Chapter 9: Annual Cycles

Question 1

What are the three main efforts?

Answer 1

1. reproduction
2. molt
3. migration (often)

Question 2

The annual cycles of birds coincide with _____ _____ and ______.

Answer 2

seasonal resources and opportunities

Question 3

Birds that are permanent residents undergo three main sequential tasks:

Answer 3

1. breeding
2. molt
3. survival until the next breeding season

Question 4

Tropical birds base their annual cycles on __ and ___ seasons

Answer 4

wet and dry

Question 5

Migratory birds face an additional annual challange of

Answer 5

needing to increase body mass for nutrient supply during the migration

Question 6

All plants and animals exhibit self-sustained oscillations called ______ ______

Answer 6

endogenous rhythms.

Question 7

Through use of the nervous system and through release of hormones (endocrine system), these biological clocks regulate daily cycles of metabolism, physiology, and behavior. These are called _____ _____

Answer 7

circadian rhythms

Question 8

Some clocks measure day length and govern events that are tied to an annual cycle (e.g. egg laying, molt, premigratory fattening, migratory restlessness, etc.). These are called______ _____

Answer 8

circannual rhythms.

Question 9

Circadian rhythms in birds are tied to the activities of two important structures

Answer 9

1. the pineal gland
2. the suprachiasmatic nucleus of the hypothalamus

Question 10

The pineal gland is located

Answer 10

on the top of the brain

Question 11

The pineal gland includes photosensitive cells that direct the rhythmic release _____

Answer 11

melatonin

Question 12

melatonin regulates …

Answer 12

daily rhythems in accordance with the light-dark cycle

Question 13

Removal of the pineal gland in House Sparrows causes

Answer 13

normal 24-hour cycles to disappear

Question 14

One affect of the melatonin is

Answer 14

to regulate the circadian activity of the suprachiasmatic nuclei

Question 15

All birds have an intrinsic circadian rhythm that is about ___ hours in length

Answer 15

23

Question 16

increases in daylength cause the growth of testes in

Answer 16

Dark-eyed Juncos.

Question 17

In the case of reproduction, increasing daylength causes the hypothalamus to release a hormone called

Answer 17

gonadotropin-releasing hormone (GnRH),

Question 18

GnRH induces the anterior pituitary to release two hormones…

Answer 18

1. luteinizing hormone
2. follicle-stimulating hormone

Question 19

What is the effect of luteinizing hormone and follicle-stimulating hormone?

Answer 19

travel to the gonads to cause and increase in growth as well as the production of sperm and eggs

Question 20

After reproduction has occurred, the gonads will regress. At this point they enter a state called the _____ period, during which the gonads will not regrow, even though photoperiods are still long

Answer 20

photorefractory

Question 21

Ultimate vs proximate

Answer 21

Ultimate is what has driven the evolution of the breeding season, while proximate factors only effect that one breeding season

Question 22

Ultimate factors in different species include…

Answer 22

• timing of adequate food sources
• availability of nest sites
• locations of facorable climates
• incidence of predation risk

Question 23

Proximate factors that induce reproduction include

Answer 23

• temperature
• availability of food
• courtship behaviors
• etc

Question 24

Reproduction in _____ is closely linked to the availability of pinyon pine seeds.

Answer 24

Pinyon Jays

Question 25

_____ will breed in the cold of January and February if enough conifer seeds are present.

Answer 25

Red Crossbills

Question 26

Nesting seasons in temperate latitudes generally last for

Answer 26

3-4 months

Question 27

Nesting seasons in the tropics last longer, perhaps...

Answer 27

6-10 months

Question 28

Why do kingfishers and hummingbirds tend to nest during dry seasons when it is common for other birds to nest during the wet season?

Answer 28

Kingfisher: water levels lower Hummingbirds: when flowers begin to bloom

Question 29

Caged birds become restless just before the time they would migrate in the wild. This is called

Answer 29

migratory restlessness (Zugenruhe)

Question 30

What stimulates migratory restlessness, hyperphagia, and fat deposition?

Answer 30

Increaseing day length in the spring

Question 31

Increaseing day length in the spring stimulates

Answer 31

migratory restlessness, hyperphagia, and fat deposition?

Question 32

What is hyperphagia?

Answer 32

Overeating

Question 33

The timing of migration is based roughly on ..., but weather factors can alter the timing by fine-tuning it.

Answer 33

internal physiological clocks

Question 34

The timing for fall migration is actually set by... but the... is the proximate trigger

Answer 34

long photoperiods earlier in the year shortening of days in the fall