Two, and four supplementary, chicks of the Grey Staring,
Sturnus cineraceus, were handraised under close observation. The occurrence and development of their behaviours were carefully noted and over 50 kinds of behaviour and vocalization were recorded as classified in the introduction, and 34 of which were listed in Fig. 8, showing the days of occurrence after hatching. The ontogenetic analysis by behaviour system was made based on Kortlandt's method as shown in Figs. 3-7. Each behaviour was named and described in the text which are summarized as follows:
Without external stimulation, the gaping of early chicks (5-7 days) was gradually induced by hunger, 20 minutes after being fed 1g. of food, and advanced from: bill up-pointing → yawning → neck-stretching to gaping. Any sound, the door-closing, dog-bark, badgerigers' voice, became the stimulus for gaping. Touching the nest caused freezing but also gaping in hungry condition. The strong bursting sound caused freezing. Rising temperature induced, and decreasing one suppressed the gaping impulse.
At least by 12th day, the chicks had been imprinted by the author's voice and not reacted to high-pitch sounds. This was confirmed also after they were fledged.
Eyes opened on the 10th day but directed gaping was first noticed on the 13th day. The sight was best at 1-60cm., reacting also at 1m. and weakly at 2.5m. However, the lateral sight did not developed until the 15th day, when the hostile behaviours became developed.
The pecking action first appeared on the 13th day as a weak impulse with the upward-pointed bill in the absence of real object to peck, but they also pecked the tip of forcets 1cm. before the bill. Eating of food after such a peck and the mutual pecking of the bill were noticed from 13-15th days.
After the 20th day, the tongue-tip tasting particularly of small black particles became frequent. They liked to taste the sugar but hated the salt. The fledged young did not eat by themselves the pasted food in the container until at least 35th and 37th days, two weeks after leaving the nest.
Vomitting the stones of fruits (and hard objects) given by parents is an important physiology in the chicks. The cherry stones are vomitted about 1.20h. (once 50min.) after intake. Also in fledged young which may often eat inedible substance, the vomitting is of survival value (observed). The food-refusing was observed on the 13th day and the humility behaviour with False begging was noticed on the 17th day.
The Bill-opening, characteristic to the starlings, occurred on the 18th day as a weak innate impulse in the absence of definite object (there was a little cotton). From about the 20th day, various use of bill became developed (see list in the text) and the Bill-rubbing (or cleaning) behaviour was first noticed.
The foraging of fledged young is very inefficient, being much interested in shaking the feather, string or fallen leaves (a long string was half swallowed!) and could find little real food.
When the water was given on the 22nd day, they first pecked at it and then real drinking followed. Beside scooping the water, they also can suck it, with the vertically inserted bill (from the perch above the water).
Bathing was willingly done on the 26th and 22nd, but not 21st (same bird), day when they were first given water.
Panting in both naked chicks and fledged young was induced at 30°C (or 29°C) by heating them with electric light or in natural summer temperature, and the breathing increased to 26times/15sec. in 15 day solds, which breathed 14times/15sec. at 26°C.
The Lateral heat (or Sun) bathing could be at once induced in 22 days olds by 60 wat electric light, but after a while panting occurred (perhaps at over 30°C). The Back heat-bathing was reflectively performed when the bird was brought out to the sunshine.
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