Do birds know counting ?

[jpittelo]

I wanted to know if some observer could notice if those birds replacing other bird's eggs are counting when doing it, so that the "host" does not notice it...or they don't even care, on neither side ?... I know once the egg of the pirating bird eclosed, the new born throw aways remaining eggs, because he grows up faster...but I wanted to know before posing the egg...?..

[CraigD]

It’s been fairly conclusively demonstrated that at least one bird Alex, an African Gray parrot, can.

 

It’s accepted zoological fact that most birds either can’t, or don’t. Proof of this is that many bird species, such as the cuckoo successfully use the strategy of laying their eggs in other birds’ nests, which wouldn’t work if most birds were good at detecting such trickery.

[InfiniteNow]

Most animals can count. It's figuring out a way to test this that proves most challenging.

[Mercedes Benzene]

Counting is actually a fairly interesting concept.

Perhaps birds cannot "count" per se, but just identify with a certain image.

For example, if we look at an image of 5 eggs, before we count the eggs, we could immediately look at another picture and tell whether or not that picture had the same number of eggs.

We wern't really counting, but were drawing conclusions based on a pre-defined image.

I don't know if that was the best example, but maybe you get what I mean.

[Cedars]

I wanted to know if some observer could notice if those birds replacing other bird's eggs are counting when doing it, so that the "host" does not notice it...or they don't even care, on neither side ?... I know once the egg of the pirating bird eclosed, the new born throw aways remaining eggs, because he grows up faster...but I wanted to know before posing the egg...?..

 

The cowbird is a parasitic egg layer in the USA. I am familiar with the brown-headed cowbird. This bird has been observed laying eggs in over 200 other species nests, with most being smaller than themselves.

 

More info here:

http://www.birds.cornell.edu/AllAboutBirds/BirdGuide/Brown-headed_Cowbird.html

 

What has been observed in the Yellow warbler when a cowbird egg is inserted, is they will respond by building a new layer over the batch of eggs, and start laying again. Some nests have been found with 5 layers. So for some reason, these birds do spot foreign eggs. The pattern seems to be if two or more original eggs are in the layer, the warbler will hatch out the cowbird.

 

More info here:

http://www.birds.cornell.edu/BOW/YELWAR/

 

The cowbird does not seem to search for hosts whos eggs match their own. The cowbird eggs are white and lightly speckled with brown. The Yellow warbler eggs are blue thickly spotted with brown.

 

The blue doesnt show up well in this Yellow warbler egg picture:

http://www.mbr-pwrc.usgs.gov/id/framlst/i6520id.html

 

You can see they are similar in many ways:

http://www.mbr-pwrc.usgs.gov/id/framlst/i4950id.html

 

According to my audubon book, old world cuckoos do tend to insert eggs into host nests that have similar colored eggs. So to possibly test this idea, one could find old world cuckoo information and which birds tend to thwart the host, or one could try to test it with american type birds by finding the hosts whos eggs match color and try to determine whether a host is avoiding raising cowbird young via counting or some other method.

 

As far as I know, the cowbird does not toss out an egg from the host nest to try to cover their tracks.

[Turtle]

Here ya go::hyper:

 

http://www.pigeon.psy.tufts.edu/avc/emmerton/default.htm

 

From Introduction:

Anecdotal Beginnings

 

For at least two hundred years, people have speculated about whether animals can in some sense "count", or make choices based on number. This possibility was first raised in a popular anecdote about crows. The story goes that whenever a hunter tried to approach a crow and shoot it, the bird kept its distance. So the man enlisted the help of others in a ruse that was designed to trick the bird into deciding it was safe to return to its nest. A group of hunters entered a hiding place in sight of the bird, then after a while all but one left again, leaving the last person concealed. When there were up to 5 people in the group, the crow stayed out of harm’s way until the remaining hunter had also given up and left. The bird was fooled into returning prematurely, and met its demise, only when there was a total of 6 hunters. No doubt this story is apocryphal, but it points to two ideas. The first is that birds can accurately keep track of the number of things (such as hunters in a group) up to some limit (in this example 5 but not 6); the second is that being able to do so might have survival value, and so be of evolutionary significance.

 

From Conclusions:

Even the earliest anecdotal speculations about animals’ "counting" behavior implied that the ability to make numerical discriminations is functionally significant. Choice biases seen in the artificial foraging situation of experiments that use food-rewards are one reflection of this. As long as there are no other factors (such as predators or aggressive competitors) to complicate the picture, it is often advantageous to choose the items that are greater in number.

[CraigD]

… birds can accurately keep track of the number of things (such as hunters in a group) up to some limit (in this example 5 but not 6); …

An interesting anecdote, since there’s evidence than 5 but not 6 objects is about the limit of how high a human being can count “at a glance”.

 

My high school astronomy class reproduced a well-known experiment supporting this hypothesis. Subjects are tested in a blacked out room. A single strobe flash illuminates a stand, on which a random number of white dowels were clamped. The test subject reports the number of dowels they saw. When reported counts are compared to actual, it’s found that, for about 90% of test subjects, accuracy drops off sharply for counts above 5, and for 100%, for counts above 7. Accuracy above 7 is not significantly better than chance.

 

It appears that some basic “neurological machinery” is strongly shared – “conserved” – among all animal species. Though nearly all human beings can count into at least the thousands, this ability appears to be due to cognitive “tricks”, such as grouping, and numerating. Apparently, these tricks are unavailable to crows (though maybe not to parrots).