Black-Headed Grosbeak: Nestling or Fledgling?

Black-headed Grosbeaks (BHGR) are not only beautiful, but they are fascinating birds. Like so many, they are unique in their lifestyle, how they use their habitats, and, of course, their baby development stages. The images above are of the same bird taken almost two weeks apart. The first image is of the baby upon intake, guessed to be about 10 days old and weighing 29 grams. The second picture is of the same bird, now a fledgling at 25 days old and weighing 47 grams. Neither are self-sufficient or able to feed on their own yet. The younger one can also not keep herself warm or cool (thermoregulate). One is a nestling, the other a fledgling. 

People often mistake nestlings for fledglings because the internet is full of incorrect information that says feathered baby birds are fledglings. Actually, there are three stages (or four for some species) of baby bird development: hatchling (naked or undeveloped feathers in shafts ('pins'), nestling (feathered with variations of pins remaining to no pins remaining, and fledgling (most birds are flighted at this stage, or they can flutter as they hide deeply in trees and shrubs).

The Black-headed Grosbeak does get out of the nest before they can fly. Cornell Birds of the World reports that they leave the nest as young as 12 days. However, those studies involve a lot of nest disturbance by the researchers - and we know that fiddling with, getting close to, or handling baby birds a few days before normal fledging results in babies jumping out of the nest too soon. In the case of this BHGR baby, her (or his) missing feathers around the face, tufts popping out on the head, no tail, and overall development indicate that this one jumped too soon. (Why we took the baby into care).

There are many reasons babies jump too soon. The primary reason is predation by any number of omnivorous or carnivorous birds and mammals. For BHGR, Scrub Jays and Steller's Jays are the primary predators. Predators can also include parasites, and nests can be overloaded with bot flies, mites, live, or even ants. Babies might also jump because of nest disturbance (as in researchers handling babies at 12 days old, someone getting close to a nest to photograph, or someone limbing trees and shrubs).

Another reason for babies to leave the nest too early is that not all babies may grow at the same rate. In some birds, the parents are not attentive to whether all babies are fed equally. This is true of the BHGR. So, in this species, runts are not uncommon.  Our baby indeed had signs of malnutrition (poor head feathering, for example). She's come a long way, though. She is now fully flighted but completely dependent on her mom for feeding. She is toying with foods, sticks, branches, and other things, but her bill is not hard enough to crack a seed, crush a bud, or dig into fruits. She will need to be able to do all of these things as that is the diet of the BHGR, along with insects. With grosbeaks, the bill takes much longer to harden than other songbird babies. Bills are made of both bone and keratin, and in grosbeaks and other birds with heavy bills who eat hard things, it takes time for the bill to develop. Adequate nutrition is paramount for that to happen, so malnourished birds are at a disadvantage. We can only guess what happened to this little one, but she is thriving since she has been in care and provided a nutrition-packed menu. ​

When these babies do leave, they do leave unflighted but with more feathering and further developed than this tyke. They split with their sibling and bury themselves deep in the most dense canopy or shrub they can find. This skill of hiding themselves is why we rarely see BHGB nestlings or fledglings until they are flighted and at a feeder. The female adult would continue to feed her babies for much of the summer. One report found an adult female and her young migrating together, with the parent still feeding the young bird.
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So, what do you do if you find a baby BHGR? The best thing to do is not listen to advice that says all baby birds with feathers are fledglings. Second, do not listen to advice that says all baby birds spend time unflighted on the ground. These statements are verifiably incorrect and harm more birds than help them.
What do you do?

1. In most cases, finding an experienced songbird rehabilitator who can assess the baby by phone is best. Text a couple of pictures of the baby along with a description of what you know happened.
2. Evaluate the physical condition of the baby bird. Does the baby look weak, tiny, and sickly? How far did the baby fall, approximately?
3. Use the pictures above to estimate the age of the bird. Are there apparent feathers missing? Look at the head and abdomen; do they have naked patches? Is there no tail?
4. Is there a parent around? If so, how attentive are they?
5. Where was the bird found? Deep in a shrub or out on the ground in the open? They are likely okay if the baby is developed enough and well-hidden deep in a shrub. Out in the open is not; in most cases, a nestling baby bird found out on the ground exposed to predators and the elements is not good.

We can do much to help baby Black-headed Grosbeaks. One of the most important is to have a safe, productive habitat for them. Growing native plants, like our native shrubs, helps put insects on the table for feeding parents (no, not feeding domestic insects!). Protecting new fledglings from hitting windows is crucial since fledglings are more likely to hit windows than adults. Also, because these babies are vulnerable and hide in shrubs, keep your kitties in the catio or inside the home.

Juvenile BHGR ready for testing out the world on her own. Native Bird Care