Singing Birds, Northwood
Singing Birds differs from Imperial's Robin in that the birds here are framed by panels. Northwood's own Springtime pattern was made in some of the same shapes as Singing Birds and has some of the same features--including the panels. If it has a butterfly and basketweave around the bottom, it's Springtime. Note that reproduced Singing Birds tumblers have been found in amethyst, aqua opal, cobalt and ice green.

Article on Singing Birds pattern

Hartung Book One: Singing Birds

Water sets, 7 piece

Amethyst/purple, 300, 450 (both 2019), 150, 180, 200 (all 2020)

Green, 120, 250, 275, 300 (all 2020), 200, 260, 600 (all 2021)

Green, emerald, 1,700 (1994), 4,100 (2009), 850 (2016)

Green, 5 piece, 225 (2020)

Marigold, 100, 300 (both 2017), 170 (2019), 250 (2021)

Marigold, 5-6 pieces, 130 (2019), 255 (2021)

Water pitchers

Amethyst/purple, 225, 325 (both 2017), 475 (2018),
   130, 145, 650 (all 2019), 200 (2021)

Amethyst, electric, 700 (2008)

Amethyst'purple, with 1 tumbler, 180 (2019), 95 (2020)

Amethyst, with 2 tumblers, 400 (2018)

Green, 550 (2020), 320, 1,700 (2021)

Green, wirh 1 tumbler, 275 (2017), 275 (2019), 130 (2020)

Green, emerald, 2,300 (2011), 1,000 (2012)

Green, emerald, with 1 tumbler, 850 (2020)

Marigold, 95 (2017), 170 (2018), 75 (2019), 70 (2020)

Marigold, wirh 1 tumbler, 180 (2018), 100 (2019)

Olive green known

Tumblers

Amber known

Amethyst/purple, 35, 40 (both 2019), 10 (2021)

Green, 10, 20 (both 2020), 10, 15, 20 (all 2021)

Green, emerald, 25, 35 (both 2016), 40 (2019)

Lime green, 175 (2001)

Marigold, 40, 50 (both 2019), 25 (2020), 20 (2021)

Olive green, 43 (2002), 25 (2013)

Smoke, scarce

Teal, 35, 90 (both 2003), 25 (2010)
Mugs are the most often seen shape in this pattern. There are two versions, one without stippling (left) and one with stippling (right). Similar to Robin mugs, but this one has the birds displayed on panels.
Mugs, unstippled or not specified

Amber, 300 (1995), 350 (2003), 140 (2018), 25 (2020)

Amethyst/purple, 15, 20, 105 (all 2019),
   15, 20, 25, 45, 65, 95 (all 2020), 15, 50, 75 (all 2021)

Amethyst/purple, paper label "The Crown Mft, Co. N.Y.,"
   145 (2006)

Amethyst/purple, "Compliments of Hotel Vendome,"
   175 (2009)

Amethyst/purple, "Compliments of Amazon Hotel
   & Cafe," 75 (2009), 225 (2010), 20 (2012),
   55, 135 (both 2016), 135 (2018), 20, 65 (both 2020)

Amethyst/purple, "Wilkes Barre PA," 55, 145 (both 2016)

Amethyst, swirl effect, 275 (1995)

Aqua, 10 (2015)

Aqua opal, 325, 378, 425 (all 2019),
   300, 325, 500, 525 (all 2020), 320, 425 (both 2021)

Blue, 10, 15, 20, 25, 30, 35, 40, 85 (all 2020), 35 (2021)

Blue opal, 900 (2012)

Custard, nutmeg, 100, 110 (both 2007), 15 (2021)

Green, 15, 20, 30, 45, 65 (all 2020), 15 (2021)

Horehound, 150, 475 (both 2017), 75, 225 (both 2020)

Ice blue, 70, 80, 110, 125, 160, 175, 250 (all 2020),
   300 (2021)

Ice green, 225 (2019)

Lavender, 25, 35 (both 2019), 20, 30 (both 2020), 25 (2021)

Marigold, 10, 15, 20 (all 2020), 5, 10, 15, 20, 25 (all 2021)

Renninger blue, 950 (1999), 35 (2015)

Sapphire blue, 550 (2015), 500 (2016), 155 (2017)

Smoke, rare

White, 275 (2017), 130 (2019), 90, 95, 160, 175 (all 2020)
Mugs, stippled

Amethyst/purple, 800, 925 (both 2011)

Aqua opal, 325 (2019)

Blue, 115, 155 (both 2014), 105 (2016),
   80, 190 (both 2019)

Blue, electric, 425 (2010), 475 (2012),
   325 (2013)

Blue opal, 1,450 (2002), 500 (2004)

Custard, nutmeg, 65 (2016), 25 (2020)

Green, 150 (2016), 425 (2020), 250 (2021)

Marigold, 30 (2018), 10, 15 (both 2020)

Renninger blue, 950 (1999), 900 (2014)

Sapphire blue, 550 (2002)
Bowls are rather difficult to find in this pattern and the large ones as shown here are particularly scarce.
Berry sets

Amethyst, 7 pieces, 90 (2020)

Green, 4 pieces, 85 (2013)

Green, 5 pieces, 100 (2019)

Green, 7 pieces, 225 (2012), 190 (2020)

Marigold, 5 pieces, 270 (2010), 70 (2011)

Marigold, large bowl & two small, 85 (2016)

Purple, 6 pieces, 210 (2003)

Large berry bowls

Amethyst/purple, 115 (2012), 85 (2014), 85 (2021)

Amethyst/purple, one large, three small, 80 (2021)

Blue, one known, 1,500 (2008)

Green, 200 (2007), 200 (2020), 75 (2021)

Marigold, 55 (2005), 270 (2008)

Small berry bowl or sauce

Amethyst/purple, 25 (2008), 25 (2011), 25 (2012)

Blue, 80 (2001), 275 (2008)

Green, 30 (2007), 20 (2009), 25 (2017)

Green, emerald, 105 (2006)

Marigold, 33 (2011), 55 (2012), 13 (2015)

Table sets, 4 pieces

Amethyst/purple, 190, 400 (both 2016),
   650 (2019), 90 (2020)

Green, 525 (2001)

Marigold, 1,100 (2007), 350 (2010)

Butter dishes, covered

Amethyst/purple, 375 (2017), 300 (2019),
   170 (2020)

Green, 425 (2000)

Marigold, 190 (2013), 55 (2016), 75 (2019)

Butter, creamer, spooner

Marigold, 200 (2016)

Creamers

Amethyst/purple, 80 (2020), 25, 50 (both 2021)

Green, 100 (2008), 70, 75 (both 2010), 35 (2014)

Marigold, 10 (2016), 45 (2018), 15 (2019)

Spooners

Amethyst/purple, 30, 40 (2020),
   20, 40 (both 2021)

Green, 300 (2002), 85 (2014)

Marigold, 55 (2015), 60 (both 2020), 60 (2021)

Sugar bowls, covered

Amethyst/purple, 80, 85 (both 2010),
   85 (2014), 170 (2020)

Marigold, 190 (1999), 55 (2018)

Whimsey creamer, from mug

Marigold, 775 (2008)

Updated 9/28/2021