Breeding success of the Grey Hypocolius Hypocolius ampelinus in Haft-Tappeh and Miyan-Ab Agriculture complexes

This study was carried out during the March to June 2010. Grey Hypocolius Hypocolius ampelinus breeding season began on 3 May with the egg laying behavior and finished on 10 June with fledging stage. During the study period، 11 nests including 50 eggs surveyed. Mean of the clutch sizes were 4. 54 (4-5) and brood sizes varied from 1-2 chicks. The average of the length، width and weight of the eggs were calculated respectively; 23. 52±0. 99 mm، 18. 85±0. 47 mm، 4. 76±0. 33 gr. The egg laying and incubation time lasted 3. 0±0. 81 and 15. 75±1. 25 days respectively. The rate of the hatching، nestling، and post-nestling success were calculated 56%، 52% 52%، respectively. The breeding success calculated 53. 33%. There were no significant difference with respect to the different clutch and brood sizes. But، significant difference observed between the mortality rates in different stages of breeding cycles (P<0. 05). This difference between the egg and nestling (P<0. 05) and egg and post-nestling (P<0. 001) stages indicated the significant effect. Touching the eggs due to the researcher presence indicated a negative significant effect on the breeding success especially in the egg stage (P<0. 05). Presence of different predators such as Grey Hypocolius، Echis carinatus، Coluber rhodorachis، rodents، Vulpes vulpes and Canis aureus are the most important of natural factors resulting the decline of breeding success Most of the eggs mortality occurred due to touching effect result in researcher presence. Grey Hypocolius pairs in 80% of cases left their nests and built a new ones in 50-70 m around the previous nests.