EggsSmall Cavity Egg ID Matrix

Small Cavity Egg ID Matrix

The easiest way to find out who is nesting in your nestbox is to ID an adult bird incubating, but incubation doesn’t start the last or nest to last egg is laid (depending on the species.) The location and nest construction are also great tips. For detailed descriptions of nest construction and egg identification, see Nest and Egg ID (also with links to photos of nests, eggs and young) and the nest contents ID matrix. U= uncommon, but it happens (e.g., about 3-5% of bluebirds eggs are white. Y=Yes. MB=may be. A “wreath” is a concentration of pigment on one end of the egg. More ID links below. For non-cavity nesting bird eggs, or eggs found outside the U.S.

CLUE->
SPECIES
White
Blue
Spotted
Wreath
Shape
Gloss
Relative Size
Confused
With
U Powder NO Oval Y Larger Finch, Starling
Bluebird, Mountain U Pale Oval Y Larger Finch, Starling
Bluebird,
Western
U Pale Oval Y Larger Finch, Starling
Cream Lt. brown or red. Dots or blotches MB Rounded Little or no Tiny Titmouse
Chickadee, Carolina White Reddish-brown dots or blotches MB Rounded Little or no Tiny Titmouse
Chickadee, Mountain White Some no, some covered with dots MB Rounded Little or no Tiny Titmouse
Cowbird or Grayish Heavy, even brown/red dots. One replacement egg MB Rounded Larger House Sparrow
Blueish green Sparing black dots Oval Slight Medium Bluebird
Or creamy or pinkish Heavily scrawled/streaked with brown/purple/gray Oval Larger Fewer markings than Great
Flycatcher, Great-crested Or creamy or pinkish Densely streaked/scrawed with pruple, gray, red brown/olive Often Oval Moderate Larger More markings than Ash, larger than House Sp
Creamy or greenish Irregular, fine brown speckles MB Oval Slight Medium Cowbird, Great-crested, Nuthatch
CLUE->
SPECIES
White
Blue
Spotted
Wreath
Shape
Gloss
Relative Size
Confuse
With
Y Fine reddish-brown dots/blotches Short Oval Almost no Small Titmouse, House Sp, Chickadee
Nuthatch, Pygmy Y Uneven fine sparing speckles reddish MB Short Oval Little or no Small Titmouse, House Sp, Chickadee
Nuthatch, Red-Breast Or creamy or pinkish Heavily cinnamon/lavender/gray speckles MB Short Oval Very little Smaller than White Titmouse, House Sp, Chickadee
Nuthatch, White-brea Or creamy or pinkish Heavily cinnamon/lavender/gray speckles MB Short Oval Very little Larger than Red Titmouse, House Sp, Chickadee
Bold, liberal dull red brown or purple gray all over
Purple
Martin
Pure Slightly Larger than Tree Swallow
Pale blueish/greenish Pointy No Large Bluebird
Pure, sometimes pinkish Pointy No or slight Medium
White Some with faint sparing tiny red/brown speckles Oval Little or slight Tiny Chickadee, Nuthatch
Y Irregular brown/purple/gray dots Often Rounded oval Little or no Tiniest Not glossy like House Wren
White or rosy Heavy reddish/brown flecks often Little or no Tiny Larger than other wrens, not glossy like House
White or pinkish Numerous pinkish/brown specks Often Very Tiniest Bewick
CLUE->
SPECIES
White
Blue
Spotted
Wreath
Shape
Gloss
Relative Size
Confuse
With

Also see Nest ID Matrix (contents) and Egg ID Matrix (color, spots, etc.) descriptions of nests and eggs | PHOTO ALBUM with pictures of cavity nesting birds, nests and eggs.  TABLE showing relative sizes of eggs, and egg photos side by side. To see other cavity nester bios/photos:


I would rather live in a world where my life is surrounded by mystery
than live in a world so small that my mind could comprehend it.
Harry Emerson Fosdick


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