Sub-lethal effects of the anticoagulant rodenticides bromadiolone and chlorophacinone on breeding performances of the barn owl (Tyto alba) in oil palm plantations (original) (raw)
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The breeding performance of barn owl, Tyto alba javanica, in areas treated with rodenticides in immature oil palms in Malaysia was investigated. Four plots were established, each at least 100 ha in size and treated with warfarin, brodifacoum, a biorodenticide (Sarcocystis singaporensis) and a non-baited control plot. Three rat baiting campaigns, which coincided with the barn owl breeding season, were carried out in October 2008, February and March 2009, and in October 2009. The nest boxes were distributed at a mean density of one unit per 25 ± 3.83 ha. The clutch size, hatching and fledging rates of barn owls in each plot was monitored monthly from September 2008 to January 2010. There was no significant difference in mean clutch size for all four treatments. The lowest percentage of hatching success was recorded in the brodifacoum-treated plot in all three breeding seasons. Fledging success was highest in the control plot, followed by the S. singaporensis-, warfarin-and brodifacoum-treated plots. The mean clutch size and mean hatching success was not significantly correlated with mean rat damage (clutch size, r = 0.754, p > 0.05; mean hatching success, r = 0.832; p > 0.05). The mean fledging success was significantly correlated with mean rat damage (r = 0.969; p < 0.05). Brodifacoum achieved the lowest level of rat damage but not significantly lower than warfarin and S. singaporensis. This indicates that S. singaporensis is a better rodenticide than warfarin and brodifacoum in controlling rats and yet achieved the highest reproductive rates in the baited areas as reflected by the rate of fledging success.
Growth performance of nestling barn owls, Tyto Alba javanica in rat baiting area in Malaysia
2010
The growth of nestling barn owls, Tyto Alba javanica in immature oil palm in Malaysia was investigated under rat baiting with three different rodenticides. Four treatment plots were established with three plots baited each with warfarin, brodifacoum and a protozoan based biorodenticide, Sarcocystis singaporensis plus a fourth non-baited control plot. Three rat baiting campaign were carried out during the study, the first rat baiting campaign was conducted in October 2008, the second was in March 2009 (except for biorodenticide baiting was conducted a month earlier), and the last third baiting campaign in October 2009. The baiting campaigns coincided with the breeding season of barn owl. Nestlings body measurements namely: body mass, culmen length, tarsus length, wing length and tail length were taken after the third baiting campaign, from September 2009 to January 2010. Measurements were recorded every three days from hatching up until 49 days old, i.e., several days before fledging. Nestlings in control plot showed superior for all parameter taken compared to rodenticides treated plots. Body mass of nestlings in control plot were heavier by 8.17%, 13.04%, and 6.88% compared to warfarin, brodifacoum and biorodenticide treated plots respectively. The culmen and tarsus length of nestling barn owls reached the adult size during the growth period; while culmen length in control plot was longer by 3.07%, 5.28%, and 1.41% compared to warfarin, brodifacoum and biorodenticide treated plots respectively. The tarsus length of nestlings in control plot was also longer by 2.40%, 3.08% and 3.36% compared to warfarin, brodifacoum and biorodenticide treated plots respectively. In contrast with culmen and tarsus length, wing and tail length still grew until day 49 i.e., several days before fledging. The wing and tail length in control plot was shorter by 15.77% and 13.73% compared to adult size. Teratogenic sign was shown by one nestling in brodifacoum treated plot, where its primary feathers were malformed rendering it flightless besides tail length that were very short if compared to nestlings in control plot. Wing and tail length in brodifacoum treated plot was shorter by 15.26% and 18.24%, respectively compared to control plot.
Owls [Working Title]
Rat infestation in crops has been dealt with the crudest method of hunting and trapping to reliance on natural enemies to application of rodenticides and the present approach of IPM by combining baiting with biological control by a suitable predator. Sustainability is the key feature where rat pest is kept below the carrying capacity of the habitat avoiding harming nontarget animals and preserving the environment. Combining rodenticides with predators calls for a balancing act whereby the latter is not exposed in as much as possible to intoxication by the former through secondary poisoning. Long-term exposure to the first-generation anticoagulant rodenticide (FGAR) has given rise to bait resistance, prompting the formulation of highly toxic second-generation rodenticides (SGAR) that may overcome resistance in rat but lead to bioaccumulation of rodenticide residues in the predator leading to lethal or sublethal effects on the latter, which defeats the purpose. Therefore, the choice of rodenticides and applications may bring out the desired effects for a sustainable rat control programme in combination with predators as natural enemies. This paper reports on a number of studies to achieve sustainable rat control programme by combining available rodenticide formulations with the natural propagation of barn owls Tyto javanica in oil palm plantation in Malaysia.
Secondary poisoning of captive barn owls
2014
The potential secondary hazards of two anti-coagulant rodenticides commonly used in Malaysian oil palm plantations were evaluated through feeding trials with captive barn owls. A total of 12 adult barn owls (six pairs) were assigned to two rodenticide treatments and a control. The two treatments were rats fed with bromadiolone (0.005% a.i) and chlorophacinone (0.005% a.i) respectively. All rodenticide treated owls received four poisoned rats at Day 1, 3, 5 and 7 and a non-poisoned rat on each intervening day for 30 days. Each barn owl of the control group received a non-poisoned rat throughout the study. The reliability of a non-invasive technique such as an estimation of anti-coagulant rodenticide residue in regurgitated pellets and blood samples, were also evaluated. Barn owls showed behavioural aberrations such as coarse breathing, frequent closing of the eyes and reduced flying activity as early as Day 5 after consuming three poisoned rats. The weight recorded at Day 7 after treatment showed that all treated owls registered a reduction in weight. The owls in the control group on the contrary gained weight. Bromadiolone and chlorophacinone were found to have high degree of toxicity on captive barn owls. After feeding the birds with as few as four poisoned rats in a week the signs of toxicity in birds such as haemorrhages (beak) and haematoma (wing) were found. This finding is very crucial since barn owls have been reported to consume up to three rats per night and this would certainly increase their potential exposure to lethal secondary poisoning. The detection of residue in the pellets regurgitated by barn owls can be used to indicate exposure of the latter to both compounds. However, as the blood residue method is limited to the exposure duration of the compounds, this technique can only detect recent exposure to bromadiolone and chlorophacinone.
Anticoagulant Rodenticides in Three Owl Species from Western Canada, 1988–2003
Archives of Environmental Contamination and Toxicology, 2009
Anticoagulant rodenticides are widely used to control rodent infestations. Previous studies have shown that nontarget organisms, such as birds, are at risk for both primary and secondary poisoning. This paper presents rodenticide residue information on the livers from 164 strigiformes which included barn owls (Tyto alba), barred owls (Strix varia), and great horned owls (Bubo virginianus), collected from 1988 to 2003 in the province of British Columbia and the Yukon Territory, Canada. Livers were analyzed for brodifacoum, bromadiolone, chlorophacinone, diphacinone, difethialone, and warfarin. Our results show that, of the 164 owl livers analyzed, 70% had residues of at least one rodenticide, and of these 41% had more than one rodenticide detected. Of the three species of owls examined, barred owls were most frequently exposed (92%, n = 23); brodifacoum and bromadiolone were most often detected, with liver concentrations ranging from 0.001 to 0.927 mg/kg brodifacoum, and 0.002 to 1.012 mg/kg bromadiolone. Six of the owls (three barred owls, two barn owls, and one great horned owl) were diagnosed as having died from anticoagulant poisoning; all six owls had brodifacoum residues in the liver.
Ornithological Applications, 2021
Pesticide use is pervasive and the exposure of non-target wildlife has been well documented over the past half-century. Among pesticides, anticoagulant rodenticides (AR) have emerged as a particularly important threat in forests of the western United States, with exposure and mortality reported for several species of conservation concern. To further quantify this threat, we collected specimens of Barred Owls (Strix varia) and Barred Owl x Spotted Owl hybrids from the Klamath and Cascade Mountains and Sierra Nevada in California, USA to use as indicator species for environmental contamination with AR and to infer exposure of closely related and ecologically similar Northern and California Spotted Owls (S. occidentalis caurina, and S. o. occidentalis, respectively). We tested 115 Barred Owl and 12 Barred Owl x Spotted Owl hybrid livers for 8 AR compounds and found high rates of exposure (62%) across our study area, and greater than previous studies in the Pacific Northwest. In additio...
The Effects of Rodenticide Residues Deposited in Eggs of Tyto alba to Eggshell Thickness
Sains Malaysiana, 2015
The deposition of anticoagulant residues in the eggs of barn owls, Tyto alba by assessing eggshell thickness were investigated in oil palm plantations. Three study plots were set aside; one plot each baited with chlorophacinone and bromadiolone, respectively and the third was left unbaited. Four baiting campaigns were conducted on the rodenticide designated plots, coinciding with the breeding seasons of T. alba. High performance liquid chromatography (HPLC) showed that 29.73% (n=37) and 5.35% (n=56) of addled eggs collected from rodenticide treated plots contained bromadiolone and chlorophacinone, respectively, with mean concentration of residues from 0.009 to 0.031 µg/g wet weight. None of the addled eggs (n=28) collected from the unbaited plot contained bromadiolone or chlorophacinone residues. The detection of rodenticide residues in both albumen and yolk indicated high risk of secondary poisoning to both compounds. However, low levels of residues detected have no effects on shape of egg, eggshell mass or thickness.