Territoriality

When talking about Agonistic Behavior you can divide it up into Territoriality and Dominance:
1. Territoriality
a. Space related
b. Primary or exclusive use
c. Fixed area defended continuously for sometime.
2. Dominance
a. Aggressive encounter to reinforce status
b. Not necessarily space related.

If two birds were consistently displaying to each other along a seemingly invisible line, you would call that territoriality. If two males would go into the display wherever the met each other you would call it dominance.

For a territorial bird you can go to the same spot every day and find the birds. Thus, it is much harder to find and study a non-territorial bird.

Sanderlings can forage in flocks OR establish a territoriality. Phil Brunner has shown the same things for the Pacific Golden Plovers.

There is some difference in birds depending on the size of the territory being constrained by neighbors or by the energetics of moving around within it.

Theories
Elastic Dickcissels theory: With the number of males increasing, the territory size decreases, down to some minimum number. If the size of the territory is too small it seems to loose any sort of value.

Types of Territories An all-purpose territory: if nesting and feeding is in the territory, and to some extent, sexual privacy.

  1. Nest site only territory: only within a short distance around the nest will the male drive off another male. Based on space.
  2. Leks: Aggregations of males to mate with females.
  3. Facultative territoriality: for instance, nectar feeders working to defend a spot.
  4. Blurred territories: some males may just defend the female's space. The type of territory is not always cut and dry.

All birds of a home range (area that a bird uses), but only some of the birds have a territory. Most territories are a subset of the home range. All-purpose territories may equal the home range.

Tropical territorial species have territories year-round, while most temperate birds have territories only in the breeding season.

In a territorial system, there are a certain number of residents as well as a lot of floaters. Floats roam around looking for a territory but do not have one.

Manu national park in Peru (Amazing birding area)
• There are many different territories set up in the park.
• There are many species that share the exact same territorial boundries.

Brown was one of the first to put territoriality into a conceptual framework

  1. Territoriality
  2. Aggressiveness Economic defend ability.
  3. Competition

In the 1970s someone put out a hypothesis that got everyone riled up: The hypothesis was called the Super-territory Hypothesis. It was published in 1977. There must have been ten letters after this that said it was junk.
• Jerred Verner was the author of the super-territory. He basically said that you can look at birds and they are defending an area that is too large for what they need. He said that by looking at this, that by increasing the size of your territory you are decreasing the size of floaters. This would in-turn increase you relative fitness.
• Maybe when the birds set up the territory, they don’t know what its going to be like during the breeding time. In essence, unfavorable years may require a much larger territory.
• The concept of the Pubic Good was introduced. Anyone that would defend a smaller territory would reap the benefits of the others who were defending a larger territory. Thus it is not sustainable.

I’iwi’s in Hawaii show a classic example of facultative territoriality. When there is low-productivity, its not worth it to be territorial. When the productivity is really high, why be territorial because there is an over-abundance. It’s really at an intermediate level where it would be advantageous to be territorial. – conceptually its not worth it, but is this what happens in nature? Yes.

GREAT TIT DOMINANCE
They would put a dummy in a feeder-box and vary the size of the stripe.
If the live great tit had a stripe bigger than the dummy, it would attack the dummy. If this is an honest signal, you can look at the stripe and know how to attack/defend it.
Shows that it doesn’t even have to be a living bird, but that the size of the badge is very important.

House Sparrow dominance
• There is a lot of variation in the badge on the sparrows chest. He found that the most dominant birds had larger patches.
• The important thing is that badge size really maters.

Variation in patches on Harrises Sparrows:
• With significant variation in the markings on a bird you are able to tell the difference between birds.
• This allows for individual recognition.
• More dominant individuals and older indivuals seem to have more dark plumage.
• SO, can you fake it!
• Dominant birds usually have a higher metabolism, higher hormone counts in their blood, and so it seems that it wouldn’t be possible to do this.
• But, you can color these individuals to see what happens.
• Turns out that most of the time they got attacked more often.

By Rob Nelson


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