Weird Eggs Laid by Backyard Chickens

Most chicken eggs are oval in shape, with one end rounded or blunt and the other end somewhat pointed. An egg is shaped in the part of the hen’s oviduct called the isthmus, where shell membranes wrap the yolk and white. Each hen lays eggs of a characteristic shape. Therefore you can usually identify which hen laid a particular egg by its shape. Occasionally, however, backyard chickens lay weird eggs. Here are eight typical examples and their most common causes.

Misshaped Egg

A misshaped egg is one that differs from the normal shape for the hen’s breed. It may be smaller or larger than usual. It may be round or elongated, or have an entirely non-standard shape. Common causes for misshaped eggs:

• pullet lays before fully mature
• hens are overcrowded or otherwise stressed
• possible disease, such as infectious bronchitis or laryngotracheitis

Freckled Shells

Some breeds or strains typically lay eggs with dark speckles on the shells. A few of my Marans lay dark brown eggs with darker brown freckles. My friend George delighted in telling people he had a hen that laid pink eggs with purple polka dots. When a speckled egg shows up in the nest unexpectedly, here some possible causes:

• hen was disturbed during shell calcification
• excess calcium, possibly resulting from seasonal slow-down in laying
• shell gland defect

Chalky Speckles

Chalky speckles are white irregular spots of calcium on an egg’s surface. They can appear on eggs with white shells, but are more easily visible on eggs with colored shells. Sometimes tiny chalky speckles deposit on top of an egg’s cuticle, or bloom, which is normally the final step in an egg’s development. Common causes for chalky speckles are the same as for freckled shells (above).

White Band

A white band, or circle, on an egg’s shell consists of an extra layer of calcium. It occurs when an egg is still in the shell gland, or uterus, when a second egg enters the gland. Calcification gets interrupting, resulting in the appearance of a white band on the first egg. Causes of this interesting-looking mark include:

• hen under stress
• a change in coop lighting
• possible disease

Pimpled Shell

A rough, or pimpled, shell is caused by tiny lumps of calcium on the shell’s surface. Pimpling generally occurs when an egg spends too much time in the shell gland. In some breeds or strains pimpling is hereditary. Other causes include:

• quite young or quite old hen
• insufficient drinking water
• excess calcium, possibly resulting from seasonal slow-down in laying

Wrinkled Shell

Sometimes a shell appears creased and wrinkled. Deep wrinkles that occur during plumping of the shell membranes in the isthmus may be hereditary. Common causes for shell surface wrinkling include:

• rough handling of hen
• hens are overcrowded or otherwise stressed
• possible disease

Slab Sided

A slab-sided egg is one that’s flat on one side. Usually it also has a thin and wrinkled shell. An egg gets flattened when a second yolk releases soon after the first, so they move through the oviduct close together. If the second (membrane covered) egg bumps up against the first egg already in the shell gland, it will become slab sided. The first egg will have a white banded shell, so the two issues are related and have a common cause.

Checked Shell

Sometimes an egg shell cracks in the shell gland, and then additional calcium covers the cracks, resulting in a checked egg, or body check. If the calcium outer layer is thin, the repair is readily visible. If the layer covering the crack is thick, the only way to detect a checked egg is by candling it. An egg that bumps into an egg already in the shell gland can cause checking. Other causes include:

• quite old hen
• stress or excitement, especially in late afternoon or overnight
• overcrowding

Weird Chicken Eggs

Occasional variations in egg shape and size, sometimes seasonal, are normal. Even though they may look weird, they’re perfectly fine for eating.

If you hatch eggs from your own backyard chickens, select eggs only of normal shape and size for your breed. A hen that persists in laying weird eggs will pass the trait on to her offspring.

The occasional misshaped egg, however, is no cause for concern, and may even be amusing. One of my hens once laid an egg monogrammed with the letter “D” for Damerow: