Which extinct pigeon species would you bring back if you could?

You do know that both species *were* true pigeons?

 

If we were talking about a realistic cloning project, you would be correct in almost all of these points - I think you are probably incorrect about there being sufficient natural habitat remaining for the species, sad to say, given the strong impact their cloning and reintroduction would have on the agricultural land of North America.

However, I would argue that the loose wording of this question implies we need not be limited to constraints of how realistic the revival of the species is and hence there is scope for a little more imagination than to immediately jump to "which species has the most remaining material" - which is why I went for Choiseul Pigeon. Put quite simply, we know a lot about the Passenger Pigeon but there is a lot to learn about the Choiseul, including certain details of its life appearance and more-or-less everything about its behaviour and habits in life. Moreover, it was a more attractive species and represented a more evolutionarily-significant-unit (being distant kin to both Goura and Trugon, and possibly basal to both) than the Passenger Pigeon, which was sister to the Patagoenas doves and looked much like one.

As for the other species listed in this poll:

Liverpool Pigeon (Caloenas maculata) - this one shares a few of the plus-points of the Choiseul, although it is nowhere near as distinct being congeneric with the Nicobar Pigeon. If we were to magically bring this one back with will alone, however, we wouldn't know where we had brought it back to

Rodrigues Blue Pigeon (Alectroenas rodericana) - as written, this one never actually existed @Sarus Crane has conflated two extinct species known only from isolated bones, the Rodrigues Turtle-dove (Nesoenas rodericanus) and the Rodrigues Blue-pigeon (Alectroenas payandeei). The former was probably conspecific with the extant N. picturatus, incidentally. Neither is quite as alluring a prospect for revival as some of the other species in the list, however, given they are congeneric with extant species and probably differed little from them.

Mauritius Blue Pigeon (Alectroenas nitidissima) - now, this one is a little more tempting given the fact I have seen one of the three extant specimens but it has the same drawbacks of distinctiveness from an extant species.

Reunion Pigeon (Columba duboisi) - this one was actually another Nesoenas, and may have been conspecific with the extant N. meyeri.

Bonin Wood Pigeon (Columba versicolor) - again, distinctiveness it was very similar to the extant C. vitiensis and C. janthina.

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On another note, although @Sarus Crane has already explained why he omitted the Dodo and Solitaire from this poll (under the misapprehension they were not true pigeons) I am curious why he omitted the following three taxa, which are known from significantly better material than some of the species he counted:

Ryukyu Woodpigeon (Columba jouyi) - last recorded in 1936, last reported in 1960s.
Red-moustached Fruit-dove (Ptilinopus mercierii) - last recorded in 1922.
Thick-billed Ground-dove (Alopecoenas salamonis) - last recorded in 1927.

 

Fair enough for the record, they are deeply nested within a clade containing the following genera:

Trugon (Thick-billed Ground Pigeon)
Microgoura (Choiseul Pigeon)
Otidiphaps (Pheasant Pigeons)
Goura (Crowned Pigeons)
Didunculus (Tooth-billed Pigeon)
Caloenas (Nicobar and Liverpool Pigeons)
Raphus (Dodo)
Pezophaps (Solitaire)

 

As noted above, it now appears to have been the sister taxon to the Patagoenas doves particularly the leucocephala clade, I believe.

 

Didn't you just say you thought they looked quite different to Zenaida?

The fact that Passenger Pigeon fared very well in captivity is one of the big missed opportunities in extinction, sad to say - as is the similar situation with Carolina Parakeet.

 

Not particularly so

 

Although strangely enough this was not required in captivity, so the precise social mechanics are still (and forever will be) unclear.