Chapter 9: Annual Cycles Flashcards

1
Q

What are the three main efforts?

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

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

A

seasonal resources and opportunities

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3
Q

Birds that are permanent residents undergo three main sequential tasks:

A
  1. breeding
  2. molt
  3. survival until the next breeding season
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4
Q

Tropical birds base their annual cycles on __ and ___ seasons

A

wet and dry

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5
Q

Migratory birds face an additional annual challange of

A

needing to increase body mass for nutrient supply during the migration

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6
Q

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

A

endogenous rhythms.

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7
Q

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 _____ _____

A

circadian rhythms

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8
Q

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______ _____

A

circannual rhythms.

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9
Q

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

A
  1. the pineal gland
  2. the suprachiasmatic nucleus of the hypothalamus
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10
Q

The pineal gland is located

A

on the top of the brain

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11
Q

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

A

melatonin

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12
Q

melatonin regulates …

A

daily rhythems in accordance with the light-dark cycle

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13
Q

Removal of the pineal gland in House Sparrows causes

A

normal 24-hour cycles to disappear

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14
Q

One affect of the melatonin is

A

to regulate the circadian activity of the suprachiasmatic nuclei

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15
Q

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

A

23

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16
Q

increases in daylength cause the growth of testes in

A

Dark-eyed Juncos.

17
Q

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

A

gonadotropin-releasing hormone (GnRH),

18
Q

GnRH induces the anterior pituitary to release two hormones…

A
  1. luteinizing hormone
  2. follicle-stimulating hormone
19
Q

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

A

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

20
Q

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

A

photorefractory

21
Q

Ultimate vs proximate

A

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

22
Q

Ultimate factors in different species include…

A
  • timing of adequate food sources
  • availability of nest sites
  • locations of facorable climates
  • incidence of predation risk
23
Q

Proximate factors that induce reproduction include

A
  • temperature
  • availability of food
  • courtship behaviors
  • etc
24
Q

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

A

Pinyon Jays

25
Q

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

A

Red Crossbills

26
Q

Nesting seasons in temperate latitudes generally last for

A

3-4 months

27
Q

Nesting seasons in the tropics last longer, perhaps…

A

6-10 months

28
Q

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

A

Kingfisher: water levels lower

Hummingbirds: when flowers begin to bloom

29
Q

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

A

migratory restlessness (Zugenruhe)

30
Q

What stimulates migratory restlessness, hyperphagia, and fat deposition?

A

Increaseing day length in the spring

31
Q

Increaseing day length in the spring stimulates

A

migratory restlessness, hyperphagia, and fat deposition?

32
Q

What is hyperphagia?

A

Overeating

33
Q

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

A

internal physiological clocks

34
Q

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

A

long photoperiods earlier in the year

shortening of days in the fall