Ecologie trophique de l’étourneau sansonnet (Sturnus vulgaris) en milieu agricole

Abstract

The Common starling (Sturnus vulgaris) is an invasive species in Algeria, including in the Ziban region. A study of biometrics, sexual dimorphism, allometry, food availability and trophic menu of this species is conducted at the level of the Ziban region. Biometrics of this species was studied following body measurements of 177 individuals it was found that the weight is 74.66± 8.82 g, the total length is 21.13± 1.26 cm, and the wingspan is 37.83± 1.64 cm, the folded wing is 12,67± 0.53 cm, the length of the beak is 2.62± 0.37 cm, the length of the beak is 2.62± 0.37 cm, the head measures on average 5.23± 0.20 cm, and the length of the tarsus is on average 3.02± 0.28 cm. The external biometrics of adult starlings measured showed a high degree of sexual dimorphism, the average weight of the male is 78.82± 6.42 g, and the female is 70.45± 8.96 g. The total length of the male’s body is 21.47 ±1.26 cm, and the female is 20.78± 1.17 cm. The wingspan of males is 38.12± 1.48 cm and females is 37.54± 1.75 cm. The folded wing of males is 12.79± 0.57 cm, and females is 12.55± 0.47 cm. The length of the beak in males is 2.63± 0.19 cm, and in females is 2,60 ±0.21 cm. The heads of males average 5.30± 0.32 cm, and those of females 5.16± 0.35 cm. And the length of the tarsus of the male is on average 3.02± 0.27 cm, and the female 3.03± 0.29 cm. The results show that the variation between the sexes was significant, except for the tarsus. An allometric correlation is marked between the different metrics examined and morphological parameters that indicate sexual dimorphism between the two sexes (♂= 89; ♀= 88) and this analysis shows a minor relationship between most of the measured parameters and the total length of the body and weight in both sexes. On the other hand 185 spontaneous plants were identified and 4900 specimens of insects collected by both methods (Barber pots and yellow traps) in 6 study stations in the Ziban region. The species counted belong to 8 orders with 38 families and 78 species. While after dissection of the individuals 9 species were found or Olea europaea (with 136 nuclei and pulp) and Phoenix dactylifera (with 126 pulp) are the most consumed by the starling, and 881 individuals of animal prey were identified, of which 53 species, spread over 18 orders and 34 families, whose beetles are the most represented. The values of the diversity of Shannon-Weaver at the level of the different environments in Ziban, are between 2.23 bit in the Sidi Okba region and 4.40 at the level of I.T.D.A.S. The values of E are relatively close to 1, between 0.68 in El Outaya and 0.89 in Tolga. These data show that the diet of the European starling in the Ziban region can be classified as diverse. And finally the calculated Ivelv index shows that there are items ingested by the starling and are present in the trophic media, while there are other individuals that are present in the media while are not found in the trophic menu.