This study investigated the effects of the first generation anticoagulant rodenticide chlorophacinone and the second generation rodenticide bromadiolone on the population and breeding performances of barn owls at oil palm plantations. Three treatment plots were established: one baited with chlorophacinone, one with bromadiolone, and the third kept rodenticide-free. Four rat-baiting campaigns which coincided with barn owl breeding season were carried in the rodenticide-treated plots. The occupancy rate of nest boxes, clutch size, brood size and fledging rates of the barn owls in each plot were monitored weekly throughout the study. Freshly regurgitated pellets from barn owls were collected from all occupied nest boxes at weekly intervals during the development of nestlings in each breeding season. The results show that the occupancy rate of the nest boxes was significantly higher in the rodenticide-free area compared with both rodenticide-treated areas. Similarly, the breeding performances, such as clutch size, brood size and fledging success, were higher in the rodenticide-free area compared with the rodenticide-treated areas. Results of high performance liquid chromatography (HPLC) analysis showed that 20.56% (mean residue: 1 .335 ± 0.073 lg/g) and 28.89% (mean residue: 0.777 ± 0.032 lg/g) of the collected regurgitated pellet samples from the rodenticide-treated areas contained bromadiolone and chlorophacinone residue, respectively. The mean brood size and fledging success of the barn owls showed a strong negative correlation with the mean concentration of rodenticide residues present in the regurgitated pellets and with the percentages of pellets detected having such residues (R2 k 0.44, P < 0.05). Similarly, the mean clutch size of barn owls was negatively correlated with the mean concentration of rodenticide residues and with the percentages of pellets detected with these residues. However, the correlation was not significantly different (R2 k 0.34, P > 0.05). In general, the higher the amount of residues detected, the lower the breeding performance parameters measured in this study
Albert CA & Wilson LK 2009: Anticoagulant rodenticides in three owl species from Western Canada, 1 988-2003. Arch Environment Contamination Toxicology 34: 11 2-1 32. DOI: 1 0.1 007/s00244-009-9402-z
Chung GF 201 2: Rat management in oil palm, 1-52. In: Proceedings 4th MPOB-IOPRI international seminar: Existing and emerging pests and diseases of oil palm advances in research and management. Bandung, Indonesia, 1 44.
Coueurdassier M, Poirson C, Paul J, Rieffel D, Michelat D, Reymond D, Legay P, Giraudoux P & Scheifler R 201 2: The diet of migrant red kites (Milvus milvus) during a water vole (Arvicola terrestris) outbreak in eastern France and the associated risk of secondary poisoning by the rodenticide bromadiolone. Ibis 1 54: 1 36-1 46. DOI: 1 0.1111 /j.1 474-91 9X.2011 .011 93.x
Duckett DE 1 984: Barn owls (Tyto alba) and the “second generation” rat-baits utilised in oil palm plantations in Peninsular Malaysia. The Planter 60: 3-11 .
Eadsforth CV, Gray A & Harrison G 1 996: Monitoring the exposure of barn owls to second-generation rodenticides in southern Eire. Pesticide Sciences 47: 225-233. DOI: 1 0.1 002/(SICI)1 096-9063(1 99607)47:3<225::AID-PS407>3.0.CO;2-P
Erickson W & Urban D 2004: Potential risks of nine rodenticides to birds and nontarget mammals: a comparative approach. United States Enviromental Protection Agency, Washington, DC, USA, 225.
Gray A, Eadsforth CV & Dutton AJ 1 994: Non-invasive method for monitoring the exposure of barn owls to second-generation rodenticides. Pesticide Sciences 41 : 339-343. DOI: 1 0.1 002/ps.278041 0409
Henny CJ 1 969: Geographical variations in mortality rates and production requirements of the Barn Owl (Tyto alba). Bird-Banding 40: 277-290.
Khoo KC, Peter ACO & Ho CT 1 991 : Crop pests and their management in Malaysia. Tropical Press Sdn. Bhd. Kuala Lumpur, 242.
Lenton GM 1 984: The Feeding and Breeding ecology of Barn Owl (Tyto alba) in Peninsular Malaysia. Ibis 1 26: 551-575. DOI: 1 0.1111 /j.1 474-91 9X.1 984.tb02080.x Naim M 201 0: Evidence and effects of secondary poisoning from two anticoagulants and a biological rodenticides on barn owl. Universiti Putra Malaysia. PhD-thesis, 1 67.
Naim M, Hafidzi MN, Kassim A & Abu J 2011 : Comparison of the breeding performance of the barn owl (Tyto alba javanica) under chemical and bio based rodenticide baiting in immature oil palms in Malaysia. Dynamic Biochemistry, Process Biotechnology and Molecular Biology 5: 5-11 .
Newton I, Willie I & Freestone P 1 990: Rodenticides in British barn owl. Environmental Pollution 68: 1 01-11 7.
Olsen P, Fuller P & Marples TG 1 993: Pesticide-related eggshell thinning in Australian raptors. Emu 93: 1-11 . DOI: 1 0.1 071 /MU9930001
Sanchez-Barbudo IS, Camarero PR & Mateo R 201 2: Primary and secondary poisoning by anticoagulant rodenticides of non-target animals in Spain. Science of the Total Environment 420: 280-288. DOI: 1 0.1 01 6/j.scitotenv.201 2.01 .028
Stone WB, Okoniewski JC & Stedelin JR: 2003. Anticoagulant rodenticides and raptors: recent findings from New York, 1 998-2001 . Bulletin Environmental Contamination Toxicology 70: 34-40. DOI: 1 0.1 007/s001 28-002-01 52-0
Thomas PJ, Mineau P, Shore RF, Champoux L, Martin PA, Wilson LK, Fitzgerald G & Elliott JE 2011 : Second generation anticoagulant rodenticides in predatory birds: Probabilistic characterization of toxic liver concentrations and implications for predatory bird populations in Canada. Environment International 37: 91 4-920. DOI: 1 0.1 01 6/j.envint.2011 .03.01 0
Turner PD & Gillbanks RA 2003: Oil Palm Cultivation and Management - 2nd Edition. The Incorporated of Planters, Kuala Lumpur, Malaysia, 91 5.
Walker LA, Llewellyn NR, Pereira MG, Potter ED, Sainsbury AW & Shore RF 201 2: Anticoagulant rodenticides in predatory birds 201 0: a predatory bird monitoring scheme (PBMS) report. Centre for Ecology & Hydrology, Lancaster, United Kingdom, 1 7.
Wood BJ & Chung F 2003: A critical review of the development of rat control in Malaysian agriculture since the 1 960’s. Crop Protection 22: 445-461 . DOI: 1 0.1 01 6/S0261 -21 94(02)00207-7
Wood BJ 1 994: Rodents in agriculture and forestry, 45-83. In: Buckle AP & Smith RH (eds), Rodent pests and their control. CAB International, Wallingford, Oxon, UK, 405.
Wood BJ 2001 : Rat control in oil palms and rice fields. Pesticide Outlook 4: 71-74. DOI: 1 0.1 039/B1 02665A