Shakinah Ravindran

Human disturbance to nesting raptors can influence breeding success, especially during early breeding. This study examined the impact of researcher presence, a relatively low impact human disturbance, on eastern barn owls Tyto javanica javanica during monitoring of 57 nest‐boxes in oil palm plantations in Malaysia over a period of 30 months. We analysed the impact of number of researcher visits on breeding success of barn owls, and recorded the immediate response of barn owls to researcher presence, namely nest‐box return times. We investigated the influence of potential variables (number of visits, visit frequency, breeding stage, habitat, study site, etc.) on barn owl nest survival using a logistic‐exposure model. Additionally, we explored the influence of female return times on hatching success using generalized linear models (GLMs) and used generalized linear mixed models (GLMMs) to analyse variables influencing female return times. A total of 108 breeding attempts were recorded in this study and we found that researcher visits, specifically frequency of visits, had a significant effect on nest survival of barn owls, especially during the incubating stage. Breeding female barn owls showed moderate individual variability in return times, and had shorter return times in mature habitats and when incubating. Longer nest‐box return times also influenced hatching success and we recorded several cases of immediate predation on eggs and young in nests after females were flushed from nest‐boxes by researcher visits. We recommend that researcher presence be minimized with lower frequency and shorter duration of researcher presence during incubation to encourage higher breeding success in barn owls. We also recommend that nest‐box checks be conducted at dusk to ensure nests are not left unattended for extended periods.

Tyto alba javanica desempeña un papel crucial en el control biológico de ratas, y la efectividad de este agente de control biológico depende en gran medida del éxito reproductivo de las aves, que a su vez podría verse influido por el tiempo (i.e., condiciones atmosféricas actuales). Por lo tanto, este estudio tuvo como objetivo investigar la influencia de las variables del tiempo en el éxito reproductivo de T. a. javanica en un país tropical. Se realizaron censos mensuales durante cuatro años para registrar los parámetros reproductivos de las lechuzas, a saber: tasa de ocupación de cajas nido, intentos de reproducción, tamaño de puesta, éxito de eclosión, tamaño de nidada, número de volantones y éxito de emplumamiento. Las variables del tiempo analizadas fueron el número de días lluviosos, la precipitación total (mm), la intensidad de la lluvia, la duración de la insolación, la temperatura mínima y máxima, y la evapotranspiración. Realizamos un análisis descriptivo exploratorio para visualizar las interacciones entre las variables del tiempo y los parámetros reproductivos. En general, la temperatura se correlacionó negativamente con la mayoría de los parámetros reproductivos, lo que sugiere que las temperaturas más altas pueden reducir la capacidad reproductiva de las lechuzas. El tamaño de la nidada también estuvo influido por la precipitación. Este estudio aporta información sobre cómo el tiempo—específicamente la temperatura—podría afectar la reproducción de T. a. javanica, lo que sugiere que la especie puede ser sensible al cambio climático, con implicaciones para su biología poblacional. [Traducción del equipo editorial]

Anticoagulant rodenticides (ARs) are used worldwide for the control of rodent pests and are the main method of control of rat pest populations in agricultu

This study investigated the diet of introduced barn owls (Tyto alba javanica, Gmelin) in the urban area of the Main Campus of Universiti Sains Malaysia, Penang, Malaysia, based on collected regurgitated pellets. We also compared the diet of the introduced barn owls with the diet of barn owls from two agricultural areas, i.e. oil palm plantations and rice fields. Pellet analysis of introduced barn owls showed that commensal Norway rats, Rattus norvegicus, made up the highest proportion of the diet (65.37% prey biomass) while common shrews, Suncus murinus were the second highest consumed prey (30.12% prey biomass). Common plantain squirrel, Callosciurus notatus, made up 4.45% of the diet while insects were taken in a relatively small amount (0.046% prey biomass). Introduced barn owls showed a preference for medium-sized prey, i.e. 40–120 g (52.96% biomass and 38.71% total). In agricultural areas, rice field rats, Rattus argentiventer predominated the diet of barn owls (98.24% prey biomass) in rice fields while Malayan wood rats, Rattus tiomanicus, were the most consumed prey in oil palm plantations (99.5% prey biomass). Food niche breadth value was highest for barn owls introduced in an urban area with a value of 2.90, and 1.06 in rice fields and 1.22 in oil palm plantations. Our analysis reiterates the prey preference of barn owls in various landscapes for small mammals. Our results also indicate the suitability of utilizing barn owls as a biological control not only in agricultural areas, but also as a biological control agent for commensal rodent pests in urban areas.

Physical trapping is an important first step in controlling pest populations and species identification; and bait preferences are crucial information for effective management. This study was conducted to explore species diversity and bait preferences of commensal species in urban areas on Penang Island. Live trapping was carried out in eight sampling sites on Penang Island in commercial and residential areas. Eight different type of baits were used; apple and peanut butter (APB), white bread and peanut butter (BPB), salted fish (SF), salted fish and peanut butter (SFPB), white bread and fish extract (BFE), fried chicken leftover (FCL), vegetables and peanut butter (VPB) and sausages (S). The most successful bait was the high protein bait, fried chicken leftover (FCL), with a capture success rate of 35.56%. We also analysed the bait preferences for the different species of small mammals captured in our study. Five species of small mammals were captured in our study sites: Rattus norvegicus, Rattus rattus, Mus musculus, Bandicota bengalensis and Suncus murinus. Norway rats, R. norvegicus was the most trapped species in commercial areas whereas lesser bandicoot rats, B. bengalensis was the most captured species in residential areas.

This study investigated the diet of introduced barn owls ( Tyto alba javanica , Gmelin) in the urban area of the Main Campus of Universiti Sains Malaysia, Penang, Malaysia, based on collected regurgitated pellets. We also compared the diet of introduced urban barn owls with the diet of barn owls from two agricultural areas, i.e. oil palm plantations and rice fields. Pellet analysis of barn owls introduced in the urban area showed that commensal Norway rats, Rattus norvegicus , made up the highest proportion of the diet (65.37% prey biomass) while common shrews, Suncus murinus were the second highest consumed prey (30.12% prey biomass). Common plantain squirrel, Callosciurus notatus , made up 4.45% of the diet while insects were taken in a relatively small amount (0.046% prey biomass). Introduced barn owls showed a preference for medium-sized prey, i.e. 40 to 120g (52.96% biomass and 38.71% total). In agricultural areas, Rattus argentiventer predominated the diet of barn owls (98.24% prey biomass) in rice fields while Malayan wood rats, Rattus tiomanicus , were the most consumed prey in oil palm plantations (99.5% prey biomass). Food niche breadth value was highest for barn owls introduced in an urban area with a value of 2.90, and 1.06 in rice fields and 1.22 in oil palm plantations. Our analysis reiterates the prey preference of barn owls in various landscapes for small mammals. Our results also indicate the suitability of utilizing barn owls as a biological control not only in agricultural areas, but also as a biological control agent for commensal rodent pests in urban areas.