Use calcium suet for eggshell formation

Calcium is an essential mineral for eggshell formation as well as bones formation and growth. Without sufficient calcium, eggshells can become thin and the eggs will break. Or young birds may develop deformities in their bones.

Female birds change their diets during nesting season to obtain calcium-rich nutrients. Seed and insects alone are insufficient. They provide only 10 percent of the calcium needed for egg laying.

Garden songbirds do not "store" extra calcium needed for egg laying. That would make the females too heavy and less maneuverable. So where do they get it? By gobbling up calcium within hours of egg laying.

One British study found that a female bird deposits 60 percent of the calcium needed for the eggshell within eight hours prior to laying. At this critical time, females must forage to collect huge quantities of calcium. They depend on calcium-rich nutrients naturally found in the soil, usually calcium carbonate. Fortunately that is found in many limestone-rich deposits in the Lehigh Valley area. But when acid rain saturates the soil, the amount of calcium may become insufficient.

Millipedes, worms and woodlice are part of birds' diets. The insects themselves don't provide all the necessary calcium needed for egg laying, but the soil in the insects' gut does. Some birds even consume shells of spent eggs from their own broods.

You can assist female birds in two ways.

First, you can add egg shells to your bird seed. Be sure to sterilize the shells. Rinse the eggshells first to clean off the raw egg. Place the washed shells on a cookie sheet in an oven heated to 250 degrees for about a half hour. This will eliminate the salmonella in the egg shells. Then crush the shells using a rolling pin and add the material to the bird seed.

Another way of providing calcium to female birds' diet is by offering them calcium-rich suet dough. "Calcium Delight" is available at The Bird House. The females can feast on the suet, taking up as much calcium as they need. Other ingredients include roasted peanuts, corn, rendered beef suet, oats and soy oil—which together provide plenty of fat and protein needed as energy right after egg-laying.

By offering calcium-rich suet dough, the fledglings and young birds can develop stronger bones to help them for long-distance migration in the fall.

Calcium Delight is a no-melt suet dough that comes in standard-sized suet feeders.

Calcium is crucial for egg production

Eggs of a female Northern Cardinal

Calcium is an essential element in the diet of birds, especially for producing eggs, or more specifically, for shell production. Without enough calcium, eggshells can become defective and the hatchlings never hatch, or young birds may develop deformities of their beaks.

Female birds must change their diets during the nesting season to obtain calcium-rich nutrients. Seeds and insects alone are not enough, as they provide only 10 percent of the calcium needed for egg laying.

Backyard songbirds do not "store" extra calcium in their skeletons. It probably would make them too heavy to fly well or escape predation. Egg production is in stages. Fat and protein are deposited in the egg within the female's body over a four-day period. Eight hours prior to laying the eggs, 60 percent of the calcium is deposited in the shell. So where do female birds get the calcium in that narrow window of time?

Millipedes, worms and woodlice are ground dwellers and are part of bird diets. The insects don't provide all the necessary calcium but the soil in the insects' gut does. Snail shells also provide plenty of calcium. So does sand, dirt and ash. Some birds get calcium from bones of carrion or shed deer antlers. They will even consume shells of spent eggs from their own broods.

Historically, calcium carbonate is harvested from the soil's surface by birds. However, air pollution and the resulting acid rain can dissolve any calcium carbonate on the soil surface.

Calcium suet benefits egg production and young birds' bones

We can help by using egg shells from your kitchen as a supplement for birds. Wash out the empty shell and bake at 250 degrees for a half hour. This will prevent salmonella contamination of the bird feed. Crush the shells between your hands into small pieces. Mix these pieces into the bird seed. This provides a needed nutrient. It also may attract a greater variety of birds to your yard.

Also, you can provide "Calcium Delight," which is available at The Bird House. The product is a no-melt suet dough that comes in standard-sized suet cakes. In addition to calcium, other ingredients include roasted peanuts, corn, rendered beef suet, oats and soy oil—which together provide plenty of fat and protein. The ingredients are especially helpful for fledglings and young birds. They need the calcium to strengthen their bones. The fat and protein help them develop so they are ready for long-distance migration in the fall.

Take these steps and the end result will be more successful broods and greater joy as we watch the antics of young birds.

The egg

Robin's eggs

Which came first: the chicken or the egg? The first egg-laying reptiles, distant relatives of birds, showed up about 280 million years ago. The tough leathery eggshell was great—it kept water in and everything else out. The first real birds came along about 150 million years ago. So the answer is, the egg came first.

Eggs are strong. They have to be. They have to support the weight of an adult bird sitting on them. An ostrich egg, for instance, must support the weight of the male ostrich, who can weigh 350 pounds! 

The important thing about egg size is how big is the egg relative to the size of the mother. A mother ostrich weighs 50 times more than the egg. A mother hummingbird weighs 8 times more than her egg. Relatively speaking, hummingbirds have bigger eggs than ostriches! In these terms, the biggest egg of all belongs to the New Zealand Kiwi. The kiwi weighs only 4 times more than her egg. In people terms, that would be like a 60-pound child laying an egg as big as a watermelon!

Hummingbird's eggs

The last step in egg production is the addition of the color. Robins lay eggs with a distinctive blue color; the flightless emu lays dull green eggs that turn a shiny black in a few days. The Northern Flicker lays eggs covered with mysterious-looking brown scribble marks. Owls, woodpeckers and hummingbirds lay white eggs; blackbirds and gulls, speckled eggs. Blue and green colors come from bile pigments. Reds, blacks and browns come from the breakdown of red-blood cells. Speckled eggs are for camouflage. Owls lay white eggs that show up well in the dark; this may prevent the mother from trampling them accidentally. No one really knows why robins' eggs are blue.

Egg notes:

• Six-year-old Thomas Edison tried sitting on the eggs of the family goose. He thought he could get them to hatch faster. It didn't work.
• Here is an old superstition: "A person who finds an egg with two yolks should make a wish while eating it."
• Ancient Greeks used ash of eggshells mixed with wine as toothpaste.