Bird Behavior

First of all what is Behavior: Anything an organism does in space and time.

What are the fundamental basis’s for behavior?
1. Nervous systems: you couldn’t have behavior if you didn’t have basic nervous system.
2. Hormones
3. Genetics

The two foci for studying behavior are ethology, which is the traditional form and behavioral ecology which is a more modern science.
• Ethology studies development, proximate causation, evolutionary history, and function of behavior:
• Behavioral Ecology seeks to ask, how do animals behave under particular ecological conditions? And what are the evolutionary inferences involving natural selection. This field is only about 30 years old. This field is fairly melded with evolutionary biology. One question a behavioral ecologist might ask, “Why are species that breed in marshes normally polygamous while species that breed in forests, normally monogamous?” A behavioral ecologist asks questions about how a behavior might have originated in a population.

Pelecaniform birds: Here is a diagram of several different types of pelecaniform birds. The types of behavior that occur in a family of birds are more similar to each other than the behaviors between families. One way of looking at this then, you might be able to classify birds based on their behaviors. Of course, behavior in a traditional sense is very labile and not useful to taxonomists, but it shows that behavior has some phylogenetic component to it.

On way behaviors manipulate the environment is nest building by the bower-birds. So, the act of constructing something is as much a behavior as taking a bow, etc. Some other Bower behaviors: nest building, steeling behavior, copulation, copulation disruption, raising young, etc.

Doug Mott is a world expert on egrets and Herons. He started out as an ethologist and began studying boat-billed herons. He looked at the repertoire of behaviors. He tried to see what conditions in the neotropics may effect them differently than herons in temperate areas. Turns out that neotropical birds are usually in mangroves where is dense, and tangled. Thus, it seems that a display for a neotropical bird may not be as usefull as that for more temperate herons.

Ritualization: One of the contexts of behaviors is that of ritualization. It takes functional behaviors and makes them symbolic. Thus it takes one behavior and puts it into a different form. Ritualized behaviors, thus, are rather invariant. As an example, the display of a peacock are used by males to display to females.
• A golden-eye has a ritualized threat display.
• A great tit has a threatening posture
• Great tits have submissive displays as well.

Behaviors that evolved in one context can become ritualized to another. For exaple, the forward position of a gull is an aggressive display. The meeting ceremony is ritualized with the same forward position. Thus, when the gulls meet each other, it includes elements of aggression.

Skewwas have aggressive behavior and then turn away, when they don’t want to attack. Its interesting that behaviors will have an ancestral form that gets added onto another behavior.

Behaviors can be innate as well. For example, a young cuckoo, when its born will push out the other birds in the nest.

Some behaviors are imprinted: Imprinting is a type of single-trial learning, during a ‘critical period’ in development. An example would be a California condor. One of the greatest problems with captive breeding is trying to get young birds to not imprint on something that looks like a condor.

Practice makes perfect learning: For example, nest building takes a lot of practice. Most of the nests built by younger birds are very different and not as good as older birds.

Turnstones have distinctive markings on them that allow us to identify unique differences between them.

Some learning in birds requires a critical learning period. Imprinting is an example of a very short period which either happens shortly after hatching or not at all. Bird song has about a 10 month critical learning period. If a bird doesn’t hear a tudor song in the first ten months, it just won’t sound the same. Shows that what an individual encounters in its critical learning period will influence how it sounds when its an adult.
• Dialects are one example. Birds in different areas will have a unique dialect that accompanies it. Northern SF birds sound different from the ones that are below.

Animated displays, occur when there are lots of motion involved. The question then becomes, how do these displays work. What if a bird leaves out a step in the motion? You might be able to quantify each step, but how do you determine which portions are the most critical?

Graded Displays: a Stellar Jay can raise its crest from 0 degrees (submissive) to 90 degrees (aggressive). AT 30 degrees the bird expresses displeasure at something. At 60 degrees its more ‘upset’ and at 90 degrees an aggressive act is eminent.

Behaviors can be used as low-cost ways of challenging an individual. In essence the greatest cost is an actual fight. Fights can be avoided by threat displays.

Group displays: By far the most complex behavior is group behaviors. Mannakins for instance will have giant leks, where they try to attract females to their leks.

By Rob Nelson


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