A high quality painting with a garland based closely on this one was sold in London (Sotheby's 6.xii.2006 #6), canvas, 163 x 137. The London painting has little narrative medallions planted in the garland with scenes from the life of the Virgin. It was sold as Jan Brueghel the Younger collaborating with Van Balen; it's not published anywhere else and could certainly be a studio production.
This is probably the painting described by Brueghel in a letter to Bianchi of September 5, 1621: "the most beautiful and rare thing I have ever done in my life. Rubens too has well demonstrated his talent in the painting in the middle, which is a most beautiful Madonna. the birds and the animals are made from life from some [owned by] the Infanta. I think that the charm [vagagessa] and [diligenza] used in this work will please your Eminence." Eventually Jan received 300 scudi for this and Rubens received a gold coin. Freedberg feels that this correspondence refers instead to the painting now in the Prado, although it does not have a provenance to the Borromeo collection and the present work definitely does. Jones agrees with Freedberg on this question.
Freedberg points out that a version of this appears in the 1617 Sense of Sight as a larger painting. This does not mean (as he speculates) that a larger version ever really existed, but it does mean that the composition must have originated by 1617 even though Jan was flogging this to Borromeo four years later. So perhaps Ertz's earlier dating is correct.
Letter to Borromeo, 12 October 1618. “come io ho fatto una ghirlands di fiori di mia mano” (Crivelli, pg. 248).
Letter to Borromeo, 29 October 1621. “il quader ellemento del ario I fatto con ordini, ma il girlando de fiori, gustose per la divina Madonne del sing. Peitro Pauol Ruberns, con le vagesse d animaletti et oitcelli et molta gallanteria” (Crivelli, pg. 274).