One of the hardest things to do when looking for some nests is
to follow the parents, because good parents lead you away from the nests.
One example is faking an injury, etc.
Birds that nest of a cliff show huge amounts of aggression.
Lars von Haartman (1949) was a Finish ecologist looked at the
stimulus that parents used to give stimuli to the kids. Von Haartman then
created an experimental nest box. He had a trapdoor in the bottom that
allowed him to remove the bottom to see what the adult would do when it
encountered young. So do the parents respond to hearing or to seeing.
You can start out with several young from several nest boxes, and make
sure that everyone is very hungry. Now all the kids are very stressed.
You can manipulate the young so that all kids are ALWAYS hungry. When
you do this the parents increase their foraging behavior.
The kids have a number of features that should be very attractive
to the parents. There are markings on the pallet that are very bright.
Thus, when they open their mouths, there is a lot of selection on the
brightness of the mouth. They call these ‘reflection pearls’.
Its been shown that parents prefer giving food to young with the most
colorful mouths. The sides of the mouths are swollen in newborns. These
edges of the mouth are very colorful. They are often filled with blood
and red. If it is bright red it means that it doesn’t have much
food in its stomach (food in the stomach takes blood away from this area).
Brood parasites, will sometimes mimic the palatal markings of their host
By Rob Nelson
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