Why do animals sometimes nurse the offspring of other species?

The mothering instinct can be very strong.

Not exactly an expert here, but I wonder if it has more to do with the fact that their brains are not as good at forming “categories.”

Like, I seriously doubt a dog, or even a chimpanzee, has a conception of “species.” Humans are very good at slicing reality up into categories and figuring out what doesn’t belong, but if your brain can’t do that, you have to rely on other stimuli.

In the case of cuckoos —“brood parasite” birds who lay eggs in other species’ nests—it’s clearly not empathy that makes the dupe birds feed the cuckoo chicks. The cuckoos have evolved to take advantage of the other birds’ instinct.

@Qingu . good point about the cuckoos, but i think some animals must be more intelligent or mothering, Because some animals eat their own young.

I had a dog who nursed a foundling cat for me. She also babysat for a few bunnies and an injured pigeon. She was a very generous loving soul. My other dogs would have had lunch.

Animals indeed know other species. My cat only reacts to other cats in the yard, not squirrels, birds, or dogs, or anything else.

Just to pick up on @Qingu‘s point about animals not being able to figure out whether a baby animal is of their own species or not. Most mothers will not accept offspring after the baby of the alien species or their own young are old enough to move around. It is at the point where baby animals gain the ability to move around that recognition systems kick in at full strength. So one reason is plain inability to distinguish between the two species. An adult cat will recognise other adult cats, yes, but may not be able to differentiate a kitten and a puppy when neither of them is able to move.

I’ve also read that nursing mammals, or mammals who have lost newborn offspring have strong residual maternal instincts and will foster or abduct the offspring of other species.

@slick44 I don’t know if you should use the word “intelligent” when talking about mothering, since mothering is very instinctual. Besides, birds have a bad reputation for being stupid – birds actually have a pretty large brain to body size ratio – we just think all birds are as stupid as chickens (some of the stupidest birds that exist) – this chart kinda shows that. (I remember seeing a better one in some class I took last year, but I can’t find that one).

As for the actual question, I think @xxii‘s got a point. They may not be able to recognize which babies are theirs. However, the housecat nursing those baby bobcats wouldn’t really apply – I don’t understand why that happens at all, but it’s pretty friggin’ adorable!

I think it’s mostly about hormones affecting their instincts. In a human female, nursing generates hormones that causes the milk to let down.

Years ago when I was quite young, I had a cat who had kittens, probably too young, and the kittens were obviously premature. They seemed to be unable to nurse, and the mother cat took no interest in them.

I tried to induce them to nurse, placed them in the right position and even tried to put their mouths to the nipples. One by one they died, in spite of all I could do. Offering them an alternative to their mother didn’t work either.

For a brief time, one of the kittens was finally able to attach to the mother and tried to nurse. For a little while after that, the mother showed some attachment to this one, cleaning it and showing maternal interest. When the kitten didn’t get stronger and the nursing didn’t continue, her interest died. From that observation I felt that the nursing created the instinctive maternal feelings, so perhaps when a different species begins to nurse on a lactating female animal, that same instinct occurs, irregardless of the species.

@eden2eve That story was so sad! Maybe the mother knew the kittens wouldn’t survive since they were premature, and that’s why she didn’t nurse them? Still… as a cat lover I can’t imagine watching all those kittens die like that. I would just cry.

My Chinese goose was mothered by a Golden retriever as a gosling.

He came through a wildlife rescue I volunteerd for and we were all appalled that the people that found him left him with their dog! Usually a deadly match, dogs and birds, especially things such as geese, ducks and chickens.

They sent me pics of their female Golden cradling him in her paws.

He was one lucky goose! lol

12 years later he still has a curiousity about dogs, not a good thing.

This is one reason in wildlife rehab that it is imperative to keep domestic animals and wildlife separate as well as minimizng human contact for successful release.

Since he was a domestic breed I inherited him…my buddy!