Predation of birds by the Barn Owl (Tyto furcata Temminck, 1827) in four envi-ronments in southern Santa Fe province, Argentina

ABSTRACT In this paper we present the birds that make up the diet of Tyto furcata in four environments in the south of the province of Santa Fe, where previous data were practically nonexistent. From this contribution, 37 individuals corresponding to three Orders and 10 Families could be established as part of the diet of this raptor. The family with the most predated representatives was Thraupidae (n=19) with three genera: Sicalis, Zonotrichia and Sporophila. The average body size of the prey was 17cm. The peri-urban/suburban (AP/S) environment had the greatest diversity of prey consumed. In all environments, the highest abundance occurred in the warm seasons (spring-summer), corresponding to the decrease in micromammal populations. This type of study demonstrates the effectiveness of pellet analysis as a tool to know the existing species in highly anthropized environments. RESUMEN En este trabajo se presentan las aves que componen la dieta de Tyto furcata en cuatro ambientes del sur de la provincia de Santa Fe, donde los datos anteriores eran prácticamente inexistentes. A partir de este aporte se pudo establecer que 37 individuos correspondientes a tres órdenes y 10 familias forman parte de la dieta de esta rapaz. La familia con más representantes depredados fue Thraupidae (n=19) con tres géneros: Sicalis, Zonotrichia y Sporophila. El tamaño medio del cuerpo de las presas fue de 17 cm. El entorno periurbano/suburbano (PA/S) presentó la mayor diversidad de presas consumidas. En todos los entornos, la mayor abundancia se produjo en las estaciones cálidas (primavera-verano), lo que se corresponde con la disminución de las poblaciones de micromamíferos. Este tipo de estudio demuestra la eficacia del análisis de egagrópilas como herramienta para conocer las especies existentes en ambientes altamente antropizados.

Breeding behaviour and diet of Rufous Owls Ninox rufa in the Darwin Botanic Gardens

The breeding cycle of a pair of Rufous Owls Ninox rufa was observed over five breeding seasons, 2016–2020, in the Darwin Botanic Gardens, Northern Territory. A pair failed or did not breed in four of those years and raised one fledgling in 2018. The Owls occupied a hollow 2.5 m above ground in the trunk of an exotic Earpod Tree Enterolobium cyclocarpum. In 2018, laying occurred sometime between 11 June and 2 July, hatching between 21 and 25 July, and fledging (first true flight) on 6 September, with branching on 2–5 September, giving a nestling period of 44–48 days. The juvenile remained dependent until mid November, giving an estimated post-fledging dependence period of 10 weeks. For the following 3 weeks, it roosted alone within its natal home range, increasingly far (270–320 m) from the nest tree and roosting adults. Calling behaviour (including duetting by the pre-laying pair), courtship, copulation and parental behaviour and routines are described. From observations and pellet analysis, the Owls’ diet consisted of 78% mammals [Common Brushtail Possums Trichosurus vulpecula arnhemensis, flying-foxes (probably all Black Flying-foxes Pteropus alecto) and rats (probably Black Rats Rattus rattus)] and 22% birds (passerines and non-passerines up to Orange-footed Scrubfowl Megapodius reinwardt in size) by number.

Diet of the lesser kestrel Falco naumanni at post-breeding roosts in southern Albania

The lesser kestrel is an insectivorous and migratory falcon species, frequently using communal roosts in the post-breeding period in southern Europe. Using pellet analysis from two post-breeding roosting sites in southern Albania collected in August 2017, we identified 1539 prey items belonging to approximately 58 prey species, 20 families and 7 orders in 110 pellets from two sites. Invertebrates made up the major part of the diet spectrum (PNI = 99.8 %, PFI = 100 %). Invertebrate prey body size varied between 8 and 62 mm (mean 28.1 mm). Bush-crickets (Tettigoniidae) and locusts (Acrididae) were the most abundant and frequent prey groups (PNI = 33 % resp. 48.6 % and PFI = 97 % resp. 94 %). Within the bush-cricket family we could identify the species of genera Tettigonia, Decticus, Platycleis, Isophya and Metrioptera. The species of genera Calliptamus, Stenobothrus and Locusta belonged among the locust species identified in the food. Birds and mammals were found in pellets only occasionally. The prey composition was rather similar at both studied sites, while locusts (Acrididae) were more abundant at the Jorgucat site and bush-crickets (Tettigonioidea) at the Mollas site in the same time. Prey groups Scarabeidae beetles and other beetles (Coleoptera other) were more abundant and frequent at Mollas than at Jorgucat, and spiders were more frequent at Jorgucat. These results suggest that the high abundance of orthopterans and beetles in the food supply in certain localities is the main reason for selection and stable occupancy of these massive communal roosting sites by lesser kestrels in Albania.

First observations of the diet of the Pearl Kite (Gampsonyx swainsonii magnus) in southwestern Ecuador

We describe the diet of Pearl Kite (Gampsonyx swainsonii magnus) by pellet analysis collected in an active nest in southwest Ecuador in May 2018. Reptiles were the most consumed taxonomic group both in frequency of occurrence (FO = 46.4%) and in biomass (B = 59.8%), followed by birds (FO = 33.9% and B = 38.3%) and insects (FO = 19.6% and B = 1.8%). Our results showed Pearl Kite as a generalist raptor but with a higher consumption of reptiles, which is according with previous studies in other areas where other subspecies inhabit, despite this subspecies showed a higher consumption of birds. Despite the low sample size, this study is interesting as it is the first one on the diet of the Pearl Kite for Ecuador and also for this subspecies. Basic studies on the trophic ecology of Neotropical raptors such as this are needed. For this reason we encourage further studies to fill existing gaps in knowledge and improve effective long-term conservation strategies.

Dietary resource partitioning among age-sex classes of Agama agama (Squamata: Agamidae) assessed by fecal pellet analysis

Dietary resource partitioning among age-sex classes of Agama agama (Squamata: Agamidae) assessed by fecal pellet analysis. Dietary analysis is critical to understand the ecological roles of lizards, especially of species of Agama that are colonizing continents and islands from which they were previously absent. The foraging habits of four groups—viz., adult females, adult males, and young and juveniles (of both sexes)—of Agama agama in Nigeria were observed to assess the diet of the lizards and the contribution of the diet to separating age-sex classes. The claim that fying arthropods are less likely to be eaten by lizards was tested, and the hypothesis of dietary opportunism was explored. Sets (3–5 pellets) of 1453 fecal pellets collected during a 2-yr period were linked to individual lizards. Multivariate discriminant analysis of individual food items showed 61% lizards were correctly classifed to age-sex. However, items pooled into composite food groups, yielded fewer (43%) correctly classifed lizards. Cluster Analysis indicated that individual foods were less common (46.3%) to lizard classes than composite foods (76.1%). Thus, lizard age-sex classes are better differentiated when prey item is identifed at the lowest possible taxonomic level. Overall, arthropods are the largest, composite food for all lizard classes but, the relative amounts of different arthropod taxa varies signifcantly, and is highest for Diptera. Other foods include plants, seeds, and non-arthropod animal material. Differing coeffcients of variation accentuate dietary disparities within classes. Proportions of most individual and composite diet items differ signifcantly by month, season, and study site. Although consumed by lizards, no traces of white mold were found in the feces; this underscores the value of combining fecal analysis with surveillance of foraging habits of Agama agama.

Indirect Influence of African Swine Fever Outbreak on the Raven (Corvus corax) Population

Carrion plays a crucial role in the raven’s diet. In the past, domestic pig carrion was widely available in Poland. This changed with an African swine fever (ASF) outbreak and the introduction of strict procedures aimed at stopping the virus from spreading. We compared data from Central Poland (field and forest mosaic, study area of 105 km2) for two periods, i.e., before (2011–2014) and after the ASF outbreak (2015–2018). In breeding seasons, nests of ravens were found, juveniles were counted, and the time when juveniles left their nests was recorded. Diet composition data were based on pellet analysis and direct observations of feeding birds. The number of breeding pairs dropped from 12.3 to 7.5 in the second period. Breeding parameters were similar. However, birds in the second period had fewer fledglings per successful pair. Domestic pig carrion was found to be an important food item, and with its limited supply, ravens changed their diet, i.e., they fed on the carrion of dogs and cats or preyed on small vertebrates more often. Overall, our study points to a crucial role of the availability of the carrion of big farm animals (i.e., domestic pig) in maintaining the high density of breeding raven populations.

Food composition of the Little Owl (Athene noctua) in a farmland area of Central Hungary, with particular attention to arthropod diversity

The feeding of Little Owl (Athene noctua) was studied in a farmland area of Kiskunság, Central Hungary. For the analyses, a total of 661 Little Owl pellets were collected between February and September 2005 from three locations, corresponding known Little Owl territories situated nearby the settlements Apaj, Kunpeszér and Ladánybene. The aim of the present study was to explore the diet composition of Little Owl and to give a detailed evaluation of the arthropod diversity based on the pellet analysis. The identified prey items represented 15 vertebrate and 39 invertebrate species/taxa. In terms of prey number, dominance of small mammals was observed in two sites (Apaj – 55%, Kunpeszér – 68%), while birds and mammals shared almost equal dominance (~25%) in Ladánybene. The most numerous mammal species was the Common Vole (Microtus arvalis), while the Starling (Sturnus vulgaris) played key role among the birds. Contribution of amphibian Common Spadefoot (Pelobates fuscus) was considerable, while share of reptiles was marginal. Vertebrates also played a predominant role by contributing over 99% of the overall prey biomass in all study sites. Invertebrate prey dominance ranged from 24.8–30.0% while their contribution to the overall biomass was very low (0.14–0.34%). Large sized beetles (Pentodon idiota, Melolontha hippocastani) and orthopterans (Tettigonia viridissima, Gryllotalpa gryllotalpa) were preferred. Arthropod species richness and diversity were the highest in Kunpeszér, supposedly owing to the rich mosaic habitat structure.

Eco-geographical variation in the diet of the Barn Owl (Tyto alba) in mountainous areas of France

Because of the worldwide distribution of the Barn Owl (Tyto alba) and the easily way to find its pellets, it is often used to diet studies. To investigate the eco-geographical impact of mountainous areas on its diet, we conducted studies in the Jura, Alpes, Central and Pyrénées mountains and we also did pellet analysis from 8 sites in the Jura mountains. Analysis of the tooth and skull content of pellets allowed us to draw up two types of change in the diet of Tyto alba in correlation with mountain elevation. The first one concerns the Jura, Alpes and Central mountains, where the diversity of the diet declines with the increase in elevation. The second one concerns the Pyrénées mountains, where there is no change in the diversity of the diet, perhaps because of the higher diversity of small mammals caused by mediterranean influence. Thus, it seems that elevation cau ses a decrease in diet diversity of Tyto alba in continental mountains (Jura, Alpes and Central mountains) probably because of more homogeneous landscapes dedicated to grass production. However, in Mediterranean mountains (Pyrénées), a more diversified small mammal guild provides a constant level of diet diversity.