Take the 2-minute tour ×
Skeptics Stack Exchange is a question and answer site for scientific skepticism. It's 100% free, no registration required.

enter image description here

Welcome to installment #2 of my "the science of animals falling" series of questions....

I've heard it said many times since childhood that if you are to find a baby bird on the ground which appears to have fallen from the nest you should not pick it up and put it back.

I was told that once the baby bird has your scent on it, the mother will not take it back.

It's possible that this is just something parents tell their kids to keep them from touching birds which are notorious for carrying germs (as are kids), but it is a very commonly held belief in America.

  • Is there any scientific evidence to explain why this would happen?
  • Has this been studied?
share|improve this question
10  
I'm from Germany and got this told as child as well. Not just for birds but for also for fawns etc. –  Martin Scharrer May 12 '11 at 19:36
3  
I got told once that animals recognize their own offspring over the scent and refuse to raise other children. Not sure if this is true for all animals, especially for birds. After all the cuckoo is a brood parasite which relies on the fact that the host mother bird does not recognize that it isn't its own offspring. –  Martin Scharrer May 12 '11 at 19:42
3  
Birds have a fairly poor sense of smell, but I'd imagine things might be different for deer, etc. –  Jason Plank May 12 '11 at 19:53
2  
The Reality Check podcast ep #116 ends with a discussion on this topic, reaching the same conclusion as the answers here; birds generally have a poor sense of smell, and they typically recognize their young by hearing. It's a good show, anyhow. –  David Hedlund May 12 '11 at 20:49
2  
I am from Pakistan and we got told this thing as well. –  Aamir May 13 '11 at 5:10

3 Answers 3

up vote 138 down vote accepted

Bird Image Source

From Fortean Times:

Birds have little or no sense of smell, and will be unaware of your molestation. Besides, they will not lightly abandon their offspring.


From National Geographic:

"Most birds have a poorly developed sense of smell," says Michael Mace, bird curator at San Diego Zoo's Wild Animal Park. "They won't notice a human scent."

One exception: vultures, who sniff out dead animals for dinner. But you wouldn't want to mess with a vulture anyway!


Snopes also debunks it:

[It] is hogwash. Mothers will not reject their babies because they smell scent on them, nor will they refuse to set on eggs that have been handled by a person. Most birds have a limited sense of smell and cannot detect human smell.

share|improve this answer
21  
+1 for the picture –  Peter Olson May 12 '11 at 22:13
24  
+1 for "molestation" of birds –  billynomates May 13 '11 at 8:04
8  
+1 for both of the above, and for quoting someone who used the word "Hogwash" –  Wipqozn May 13 '11 at 11:34
2  
The only birds with highly developed olfactory senses are vultures and buzzards that search for and eat carrion. However, I doubt that they would use smell as a means of rejecting their young if touched or handled by humans. Generally speaking, birds will abandon a nest not because of human scent, but because of frequent or prolonged human presence. Someone putting up a ladder to return a young bird to the nest, taking an hour or more, interrupting feeding cycles, is likely more cause for abandonment than anything else. –  JYelton May 13 '11 at 15:46
2  
@wipqozn I just noticed it now, but you have the best name ever. I have more than once found myself in deep wipqozn –  Monkey Tuesday May 31 '11 at 5:25

No.

A mother bird will not abandon her young if it's touched by a human.

  • Birds do not identify their offspring by smell nor do they abandon their young without a good reason.

No matter how flighty birds appear, they do not readily abandon their young, especially not in response to human touch, says Frank B. Gill, former president of the American Ornithologists' Union.
Source

  • Sight and sound: Baby birds chirp for a reason.

It's a myth that parent birds will abandon young that have been touched by humans—most birds have a poor sense of smell, and birds in general identify their young using the same cues we humans do—appearance and sound. It's perfectly safe to pick up a fallen nestling and put it back in the nest, or to carry a fledgling out of danger and place it in a tree or shrub.
Source

  • Some don't even care, or know, if it is not their offspring

Both the male and female Western Bluebirds fed unrelated nestlings at the same rate as their own offspring.

Neither male nor female Western Bluebirds preferentially fed related nestlings, suggesting that they may not recognize their own young.
Source

  • Preservation of the species.

This prevalent belief, however, is for the birds: it denies animal parents' innate drive to nurture their broods and ignores a bird's basic biology.

In fact, most creatures find extraordinary ways to ensure the survival of their young. Killdeer and ducks will feign a broken wing to lure a predator away from their babies, and raccoons and tree squirrels will speedily relocate their progeny to more protected pastures when a potential threat is skulking about.
Source

  • Nests are a different matter.

Still, there's good reason not to go fiddling around in an occupied nest. "The fact is, birds don't abandon their young in response to touch, [but] they will abandon [their offspring and their nest] in response to disturbance," explains biologist Thomas E. Martin of the University of Montana and the U.S. Geological Survey, who has handled birds from Venezuela to Tasmania without instigating abandonment. "They are likely responding to disturbance in relation to risk of harm to young."
Source

  • Disease may be one source of this myth...

Each spring, some children become infected with Salmonella after receiving a chick or other baby bird for Easter. It is important to remember that illness can occur from these baby birds or adult birds at any time of the year, and not just during the Easter season.
Source

  • Rabbits are not birds

Wild rabbits are the exception to this rule. "These animals seem to be the most sensitive to human and other smells. They're a flighty, high-stress species,"

If you suspect that a rabbit's nest has been abandoned, the Humane Society recommends making an "X" out of yarn or string over the nest and checking approximately 10 hours later to see if it has been moved. If the X has been pushed aside but the nest is still covered, that's a good indication that the mother has returned, nursed her young, and then re-covered them. If the X stays in place for 12 hours after the traumatic event, it's likely that the young rabbits have been deserted.
Source

The Bottom Line.

  • Birds identify their young by sound and appearance not smell (or taste) and being touched by a human does not modify a young bird's appearance or the sounds it makes.
  • Studies have show many species of bird will feed and care for offspring other than their own.
  • Like most creatures, birds have a strong biological instinct to care for their young and will not abandon them without just cause.

Notes:

  • If you find a baby bird put it back in its nest. If it is in danger: Get it out of danger and place it in a tree or shrub.
  • Do not disturb bird nests.
  • Wash your hands.
share|improve this answer
10  
Technically speaking "The bottom line" is "Wash your hands". Interesting. ;-) –  Sklivvz May 12 '11 at 22:38
    
@Sklivvz Corrected. –  Rusty May 13 '11 at 1:17
1  
Is this true for newborn kittens? –  Ark-kun Jan 17 at 1:20

As others have pointed out, birds certainly wouldn't be likely to use their sense of smell to identify and reject a replaced fledgling. Luckily for cuckoos!

As a general principle you shouldn't interfere with the natural process. That fledgling may be defective in some way. Maybe it's too stupid or too adventurous to stay safely in the nest. Maybe it's diseased and the parent recognises this in some way. This link might not put the position as strongly as I would, but it leans in the same direction.

It doesn't really matter. The point is if you save that potentially unfit animal, it may grow up and mate. Possibly leading to more defectives that otherwise wouldn't have been born. Possibly depriving some other fit bird from getting the chance to mate.

Nature got along fine for billions of years without human intervention, and much of the current evidence (such as Tire Reef and just about everything in New Zealand) suggests that when we do intervene, we often mess things up anyway. Grit your teeth and let Nature take its course.

share|improve this answer
2  
This answer is not properly referenced. Please add citations to support your claims! :-) –  Sklivvz May 12 '11 at 22:54
4  
“much of the current evidence suggests that when we do intervene, we often mess things up anyway” — it’d be good to get some references to support this statement. –  Paul D. Waite May 13 '11 at 0:01
3  
@FumbleFingers I agree with your point. However, commonplace/common-sense is looked on with skepticism around here :) –  Rusty May 13 '11 at 0:14
5  
@Fumblefingers this site requires references to back valid points. It's part of the "show your work" policy that not only makes your answer more credible, but makes it easier to understand for those who may not have your knowledge on the subject. In short, without citations, answers can be correct, but are often not complete. –  Monkey Tuesday May 13 '11 at 4:59
2  
@FumbleFingers, I actually wish more SE sites required this level of referencing instead of allowing many answers based on personal opinion alone. It reduces the reliability of answers imo. –  Kevin Peno May 13 '11 at 15:03

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.