Growth stages of the Common Swifts

Growth stages of the Common Swifts

This is dependent on diet and weather, as variations are possible. Below you will find a table with reference points for the weight development of a nestling.

Day 1 © E. Brendel

1 day old Common Swift
At first featherless and blind.
Handling: Need a permanent heat source, every quarter to half hour they need to be fed with very small crickets and checked.

The heat source must not be warmer than 30-32°C (check this!). It is best to use a heat source from below (e.g. heating pad, Snuggle Safe). Heat from above is to be avoided, as there is a risk of the baby drying out. Humidity should be kept at approx. 50%.

Day 2 © E. Brendel

2 - 4 day old Common Swifts
Still blind, at the 3rd or 4th day down feathers starting to show up as black dots.
Between the 6th and 13th day they start to open their eyes.
As of the 7th day the quills of the pennaceous feathers begin to pierce the skin.
Handling: Need a permanent heat source, every quarter to half hour they need to be fed with very small crickets and checked.

Day 6 © E. Brendel

From day 6 onwards, feeding every half hour with very small crickets is sufficient.

Day 10 © E. Brendel

10 day old Common Swift
Eyes are open.
Quills of pennaceous feathers have pierced the skin.
Handling: Need a permanent heat source (28-30°C), every hour they need to be fed with approx. 10-20 small crickets and checked.

Day 11 © E. Brendel

11 day old Common Swift
Handling: Need a permanent heat source (28-30°C), every hour they need to be fed with approx. 10-20 small crickets and checked.

Day 12 © E. Brendel

12 day old Common Swift
Handling: Need a permanent heat source over night, every 2 hours they need to be fed with small crickets and checked. The amount is now based on the weight table (see below) and should result in a continuous increase in weight.

Day 15 © E. Brendel

15 day old Common Swift

Handling: May still need a heat source over night.

Exception: severely starved or weakened birds need permanent heat.

They need to be fed with medium-sized subadult crickets and checked every 2 hours, from approx. 7 am to 10 pm.

Day 17 © E. Brendel

17 day old Common Swift

Handling: Heat source only necessary for severely starved and weakened birds.

They need to be fed with medium-sized subadult crickets and checked every 2 hours, from approx. 7 am to 10 pm.

Day 19 © E. Brendel

Between 15 and 20 day old Common Swift

Handling: Heat source only necessary for severely starved and weakened birds.

They need to be fed with medium-sized subadult crickets and checked every 2 hours, from approx. 7 am to 10 pm.

Day 20 © E. Brendel

20 day old Common Swift

Handling: Heat source only necessary for severely starved and weakened birds

They need to be fed with medium-sized subadult crickets and checked every 2 to 2.5 hours, from approx. 7 am to 10 pm.

Day 22

Day 23

Day 24

Day 26 © E. Brendel

Day 29 © E. Brendel

Between 20 and 30 day old Common Swift

Handling: Heat source only necessary for severely starved and weakened birds

They need to be fed with medium-sized subadult crickets and checked every 2 to 2.5 hours, from approx. 7 am to 10 pm.

Day 31 © E. Brendel

30 day old Common Swift

They need to be fed with medium-sized subadult crickets and checked every 2.5 hours, from approx. 7 am to 10 pm.

© Dr. A. Pauliny

32 day old Common Swift

They need to be fed with medium-sized subadult crickets and checked every 2.5 hours, from approx. 7 am to 10 pm.

Day 34 © E. Brendel

34 day old Common Swift

They need to be fed with medium-sized subadult crickets and checked every 2-3 hours, from approx. 7 am to 10 pm.

Day 40 © E. Brendel

40 day old Common Swift

They need to be fed with medium-sized subadult crickets and checked every 2-3 hours, from approx. 7 am to 10 pm.

Heavy young swifts may now reduce their weight by increasingly refusing food, in order to reach their optimal flight weight.

Day 43 © E. Brendel

42/43 day old Common Swift

They need to be fed with medium-sized subadult crickets and checked every 2-3 hours, from approx. 7 am to 10 pm.

The weight at fledging can vary between 37 g and 45 g, depending on body size and wing length. The bird continues to be cared for until the plumage is completely developed, not a single calamus is visible any more, and it shows by its restless behaviour that it wants to fly out. Before release, one final administration of vitamin B complex is necessary if the last one was more than 4 days ago.

© I. Polaschek

Calamus on the inferior side of the wing
Decisive for the release is a weight of approx. 38 - 40g and always the complete development of the plumage: Common Swifts are fledged when the calamus (small gray/white tubes, where the feathers grow out, see photo) on the flight feathers of the inferior part of the wing is not viewable anymore.
Photo: Calamus still viewable - bird is not yet fledged!

Weight stages of Swift nestlings

Please be sure to use the feeding table below as your guide, as the amount of food (normally approx. 2-3 g of medium-sized subadult crickets per meal per swift) can vary depending on age and size.

Much like humans, some swifts are taller or smaller than others. Environmental conditions may inhibit the nestling's development, too. Hence, the nestling's weight-to-age relationship is not fixed, but may vary without this necessarily being a problem. In case of a found bird, you should also check the amount of fodder. ("Found birds => Feeding => How to do it right").

The table below displays observations taken from "Jakob", a swift that was bred in the swift clinic, raised by hand, and successfully released in 2012. As such, they should not be interpreted as representative mean values. They rather serve illustrative purposes and as an orientation point, showing that weight gain does indeed proceed irregularly. Note for instance, that Jakob did not gain weight between the 15th and 17th day as well as between the 19th and 22nd day. In the final growth stage, when the swift is only growing feathers, it also loses weight again. This effect, visible in Jakob's case from the 35th day onwards, is normal and no cause for concern.

Day	Weight in g		Day	Weight in g	Comment
1	2.4		23	40.6
2	3.3		24	40.7
3	4.4		25	41.7
4	6.7		26	43.8
5	8.1		27	42.2
6	10.6		28	43.7
7	13.7		29	43
8	17		30	46
9	20.7		31	43.2
10	22.9		32	45.7
11	26		33	45.2
12	29.4		34	46.3
13	31.8		35	44	appetite decreasing
14	34.6		36	43.8
15	36.4		37	44.4
16	36.5		38	43	weight reduction
17	36.6		39	42.6	takes little food
18	37.7		40	42.2
19	38.4		41	43	looks towards the window
20	38.6		42	40.9	still crawls back
21	38.2		43	39.2	becomes restless
22	38.4		44	39	flown !!!

Jakob was a slightly built Common Swift. The values given here should therefore rather be interpreted as a lower limit.