Question

A region of the canary forebrain shrinks during the nonbreeding season and enlarges when breeding season begins. This change is probably associated with the annual

(A) addition of new syllables to a canary’s song repertoire.

(B) crystallization of subsong into adult songs.

(C) sensitive period in which canary parents imprint on new offspring.

(D) elimination of the memorized template for songs sung the previous year.

Short answer

1. The statement “addition of new syllables to a canary’s song repertoire” istrue.

2. The statement “crystallization of subsong into adult songs” isfalse.

3. The statement “sensitive period in which canary parents imprint on new offspring” is false.

4. The statement “elimination of the memorized template for songs sung the previous year” is false.

Step-by-step solution

Canary

A canary is a passerine bird or perching bird which is known for its singing capacity. It belongs to the family finch and genusSerinus.

These birds are extensively used in research due to their capacity to encode and produce a song, and also to study neurogenesis in adult brains. Canaries are domestic in European countries.

Explanation of option ‘(A)’

Studies say that there is a positive correlation between age of the canary and the addition of new syllables or volume of the song. As the age increases, the length of the song also increases.

Therefore, the addition of new syllables is associated with age.

Thus, the given statement is true.

Explanation of option ‘(B)’

Crystallization of subsong does not occur. In the sensitive period, young birds learn the songs from the adults and memorize them during the adult period.

Therefore, even though canary birds begin with subsongs, subsong crystallization does not occur in the breeding season. The new syllables are added to the song with each passing year.

Thus, the given statement is false.

Explanation of option ‘(C)’

Sensitive period and imprinting on new offspring by a parent are absent in canary birds. These birds do not have a sensitive period for the song. The annual addition of new syllables each year leads to a flexible song.

Therefore, a sensitive period is not found in canary birds.

Thus, the given statement is false.

Explanation of option ‘(D)’

In canary birds, the annual addition of syllables to the song is seen in adults. Song template is not eliminated from their brain. The memory of the song converts into a motor form during their breeding season.

Therefore, canary birds show the annual addition of syllables.

Thus, the given statement is false.