Trick the birdie
I'm putting together a talk proposal for Notacon. In the process, I'm finding myself jumping ahead (all they want this month is a 150 word abstract) and thinking about things that should actually be in the talk. One thing that should definitely be included is an example of how biological evolution can sometimes produce highly specialised controllers that are easy to trick, just like artificial evolution. It should only be a small anecdote, but it's starting to bug me because I know the specific example I want to give, but I can remember too few details of it. It's something that was described in a lecture back when I was an undergrad, but seeing as that was last millenium my memory of it is a little hazy on details. So here is the phenomenon:
An ethologist discovered that the young of at least one species of bird exhibit a fear response if a fairly simple shape is used to cast shadows in the right way. The shape was more or less the silhouette of a swan, and if it is flown forwards (moving in the direction of the long neck) it gets no reaction. If it's flown backwards, however, the chicks panic. This was taken as sign that the evolved fear response was rather tuned to specific triggers, which matched the environment in which this species of bird had evolved. In that environment, birds of prey all have short necks, while swans and cranes are no threat to birds.
Anyway, this is all too vague for me to use as even a passing anecdote, so if anyone can provide me with any of the following details—or better still a reference—I would be most grateful:
- Who was the researcher? [I have a feeling it was Konrad Lorenz, but I'm not sure]
- When was this work carried out? [I think 1930s]
- What species of bird was it?
- Is this is a common effect, or very species-specific?
- Where could I find an image of the shadow-caster they used?
Of course, if the first couple of those are answered, it will be much easier for me to find the answers to the rest.
Comments
found it!
http://www.cartage.org.lb/en/themes/Biographies/MainBiographies/L/Lorenz/1.html
Together, Lorenz and Tinbergen discovered how birds of prey are recognized by other birds. All birds of prey have short necks, and the sight of any bird - or even a dummy bird - with a short neck causes other birds to fly away.
I think it is in the study of instinct book that these guys wrote in the 50s. I have no clue where the original paper is, but I will see if i can find a citation for it in my behavior textbook.
cindy
Thanks! I don't really need the original source for the very small part that this might play in a talk, but the information you've just cited is very helpful, not least because it reassures me that I wasn't making this up.