The true sparrows of the genus Passer consist of some 28 species, but there are many other birds in the Passerellidae family that have ‘sparrow’ in their common name. Sparrows are undoubtedly one of the most common garden birds, and the House sparrow is a common sight across much of the world.
Baby sparrows are tiny and seldom seen with the naked eye - this is a guide to all you need to know about baby sparrows!
Baby sparrows are always born naked, and most have closed eyes that don’t open for a few days after hatching. Common and Eurasian baby sparrows weigh just 2g upon hatching, the same as a dime or plastic bottle cap. Their skin is pinkish-yellow with red mouths and tiny, stubby ‘arms’ and legs.
Some sparrows from the New World sparrow family, including the Juncos, are not totally naked at birth and are instead covered in a soft, light down. Hatching covered in down or feathers is likely advantageous in colder climates.
While baby sparrows are almost totally silent and unresponsive for the first couple of hours after hatching, they quickly begin to squirm and open their mouths to call for food. After just one day, their weight may have increased by as much as 50%. After around five days, most baby sparrows will have gained 6 to 8g of weight, and after 14 or so days, most will have reached adult weight.
A young sparrow fledgling
Depending on the species, most baby sparrows are just a matter of a few centimetres long.
The hatchlings of Eurasian and American tree sparrows and Clay-coloured sparrows, and House sparrows are all exceptionally small at birth. However, some New World sparrows are slightly larger and heavier, and their hatchlings are not always born naked.
Of the true sparrows from the Passer genus, hatchlings tend to weigh just 2 to 3g (0.7 to 1.0oz). The House sparrow is the smallest true sparrow - hatchlings can weigh slightly under 2g but tend to fall within this range.
Other New World sparrows in Arremon, Artemisiospiza, Junco, Melozone and other similar genera are slightly larger at birth. For example, Junco hatchlings may weigh 3 to 4g.
Close up of a sparrow chick
It’s tough to spot a baby sparrow as they’re usually hidden away and don’t leave the nest until they look much like adults.
Sparrows tend to nest in the deep undergrowth, or even inside if they can, hence the name House sparrow. While many baby sparrows are born naked and blind, they quickly gain weight and resemble adults after just 14 to 18 days. At that point, they’ll fledge.
A juvenile sparrow is often hard to tell apart from an adult, hence why it’s tough to spot a baby sparrow.
Juvenile sparrows tend to be lighter in colour than adults with softer, more downy plumage.
Juvenile House sparrows are a lighter dusky brown and have greyish undersides and light brown backs. In addition, juvenile sparrows sometimes lack the darker bibs of adult birds.
The easiest way to differentiate a juvenile sparrow from an adult is by its plumage - nearly all juvenile sparrows are duller and lighter than adults.
A juvenile house sparrow perched on a branch
There is no specific name for a baby sparrow. The bird is called a hatchling for the immediate days or hours after hatching. While they remain in the nest, young birds are called nestlings. Once fledged, young birds are called fledglings.
Studies of American and Eurasian tree sparrows discovered that some 70% of the nestlings’ diets consist of soft arthropods, including larvae and beetles.
Baby sparrows are typically fed by both parents, who forage soft arthropods from within 100 to 300m of the nest. Soft berries and kernels tend to make up the remainder. Like many baby birds, young sparrows are unable to digest harder foods until later in their development.
Sparrow feeding chicks in a nest box
The parents will forage soft foods from close the nest. Both the male and female usually forages - baby sparrows are demanding and need intensive feeding for the first few days after hatching.
Adult birds will feed soft foods to the young whole or partially digest and regurgitate food to make it easier to digest. Studies report that baby sparrows are fed some 2 to 30 times per hour. Parents prioritise feeding their babies high-fat foods like larvae and beetles rather than berries and seeds.
A sparrow feeding its chick
Generally speaking, both male and female sparrows participate in feeding their chicks together.
Of course, there is variation between different species, but this seems true for the true sparrows of the Passer genus. Many species of sparrows raise more than one brood per breeding season.
While the young birds still require parental care, the female prepares for the next brood, leaving the male to feed the near-fledgling chicks until they truly fledge.
Depending on the species, Sparrow eggs range from 15–25mm in length. Colouration is diverse - the Eurasian tree sparrow and House sparrow can lay anything from white or grey eggs to eggs with blue or green tints.
It’s not uncommon for eggs from the same clutch to look markedly different to each other. For example, some may be a glossy white and others a dark brown or green colour.
Most sparrow eggs are heavily marked with dark brown speckles. While many birds lay elliptical eggs, sparrow eggs are sub-elliptical, which means they’re slightly more spherical than average.
The nest and eggs of a house sparrow (Passer domesticus)
Sparrow eggs are usually incubated for around 10 to 13 days before hatching.
Eurasian and American tree sparrow incubation times average about 11 to 12 days. House sparrows are similar at 11 days. New World sparrows like the Junco tend to incubate for 13 days. In colder conditions, incubation times are slightly longer.
Most species of sparrows lay around four eggs on average, but larger clutches of up to 8 eggs are not uncommon.
Studies of House and Eurasian tree sparrows have found clutches of 11 eggs in rare circumstances. Many sparrows also have more than one brood per year, meaning they might raise as many as 20 or more babies!
A small group of sparrows
True sparrows from the Passer genus tend to stick to the traditional breeding season, which extends from March until early May. However, some pairs will raise another brood as late as August, depending on the conditions.
The closer to the equator you get, the more fragmented the breeding season becomes (as the differences between seasons are not as pronounced). Sparrows in Central and South America, Africa and Asia may lay eggs throughout much of the year, depending on conditions.
Baby sparrows grow rapidly, and most achieve adult weight within 14 to 16 days, after which they’ll fledge to a nearby tree, hedgerow, bush or shrub.
Young fledgling sparrows tend to stay close to their parents for another week or two or so before leaving to find a mate and establish their own territories.
Juvenile sparrows often form small juvenile flocks close to their parents, where they’ll remain until they find a mate. The lifecycle of a typical sparrow is short - there is little time to waste before the young birds establish a nest and have young of their own!
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