How Long Does It Take For A Bird To Grow Up? [Answered!]


You must be curious: “how long does it take for a bird to grow up?” Baby birds seem to be everywhere and it can be interesting to know more about their growth and how long they take to mature! A bird lover myself, I went to look into some data from NestWatch.org to answer this question myself. Here’s what I found:

Birds take an average of about 36 days, ranging from 28 – 40 days, to grow up fully into an adult. This maturation duration varies among species: Wilson’s warblers can take just 22 days to grow up, whereas Jabirus can take up to 113 days to do the same. Large birds take a longer time to grow up than smaller ones.

Now that you know some basic statistics of how long it takes for birds to grow up, let me show you more details regarding the variation of the maturation duration among birds and their likely causes. Read on to find out more:

How Long Does It Take For A Bird To Grow Up?

Since I was a young boy, I’ve also wondered how long does it exactly take for a bird to grow up, just out of curiosity. So I searched up the web and found a really neat citizen science database on NestWatch.org (thank you participants!) and retrieved data containing information on bird nesting. I got really intrigued by what I found!

Birds take an average of about 36 days, ranging from 28 – 40 days, to grow up fully into an adult. This maturation duration varies among species: Wilson’s warblers can take just 22 days to grow up, whereas Jabirus can take up to 113 days to do the same. Large birds take a longer time to grow up than smaller ones.

I measured the time it took from the time an egg was first laid to the time to fledge as the bird maturation duration, and plotting some charts. Here’s a handy INTERACTIVE tool for you to look at the results:

Bird Maturation Duration Tool

A Closer Look At Bird Maturation Durations

Distribution and statistics of bird maturation durations among different species

Now let’s look closer at the distribution of the bird maturation durations. Each color in the above graph represents a different bird species. The numbers above are represented in days!

As shown in the graph above, most birds recorded in Northern America and Canada have a maturation duration ranging from 28 days to about 40 days. (Lower hinge to upper hinge).

Top 10 birds with the longest maturation durations

Although that is the range for most birds, there are still plenty of birds falling outside of the range, especially those that have a longer maturation duration. Examples of such birds are the Jabiru, the Barn Owl, and the Ferruginous Hawk, which took 139, 97.9, and 83 days to mature respectively. Remember, you can refer to the tool above and check out the different maturation duration of the birds!

Maturation Durations of Common Backyard Birds

I’ve also compiled the data of maturation durations of birds that you’ll commonly see in your backyard. This is for those of you who have seen eggs in a nest around your neighborhood, and wondering how long it will take to grow up. Here’s a compiled chart for easy reference:

Common Backyard Bird SpeciesAverage Maturation Duration (days)Image of Bird
Mourning Dove28.2Mourning Dove, Bird, Dove, Wildlife, Nature, Avian
Downy Woodpecker31.8Downy Woodpecker, Woodpecker, Bird, Beak, Feathers
American Robin22.6American Robin, Bird, Branch, Perched, Robin, Animal
American Crow67.3American Crow, Log, Perched, Wood, Bird, Crow, Animal
European Starling33.8Starling, European Starling, Bird, Sparrows, Plumage
House Sparrow30.4Sparrows, House Sparrow, Sperling, Bird, Animal, Water
House Finch30.2House Finch, Fountain, Bird, Perched, Perched Bird
American Goldfinch28.7American Goldfinch, Finch, Bird, Songbird
Northern Cardinal22.9Red Bird, Northern Cardinal, Bird, Perched
Anna’s Hummingbird36.4Anna'S Hummingbird, Flight, Hummingbird, Beak, Wings

If you managed to identify the eggs and nest growing in your backyard, get ready to see your bird grow and take its first flight! If you don’t know how to identify nests, check out an article I wrote here. If you are struggling with identifying eggs, head over to NestWatch.org for some ID help!

Different Weights of Birds Have Different Maturation Durations

As I looked more into the data, I realized that generally, birds that had a bigger and heavier size took a longer time to grow up and mature than smaller and lighter birds! This could be the case for some of the birds, and hopefully, scientists can look more into this in the future.

Here’s a chart for you to compare maturation durations and their respective bird mass:

Bird SpeciesAverage Maturation Duration (Days)Weight At AdulthoodWeight CategoryImage of Bird
Jabiru1399.5 – 19.8lbsHeavyBird, Beak, Orange, Plumage, White, Feathers, Zoo
Great Blue Heron103.14.5 – 8lbsHeavyGreat Blue Heron, Nature, Bird, Wildlife, Pond, Fish
Bald Eagle111.86 – 15lbsHeavyAdler, Raptor, Bird Of Prey, Bird, Feather, Close Up
Mountain Chickadee38.40.4ozMediumChickadee, Mountain Chickadee, Bird, Bird Feeder
Tree Swallow37.70.8ozMediumTree Swallow, Swallow, Tree, Nest, Nature, Bird, Green
European Starling33.82.0 – 3.5ozMediumEuropean Starling, Bird, Starling, Nature, Wildlife
Wilson’s Warbler22.00.2 – 0.3ozLight
White-crowned Sparrow21.70.9 – 1.0ozLightWhite-Crowned, Sparrow, Songbird, Backyard, Bird
White-eyed Vireo27.5 0.3 – 0.5LightThis image has an empty alt attribute; its file name is White-eyed-Vireo-1024x683.png

Interestingly, as derived from the data provided, we can see that the heavier birds (bigger size) tend to have longer maturation durations. This makes quite a bit of sense, as it would require more time for heavier birds to amass the size before they are ready to be called a ‘full-fledged’ adult bird.

As smaller birds such as songbirds are much lighter, they require less time to mature and develop faster.

How Long Does It Take For A Bird Egg To Hatch?

Bird eggs take an average of 18 days to hatch and can range from 10 – 30 days, depending on the bird species. Dark-eyed Junco eggs take 14 days, but Wood Duck eggs can take up to 40 days to hatch. Factors influencing hatch duration are egg weight, egg neglect, first lay date, and climate change.

If you’d like to know more about bird egg hatch durations, check out another article I wrote here where I dove into data to derive some answers. (includes an interactive chart!)

How Long Do Baby Birds Take To Fly?

Birds take an average of about 19 days, ranging from 12 to 21 days, to learn to fly after hatching. This fledging period varies among species: American Robins fledge in just 9 days, but Bald Eagles can take up to 72 days. Generally, larger birds take longer to learn to fly than smaller birds.

Read a full article I wrote on this topic here! I included an interactive tool for you to search a species to find its fledging duration. Check it out!

Final Thoughts

In this article we’ve learned how long it takes for birds to mature; from when their egg is first laid, to the point it fledges. Also, we’ve learned how different birds of different sizes and weights have different times they take to mature! What a fascinating insight, don’t you think? I hope you’ve taken something from reading this article and thank you for reading. Happy birding!

Justin

Justin is a hobbyist birder that hopes to share his birding knowledge with the world. His favorite bird is the Large-tailed Nightjar and he really loves potato chips!

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