By the early 1970s, songbirds known as Kirtland’s warblers were under threat of extinction. Scientists began to investigate what was responsible for their decline. Kirtland’s warblers winter in the Bahamas and then fly north to the state of Michigan in the United States, where they breed in an exacting set of conditions in jack-pine woodlands.Although jack-pine trees grow widely throughout the northern coniferous forests, Kirtland’s warblers nest only in jack-pine woods on one soil type, called Grayling sands, which occurs in central Michigan at the very southern end of the jack-pine range. These warblers build their nests on the ground and, apparently because the nests must remain dry, prefer to build them on dead tree branches still attached to a tree at ground level, and only on coarse, sandy soil that drains away rainwater rapidly. Young jack pines provide the dead branches at the ground surface, and Kirtland’s warblers are known to nest only in jack-pine woodlands that are between 6 and 21 years old, ages when the trees, 5 to 20 feet tall, retain dead branches at ground level.Males are territorial, and each defends an area as large as 80 acres in a uniform jack-pine stand.
These requirements leave the warbler with few nesting areas, all the fewer because jack pine is a “fire species”-it persists only where there are periodic forest fires. Jack-pine cones open and expose their seeds only after they are heated by fire, and the trees are intolerant of shade, able to grow only when their leaves can reach into full sunlight.Even if seeds were to germinate under mature trees, the seedlings could not grow in the shade and would die. Jack pine produces an abundance of dead branches that promote fires, which is interpreted by some as an evolutionary adaptation to promote those conditions most conducive to the survival of the species.
Kirtland’s warblers thus require change at rather short intervals-forest fires approximately every 20 to 30 years, which was about the frequency of fires in jack-pine woods prior to European settlement But where was the warbler during the past 10,000 years. when the continental ice sheets from Earth’s last great ice age were retreating?With such specific nesting habits, the warbler must have followed the jack pine as it migrated northward, and must have nested in trees on outwash plains, where roaring rivers created by melting ice deposited coarse sands. At the time of the first European settlement of North America, jack pine may have covered a large area in what is now Michigan. Even as recently as the 1950s, jack pine was estimated to cover nearly 500,000 acres in the state. At best, the warbler could have reached Michigan when the jack pine returned there no sooner than 6,000 to 8,000 years ago, but the males seem unwilling to set up new territories that are far away from old ones-they nest only a short distance from where they were born-so the species may have migrated northward even more slowly than the forests.
European settlers first reached the warbler’s habitat in 1854, when Tawas City, in present-day Michigan, was founded on Lake Huron, after which lumbering of red and white pine in the area began in earnest. Jack pine, a small, poorly formed tree, was then considered a worthless species by commercial loggers and was left alone, but many big fires followed the logging operations when large amounts of slash (branches, twigs, and other economically uninteresting parts of the trees) were left in the woods. Elsewhere, fires were set in jack-pine areas to clear them and promote the growth of blueberries.Some experts think the population of Kirtland’s warblers peaked in the ate nineteenth century as a result of these fires. After 1927. fire suppression became the practice, and control of forest fires reduced the area burned and the size of fires. Where possible, people were encouraged to replace jack pine with economically more useful species. All of this shrank the areas in which the warblers preferred to nest.
The importance of forest fires for warblers was not always understood. In 1926, one expert wrote that “fire might be the worst enemy of the bird.” Only with the introduction of controlled burning after vigorous advocacy by conservationists and ornithologists was habitat for the warbler maintained.
1
By the early 1970s, songbirds known as Kirtland’s warblers were under threat of extinction. Scientists began to investigate what was responsible for their decline. Kirtland’s warblers winter in the Bahamas and then fly north to the state of Michigan in the United States, where they breed in an exacting set of conditions in jack-pine woodlands.Although jack-pine trees grow widely throughout the northern coniferous forests, Kirtland’s warblers nest only in jack-pine woods on one soil type, called Grayling sands, which occurs in central Michigan at the very southern end of the jack-pine range. These warblers build their nests on the ground and, apparently because the nests must remain dry, prefer to build them on dead tree branches still attached to a tree at ground level, and only on coarse, sandy soil that drains away rainwater rapidly. Young jack pines provide the dead branches at the ground surface, and Kirtland’s warblers are known to nest only in jack-pine woodlands that are between 6 and 21 years old, ages when the trees, 5 to 20 feet tall, retain dead branches at ground level.Males are territorial, and each defends an area as large as 80 acres in a uniform jack-pine stand.
According to paragraph 1, which of the following is NOT mentioned as necessary in order for Kirtland’s warblers to build their nests?
ASoil that does not allow water to remain
BNearby supplies of clean rainwater
CDead tree branches still attached to the tree
DTrees that have grown to a height of 5 to 20 feet
2
By the early 1970s, songbirds known as Kirtland’s warblers were under threat of extinction. Scientists began to investigate what was responsible for their decline. Kirtland’s warblers winter in the Bahamas and then fly north to the state of Michigan in the United States, where they breed in an exacting set of conditions in jack-pine woodlands.Although jack-pine trees grow widely throughout the northern coniferous forests, Kirtland’s warblers nest only in jack-pine woods on one soil type, called Grayling sands, which occurs in central Michigan at the very southern end of the jack-pine range. These warblers build their nests on the ground and, apparently because the nests must remain dry, prefer to build them on dead tree branches still attached to a tree at ground level, and only on coarse, sandy soil that drains away rainwater rapidly. Young jack pines provide the dead branches at the ground surface, and Kirtland’s warblers are known to nest only in jack-pine woodlands that are between 6 and 21 years old, ages when the trees, 5 to 20 feet tall, retain dead branches at ground level.Males are territorial, and each defends an area as large as 80 acres in a uniform jack-pine stand.
Which of the following can be inferred from paragraph 1 about why Kirtland’s warblers do not nest in woodlands older than 21 years?
ATheir offspring cannot survive in nests that are more than 20 feet off the ground.
BThey cannot easily defend woodland areas that have become heavily populated with trees.
CThe ground-level branches that they need are no longer available in older woodlands.
DThey nest on a type of sand found mostly in relatively young forests.
3
These requirements leave the warbler with few nesting areas, all the fewer because jack pine is a “fire species”-it persists only where there are periodic forest fires. Jack-pine cones open and expose their seeds only after they are heated by fire, and the trees are intolerant of shade, able to grow only when their leaves can reach into full sunlight.Even if seeds were to germinate under mature trees, the seedlings could not grow in the shade and would die. Jack pine produces an abundance of dead branches that promote fires, which is interpreted by some as an evolutionary adaptation to promote those conditions most conducive to the survival of the species.
、
According to paragraph 2, what is one reason why fire is important for the survival of jack pines?
AFire makes it possible for jack-pine cones to release their seeds.
BFire produces many dead branches from which warblers build nests
CFire prevents cone seeds from maturing into seedlings too soon.
DFire helps scatter jack-pine cones and seeds to new areas
4
Kirtland’s warblers thus require change at rather short intervals-forest fires approximately every 20 to 30 years, which was about the frequency of fires in jack-pine woods prior to European settlement But where was the warbler during the past 10,000 years. when the continental ice sheets from Earth’s last great ice age were retreating?With such specific nesting habits, the warbler must have followed the jack pine as it migrated northward, and must have nested in trees on outwash plains, where roaring rivers created by melting ice deposited coarse sands. At the time of the first European settlement of North America, jack pine may have covered a large area in what is now Michigan. Even as recently as the 1950s, jack pine was estimated to cover nearly 500,000 acres in the state. At best, the warbler could have reached Michigan when the jack pine returned there no sooner than 6,000 to 8,000 years ago, but the males seem unwilling to set up new territories that are far away from old ones-they nest only a short distance from where they were born-so the species may have migrated northward even more slowly than the forests.
Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.
AMales in Michigan are unwilling to leave their territories and build new nests to the north because they have now been in the area for 6.000 to 8.000 years.
BAlthough the jack pine returned to Michigan 6,000 to 8,000 years ago, there were very few suitable areas at that time where males could build their nests
CWarblers probably migrated northward more slowly than the jack-pine forests did because warblers prefer to nest near where they were born.
DThe return of the jack pine to Michigan between 6,000 and 8,000 years ago allowed warblers to once again build their nests only a short distance from where they were born.
5
Kirtland’s warblers thus require change at rather short intervals-forest fires approximately every 20 to 30 years, which was about the frequency of fires in jack-pine woods prior to European settlement But where was the warbler during the past 10,000 years. when the continental ice sheets from Earth’s last great ice age were retreating?With such specific nesting habits, the warbler must have followed the jack pine as it migrated northward, and must have nested in trees on outwash plains, where roaring rivers created by melting ice deposited coarse sands. At the time of the first European settlement of North America, jack pine may have covered a large area in what is now Michigan. Even as recently as the 1950s, jack pine was estimated to cover nearly 500,000 acres in the state. At best, the warbler could have reached Michigan when the jack pine returned there no sooner than 6,000 to 8,000 years ago, but the males seem unwilling to set up new territories that are far away from old ones-they nest only a short distance from where they were born-so the species may have migrated northward even more slowly than the forests.
What can be inferred from paragraph 3 about Kirtland’s warbler populations during the last great ice age?
AKirtland’s warbler populations survived because there were shorter intervals between fires
BKirtland’s warblers lived much further south than they do today.
CKirtland’s warbler populations had to adapt to nesting in different types of trees
DMost Kirtland’s warblers lived in what is now modern-day Michigan.
6
European settlers first reached the warbler’s habitat in 1854, when Tawas City, in present-day Michigan, was founded on Lake Huron, after which lumbering of red and white pine in the area began in earnest. Jack pine, a small, poorly formed tree, was then considered a worthless species by commercial loggers and was left alone, but many big fires followed the logging operations when large amounts of slash (branches, twigs, and other economically uninteresting parts of the trees) were left in the woods. Elsewhere, fires were set in jack-pine areas to clear them and promote the growth of blueberries.Some experts think the population of Kirtland’s warblers peaked in the ate nineteenth century as a result of these fires. After 1927. fire suppression became the practice, and control of forest fires reduced the area burned and the size of fires. Where possible, people were encouraged to replace jack pine with economically more useful species. All of this shrank the areas in which the warblers preferred to nest.
The word “promote” in the passage is closest in meaning to
ARestore
BControl
Cprepare for
Dhelp advance
7
European settlers first reached the warbler’s habitat in 1854, when Tawas City, in present-day Michigan, was founded on Lake Huron, after which lumbering of red and white pine in the area began in earnest. Jack pine, a small, poorly formed tree, was then considered a worthless species by commercial loggers and was left alone, but many big fires followed the logging operations when large amounts of slash (branches, twigs, and other economically uninteresting parts of the trees) were left in the woods. Elsewhere, fires were set in jack-pine areas to clear them and promote the growth of blueberries.Some experts think the population of Kirtland’s warblers peaked in the ate nineteenth century as a result of these fires. After 1927. fire suppression became the practice, and control of forest fires reduced the area burned and the size of fires. Where possible, people were encouraged to replace jack pine with economically more useful species. All of this shrank the areas in which the warblers preferred to nest.
According to paragraph 4, some experts believe that the big fires created by logging operations had which of the following effects on Kirtland’s warbler populations?
AWarbler populations declined due to the destruction of the jack-pine habitat
BWarbler populations remained mostly stable as they adapted to the absence of jack pine in the habitat.
CWarbler populations migrated northward to areas with fewer fires caused by settlers.
DThe habitat changes caused by fires allowed warbler populations to become larger than ever.
8
The importance of forest fires for warblers was not always understood. In 1926, one expert wrote that “fire might be the worst enemy of the bird.” Only with the introduction of controlled burning after vigorous advocacy by conservationists and ornithologists was habitat for the warbler maintained.
Why does the author provide the quotation of an expert who wrote in 1926 that “fire might be the worst enemy of the bird”?
ATo support the claim that the importance of forest fires for warblers was not always understood
BTo explain how new research led to the introduction of controlled burning
CTo explain the important role experts played as early as 1926 in maintaining the warbler population
DTo demonstrate that controlled burning was not very successful when it was first introduced
9
By the early 1970s, songbirds known as Kirtland’s warblers were under threat of extinction. ■ Scientists began to investigate what was responsible for their decline. ■ Kirtland’s warblers winter in the Bahamas and then fly north to the state of Michigan in the United States, where they breed in an exacting set of conditions in jack-pine woodlands. ■ Although jack-pine trees grow widely throughout the northern coniferous forests, Kirtland’s warblers nest only in jack-pine woods on one soil type, called Grayling sands, which occurs in central Michigan at the very southern end of the jack-pine range. ■ These warblers build their nests on the ground and, apparently because the nests must remain dry, prefer to build them on dead tree branches still attached to a tree at ground level, and only on coarse, sandy soil that drains away rainwater rapidly. Young jack pines provide the dead branches at the ground surface, and Kirtland’s warblers are known to nest only in jack-pine woodlands that are between 6 and 21 years old, ages when the trees, 5 to 20 feet tall, retain dead branches at ground level.Males are territorial, and each defends an area as large as 80 acres in a uniform jack-pine stand.
Look at the four squaresthat indicate where the following sentence could be added to the passage
Indeed, an official count revealed only 201 nesting males.
Where would the sentence best fit？Click on a square sentence to the passage.
10
Scientists have studied the long history of the relationship between Kirtland’s warblers and jack-pine trees.
ASome scientists believed that the near extinction of Kirtland’s warblers was because jack-pine woodlands in central Michigan were still young and not mature enough for the birds to nest there.
BOver most of the past 10,000 years.Kirtland’s warblers adapted to a warmer climate by slowly migrating to new areas as the geographic range of the jack pine shifted.
CJack pines require fire to survive, and the introduction of fire suppression in the 1920s led to fewer jack pines and thus fewer warblers
DWarblers have a limited habitat because they will only build nests on the branches of jack pines that grow on a certain type of soil in the state of Michigan
EJack-pine populations began to decline when Europeans first arrived in Michigan and began to cut down trees for lumber to build their houses.
FThe widespread practice of controlled burning has now made it possible for Kirtland’s warblers to build nests in new species of trees.rather than nesting only in jack pines
