The December 12th USPS Postal Bulletin indicates that this issue will be released in April at an unspecified city.

From my article from the October press preview:

flowers figure prominently in the designs for the ten Songbirds stamps. Each bird is shown perching on a fence post or branch embellished with vines, pinecones, leaves, or flowers. The ten species are:

• the western meadowlark
• the mountain bluebird
• the western tanager
• the painted bunting
• the Baltimore oriole
• the evening grosbeak
• the scarlet tanager
• the rose-breasted grosbeak
• the American goldfinch
• the white-throated sparrow

From the USPS on January 24th:

The U.S. Postal Service celebrates ten melodic voices with the Songbirds stamps: the western meadowlark (Sturnella neglecta), the mountain bluebird (Sialia currucoides), the western tanager (Piranga ludoviciana), the painted bunting (Passerina ciris), the Baltimore oriole (Icterus galbula), the evening grosbeak (Coccothraustes vespertinus), the scarlet tanager (Piranga olivacea), the rose-breasted grosbeak (Pheucticus ludovicianus), the American goldfinch (Spinus tristis), and the white-throated sparrow (Zonotrichia albicollis).

Each colorful bird is shown perching on a fence post or branch embellished with vines, pinecones, leaves, or flowers. The artwork appears against a plain, white background.

Why do songbirds make such a glorious racket every morning? In a word, love. Males sing to attract females, and to warn rivals to keep out of their territory. Between 4,000 and 4,500 different types of songbirds can be found around the planet, accounting for nearly half of all bird species. Songbirds are identified by their highly developed vocal organs, although some, like the crow, have harsh voices, and others sing rarely, or not at all. All songbirds are classified as perching birds. With three toes that point forward and one that points backward, they can grip branches, grasses, or telephone wires with ease.

Illustrator Robert Giusti painted the portraits, based on photographs. Art director Derry Noyes designed the stamps.

Songbirds will be issued as Forever® stamps in booklets of 20. Forever stamps are always equal in value to the current First-Class Mail® one-ounce rate.

From the March 20th Postal Bulletin:
On April 5, 2014, in Dallas Texas, the U.S. Postal Service® will issue Songbirds First-Class Mail® stamps (Forever® priced at 49 cents), in ten designs, in a pressure-sensitive adhesive (PSA) booklet of 20 stamps (Item 689300).

The stamps will go on sale nationwide April 5, 2014.

The U.S. Postal Service® celebrates ten melodic voices with the Songbirds stamp issuance, which features the western meadowlark (Sturnella neglecta), the mountain bluebird (Sialia currucoides), the western tanager (Piranga ludoviciana), the painted bunting (Passerina ciris), the Baltimore oriole (Icterus galbula), the evening grosbeak (Coccothraustes vespertinus), the scarlet tanager (Piranga olivacea), the rose-breasted grosbeak (Pheucticus ludovicianus), the American goldfinch (Spinus tristis), and the white-throated sparrow (Zonotrichia albicollis). Illustrator Robert Giusti painted the portraits based on photographs. Art director Derry Noyes designed the stamps.

How to Order the First-Day-of-Issue Postmark:
Customers have 60 days to obtain the first-day-of-issue postmark by mail. They may purchase new stamps at their local Post Office, at The Postal Store® website at www.usps.com/shop, or by calling 800-STAMP-24. They should affix the stamps to envelopes of their choice, address the envelopes (to themselves or others), and place them in a larger envelope addressed to:

Songbirds Stamp
Postmaster
401 Tom Landry Frwy, Room 645

Dallas, TX 75260-9998

After applying the first-day-of-issue postmark, the Postal Service will return the envelopes through the mail. There is no charge for the postmark up to a quantity of 50. For more than 50, customers have to pay five cents each. All orders must be postmarked by June 4, 2014.

There are six philatelic products for this stamped issue:

• 689306, Press Sheet with Die Cut, $78.40 (print quantity of 2,500).
• 689308, Press sheet w/o Die Cut, $78.40 (print quantity of 2,500).
• 689310, Keepsake (booklet & random DCP), $11.95.
• 689316, First-Day Cover (set of 10), $9.30.
• 689321, Digital Color Postmarks (set of 10), $16.40.
• 689331, Stamped Deck Card, $0.95.

Technical Specifications:

Issue: Songbirds Stamp
Item Number: 689300
Denomination & Type of Issue: First-Class Mail Forever
Format: Double-sided Booklet of 20 (10 designs)
Series: N/A
Issue Date & City: April 5, 2014, Dallas, TX 75260
Art Director: Derry Noyes
Designer: Derry Noyes
Typographer: Derry Noyes
Artist: Robert Giusti
Modeler: Joseph Sheeran
Manufacturing Process: Offset
Engraver: N/A
Printer: Ashton Potter
Printed at: Williamsville, NY
Press Type: Muller Martini A76
Stamps per Booklet: 20
Print Quantity: 400 million
Paper Type: Nonphospheored Type III, Overall Tagged
Adhesive Type: Pressure-sensitive
Processed at: Ashton Potter Williamsville, NY
Stamp Orientation: Vertical
Image Area (w x h): 0.84 x 1.42 in./21.34 x 36.07 mm
Stamp Size (w x h): 0.98 x 1.56 in./24.90 x 39.62 mm
Full Booklet Size (w x h): 6.18 x 3.12 in./156.97 x 79.25 mm
Press Sheet Size (w x h)
25.10 x 6.24 in./ 637.41 x 158.50 mm
Colors: Black, Cyan, Magenta, Yellow
Plate Size: 640 stamps per revolution
Plate Numbers: “P” followed by four (4) single digits
Marginal Markings: © 2014 • Songbirds, Twenty First-Class Forever Stamps • Barcode • Plate numbers in peel strip area • USPS in peel strip area

  We don’t have a good image yet of the Digital Color Postmark for this issue, but here’s a small version from the Postal Bulletin.

There will be a First Day of Sale ceremony at 12 noon on April 5th at the Philadelphia National Stamp Exposition in Oaks, Pa. Two different pictorial postmarks will be offered: From Oaks and from neighboring Audubon, Pa. These pictorials, designed by American First Day Cover Society immediate past president Chris Lazaroff, who will also lead the ceremony, are shown here.

Here is the design of the FDOS program:

Here’s the Digital Color Postmark: