Dogs will nurse orphaned cats and even tigers. Dolphins will go above and beyond to care for an injured pod member, sometimes swimming underneath another dolphin and pushing it to the surface so it can breath.
This kind of behavior isn't surprising for social animals that tend to stay in packs, scientists say. What is surprising is the new finding that solitary animals do it too.
Scientists say that squirrels will adopt orphaned pups, but only if the babies are relatives. Even so, the occurrence was incredibly rare.
The research team reported five adoption occurrences among 2,230 litters over 19 years in red squirrels (Tamiasciurus hudsonicus). Adoptions were always between kin, while orphans without nearby kin were never adopted.
Their paper was published online today in the journal Nature Communications.
"Social animals, including lions and chimpanzees, are often surrounded by relatives, so it's not surprising that a female would adopt an orphaned family member because they have already spent a lot of time together," Andrew McAdam, an evolutionary biologist, said in a press release.
"But red squirrels live in complete isolation and are very territorial. The only time they will allow another squirrel on their territory is the one day a year when the females are ready to mate or when they are nursing their pups."
Also remarkable was the fact that the squirrels were able to tell which pups were related to them. In all five adoption scenarios, the pups were nieces, nephews, siblings or grandchildren to the adoptive mother.
As squirrels rarely interact, they learn who their nearby relatives are by hearing their unique calls, McAdam said. If they fail to hear a relative's calls for a few days, they may investigate.
The researchers speculate that adoption may afford a unique opportunity for the squirrels to help their own gene pool. That may be why they will only adopt relatives, they said.
Image by Ryan W. Taylor. Courtesy of the University of Guelph.
Tags: Animal Behavior, Animals, Mammals
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