Motti Charter

Does nest box location and orientation affect occupation rate and breeding success of Barn Owls Tyto alba in a semi-arid environment?

Abstract. To date, nest orientation and location in hole-nesting birds have been studied mainly in temperate regions and in diurnal cavity breeders. Here we studied the effect of exposure, orientation, and habitat on nest box occupation and breeding success of Barn Owls in a semi-arid environment. The occupation of nest boxes varied with exposure and orientation. A higher percentage of occupation and more Barn Owl nestlings per breeding attempt were found in nest boxes located in the shade than in the sun, and in those facing east/north rather than other directions. The temperature in the nest boxes varied, being lowest in those located in the shade and in those facing east. Nest boxes located in crop fields fledged more young per breeding attempt than those located in date plantations. We suggest that the higher nest box occupation and number of nestlings fledged was probably due to the lower temperatures in those boxes, an important factor in a hot/arid environment, although alternative explanations are also considered.

Diets of Urban Breeding Barn Owls (Tyto alba) in Tel Aviv, Israel

Abstract Examination of 193 whole pellets and a number of partial pellets of a pair of Barn Owls (Tyto alba) in Neve Shiret, a neighborhood of Tel Aviv, Israel during the 2005 and 2006 breeding seasons revealed a total of 711 prey specimens. Six species of small mammals comprised 99.3% of the diet with a frequency of occurrence of 100% in pellets. Levant voles (Microtus socialis guentheri) (48.1%) and house mice (Mus musculus) (32.9%) were the most common prey species. The Barn Owl pair hunted in croplands adjacent to an urban residential area.

Diets of Barn Owls Differ in the Same Agricultural Region

Abstract We studied the diet of 20 Barn Owl (Tyto alba) pairs breeding in three habitats (alfalfa fields, date plantations, and villages) in the same agricultural region in the Jordan Valley, Israel. Small mammals, particularly three rodents (Levant voles [Microtus socialis guentheri], house mouse [Mus sp.], and Tristrams jird [Meriones tristrami tristrami]), comprised 73 to 88% of the 3,544 prey items taken by Barn Owls in the three habitats. Frequencies in number and biomass of the rodent species differed among habitats. The number of bird species, their frequencies, and biomass in the diet were higher in villages than in the other two habitats, and were related to the higher diversity of birds breeding in villages. The frequency of birds in the diet was negatively correlated with distance from the village to open fields. Differences in the diet of Barn Owls among the three habitats most likely reflected differences in the distribution and abundance of the prey items in each habitat.

BREEDING SUCCESS OF THE EURASIAN KESTREL (FALCO TINNUNCULUS) NESTING ON BUILDINGS IN ISRAEL

EXITO REPRODUCTIVO DE FALCO TINNUNCULUS AL NIDIFICAR EN EDIFICIOS EN ISRAEL Medimos el exito reproductivo de individuos de la especie Falco tinnunculus que nidificaron en edificios en tres localidades: ciudades grandes, ciudades pequenas y pueblos pequenos. Debido a que estos halcones cazan principalmente en campos abiertos y alimentan a sus polluelos principalmente con pequenos mamiferos, el exito reproductivo de las parejas que nidifican en las ciudades puede ser reducido ya que la abundancia de presas es menor en areas urbanas. Encontramos que tanto el numero de volantones por pareja como el porcentaje de parejas que fueron exitosas produciendo por lo menos un volanton, fueron menores en las ciudades que en los pueblos. Los nidos en edificios en los tres tipos de localidades pueden proveer mayor proteccion ante depredadores incluso en areas rurales, debido a que la mayoria de los depredadores evita los edificios habitados por humanos. Nuestro hallazgo de que el exito reproductivo de halcones que se rep...

THE EFFECT OF DIFFERENT NEST TYPES ON THE BREEDING SUCCESS OF EURASIAN KESTRELS (FALCO TINNUNCULUS) IN A RURAL ECOSYSTEM

EL EFECTO DE DIFERENTES TIPOS DE NIDO SOBRE EL EXITO REPRODUCTIVO DE FALCO TINNUNCULUS EN UN ECOSISTEMA RURAL Estudiamos la tasa reproductiva de Falco tinnunculus en diferentes tipos de nido artificiales y naturales en una region rural de Israel. Los nidos se clasificaron en tres tipos: (1) nidos grandes artificiales de tipo cerrado (i.e., cajas de nidificacion), (2) nidos pequenos artificiales de tipo cerrado (i.e., cajas de nidificacion) o (3) nidos naturales de tipo abierto (i.e., nidos en palmas datileras Phoenix dactylifera). El exito reproductivo fue menor en las cajas de nidificacion grandes: el porcentaje de los nidos en que los huevos eclosionaron fue el mas bajo, al igual que el tamano de la parvada, el numero de pichones que abandonaron el nido por puesta de la pareja y el porcentaje de productividad de los huevos. Un numero significativamente menor de parejas fueron exitosas en las cajas de nidificacion grandes en producir al menos un volanton que en los otros dos tipos de nido. Esto posibleme...

The importance of micro-habitat in the breeding of Barn Owls Tyto alba

Capsule Habitat parameters associated with 706 Barn Owl (Tyto alba) nesting boxes in Israel were analysed. Pairs bred in 259 of the boxes. The intensity of agricultural practices at nestbox sites were shown to have only a weak effect on aspects of Barn Owl breeding in this region.

Feeding specialization of urban Long-eared Owls, Asio otus (Linnaeus, 1758), in Jerusalem, Israel

Abstract The diet of Long-eared Owls (Asio otus) that breed and hunt within the grounds of a bird-ringing station located in a large city park in Jerusalem, Israel, was investigated. 13 species of bird were the most common prey group (91% by number) with a frequency of occurrence of 99% in pellets, with House Sparrows, Passer domesticus, and Blackcaps, Sylvia atricapilla, as the most frequent prey species (22% and 17% by number). 29% of the bird specimens found in pellets had been ringed at the ringing station. The frequency of residential and migratory passerines caught by Long-eared Owls and ringed at the ringing station was similar, whereas more migrants were captured and ringed during the spring than summer. A comparison of bird species that were hunted relative to their frequency in the habitat revealed that the owls caught more Sylvia warblers than expected. Long-eared Owls in this study most probably specialised on birds because of the abundance of passerines and the lack of small mammals.

Characterizing the accuracy of a self-synchronized reverse-GPS wildlife localization system

We characterize the accuracy of a wildlife localization system that is based on the reverse-GPS or time-of-arrival (TOA) principle, in which radio receivers at known locations collaborate to determine the location of a transmitter attached to a wild animal. We describe the system in detail and show that it produces accurate location estimates in real settings and over long periods of time. Localization errors of wild animals carrying our transmitters have standard deviation of about 5m and mean of 5-15m. If we restrict the system to operate in the center of the receivers band-pass filters, the mean error drops to about 5m. We also show how to reliably quantify the error in each individual location estimate. In addition to the characterization of accuracy, we introduce three technical innovations in the system. First, a method to model the error of individual time-of- arrival measurements, enabling correct weighing of the data to estimate locations and allowing estimation of the covariance matrix of each location estimate. Second, extensive use of known- position beacon transmitters, to synchronize the clocks of receivers (radio-frequency TOA localization require accurate clocks), to characterize and continuously monitor the performance of the system, and to model arrival- time-estimation errors. Third, we estimate the covariance matrix of each localization.

Nest-site competition between invasive and native cavity nesting birds and its implication for conservation

Nesting cavities are often a limited resource that multiple species use. There is an ongoing discussion on whether invasive cavity nesting birds restrict the availability of this key limited resource. While the answer to this question has important conservation implications, little experimental work has been done to examine it. Here, we aimed to experimentally test whether alien cavity nesting birds affect the occupancy of cavities and the resulting breeding success of native cavity breeders in a large urban park located in Tel Aviv, Israel. Over three breeding seasons, we manipulated the entry size of nest boxes and compared the occupancy and breeding success of birds in nest boxes of two treatments. These included nest boxes with large-entrance and small-entrance holes. The large-entrance holes allowed access for both the native and invasive birds (the two main aliens in the park are the common mynas and rose-ringed parakeets). The smaller-entrance boxes, on the other hand, allowed only the smaller sized native cavity breeders (great tits and house sparrows) to enter the boxes but prevented the alien species from entering. We found that the large-entrance nest boxes were occupied by five different bird species, comprising three natives (great tit, house sparrow, Scops owl) and two invasive species (common myna, rose-ringed parakeet) while the small-entrance boxes were only occupied by the two native species. The alien common mynas and rose-ringed parakeets occupied 77.5% of the large-entrance nest boxes whereas native species, mainly great tits, occupied less than 9% of the large-entrance boxes and 36.5% of the small-entrance boxes. When examining the occupancy of those cavities that were not occupied by the aliens, natives occupied both the small and large-entrance nest boxes equally. Three quarters (78%) of the great tits breeding in the large-entrance boxes were usurped by common mynas during the breeding season and as a result breeding success was significantly lower for great tits breeding in the large-entrance boxes compared with the small-entrance boxes. The results of this study suggests that the invasive alien species can reduce the breeding potential of native cavity breeders both by exploiting the limited breeding resource (nest cavities) and by directly usurping cavities already occupied by the native species. Since the majority of large-entrance nest boxes were occupied by the larger alien birds, less native species bred in the limited number of unoccupied large-entrance nest boxes because of exploitation competition. We propose that for management purposes, nest-box programs that alter the entrance size of available natural cavities may be a practical approach, reducing the competition between native cavity breeders and alien invasive birds, and especially benefiting the smaller native cavity breeders.

Conditional association between melanism and personality in Israeli Barn Owls

Capsule Boldness defines the extent to which animals are willing to take risks in the presence of a predator. Late, but not early, in the breeding season, Israeli nestling Barn Owls displaying larger black feather spots were more docile, feigned death longer and had a lower breathing rate when handled than smaller-spotted nestlings. Larger-spotted breeding females were less docile if heavy but more more docile if light. The covariation between personality (boldness vs. timid) and melanin-based colouration is therefore conditional on environmental factors.