Bluebird Babies: Nestlings (Day 8)

Raising a brood is a 24/7 operation full of surprises, and it’s been such fun watching them grow over the last week. If you’d like to watch along with us, we livestream every day on our AzarÉl Greetings’ YouTube channel. From endless rounds of feeding to the ultimate game of avian waste management, watching them develop has brought up some pretty funny questions about what is really going on behind the scenes during those first action-packed weeks in the nest!

1. Bluebirds grow at an ‘incredible rate’. What’s an ‘incredible rate’?
   
   Their lightning-fast growth rate completely dwarfs human growth scales. A newborn bluebird starts at just 1 gram on day 1; that’s about the weight of a standard 1.3-inch paperclip. It measures roughly 1.4 inches long. By day 8, it shoots up to 22.7 grams and reaches about 2.5 inches.
   
   To put this phenomenal growth into human baby perspective. If a 7.5-pound human baby grew at that exact same rate, it would balloon to about 170 pounds by day 8. A 20-inch human baby would reach about 36 inches in length. Now that’s an incredible growth rate!

2. Do baby bluebirds grow at a steady rate?
   
   Like human babies, bluebirds have growth spurts, especially from day 1 to day 5. Their weight jumps rapidly from about .1 oz to .5 oz their weight jumps rapidly from about .1 oz to .5 oz. This is like a car cruising down an open highway at a brisk 65 mph.
   
   From days 6 through 12, the growth rate shifts down to a steady 49 mph. Their weight increases from about .6 oz to.9 oz. In length they grow from 2.3 inches to 3.4 inches in length.
   
   By next Wednesday, the growth rate will level out.   They will be in the final phase before fledging (days 13-18). It will feel like pulling over to idling at 0 mph in a rest area. By day 17 they still weigh about .9 ounces. They’ll grow about another inch to 4.3 inches. At this point their energy will shift entirely into feather development and pre-fledging wing stretching.

3. When will they grow feathers?
   They actually already have feathers! Between birth and day one, there’s soft down on their head, spine, and wings. They actually began growing pin feathers around day two. A pin feather is a new feather growing in. It’s covered by a waxy, protective white or clear coating called a keratin sheath. That makes it look like a tiny, stiff spike or quill sticking out of the skin. These sheaths are especially clear on the wings right now (day 8).
   
   If you are looking for fluffy feathers, you will see more of them between days 9 and 11 (August 5-7, 2026) when the sheath opens up.

4. What are the pink spots on the baby bluebird? Is it injured?
   
   Don’t worry, the babies are perfectly healthy! Those pink spots are simply natural bald patches. The belly, sides, and areas under the wings are the last to develop feathers. These patches will gradually shrink and eventually disappear just before the fledglings leave the nest around days 17 through 21 (August 14-18, 2026).

5. Why isn’t mama laying on them anymore?
   
   These little ones are growing their own down and pin feathers. This helps them regulate body temperature on their own. Plus, they are simply getting too big and crowded under there! Mom still checks in on them constantly and hovers nearby with food.  She still broods them each night, though, tucking them under her wings after dark to keep them cozy and warm.

6. What does ‘diaper duty’ look like for the parents?
   
   If you remember from last week, diaper duty started off pretty manageable. The babies went “bottoms up” and produced a fecal sac the size of a small grain of rice. The parents promptly ate it. (Yuck!)
   
   Fast forward to today (day 8) of non-stop food consumption, and those babies are running high-output metabolic engines. Their waste scales right up with them. It’s transformed into a large, floppy, gelatinous capsule roughly the size of a jellybean or a small grape. If they were human babies, it’s kind of like going from newborn diapers to a Size 8 in one week! Parents grab those hefty sacs with their beaks and fly far away from the box to drop them. That keeps the nest sparkling clean and hides the scent from predators!

7. When do nestlings first open their eyes?
   
   It’s day 8, and I spotted some open eyes today! At this point, when they choose to open their eyes, they look squinty, like little slits. Since they’ve spent their first week cozy and tucked away in total darkness, their early vision is mostly just about noticing changes in light and shadow, or sensing when mom and dad pop in with a snack.
   
   Adult bluebirds have incredible eyesight—they can spot an insect hiding in the tall grass from over 50 yards away!—but our little nestlings have to take it one step at a time. Their sight will keep developing progressively every day as they grow closer to fledging around days 17 to 21.

8. When can a baby bluebird stand?
   
   These nestlings (day 8) can do a “half-stand” when parents arrive with food. In one or two days, they’ll be totally on their feet!

9. How soon will they leave the nest?
   
   Bluebirds leave the nest sometime around days 16–18. It’s only two and a half to three weeks before they’re ready to fly!
   
   In terms of this nest, they will fly anywhere from a little over a week to two weeks. By next Wednesday when I write this blog, they may be ready to fledge the next day! “Lift off” is somewhere between August 13–18.

Raising bluebirds is endlessly fascinating, and there is always a new surprise waiting on the camera. We invite you to join us for our daily livestream over at AzarÉl Greetings on YouTube to catch all the action live! While you’re exploring, be sure to stop by AzarÉlGreetings.com to browse a lot of unique bluebird photography captured right here in our backyard—where our resident bluebirds enjoy “fine dining” in little scenes that I create just for them.