Chapter 11

Question 1

How do individual birds usually space themselves?

Answer 1

• The tendency of individual birds to space themselves promotes uniform dispersion patterns

Question 2

Allopreening

Answer 2

• Individuals of highly social species overcome the individual distances to preen each other
• Huddle together, sometimes in large groups, to stay warm while roosting overnight

Question 3

Territoriality

Answer 3

• 2 types: Coloniality and Flocking

Question 4

What are the different types of territory?

Answer 4

Mating/nesting/feeding
Mating/nesting
Nesting
Pairing/mating
Wintering

Question 5

What are the different types of territorial behavior?

Answer 5

Singing (Northern mockingbird)
Nest Building
Drumming
Visual Displays (black-backed gull, Capercallie)
Chasing (black-backed gull)

(most visual and auditory)

Question 6

What are the benfits of territoriality?

Answer 6

Exclusive access to some resource:

food, mates, good nest sites, good places to hide from predators

Territory may have several of these things or just a single resource

Defend an area to provide potential mates with access to resources

Question 7

What are the costs of territoriality?

Answer 7

Energetically expensive

Can take up a lot of time

Aggressive interactions with intruders can lead to fights and injuries

Can make birds very conspicuous to predators

Question 8

How do body size and diet play a role in territoriality?

Answer 8

Territories or home ranges of birds increase directly in relation to body size, energy requirements, and selection of food types

Territory size is geared to the food and energy requirements of the bird

Question 9

What factors make a territory defensible?

Answer 9

• Territories of intermediate sizes (A to B) are economically defensible because the benefits exceed the costs; The benefits relative to need increase rapidly at first but then reach a maximum value when needs are filled
• example of Golden-winged Sunbird: Raising the average nectar volume from one to two microliters per flower cuts feeding time in half; A defense investment of 20 minutes costing 3.7 kilojoules reduces the sunbird’s total costs from 32 kilojoules per day to 26 kilojoules per day, a net savings of six kilojoules

Question 10

Rank and social status: Species and Indvidual Recognition

Answer 10

• Birds can distinguish among members of their own species by means of variations in plumage patterns, size, voice, and behavior
• example: Ruddy Turnstone, variable head patterns to distinguish

Question 11

Social status in Harris’s Sparrow Population

Answer 11

• the larger the patch underneath the beak/on the neck, the higher the ranking

Question 12

Social Roles in White-throated sparrows

Answer 12

• The White-throated Sparrow has two head color forms that pair assortatively and have different social roles

Both sexes include a striking white-striped morph (A) and a duller tan-striped morph (B), which are controlled genetically by an inversion on the second (autosomal) chromosome

• white more aggressive, nonmonogamous
• tan-ish more calm and protective of mate

Question 13

Yellow-headed blackbird

Answer 13

• have territorial displays that shows they are awesome at protection, make a good mate

Question 14

Great White Egret displays

Answer 14

• aggression while in close proximity
• neck up, as big as possible in conflict or fight

Question 15

Northern White-faced owl

Answer 15

• puffs up with smaller predators to look big, stands tall and skinny with big predators to hide away like branch

Question 16

Flocking

Answer 16

Aggregation of conspecifics or several species into groups

Loose temporary aggregations to organized foraging associations of diverse species

Most birds flock outside of the breeding season

Question 17

Benefits and costs of flock feeding

Answer 17

Pros: Numerous individuals searching for food are more likely to find good food source;
Groups may be more effective at capturing prey

Cons: Producer-scrounger behavior; Exploitation of actively searching birds: Some birds (scroungers) don’t look for new food patches themselves but instead wait for others (producers) to find food and then eat some of it

Question 18

Benefits and Costs of flock for antipredator

Answer 18

• Pros: Flocks may confuse predator when they can’t isolate an individual to prey upon; Safety in numbers - the larger the flock, the less likely a given individual will be preyed upon; Increased predatory detection
• Cons: Individuals on periphery of group may experience increased predation

Question 19

Mobbing

Answer 19

• larger population of species comes in contact, and tries to attack, a bigger predator

Question 20

Mixed species flocks

Answer 20

• Tropical flocks may include 60 birds of 30 different species

Temperate flocks average 10 to 15 birds of six or seven species

Flock size increases as a result of the addition of new species, not more individual birds of a few species

Flock composition changes regularly

Question 21

Nuclear species

Answer 21

• (tend to be “sentinel” species that are highly sensitive to predators):
• Attract other species: “followers” that join flocks opportunistically, are subordinate to the nuclear species

Question 22

How do you get an optimal flock size?

Answer 22

• As flock size increases, birds spend more time fighting and less time scanning
  -When predation risk increases, scanning should increase and the optimal flock size then increases

Question 23

Benefits of a communal roost

Answer 23

• thermoregulation
• foraging effciency
  -predation avoidance

Question 24

Coloniality

Answer 24

• About 13 percent of bird species, including most seabirds, nest in colonies
• Evolves in response to a combination of two environmental conditions:
• A shortage of nesting sites that are safe from predators
• Abundant or unpredictable food that is distant from safe nest sites

Question 25

Benefits of coloniality

Answer 25

Same feeding and antipredator benefits as flocking

Question 26

Costs of Coloniality

Answer 26

Increased competition for nest sites and materials, mates, and food around the colony

Increased cuckoldry

Higher parasite loads

Increased infanticide and cannibalism