Birds have seven phases of development: egg, hatchling, nestling, fledgling, juvenile, sub-adult, and adult. Most birds in the United States are protected by the Migratory Bird Treaty Act of 1918, or MBTA. It is important to be able to identify the species and developmental stage of a bird before offering aid to prevent doing more harm than good, as well as to be sure it is within legal limits.

There are four stages that are important to be able to recognize when identifying birds: hatchling, nestling, fledgling, and adult. Offering aid to a bird that is not in distress could be a death sentence to the bird.


Hatchlings are birds that have just hatched or are only a few days old. They are completely dependent on their parents and nest bound. They are typically bare skinned or have very little down feathers covering their body. Their eyes are closed and they have a seemingly large beak with a visible gape (the fleshy connection between the upper and lower parts of the beak). Hatchlings are unable to regulate their body temperature. They do not require a meal from their parents at this stage of development, as they are surviving off the remaining yolk from hatching.

Finding a hatchling on the ground is a cause for concern. If found, attempt to locate the nest, and place the hatchling inside of it. If no nest is found, a makeshift nest can be made and secured to the tree or bush that the hatchling was found by. Watch the nest for a couple of hours to be sure an adult bird visits the nest to care for the hatchling. If not, attempt to locate a local wildlife rehabilitator to take over care or aid in finding the correct party to care for the hatchling.

House Sparrow Hatchling


Nestlings are 3-13 days old. They are still completely dependent on their parents and nest bound at this stage. Nestlings will have started to develop feathers, but many will still be within a feather sheath. Their eyes will also be open. Nestlings are beginning to be able to regulate their body temperature, but it is dependent on the amount the feathering, or plumage, that has developed. They are dependent on their parents for meals.

Finding a nestling on the ground is also a cause for concern. The same protocol for hatchlings should be followed for nestlings.

House Sparrow Nestling with Emerging Feathers in Feather Sheaths

House Sparrow Nestling with Developing Feathers


Fledglings are birds that are approximately two weeks old. Fledglings have most of their feathers, but have not yet fully developed their flight feathers. At this stage of development, they are ready to leave the nest or “fledge.” Fledglings are unable to fly, but can walk, hop, and flutter with little to no problem. They are exploring their surroundings and enhancing their skills while living on the ground. During this stage, their parents supervise them while providing their meals until they learn to fly.

If a fledgling is found, it is best to leave it alone. It is likely that the parents are nearby and watching it closely. If the fledgling is in immediate danger, herd or move the bird to safe nearby location where the parents can hear or see it. Taking a fledgling will cause the parents to abandon it, in turn, causing the fledgling to lose parental protection and its food source.

House Sparrow Fledgling (left) with Female Adult Sparrow (right)


Adults are sexually mature birds with mature plumage. They are capable of building nests, breeding, hatching eggs, and raising young. Male and female adult birds will each have distinctive plumage to attract the opposite sex, as well as unique vocalizations.

Juveniles, sub-adults, and adults can all survive on their own. Each of these developmental stages is difficult to tell apart from another. It is important to be able to identify adult birds, especially in comparison to their fledglings.

Female Adult House Sparrow

Male Adult House Sparrow

The Migratory Bird Treaty Act of 1918

The Migratory Bird Treaty Act implements four international conservation treaties entered between the United States, Canada, Mexico, Japan, and Russia. The purpose of the MBTA is to ensure protection and sustainability of migratory bird species. The MBTA is enforced federally by the U.S. Fish & Wildlife Service, while each State and territory has its own sector of Fish and Wildlife management. The MBTA prohibits the sell, trade, capture, transport, or killing of migratory birds. It also applies to collecting the feathers of these birds in most circumstances. The MBTA is enforceable by hefty fine and imprisonment, at both state and federal level depending on the crime committed.

Every migratory bird is protected under the MBTA, apart from hunted or game birds, which are offered limited protection that is dependent on the hunting season. Non-native species are not protected under the MBTA, these species are: House Sparrows, European Starlings, and Pigeons.

Be careful when picking up baby birds from the ground. Identify the species, developmental stage, and assess if any visible injury or danger is present before attempting to rescue the bird. A well-intentioned individual may inflict more harm and break the law in an attempt to save a bird that is not in actual danger. There are many local resources to provide education and aid if needed. Please seek help from a qualified individual before making a rescue attempt, besides placing a hatchling or nestling back into a nest.

NDOW (local office): 775- 777-2300

NDOW (dispatch for emergency only): 775-688-1331 or 775-688-1332.