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.
Water sets, 7 piece

Amethyst/purple, 250, 450 (both 2012), 425 (2013),
   400 (2014), 300, 325, 400, 450 (all 2015), 550 (2016)

Green, 425, 450, 475, 525, 575, 600 (all 2013),
   375, 400, 500, 575 (all 2014), 325, 500 (both 2015),
   225, 275, 300, 325, 425 (all 2016)

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

Marigold, 300 (2011), 400 (2012), 325, 400 (both 2013),
   275, 300, 325 (all 2014), 250, 275 (both 2016)

Water pitchers

Amethyst/purple, 550 (2008), 225, 250 (both 2010),
   250 (2012), 175, 300 (both 2014), 200 (2016)

Amethyst, electric, 700 (2008)

Green, 550, 850 (both 2010), 475 (2011), 750 (2012),
   450 (2013), 500 (2015), 225, 425 (2016)

Green, emerald, 1,600, 7,000 (2008),
   1,400, 1,600 (both 2010), 2,300 (2011), 1,000 (2012)

Marigold, 210 (2011), 130 (2012), 200 (2014)

Olive green known

Tumblers

Amber known

Amethyst/purple, 20, 25, 40 (all 2014),
   20, 25, 110 (all 2015)

Green, 20, 30, 70 (all 2014),
   30, 35, 40 (all 2015), 10, 15 (both 2016)

Green, emerald, 125 (2002), 325 (2008),
   200 (2012), 25, 35 (both 2016)

Lime green, 175 (2001)

Marigold, 10 (2013), 40 (2014), 10 (2015),
   25 (2016)

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

Amber, 300 (1995), 350 (2003)

Amethyst/purple, 15, 20, 25, 35, 45, 60, 70, 250 (all 2015), 10, 15, 20, 45, 85 (both 2016)

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)

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

Amethyst, swirl effect, 275 (1995)

Aqua, 10 (2015)

Aqua opal, 375, 425, 600 (all 2012),
   475, 600 (both 2013), 325, 475, 600 (all 2014),
   300, 385, 550 (all 2016)

Blue, 23, 30, 35, 50, 55, 75, 85 (all 2015),
   20, 35, 45, 75 (2016)

Blue, electric, 155 (2010), 120, 150 (both 2011)

Blue opal, 900 (2012)

Custard, nutmeg, 100, 110 (both 2007)

Green, 25, 35, 120 (all 2015), 25, 30, 35 (all 2015),
   25, 40, 45 (all 2016)

Horehound, 350 (2003), 60, 115, 155 (all 2014),
   170 (2015), 425 (2016)

Ice blue, 325, 425 (both 2013), 130, 170, 250 (all 2014),
   160 (2015), 140, 175, 325 (all 2016)

Lavender, 20, 35, 40, 85 (all 2014),
   120, 130 (both 2015), 45 (2016)

Marigold, 10, 15, 25, 45 (all 2015),
   5, 10, 13, 15 (all 2016)

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

Sapphire blue, 1,500 (1999), 1,800 (2001), 950 (2010),
   550 (2015), 500 (2016)

Smoke, rare

White, 170 (2012), 190, 225 (both 2014),
   120, 275 (both 2015), 150, 400 (both 2016)
Mugs, stippled

Amethyst/purple, 800, 925 (both 2011)

Blue, 175 (2009), 175 (2010), 150 (2011),
   115, 155 (both 2014), 105 (2016)

Blue, electric, 850 (2003), 425 (2010),
   475 (2012), 325 (2013)

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

Custard, nutmeg, 65 (2016)

Green, 300 (2011), 95, 175, 180 (all 2014),
   150, 275 (both 2015), 150 (2016)

Marigold, 25, 30, 35, 75 (all 2014),
   20, 25 (both 2016)

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

Green, 4 pieces, 85 (2013)

Green, 7 pieces, 400 (2001), 350 (2010),
   225 (2012)

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

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

Purple, 6 pieces, 210 (2003)

Large berry bowls

Amethyst/purple, 275 (2000), 180 (2008),
   115 (2012), 85 (2014)

Blue, one known, 1,500 (2008)

Green, 200 (2007)

Marigold, 55 (2005), 270 (2008)

Small berry bowl or sauce

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

Blue, 80 (2001), 275 (2008)

Green, 25 (2004), 25 (2005), 30 (2007), 20 (2009)

Green, emerald, 105 (2006)

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

Table sets, 4 pieces

Amethyst/purple, 1,650 (2007), 550 (2009),
   135, 425, 900 (2010), 275 (2014), 180 (2015),
   190, 400 (both 2016)

Green, 525 (2001)

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

Butter dishes, covered

Amethyst/purple, 155 (2012),
   105, 155 (both 2014)

Green, 425 (2000)

Marigold, 125 (2010), 75 (2012), 190 (2013),
   55 (2016)

Butter, creamer, spooner

Marigold, 200 (2016)

Creamers

Amethyst/purple, 55 (2010), 35 (2012),
   25, 45 (both 2015), 20 (2016)

Green, 75 (2006), 65, 135 (both 2007),
   100 (2008), 70, 75 (both 2010), 35 (2014)

Marigold, 45, 100 (both 2010),
   45, 65 (both 2015), 10 (2016)

Spooners

Amethyst/purple, 85 (2009), 90 (2010)

Green, 300 (2002), 85 (2014)

Marigold, 125 (2000), 250 (2002), 55 (2015)

Sugar bowls, covered

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

Marigold, 190 (1999)

Whimsey creamer, from mug

Marigold, 775 (2008)

Updated 2/3/2017