nakigoe de miwakeru.

Not necessarily. By itself, it often feels like a dictionary-form phrase or a headline-style sentence fragment rather than a fully explicit sentence.

What is omitted is usually something like:

• 鳥を鳴き声で見分ける。
  Distinguish birds by their calls.
• 鳴き声で見分けることができる。
  You can tell them apart by their calls.

Japanese often leaves out the object and topic when they are obvious from context. So 鳴き声で見分ける。 is perfectly natural if the listener already knows what is being distinguished.

Here, で shows the means, method, or basis used to do something.

So:

• 鳴き声で = by the cry / by the call / using the call
• 見分ける = to tell apart / to distinguish

In other words, で answers the question “By what means?”

Compare:

• 名前で見分ける = tell apart by name
• 色で見分ける = tell apart by color
• 音で見分ける = tell apart by sound

So in this sentence, で is very naturally translated as by, from, or using, depending on the English sentence.

鳴き声（なきごえ） means an animal’s cry, call, or sound/voice.

It is made of:

• 鳴く（なく） = to cry, sing, chirp, bark, meow, etc.
  Used for animal sounds.
• 声（こえ） = voice

So 鳴き声 literally means something like the voice/sound made by an animal.

It is commonly used for:

• birds
• insects
• frogs
• cats, dogs, and other animals

It is not usually used for ordinary human speaking voices. For humans, you would normally just use 声.

This is a very common learner question.

In 見分ける（みわける）, the 見 is not meant literally as to see with your eyes in every case. The whole verb 見分ける is a set expression meaning:

• to distinguish
• to tell apart
• to identify by noticing differences

So even if the clue is a sound, smell, pattern, or some other feature, Japanese can still use 見分ける in a broad sense.

For example:

• 声で人を見分ける
  tell people apart by their voices
• においで見分ける
  tell apart by smell

So here, 見分ける should be understood as a whole vocabulary item, not as a literal combination of see + divide.

Yes, sometimes.

聞き分ける（ききわける） means to distinguish by hearing or to tell sounds apart. So if you want to emphasize that the distinction is specifically made through listening, 聞き分ける can be very natural.

For example:

• 鳥の鳴き声を聞き分ける
  distinguish bird calls by ear

But 見分ける is more general: it means simply to tell apart or to identify differences, regardless of the kind of clue used.

So:

• 鳴き声で見分ける = tell apart by their calls
• 鳴き声を聞き分ける = distinguish the calls themselves by hearing

They are similar, but not always identical in focus.

The object is omitted because Japanese often leaves out information that is understood from context.

Depending on the situation, the full idea could be:

• 鳥を鳴き声で見分ける。
  tell birds apart by their calls
• 種類を鳴き声で見分ける。
  distinguish the species by their calls
• オスとメスを鳴き声で見分ける。
  tell males and females apart by their calls

So the sentence does not tell you by itself what is being distinguished. You learn that from the surrounding context.

Because the object is omitted.

If the sentence explicitly said what you were distinguishing, you would normally expect を:

• 鳥を鳴き声で見分ける。
• 種類を鳴き声で見分ける。

But when the object is obvious, Japanese often drops it:

• 鳴き声で見分ける。

This is extremely common in Japanese, especially in:

• explanations
• captions
• instructions
• field guides
• casual conversation

The dictionary form can be used in several ways, including:

• a plain non-past sentence
• a heading or label
• a general statement
• an explanatory style

So 鳴き声で見分ける。 can feel like:

• Distinguish them by their calls.
• You can tell them apart by their calls.
• How to identify them by their calls

The exact English wording depends on context. In a guidebook or educational material, dictionary form often gives a neutral, concise, factual tone.

It is helpful to read it as one unit:

• 鳴き声で = by the call / using the cry as the clue

Then the sentence becomes:

• 鳴き声で | 見分ける
• by the call | distinguish

This kind of chunking is useful because the particle で attaches to 鳴き声 and turns it into the method or basis for the action.

These words overlap, but they are not exactly the same.

• 見分ける
  to tell apart, to distinguish by noticing differences
  often practical and observational

• 区別する
  to distinguish, to differentiate, to classify separately
  often more formal or conceptual

• 分かる
  to understand, to know, to recognize
  much broader and less specific

For this sentence, 見分ける is a very natural choice because it suggests identifying one thing versus another based on a clue, here 鳴き声.

So it has the sense of:

• recognize which is which
• tell them apart
• identify correctly based on differences

Yes, very natural, especially in contexts like:

• birdwatching
• animal guides
• nature programs
• educational materials

For example, if a book is explaining how to identify birds, 鳴き声で見分ける is a very natural phrase meaning that their calls are the clue used for identification.

It is concise, and that kind of brevity is very common in Japanese explanatory writing.