"They are not your birds."

Translation: Vaši ptáci to nejsou.

[Needabeer]

Vaši práci nejsou?

[JoeFoxon1]

Missing the "to" would just translate to "your birds are not" which wouldn't make sense by itself

[Needabeer]

*ptáci

[BoneheadBass]

This looks like the negative version of the familiar "to je/to jsou" construction, so I don't think you can leave out the "to." "Oni nejsou..." might be an option, but a Czech expert would be better to weigh in on that.

[tatka_]

"to" is required in this sentence.

[VladaFu]

Actually, "Oni nejsou vaši ptáci." is fine, if somewhat unusual. But it would be saying that about some people.

[BossKaiden]

Isn't there a rule about "to" always being second in a sentence?

[TQrhe14U]

The second position is not necessarily the second word in the sentence. It's the second 'idea'. Here, "your birds" is the first idea.

[VladaFu]

In second position, but "vaši ptáci" is in the first position, you can't split it - if you meant that. It is really better to ask directly.

[BossKaiden]

Oh, okay. I didn't really mean that, I was just wondering why it wasn't in second position.

[VladaFu]

Well, it is.

[Vlad_Lesnievski]

Hold on. I could say "TO nejsou vaši/tvoji/tví ptáci", couln't I? So why are we even talking about the second place rule here?

[VladaFu]

To is in the second position here. It is not required to be there. "To vaši ptáci nejsou." is completely fine.