consider: "a large percentage of these birds IS/ARE

It will still be plural because you are still referring to individual bits of the totality (a tiny percentage of).

think of it like this you will say A majority of students are (because you are referring to individual parts of the totality.)

If you were to say The student majority the verb will be is (because you are referring to the totality itself).

here is my cent

a percentage of + singular Noun IS...
a percentage of + plural Noun ARE...

Its good to see concept questions rolling in.

I one of the Qs I got it wrong too.

My study details. Only in case of the following words ( SOME,ALL,ANY,MOST ) you have to look in the prepositional phase to find the number of the words.
You can remember these as SANAM words , which can be singular or prural.
Else ignore prepositional phrase.

So,
If I have
some of these birds ARE lost
I have SOME , I will look in the prepositional phase.
But,
a large percentage of these birds IS lost

I will completely ignore the prepositional phrase.

Comments/Crtitisism welocome.

I have to disagree with you huntGMAT,

just like you say a large number of students 'are' lost.

it's a similar situation here

a large percentage of birds are lost.

Thats my thought

Anymore views. Good discussion bythe way.

A number of - plural
The number of - singular

The above identifiers are different as they use "number".

For example;
A number of people are waiting for the bus.
The number of people here has increased since this morning.


In both the above sentense the "people" is plural , but it depends on the article used before number.

This is an expection to prepostion rule I mentioned above.

Indeed its getting very interesting.

Guys/Gals please put in your thaughts

Here is what I found on this:

Subjects preceded by the number of or the percentage of are singular, while subjects preceded by a number of or a percentage of are plural.

Example: The number of vacationers in Florida is increasing.
Example: A number of vacationers are young people. However, a large percentage of the vacationers are senior citizens.
Source:
https://www.uwf.edu/writelab/reviews/subjectverb.cfm

I have also found this:
Fractional expressions such as half of, a part of, a percentage of, a majority of are sometimes singular and sometimes plural, depending on the meaning. (The same is true, of course, when all, any, more, most and some act as subjects.) Sums and products of mathematical processes are expressed as singular and require singular verbs. The expression "more than one" (oddly enough) takes a singular verb: "More than one student has tried this."

Some of the voters are still angry.
A large percentage of the older population is voting against her.
Two-fifths of the troops were lost in the battle.
Two-fifths of the vineyard was destroyed by fire.
Forty percent of the students are in favor of changing the policy.
Forty percent of the student body is in favor of changing the policy.
Two and two is four.
Four times four divided by two is eight.
Source: https://grammar.ccc.commnet.edu/grammar/sv_agr.htm

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