Document Type : Research Paper
Authors
1
Associate Professor of Plant Protection Research Department, Golestan Agricultural and Natural Resources Research Center, Agricultural Research, Education and Extension Organization (AREEO), Gorgan, Iran.
2
Associate Professor Agricultural Zoology Research Department, Iranian Research Institute of Plant Protection, Agricultural Research, Education and Extension Organization, Tehran, Iran
3
Crop and horticultural science research department Golestan Agricultural and Natural Resources Research Center, Agricultural Research, Education and Extension Organization (AREEO), Gorgan, Iran
4
PhD. Student of Agronomy, Faculty of Crop Sciences, Sari Agricultural Sciences and Natural Resources University, iran and Promoter Conservation Agriculture
5
Master's degree graduate of agricultural entomology, Department of Plant Protection, College of Agriculture, Shahrood University of Technology, Shahrood,Iran.
6
Plant Protection Research Department, Golestan Agricultural and Natural Resources Research Center, Agricultural Research, Education and Extension Organization (AREEO), Gorgan, Iran
7
Plant Protection Research Department, Golestan Agricultural and Natural Resources Research Center, Agricultural Research, Education and Extension Organization (AREEO), Gorgan, Iran.
10.22059/ijpps.2026.408640.1007100
Abstract
Birds are among the most important vertebrate pest in rapeseed agroecosystems and annually cause substantial injury to crop stands, and due to its migratory and gregarious foraging behavior, it can generate considerable patchy damage at the field scale. Within each field, five damaged patches exhibiting more than 10% plant injury were identified and compared with paired reference areas showing minimal or no visible damage. In total, 90 one-square-meter quadrats were evaluated across damaged patches and reference areas, and damage indices together with yield components were quantified following a standardized sampling protocol. Grain yield was considered the primary response variable. Data were analyzed using a Linear Mixed Modelfitted by restricted maximum likelihood . Damage status (damaged vs. reference) was included as a fixed effect, whereas field identity and damaged patches nested within field were incorporated as random effects to account for spatial dependence among quadrats within the same patch and heterogeneity among fields. The smallest damaged area was observed in the conservation tillage field, whereas the largest damaged area occurred in the sprinkler-irrigated field. Results demonstrated a significant effect of damage status on grain yield . with damaged quadrats producing on average 141.289 ± 13.380 kg ha−1 lower yield than reference quadrats. These findings indicate that, within the framework of an observational field study, Eurasian skylark-associated injury was significantly associated with reduced rapeseed grain yield. However, differences observed among management were descriptive in nature and should not be interpreted as evidence of independent causal effects of tillage system or irrigation management.
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