A Tawny Owl's first 100 days

100 days, or a little over three months, is the time it takes for a Tawny Owl to reach a fully adult appearance after hatching from the egg. By adult appearance I mean having adult plumage (the owl doesn't reach sexual maturity until later). The last adult feathers to grow are those on the crown and back of the head. Nature concentrates on getting those wings growing. This photo series is mainly based on Sophie's development. She came to me aged about 20 days, so for the days before that I've used pics of other, younger owlets we've had. Development is shown at about 5-day intervals.

Note: the ages of these young chicks are estimates -- they are not precisely known. On the rare occasions pics of chicks whose age is known with certainty become available I wonder whether I have got the ages given here quite right. Appearances vary quite considerably and one owl chick may look very different from another!

Stage 1: The nestling (age 0 to about 28 days)

Tawny Owls hatch 28-29 days after the egg is laid. The hatch date can be taken as the owl's "birthday" as development in the egg can be seen as broadly equivalent to the embryonic stages in mammals. The nestling stage that follows lasts about 28 days. From about day 25 owlets become curious about the outside world and, although unable to fly, they may leave the nest or hole and hop to nearby perches, a stage known as branching. By day 29 or 30 they have sufficiently developed wings to fly properly, and they are said to be fledglings. Once all her brood have fledged, the mother often takes them away from the nest area and leads them to the parents' main hunting grounds.

Days 12 to 20. Shown at left is Tiny tot, who followed her brother off the nest at a remarkably young age. Both fell at more or less the same time after a day frolicking in warm sunshine in late May 2004. Tubby, her brother, is shown in the two pics below left. Neither survived the injuries sustained when they hit branches on the way down. The owl on the lower right is Owly, a brother from the previous year. Here he's shown the day after he fell aged about 18 days.

The ages of these very young owls are not easy to estimate exactly as there are few pics of chicks of a reliably known age on the internet. The only series I know is Peanut and siblings. These are rather indistinct gifs, but I've used them to get a fix on Owly and Sophie's ages. Eyes may open from Day 7 (Peanut), but don't seem to be opened permanently until some days later.

About day 12 (Tiny tot)

About day 12 and day 16 (Tiny tot

and, behind, Tubby)

About day 19 (Owly)

About day 16 (Tubby)

For comparison, here's a pic on the East Lancs Ornithologists' Club site showing a chick that came down this year (2007). Huddled against the base of a tree, it's about 2 weeks old and has little chance of surviving if left. Note the still very silvery down, the closed eyes, and the white fluff around the eyes with complete absence of facial disk development.

Days 20-25. The next pics show Sophie on day 20 (the day I found her) and day 25. From about day 25 until they fledge, owlets spend a lot of time standing up and flapping their wings vigorously. In the confined space of the types of nestbox sold in this country there's little room for them to do this, which is one reason I'm not keen on them. This period (days 25-30) is also the "branching" stage, when owlets often leave the hole or nest and hop to a nearby branch where they peer at their new world and exercise their fast-growing wings. It's likely that when they feel enough lift they know they're ready to go.

People often comment on the sad expression in the eyes of tawny chicks of this age. It's a true description, but I don't think it's because they really are sad!

About day 20 (Sophie)

Day 25 (Sophie)

Stage 2: Fledging (age 28-35 days)

Fledging (meaning the owlet becomes capable of sustained flight) takes place over a short period -- generally said to be when the chick is 28 to 35 days old, but a genuine ability to fly is usually reached around day 30. Here are pics of Sophie from this critical period. The first and second show her wings coming on nicely, and the third shows the typical appearance of the youngster you'd see just out of the nest and on a branch waiting to be fed by a parent.

My first owl made his first, very short flights on his 31st day, but it was several days before he mastered the skills of flying. Somehow I never got round to noting what day Sophie made her first flight! It would have been somewhere in the sequence of pics shown below. 32 days is a typical average reported for owlets leaving the nesting area with their mother.

Day 34

Day 30 (all Sophie from here)

Day 34

Stage 3: After fledging -- growing up (age 32 to 100 days)

Over the next 60 days, or two months, the owl chick slowly becomes more like an adult in appearance. The rest of the photo series shows this process. The wings continue to grow and become stronger, of course, but now another striking development is the expansion of the "facial disk", the stiff feathers that spread out from the eyes and give the owl its owl-like appearance. The young owl also becomes curious, adventurous and playful and explores its surroundings.

The fledged owlets now spend much of their time perched in a tree waiting to be fed by the parents. At this stage some refer to them as "squeakers" as for the next two months or so they'll spend much of the night calling for food. These calls, which are a sort of wheezy squawk, may be made continuously throught the night at 5 or 6 second intervals by each owl. In fact it's simple to calculate that an owlet may repeat the call over 4,000 times a night! Here's a sample: Squeakers (940.42 K). In it one of the parents arrives with food, so the calling interval is shorter than when they're waiting.

Left: Young tawnies are very easy to feed as they will eat almost anything with a huge appetite. It's important, though, to see to their dietary needs, which include feathered and furred items to promote their pellet-making ability. We use frozen mice and chicks.

Below left: Here Sophie's wearing jesses as by day 46 she was quite capable of making off on her own. She's inspecting my budgie.

Below middle: Looking mischievous -- tawny owlets have periods of intense activity when they fly around from perch to perch. Here she's wondering where to go next. Anything new in the room is noticed and investigated immediately.

Below right: Back view to show nicely developing wings. But note the still juvenile look of the head. More of wings on the next page.

Day 40

Day 51

Day 46

Day 55

Those confusing terms (again) . . .

NESTLING: Bird between hatching and fledging.

FLEDGE: A bird is said to fledge when it becomes capable of sustained flight and doesn't, for example, just flutter to the ground or barely make it to a nearby branch. Nestlings usually leave the nest when they fledge; hence "fledge" may be used to mean to leave the nest and fledgling may be used to mean a young bird that's just flown from the nest.

BRANCHING: Used specifically of owls, refers to the late nestling period before full fledging when the young owls may leave the nest and make short wing-assisted hops between nearby branches. With Tawny Owl chicks this happens in the period from 25 to 30 days after hatching when they are not fully capable of flight. Frequent returns are made to the safety of the nest during branching. Branching doesn't refer to the later stage when the chicks have fledged, left the nest area and stand around on banches waiting to be fed by the parents.

OWLET: Informal word referring to a young owl. I use it to refer to an owl that's less than 3 months old, when it becomes fully adult in appearance.

CHICK: Pass! I guess I'd use it for anything from a recent hatchling up to about 40 days, when the appearance is still sort of babylike.

Next page (days 60-100)

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