Seasonal migration in birds occurs twice yearly and seems to comprise two distinct stages: a preparatory stage followed by the actual initiation of migration. ▉Two crucial physiological events occur during the preparatory stage: fat deposition and migratory restlessness. ▉Some species fly nonstop (when possible) to their destination.and individuals of these species may lose up to40 percent of their body weight during this arduous process; clearly, fat deposition is critical to successful completion of the journey. ▉For any bird to be able to deposit so much fat, hormonal changes must occur.▉
1.The word “initiation” in the passage is closest in meaning to
A.movement
B.start
C.effort
D.journey
2.The word “arduous” in the passage is closest in meaning to
A.continuous
B.vital
C.difficult
D.Unusual
As preparation for migration continues, birds increase their activity levels. This has been monitored with electronic perches, which reveal a dramatic difference after the onset of migratory restlessness. Restless birds not only hop more on their perches, but do this all day and all night, in seeming disregard for their usual biological rhythm.
With the accumulation of sufficient fat reserves, good weather is the immediate cue for initiating migration.Indeed, migratory restlessness does not increase smoothly over time, but reflects weather conditions;restless birds are more restless in good (migration-friendly) weather.
3.According to paragraphs 2 and 3, all of the following are true of migratory restlessness EXCEPT:
A.It occurs throughout the day and night.
B.It increases during weather conditions favorable to migration.
C.It causes birds to increase their time spent hopping!
D.It helps birds maintain their usual biological rhythm.
While the image of bird migration is shaped by seeing waterfowl-ducks, geese, and cranes, in particular-migrate during the daytime, most avian (bird)migration is nocturnal. This fact is especially intriguing because when not migrating, most birds are diurnal(active during the day). Why shift activity time during migration? Birds face two critical physiological problems in their migration: energy usage and loss of water. Flying at night reduces their thermal load (the effects of heat on their bodies) and may provide some protection from predators at take-off and landing areas.
4.Why does the author note that “the image of bird migration is shaped by seeing waterfowl-ducks,geese, and cranes, in particular-migrate during the daytime”
A.To support the claim that most birds are active mainly during the day
B.To give examples of species that shift their activity time during migration
C.To suggest that waterfowl do not face the same problems as other migrating birds
D.To contrast a common belief about bird migration with an actual fact
5.According to paragraph 4, birds migrate at night for all of the following reasons EXCEPT to
A.use less energy
B.reduce water loss
C.avoid competition for water in landing areas
D.better protect themselves from predators
Although many of these night-flying birds stop on a daily basis during the daylight hours, there is another category of pausing during migration called a stopover that differs from these daily stops. For the many migrant birds that lack enough fat to fuel their entire migration, stopover locations become a necessary component of successful migration Moreover, habitats that provide food, water.and shelter–essential for surviving migration-may be infrequent on the migratory route. Time spent at a stopover can vary greatly among birds within a species;those with lower fat reserves spend a longer time feeding, sometimes as long as several weeks, before moving on. In addition, depending on the migratory route, some species routinely employ stopovers;waterfowl migrating on the central flyway in North America pass over vast expanses of dry upland and must take advantage of the relatively few low areas with water on their route, using areas such as the Platte River valley in western Nebraska for stopovers. Stopovers also frequently occur prior to crossing important barriers,such as large bodies of water or mountain ranges.
6.According to paragraph 5, the amount of time that birds spend at stopovers is determined by
A.whether they are a night-flying species
B.how many low areas with water exist on their route
C.how much fat they have stored
D.how close they are to mountain ranges that have to be crossed
Typically, information about migratory direction is innate and genetically coded. This is known from displacement experiments, in which naive birds-young birds that have never migrated-are transported a substantial distance, usually hundreds of kilometers, from their birthplace. When seasonal cues trigger migration, these birds follow the same flight direction as they would have followed had they not been displaced; the displacement does not change their flight direction. Cross-fostering of birds between populations with different migration routes yields the same result; the cross-fostered birds fly in the direction inherited from their biological parents,not in the direction flown by their foster parents. The innate directional information is coordinated with a compass: the Sun for diurnal migrants and a celestial compass for nocturnal ones. The Moon is used as a reference point less commonly than the Sun or the stars The solar or celestial compass can be complemented by information from a geomagnetic compass.
7.According to paragraph 6, displacement experiments with young birds produced which of the following results?
A.Birds that were transported to a new location did not change the direction of their migration.
B.Birds that were raised by foster parents instead of their biological parents showed reluctance to migrate.
C.Birds that were transported long distances flew back to their birthplace before beginning migration.
D.Birds that were raised by foster parents lost the ability to coordinate directional information with a compass.
A series of classic experiments used a planetarium (a model representing the solar system) to show that birds indeed, can orient to the stars in the sky when they fly at night; they are genetically predisposed to learn the night sky that they see as nestlings and use that learned map to determine the direction they should fly at migration time. For instance, in the northern hemisphere, the North Star is fixed; in experimental conditions, if the planetarium constellations rotated around a different star, the young birds used that star as an indication of north when migration time arrived.Nestlings that were not allowed to see the night sky did not learn the stellar map and were unable to identify north.
8.What can be inferred about Nestlings that were not allowed to see the night sky”?
A.They could not navigate well enough to migrate effectively.
B.They used stars other than the North Star to guide their migration.
C.Their offspring were also unable to identify north.
D.They were able to rely on instinct to learn the night sky.
9.Look at the four squares [▊] that indicate where the following sentence could be added to the passage.Where would the sentence best fit?
Day length is the primary cue for the first stage to begin.
10.Directions: An introductory sentence for a brief summary of the passage is provided below. Complete the summary by selecting the THREE answer choices that express the most important ideas in the passage. Some sentences do not belong in the summary because they express ideas that are not presented in the passage or are minor ideas in the passage. This question is worth 2 points.
Seasonal migration in birds occurs twice yearly and involves both preparation and active migration stages.
A.Because migratory restlessness decreases fat reserves, birds initiate migration as soon as fat deposition is complete.
B.Most birds migrate at night even if they are diurnal and make stopovers of varying lengths along the way to find food water and.shelter.
C.Birds prepare for migration by storing additional fat and increasing their activity levels.
D.Birds that cross significant barriers, such as large bodies of water or mountain ranges, spend a significantly longer time feeding during migration than do birds that can make daily stops.
E.Cross-fostered birds can learn to migrate in the direction of their foster parents as long as they are allowed to see the night sky.
F.Experiments have shown that birds are genetically programmed to learn celestial reference points in order to determine their flight direction during migration.
