do bird eggs grow after being laid

As we’re still in nesting season in Southern California, it’s the perfect time to discuss the wonders of the bird egg cycle. And with Mother’s Day just around the corner, it’s a fitting way to pay tribute to all the mothers out there, both bird and human. From egg laying to incubation to hatching, the bird egg cycle is a fascinating display of both nature’s tenderness and tenacity. Here’s the egg cycle process explained, from start to finish:

Bird Egg Cycle Phase #2: Incubating

do bird eggs grow after being laid

For a certain amount of time, birds must keep their eggs warm in order to promote the healthy development of the hatchling. They achieve this by sitting on their eggs and using the heat from their bodies to maintain a comfortable temperature (between 85 and 104° F). The length of this time, known as the incubation period, differs among species. Generally speaking, though, the longer the incubation period, the larger the bird. For example, the incubation period for a songbird is 12–15 days, but it’s double that or longer for most duck species. For approximately 18 days, robins incubate their eggs for 13 days, and bald eagles for about 40 days. The Megapode, which is primarily found in the Western Pacific Islands, has the longest incubation period on record at ninety days, while the Laysan Albatross has one of the longest at sixty-six days!

Certain bird species begin incubating as soon as the clutch’s first egg is laid, while others hold off until the second or third egg And before starting the incubation process, songbirds wait until they have laid all of their eggs. The incubation process will involve one or both of the bird parents. It’s typical for parents to take “shifts” when caring for their children. For instance, the mother will typically take over during the day after the father of a Northern Flicker completes the night shift. Similar shared incubation behaviors are shared by woodpeckers, starlings, pigeons, and doves, but in other species (such as hummingbirds and some raptors), the mother serves as the only incubator. However, in more recent instances, the father frequently assists by providing food for the mother and guarding the nest from intruders.

Bird Egg Cycle Phase #1: Laying

do bird eggs grow after being laid

The majority of bird species lay an egg within a day or two of fertilization. Nevertheless, some bird species may require more time than that to lay eggs following copulation. For example, it could take five to ten days for Bald Eagles, like our own Jackie and Shadow. After mating, lovebirds can lay their eggs five to twelve days later. Furthermore, some species’ egg-laying periods can be weeks or even months.

Usually, birds will lay multiple eggs; these eggs are referred to as a clutch when they are laid during a single nesting season. Bird species differ in their clutch sizes, as do individuals within the same species. A clutch can occasionally consist of just two or three eggs, or it can contain up to 20 eggs or more (like those of the Gray Partridge). Certain birds, such as thrushes, robins, and bluebirds, nest twice, three, four, or even more times a year, while other birds only nest and lay eggs once.

do bird eggs grow after being laid

do bird eggs grow after being laid

do bird eggs grow after being laid

Left to right: crow eggs, goldfinch eggs, and robin eggs.

Like the features of various bird species, there can be wide variations in the color, shape, and size of their eggs. Here’s a list of bird species and their egg characteristics:

Bird species Egg size Egg color Egg markings
Bald Eagle L: 2.3-3.3 in. W: 1.9-2.5 in. Dull white/tan Light brown blotches
Blue Jay L: 1.0-1.3 in. W: 0.7-0.9 in. Blue/pink Brown spots
Blue Tit L: 0.6 in. W: 0.5 in. Cream Brown spots
Crow L: 1.4-1.9 in. W: 1.0-1.2 in. Bluish/olive green Brown and gray blotches
Goldfinch L: 0.6-0.7 in. W: 0.5 in. White/cream Reddish-brown spots
House Finch L: 0.6-0.8 in. W: 0.5-0.6 in. Blue/white Black or lavender spots
House Sparrow L: 0.8-0.9 in. W: 0.6 in. White Black or gray spots
Jackdaw L: 1.4 in. W: 1.0 in. White/pale blue Gray or brown spots
Mourning Dove L: 1.0-1.2 in. W: 0.8-0.9 in. White Smooth
Robin L: 1.1-1.2 in. W: 0.8 in. Blue Light brown spots

The development of birds eggs is a fascinating process. Mike Toms explains what happens and how eggs form.


Can eggs grow in size after being laid?

It is a common misconception that there are eggs that grow after being laid. While this is not the case, there are some species of eggs that have unique properties that may surprise you.

Do eggs get bigger before hatching?

As incubation proceeds, an egg will normally become lighter, and the air space within the egg will normally become larger, owing to evaporation from the egg.

How long does it take for an egg to grow in a bird?

As a general rule, the bigger the bird, the longer the incubation period. Some species of white-eye and cowbird hatch only 11 or 12 days after laying, while a wandering albatross egg is brooded for about 11 weeks, with the parents working in shifts to keep it warm.

Do male birds fertilize eggs after they are laid?

In birds, first the female lays her eggs, then the males fertilize them. In birds, 90% to 95% of species are monogamous, meaning the male and female remain together for breeding for a few years or until one mate dies.