Ardea
Official journal of the Netherlands Ornithologists' Union

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Delvingt W. (1963) Ecologie de l'activite incubatrice d'un couple d'etourneaux, Sturnus vulgaris. ARDEA 51 (2-4): 196-211
Statistical analysis of the incubating behaviour of a pair of starlings during two consecutive broods gave the following results: 1. During the second brooding-time, coverage per 24 hours is shorter compared to coverage of the first brooding, this being a result of the decrease of the diurnal coverage.2. The 'sitting index' is calculated as i=100 where a = an attentive period (see Kendeigh 1952) =the daily sitting activity = the total time during which the eggs are left every day. That index becomes also lower during the second brooding time. This is due to an increase of the average inattentive period during the day, the average sitting time remaining constant. 3. The sitting index for the first brood is not related to the average air temperature (per 24 hours). On the contrary, the sitting index for the second brood varies inversely as a function of the average temperature per 24 hours. 4. For the second brood, temperature influences strongly the average attentive period, the latter being smaller at high temperatures, but not the average interruption time. For the first brood, temperature affects weakly but equally both the average sitting and interruption times. Height of rain, atmospheric humidity, barometric pressure, length of insolation and importance of sun-radiation do not influence the sitting index. These results are discussed and compared with others referring to others bird species.


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