Exam 3 Flashcards
(88 cards)
What needs determine how and where birds live?
Food and protection
These needs also determine whether a bird is:
Social or Asocial
Cooperative or Competitive
Self interests can foster hostility or corporation when two birds interact
Why do individual birds typically maintain small distances between themselves and other birds?
their individual spaces reduce hostile interactions
What is allopreening
Individuals of highly social species overcome the individual distances to preen each other
What is territorial behavior typically over? How do birds defend a territory with invisible boundaries?
Territorial behavior is a form of aggressive spacing.
This may be over a single resources territory (food) or an all-purpose territory (food, courtship, nesting)
Males and females will defend territories, sometimes a small group will defend a territory
Birds broadcast their presence and intended control of a territory with loud vocalizations or with nonvocal communication sounds, such as the familiar tree drumming or rapping by woodpeckers. Both males and females may display and defend, sometimes together. Territory residents chase trespassers until they leave, resorting to physical contact as needed. Sometimes these contests for the control of a territory last for hours. Beneath the conspicuous surface of territorial control and ownership exists an inconspicuous underground of subordinate individual birds that will surface and take charge when the owner is absent or dies.
Why would a predator need a larger territory than herbivores?
Territories or home ranges of birds increase directly in relation to body size, energy requirements, and selection of food types. The correlation suggests that territory size is geared to the food and energy requirements of the bird. Predators have higher daily energy requirements than do herbivores , which have correspondingly smaller territories.
What are some of the costs and benefits of territoriality?
Mid-sized territories have benefits that out way the cost
How do birds assert their dominance? What factors might affect dominance?
Individual birds that prevail in aggressive encounters become dominant; losers become subordinate. As social ranks are established in new groups of birds, losers cease challenging dominant birds with the result that stable dominance relations lower the frequency and intensity of overt hostility.
Dominant birds use threat displays to assert their status and reserve their access to mates, space, and food. They move without hesitation to a feeder or desirable perch, supplanting subordinates and pecking those that do not yield at their approach. Subordinates are tentative in their actions and frequently adopt submissive display postures. Age, sex, physiology, genetics, and possibly parasite load all affect dominance.
How do birds identify dominance in members of their own species?
Plumage patterns
Size
Voice
Behavior
Some species wear badges
What is mimicry?
an evolutionary convergence in appearance
Mimicry improves the competitive ability of a subordinate species to access resources controlled by dominant species (including protection and avoidance of aggression)
What are the costs/benefits of flock formation?
On the positive side of the ledger, flocking behavior enables cooperative foraging and reduces the risk of predation. Members of a flock are attentive and sensitive to what their flock mates are doing and adjust their own behavior accordingly. A wealth of information is available from one’s neighbors. Which ones find food and where?
High on the list of costs are increased competition for limited food supplies, increased risk of disease, and increased aggression to maintain individual distances.
What is the beater effect?
Feeding in flocks can flush prey
Information sharing - example pelicans
Producer-scrounger - exploitation of actively searching bird that waits for another bird to find something and then eats/takes that food
What are nuclear species?
Mixed-species flocks
Nuclear species tend to be highly sensitive to predators and followers are subordinates that join opportunistically
What are the advantages/disadvantages of colonies?
Advantage: Decreased predation and increased foraging/food
Disadvantages: Increase competition for nest sites and mates and increase disease also large number can attract predators
Give an example of disadvantages in swallow colonies
The globular mud nests in large colonies of the American Cliff Swallow, for example, are more likely to be infested by fleas or other bloodsucking parasites than are nests in small colonies (Brown and Brown 1986). Experiments in which some burrows were fumigated showed that these parasites lowered survivorship by as much as 50 percent in large colonies but not significantly in small ones. The swallows inspect and then select parasite-free nests. In large colonies, they tend to build new nests rather than use old, infested ones. On balance, the advantages of colonial nesting clearly outweigh the disadvantages given the many times at which colonial nesting has evolved independently among different groups of birds
Interspecific vs Intraspecific
The globular mud nests in large colonies of the American Cliff Swallow, for example, are more likely to be infested by fleas or other bloodsucking parasites than are nests in small colonies (Brown and Brown 1986). Experiments in which some burrows were fumigated showed that these parasites lowered survivorship by as much as 50 percent in large colonies but not significantly in small ones. The swallows inspect and then select parasite-free nests. In large colonies, they tend to build new nests rather than use old, infested ones. On balance, the advantages of colonial nesting clearly outweigh the disadvantages given the many times at which colonial nesting has evolved independently among different groups of birds
What are the gonads in males and females? What do they do?
Birds are strictly bi-sexual (Female and male)
Gonads (sex organs) located inside the body cavity on surface of kidney which secretes sex hormones and produce gametes
Paired testes in males - secrete testosterone
Single ovary in female - secretes estrogen
Describe the sex chromosomes of birds.
Birds have ZW sex chromosomes
Females are heterogametic ZW while males are homogametic ZZ
What is bilateral gynandromorphism?
Aberration in the 1st cell division of a fertilized egg will cause half of a bird embryo to become female (ZW) and the other half to become male (ZZ)
These birds will have testes on one side of body and an ovary on the other and will also display distinct male and female plumages on corresponding sides of the body
What does ovulation do?
Releases an egg (ovum) from the ovary.
An ovum in the oviduct (specifically in the open upper infundibulum) is ready for fertilization
What is parthenogenesis?
The development of unfertilized eggs into offspring
How is avian sperm different from mammalian sperm?
Avian sperm have evolved to survive higher body temperatures than mammal sperm, so they can be stored in testes housed inside the body.
What bird orders have penises in males?
Paleognathae, Galliformes and Anseriformes
Why do ostriches have a large penis? Why do ducks evolve a large, anatomically complex penis?
positively correlated with the frequency of forced extra-pair copulations
The coevolution of male and female genitalia is an antagonistic sexual arms race that proceeds through sexual conflict over paternity.
Where is sperm stored during fertilization?
It can be stored in sperm-storage tubules above the cloaca at the junction of the uterus and vagina but also at the infundibulum itself (open upper-end of oviduct)
