She was four years old, and prone to dropping food. She’d get out of the car, and a chicken nugget would tumble off her lap. A crow would rush in to recover it. Soon, the crows were watching for her, hoping for another bite.
As she got older, she rewarded their attention, by sharing her packed lunch on the way to the bus stop. Her brother joined in. Soon, crows were lining up in the afternoon to greet Gabi’s bus, hoping for another feeding session.
. . . In 2013, Gabi and [her mother] Lisa started offering food as a daily ritual, rather than dropping scraps from time to time.
Gabi and her mom:
And then the relationship became reciprocal:
Each morning, they fill the backyard birdbath with fresh water and cover bird-feeder platforms with peanuts. Gabi throws handfuls of dog food into the grass. As they work, crows assemble on the telephone lines, calling loudly to them.
It was after they adopted this routine that the gifts started appearing.
The crows would clear the feeder of peanuts, and leave shiny trinkets on the empty tray; an earring, a hinge, a polished rock. There wasn’t a pattern. Gifts showed up sporadically – anything shiny and small enough to fit in a crow’s mouth.
One time it was a tiny piece of metal with the word “best” printed on it. “I don’t know if they still have the part that says ‘friend’,” Gabi laughs, amused by the thought of a crow wearing a matching necklace.
When you see Gabi’s collection, it’s hard not to wish for gift-giving crows of your own.
“If you want to form a bond with a crow, be consistent in rewarding them,” advises John Marzluff, professor of wildlife science at the University of Washington. [JAC: That goes for human relationships, too!] He specialises in birds, particularly crows and ravens.
The Science Men also recommend feeding peanuts to crows if you want to bond with them: it’s a high-energy food and makes noise when you throw it, so the crows know it’s there.
Gabi with some of her birds
So what is going on here? My first thought was this is co-opting a normal behavior of crows—perhaps giving nuptial gifts to mates. I haven’t been able to find any reference, though, to crows doing that. Still, the Science Men who were consulted suggest it’s a cooption of nuptial feeding behavior:
Marzluff, and his colleague Mark Miller, did a study of crows and the people who feed them. They found that crows and people form a very personal relationship. “There’s definitely a two-way communication going on there,” Marzluff says. “They understand each other’s signals.”
The birds communicate by how they fly, how close they walk, and where they sit. The human learns their language and the crows learn their feeder’s patterns and posture. They start to know and trust each other. Sometimes a crow leaves a gift.
But crow gifts are not guaranteed. “I can’t say they always will (give presents),” Marzluff admits, having never received any gifts personally, “but I have seen an awful lot of things crows have brought people.”
Not all crows deliver shiny objects either. Sometimes they give the kind of presents “they would give to their mate”, says Marzluff. “Courtship feeding, for example. So some people, their presents are dead baby birds that the crow brings in.”
Well, I prefer to think of it as reciprocal affection, as does Gabi. You can see a video of her feeding her crows at the BBC site.
Gabi points out a heavily rusted screw she prefers not to touch. It’s labelled “Third Favorite.” Asking her why an untouchable object is in the favourites, she answers, “You don’t see a crow carrying around a screw that much. Unless it’s trying to build its house.”
Lisa, Gabi’s mom, regularly photographs the crows and charts their behaviour and interactions. Her most amazing gift came just a few weeks ago, when she lost a lens cap in a nearby alley while photographing a bald eagle as it circled over the neighbourhood.
She didn’t even have to look for it. It was sitting on the edge of the birdbath.
Had the crows returned it? Lisa logged on to her computer and pulled up their bird-cam. There was the crow she suspected. “You can see it bringing it into the yard. Walks it to the birdbath and actually spends time rinsing this lens cap.”
“I’m sure that it was intentional,” she smiles. “They watch us all the time. I’m sure they knew I dropped it. I’m sure they decided they wanted to return it.”
Well, who’s to say they’re wrong? Perhaps the crows do regard Gabi and Lisa as members of their murder, who will give them more noms if they bring her presents. I won’t go so far as to say that the crows feel a form of “affection” for Gabi, but is reciprocal present-giving to specific individuals not close to affection?
I’ve posted on crows and ravens before; they’re highly intelligent, curious, and mischievous. That’s shown by this video (from the Daily Mail) showing a crow going after one of those odious sausage d*gs, who deserves it by virtue of being a sausage dog:
