It is still a question of debate as to whether Vivaldi's concertos scored for «flauto» were conceived for recorder or for flute. In some cases it is even thought that both instruments may have been intended.

The manuscript and printed sources of his concertos often bear headings like «Flauto», «Flauto alla quarta», «Flauto Traverso». It is generally accepted that «Flauto» and «Flauto alla quarta» would imply recorders, with the former being an alto (treble) either in F or in G, and the latter being a soprano (descant) in C. Although the category «Flauto Traverso» would seem to refer to a transverse flute, it must be taken into consideration that in some cases these compositions were actually adaptations for transverse flute of works originally intended for recorders; adaptations driven by changes in musical taste what with the increasing popularity of the transverse flute. Particularly relevant to this is Vivaldi's Op. 10 six concertos for flute where most of these concertos are elaborations of earlier compositions for recorder.

Furthermore, most of Vivaldi's flute/recorder parts have a relatively narrow range making it even more difficult to decide as to which kind of flute or recorder the work was actually conceived for.

Let us focus our attention on the question of recorders in F (the common alto/treble recorder) and recorders in G. It seems quite certain that some of Vivaldi's concertos were written for the latter instrument. In fact the G alto recorder was an instrument that was common in Italy throughout the Renaissance and the Baroque periods. It is a remarkable fact that while all Italian literary references to the use of recorders do talk about recorders in G (Ganassi, Virgiliano, Bismantova) not a single Italian Renaissance or Baroque treatise makes any reference at all to an alto in F (for more information, see this FAQ page).

There are two useful rules of thumb for deciding whether a composition is to be played on an F or on a G recorder: the range of the part and the key it was written in. For practical reasons of fingering on the specific instrument we can, with relative certainty, assign all of the works with flat keys to the common treble in F. Likewise, if the recorder part goes down to an F it is likely that it was not written for a G alto. So, after imposing these two conditions, let us look at the remaining concertos on an individual basis. I have decided, therefore to «grade» the likelihood of a work to have been conceived for a recorder in G on a scale of one to four (with four being the most likely). It must be clear that these are all conjectures.

Concerto in C major, RV 88. Source: Ms. Giordano 31, ff. 420-27.

This concerto seems to be an autograph manuscript and although the upper voice is clearly scored for «Flauto Traversier» the composition appears to have been originally conceived for a treble recorder – either in F or in G – and in a second moment assigned to the transverse flute. Some alternative passages added to the score reinforce this theory: a few «tutti» passages were transposed «alla [ottava] bassa» (an octave below), since they reach the high E, a difficult note for the flute; furthermore, some other passages were simplified, apparently for the same reason.

Pros: The upper part never descends beyond G3. Some passages have been transposed an octave down, perhaps in order to prepare for a later adaptation to a transverse flute. Those passages include some E4, which Vivaldi rarely assigned to the recorder in F.

Cons: The 2nd movement is packed with flats, even if they are never used on the lower octave where they would be really awkward for a recorder in G.

Concerto del Gardellino in D major, RV 90. Source: Ms. Giordano 31, ff. 332-39.

Despite original indication of «Flauto Traverso» this work fits the G recorder too well to have been conceived for a flute. Perhaps the rubric above refers to the later adaptation to the more modern instrument: see also RV 428 below.

Concerto in D major, RV 92. Source: Ms. Giordano 30, ff. 41-46.

In our opinion, this concerto was definitely conceived for a recorder in G.

Concerto in D major, RV 94. Source: Ms. Giordano 31, ff. 412-19.

This is the perfect concerto for a recorder in G.

Concerto La Pastorella in D major, RV 95. Source: Ms. Giordano 31, ff. 235-42.

This concerto would be perfect for a recorder in G if it were not for a unique passage that descends to F#3 (Mov. I, bar 67); on the other hand, it seems unreasonably difficult for a treble recorder in F. Another hypothesis is this concerto was conceived for a transverse flute.

Concerto III. Il Gardellino in D major, Op. X, No. 3, RV 428. Source: VI Concerti a Flauto Traverso […] Opera Decima (Amsterdam [1729]). See RV 90 above.

This would seem to be an adaptation for a flute of a concerto (RV 90) originally conceived for a recorder in G. The work remains, in any case, perfectly suitable for a recorder in G.

Concerto IV in G major, Op. X, No. 4, RV 435. Source: VI Concerti a Flauto Traverso […] Opera Decima (Amsterdam [1729]).

We do not have the original manuscript of this concerto, but what we said about the above concerto RV 428 is here even more pertinent. Actually, in this case, it is likely that the concerto was originally conceived for a recorder in G and then simply relabeled – rather than adapted – for flute. In any case, since the solo part has no special difficulties, it can easily be performed either on a recorder in F or on a recorder in G