This study concludes of researches during May-September, 2003. There is one breeder group of Whiskered Tern (Chlidonias hybridus) (930 pairs) in zarrinkola Ab-bandan and two breeder group (1390 pairs) were in marzoonabad Ab-bandan. Reproductive phonology was started with nesting behavior in the end of May and was continued to maximum chicks fledged time in the end of July. Clutch size was 1-4 eggs in zarrinkola and second breeder group of marzoonabad, whereas, it was 1-5 eggs in the first breeder group of marzoonabad. Brood size was included 1-3 chicks. Breeding success was %57.08, %82.96 and %75.87 in zarrinkola, first and second breeder group of marzoonabad, respectively. There is not any significant difference between clutch size and brood size with breeding success (p>0.05). But, there is significant difference (p<0.05) between the rate of losses among the reproductive phonology stages. Because of intense rainfall, the maximum losses were during the incubation time. Breeding success has not any significant difference between study areas (p>0.05 .
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