RENEE MONTAGNE, host:
And let's end this week's series on siblings by expanding it to some other kinds of families, families in the animal kingdom. Here's NPR's Selena Simmons-Duffin.
SELENA SIMMONS-DUFFIN: Some animal sibling relationships look familiar, like African elephants who are born one at a time and whose older sisters babysit them when their mother is gone. Others are more unusual.
Mr. STEVE JENKINS (Author): Nine-banded armadillos are almost always born as identical quadruplets.
SIMMONS-DUFFIN: That's Steve Jenkins. He wrote a children's book about animal siblings. He says naked mole rats can have hundreds of siblings, all from one mother called the queen. Some of these relationships are helpful. Tiny, tiny European shrew siblings move in a caravan so they don't get lost.
Mr. JENKINS (Author): Each shrew holds on to the shrew in front with its teeth.
SIMMONS-DUFFIN: I went to the National Zoo in Washington, D.C. to meet another group of helpful siblings. They are six brothers, Asian small-clawed otters. They were pretty noisy.
(Soundbite of otters screeching)
Ms. ERIKA BAUER (Biologist): That's a "please, I want some fish" noise, yeah.
(Soundbite of laughter)
SIMMONS-DUFFIN: That's biologist Erika Bauer. She told me the otter brothers spend almost all their time together. They sleep in a big pile and work together on projects.
Ms. BAUER (Biologist): They pull the grasses down and carry it around. They look like they're very industrious, and they build nests together for sleeping.
SIMMONS-DUFFIN: Peregrine falcon siblings also work together. They use each other as target practice when they're learning to hunt, diving at each other at over 100 miles an hour. Bird curator Dan Boritt took us to see the cattle egrets, which illustrate the darker side of siblinghood.
Mr. DAN BORITT (Bird Curator): I mean siblicide is kind of a downer.
SIMMONS-DUFFIN: Cattle egrets' parents often can't provide for all their young, so...
Mr. BORITT: One of the chicks as it gets stronger will actually kill its siblings and throw it out of the nest so that they are the recipient of all the resources.
SIMMONS-DUFFIN: Yeah, kind of a downer.
Mr. BORITT: Even though it sounds quite cruel to us, if you had to split your limited resources amongst two, three, four chicks, chances are none of those would survive, so you're putting all your eggs in one basket, pardon the pun.
SIMMONS-DUFFIN: Okay, there's one more species we had to check out, the lions. Lions live in family groups called prides. At the National Zoo there were seven new lion cubs just a few weeks old. We couldn't visit them since they're getting all their shots, but I got the rundown from expert Craig Saffoe.
Mr. CRAIG SAFFOE (Lion Expert): They all play together. They wrestle and everybody is biting each other's tails. And they're just - I mean I'm not a big fan of the C-word but they are really, really cute.
(Soundbite of laughter)
SIMMONS-DUFFIN: So we can't exactly graft our own human stories of love and bickering onto these animal species, but think of these as extreme metaphors the next time you build a metaphorical nest with your sibling or feel like pushing them out of one. Selena Simmons-Duffin, NPR News.
MONTAGNE: And you'll find all of our stories about brothers and sisters on our website. You can also play an online match game of famous people and their lesser-known siblings, plus NPR music has a mix of songs from sibling acts. That's all at npr.org.