Owl Pellets Research Articles

Distribution, habitat and conservation status of the eastern pygmy-possum Cercartetus nanus in Tasmania.

We review literature pertaining to the distribution, habitat and conservation status of the eastern pygmy-possum Cercartetus nanus in Tasmania. Records from fauna surveys, museum specimens, and the Tasmanian Natural Values Atlas database, suggest that although C. nanus is widespread, it occurs in low numbers in Tasmania. From 51 fauna surveys examined, only 19 C. nanus were detected in a total of 47,087 Elliott trap-nights, 5,665 pitfall trap-nights, 196 scats or owl pellets, 899 spotlight hours, and 86 predator stomachs. A total of 102 Tasmanian C. nanus specimens was located in Australian and overseas museums. These records combined with 23 from the Natural Values Atlas database and 61 from an earlier published collation represent 99 of 679 grid squares (10 km x 10 km) overlaid across Tasmania (including King Island and Flinders Island). The patchy distribution of these records may be a reflection of low survey effort, low population numbers, low detectability or a combination of these and other factors. The highest number of records for a single locality was only four. Available data suggest that Tasmanian populations may be small and therefore potentially at risk from habitat loss, inappropriate fire regimes, and firewood collection. We believe there is a pressing need for further surveys to more clearly define the conservation status of C. nanus in Tasmania.

A new species of hopping-mouse, Notomys robustus sp. Nov. (Rodentia : Muridae), from cave deposits in the Flinders and Davenport Ranges, South Australia

Notomys robustus sp. nov. is described from skulls found in whole and decomposed owl pellets from caves at Chambers Gorge in the Flinders Ranges, South Australia. The holotype was contained within a complete owl pellet, as were several paratypes. The species is distinguished by the unique conformation of the cusps of the upper first molar teeth. In adults, the anterodorsal region of the zygomatic arch is much wider than in any known species of Notomys. Since the original discoveries were made in 1976, the species has been found in more sites in the Flinders Ranges and at one other site near Mount Margaret in the Davenport Range, some 350 km northwest of the nearest Flinders Ranges site.

Habitat, morphology and karyotype of the Saharan shrewCrocidura tarfayaensis (Mammalia: Soricidae)

The Saharan shrewCrocidura tarfayaensis Vesmanis and Vesmanis, 1980, has a limited disribution along the Atlantic coast of Sahara, south of Agadir (Morocco) through Western Sahara into Mauritania and is only known from few captures and some owl pellets. Here we report field data from the successful trapping of five specimens ofC. tarfayaensis in the Guelmim region. The habitat was characterized by sand dunes along a river, with dense shrubberies ofTamarix sp., the huge grassErianthus ravennae (Poaceae) and flat bushes of Atriplex glauca var. ifniensis (Chenopodiaceae). Morphological discrimination withC. whitakeri were examined. The chromosomes ofC. tarfayaensis revealed a karyotype of 2n = 36, similar to that of the Canary shrewC. canariensis and the Sicilian shrewC. sicula. In conclusion,C. tarfayaensis seems to be a descendant of the presumed continental ancestor of the two island species.

An Identification Key to Rodent Prey in Owl Pellets from the Northwestern & Southeastern United States: Incisor Size To Distinguish Among Genera

An Identification Key to Rodent Prey in Owl Pellets from the Northwestern & Southeastern United States: Incisor Size To Distinguish Among Genera

Community evolution of Neogene micromammals from Langebaanweg ‘E’ Quarry and other west coast fossil sites, south-western Cape, South Africa

This paper provides an overview of the micromammalian palaeocommunities found in fossil bearing palaeontological and archaeological west coast sites dating from the Mio-Pliocene, as represented by the site of Langebaanweg ‘E’ Quarry, and other sites dating from the late Middle Pleistocene, until the late Holocene. Recent excavations at Langebaanweg have resulted in the addition of more murid genera to previously compiled faunal lists. An updated faunal list is presented, and a comparison is made on a generic level between the micromammals from Langebaanweg, and the considerably younger west coast fossil sites of Elands Bay Cave, Steenbokfontein Cave, the Saldanha Bay Yacht Club site and Hoedjiespunt 1, and some modern owl pellet collections. The palaeobiogeographical and palaeoenvironmental significance of the different west coast micromammal communities, and the evolution of the west coast rodent community is examined. Nine of the micromammal genera found at LBW are present in some, or all, of the west coast fossil sites dating from the late Middle Pleistocene until the Holocene. This indicates the endurance of many of the genera present at LBW, and in the Kalahari South West Arid and Namib Regions, from the Mio-Pliocene, up until the present.

Winter diet of long-eared owls (Asio otus) at an urban roost in Wichita, Kansas

In February 2004, we collected 104 long-eared owl (Asio otus) pellets from beneath a large pine tree in northern Wichita, Kansas that served as a winter roost for approximately four individuals. A detailed analysis of this collection provided basic information on pellet morphology (length, width, total weight, and weight of skeletal remains), as well as gross (% mammal, % bird) and fine (mammalian species composition) determinations of the long-eared owl's winter diet in this urban location. Long-eared owl urban roosts are somewhat uncommon, and this information might be valuable to owl researchers and other ecologists interested in urban wildlife.

INTRASPECIFIC VARIATION IN LESTODELPHYS HALLI (MARSUPIALIA: DIDELPHIMORPHIA)

The Patagonian opossum, Lestodelphys halli, is known from a few skeletons of captured animals and several isolated fragments recovered from owl pellets in Argentina. Recently, more than 300 remains (mandibles, maxillae, crania, and other bones) were found in owl pellets and associated bones, comprising the largest known collection of L. halli. A detailed morphological analysis of craniomandibular and dental variation is reported and comparisons with other small didelphids also are made. Intraspecific variation is discussed and differential diagnosis of the species is presented.

Isolation and amplification of shrew DNA from barn owl pellets

The last decade has seen a number of studies reporting the extraction of DNA from ancient sources, such as fossil bones. Owl pellets, which contain an excellent skeletal record of small mammals consumed, can be used in a non-invasive sampling method for genetic studies of free-ranging animals without the need for direct capture or even observation. Such a non-invasive sampling method will allow us to address questions that cannot be answered using conventional methods and will lead to a more integrated study of micromammals. In the present study, various protocols used for ancient DNA extraction were investigated, in order to determine the applicability of owl pellets as a source of DNA for phylogenetic and phylogeographical studies of micromammals. Of the 12 bone samples used in this study, 11 gave sequences of expected species (Crocidura, Rattus and Mus) and size (around 300 bp), using the pair of primers L14841/H15149, which target a highly conserved region of the cytochrome b gene. The results obtained demonstrate that mitochondrial DNA can be isolated and amplified using bones of micromammals found in barn owl (Tyto alba) pellets. The recovery of genetic data from owl pellets will enable the identification of prey species for several phylogenetic and phylogeographical studies of small mammals (Muridae and Insectivora) appearing in the owl's diet. The main advantages of this new approach are that (a) the pellets are very easy to find and collect, (b) the pellets can potentially provide a large number of individuals of small mammals, and (c) the method can cover a wide geographical area complementary to the range of owls of this type. © 2005 The Linnean Society of London, Biological Journal of the Linnean Society, 2005, 85, 331–340.

Outbreaks of Salmonellosis at Elementary Schools Associated with Dissection of Owl Pellets

Salmonella enterica serotype Typhimurium outbreaks occurred at two elementary schools after science club students dissected owl pellets. Forty primary cases were identified (26 culture-confirmed). At the first school, pellets were dissected on a cafeteria table, concurrent with after-school child care in the cafeteria. Subsequently, the table was not sanitized before use by after-school care students for snack, or before the next school lunch. At the second school, pellets were dissected in a dedicated science room, and fewer cases occurred. Pellets in both outbreaks originated from a single captive barred owl. The outbreak pulsed-field gel electrophoresis subtype of S. Typhimurium was isolated from the owl's pellets and feces, and from four frozen chicks from a batch used to feed the owl.

A Curious Pellet From a Great Horned Owl (Bubo Virginianus)

One of the traditional methods of determining the dietary preferences of owls relies upon the identification of bony remains of prey contained in regurgitated pellets. Discovery of a pellet containing a large, complete primary feather from an adult, male Ring-necked Pheasant (Phasianus colchicus) prompted us to examine in detail a small sample of pellets from a Great Horned Owl (Bubo virginianus). Our analyses of feather and hair remains in these pellets documented the presence of three species of birds and two species of mammals, whereas bones in the pellets represented only mammals. This finding indicates an important bias that challenges the reliability of owl pellet studies making use of only osteological remains.

Age structure of yellow-necked mouse (Apodemus flavicollis Melchior, 1834) in two samples obtained from live traps and owl pellets

The age structure of yellow-necked mouse (Apodemus flavicollis Melchior 1834) has been analyzed in individuals obtained by two methods: Trapping with Sherman live traps and obtainment of skulls from long-eared owl (Asio otus Linnaeus, 1758) pellets (predator diet analysis). One hundred and forty-four mice were analyzed for the degree of wear of the surface of molar crowns, and an additional 74 measurements were performed on captive-born Apodemus flavicollis individuals. We used a refined model of comparison that included seven classes of mouse age, rather than four classes, as suggested by other authors.

Comparison of the Diet of Two Desert-living Owls, the Long-eared Owl(Asio otus) and Little Owl (Athene noctua) from Southern Mongolia

The diet of two sympatric owl species, the long-eared owl (Asio otus) and the little owl (athene noctua) was investigated in an arid area of southern Mongolia using pellet analysis. In total 334 pellets of long-eared owl and 52 pellets of little owl were analysed, revealing the presence of five small mammal species (Dipodidae, three Muridae and one Soricidae), small birds and invertebrate fragments. Accumulative composition plots indicated a batch size of 35-60 pellets was sufficient to reveal representative diet composition. Small mammals comprised the largest component of the diet of long eared owls with four species recorded, Phodopus was the most frequently occurring (85%) followed by Meriones (33%). Bird and invertebrate remains were also found in long-eared owl pellets but comprised less than 2%. In contrast, invertebrates were the highest occurring component of the diet of little owls (35%), with small mammals occurring in only 40% of pellets. Meriones was the most frequently recorded small mammal in owl pellets (23%) and contributed the greatest in terms of overall rodent biomass. There was a highly statistically significant difference in the diet of the two species (÷2 = 2043, d.f. = 4,P<0.001). Levin's measure of niche breadth was greater for little owls (0.71) than long-eared owls (0.51), but overall the two species had low niche overlap using Levin's index (0.22). These results are discussed in relation to previous findings of these two species.

Comments on the Predator-Prey Relationship of the Texas Kangaroo Rat (Dipodomys elator) and Barn Owl (Tyto alba)

Abstract Rodent prey of the barn owl (Tyto alba) partly reflects the availability of prey species of small mammals. However, small- to moderate-sized mice of the genera Sigmodon (cotton rats), Oryzomys (rice rats) and Microtus (voles) are selectively preyed upon when available, and species of Dipodomys (kangaroo rats) are often underrepresented prey items. The range of T. alba in north Texas overlaps the restricted range of the little-studied Texas kangaroo rat (D. elator). Examination of regurgitated barn owl pellets provides the first documentation of predation on this distinctive rodent. However, given the ready availability of this kangaroo rat, its representation as a prey species of the barn owl is lower than expected, even given the usually poor representation of other Dipodomys species from other localities. Selective predation on favored prey and presence of other buffer species are certainly contributory factors to the low incidence of kangaroo rats in owl pellets. Some predator avoidance mechan...

Description of a New Genus and Species of Rodent (Murinae, Muridae, Rodentia) from the Khammouan Limestone National Biodiversity Conservation Area in Lao PDR

Saxatilomys paulinae, a new genus and species of murid rodent in the Dacnomys Division is described. It is based on two whole specimens and 14 individuals represented by fragments recovered from owl pellets. The samples come from the Khammouan Limestone National Biodiversity Conservation Area in Khammouan Province in central Lao PDR. This tower karst landscape is part of the Quy Dat limestone massif, which extends eastward into north-central Vietnam (Binh Tri Thien Province). The new genus and species is morphologically (and probably phylogenetically) allied to species of Niviventer and Chiromyscus, which are also members of the Dacnomys Division, but its semispinous dark gray upperparts, dark frosted gray underparts, large, extremely bulbous footpads, and a combination of derived and primitive cranial and dental traits exclude it from membership in Niviventer, Chiromyscus, or any other described genus of Indo-malayan murid. The new species is likely petricolous, and is part of a small but unique community of small nonvolant mammals containing the petricolous gymnure, Hylomys megalotis, and hystricognath, Laonastes aenigmamus. All three species have been collected only in forested, rocky habitats of the Khammouan Limestone, but comparable environments in the adjacent Vietnamese portion of the Quy Dat limestone massif may harbor these same species specialized for living in forested, karstic landscapes.

Landscape ecological analysis of barn owl pellet data from the Drava lowlands, Hungary

Small mammal fauna monitoring in the Drava Lowlands has been done partly by barn owl pellet collecting and analysis. In the present study the correlations between landscape patterns and barn owl food composition (i.e. the indirect representation of small mammal communities) were analysed using an approach how the cummulated data of particular breeding pairs can be interpreted as characteristic for the patch composition of the mosaic landscape considerably larger than the hunting range of barn owls. For landscape ecological analysis CORTNE LANDCOVER 1:50.000 mapping categories were applied, based on which natural or semi-natural areas, differing from each other also in their barn owl hunting qualities, were differentiated. Three larger areas along river Drava were investigated: two in the upper reach monitoring zone (ZákányPorrogszentkirály, and Berzence-Heresznye), and one in the lower Drava reach (Drávaiványi-Szaporca). In the two upper-reach zones the localities differed from the greater scale landscape in less than 30% of the patches, with only 3-5 patches showing significant difference. In the lower reach there was one sampling locality with 6 patches differing from the greater-scale area, although in the entire lower section 33% or less difference was found between patch compositions of the two scales. Based on patch overlap calculations and homogeneity tests it was concluded that small mammal faunal data of the localities can be cumulated and can be evaluated on much larger landscape ecological scales than barn owl hunting ranges.

Owl Pellet Taphonomy: A Preliminary Study of the Post-Regurgitation Taphonomic History of Pellets in a Temperate Forest

Abstract Owls are important contributors to the Tertiary small-vertebrate fossil record. They concentrate small-vertebrate remains by producing pellets rich in skeletal material that provide a sample of the small-vertebrate fauna of an area. A common assumption is that different predators inflict unique fragmentation and skeletal element representation signatures, thus providing a method for identifying a field assemblage as pellet derived, and possibly identifying the predator. In addition to the digestive process of pellet formation, the taphonomic history of a pellet includes the post-regurgitation processes of weathering, disintegration, transport, and burial, all of which can introduce biases into an assemblage and confound paleoecological interpretation. Analysis of a modern accumulation of small-vertebrate remains from Great Horned Owl (Bubo virginianus) pellets in a temperate forest environment on San Juan Island, Washington, reveals that fragmentation and skeletal-element representation change wi...

Micromammal taphonomy of el-Wad Terrace, Mount Carmel, Israel: distinguishing cultural from natural depositional agents in the Late Natufian

A taphonomic analysis of micromammal remains from the Late Natufian deposits of el-Wad Terrace, Mount Carmel, Israel, was conducted in order to test the long-standing premise of owl deposition as the primary accumulating agent. The inferred taphonomic sequence was modeled within an actualistic (recent) comparative framework incorporating a locally derived barn owl pellet collection and an off-site control assemblage of micromammal remains from the cliff overhanging the terrace. The sequence was reconstructed based on multiple types of recorded taphonomic data, comprising skeletal modifications (breakage, digestion, weathering, gnawing, and charring) and age structure. Evidence for post-depositional processes including fluvial transport, trampling, and weathering was isolated and consequently the typical owl imprints were traced through the two actualistic and the archaeological assemblages. Based on the extent of breakage and patterning in skeletal element frequencies it was also possible to scale the preservation potential of primary data in el-Wad Terrace as a discrete site type, intermediate between true cave and open-air depositional environments. Verifying the role of owls as principal agents of accumulation of the el-Wad Terrace micromammal remains enabled the detection of two minor superimposed cultural patterns: consumption of mole rats (Spalax sp.) by the Natufians and commensalism of mice (Mus spp.).

40K, 137Cs, 90Sr, 238,239+240Pu and 241Am in mammals' skulls from owls' pellets and owl skeletons in Poland

Skulls of small mammals belonging to two species of rodents and three species of insectivores collected in Eastern Poland were the subject of the present investigation. The skulls were separated from owl pellets. Activities of 40K, 137Cs, 90Sr, 238,239+240Pu and 241Am were determined by means of gamma spectrometry as well as liquid scintillation spectrometry or alpha spectrometry along with relevant radiochemical procedures. A detailed description of the procedures is provided. The research was supplied with the analysis of three skeletons of owls. No measurable difference between the skulls of rodents and insectivorous animals with regard to activity of any of the examined radionuclides was found. No accumulation effect in the owl skeletons was detected. Though measured activities of 137Cs and 40K for the skulls were of the same magnitude as those found previously for large wild herbivorous animals from typical locations in Poland, those for 90Sr were even lower than previously determined. A big difference was found for activities of plutonium and americium isotopes. Their mean activities were higher by an order of magnitude when compared to the examined previously values. The maximum 239+240Pu activity was equal to 97.5±7.7 mBq/kg, with 65% of it originating from global fallout. Relatively high content of transuranic elements found for rodents and insectivorous mammals seems to be unrelated to their feeding habits and should rather be attributed to the living conditions. It is suggested that small mammals, together with tiny soil particles present in mid-soil living tunnels, can inhale the transuranic elements.

THREE METHODS FOR ASSESSING RICHNESS AND COMPOSITION OF SMALL MAMMAL COMMUNITIES

Analysis of pellets of Tyto alba and scats of Genetta genetta and Shennan livetrapping were compared to assess richness and composition of small mammal communities in a Mediterranean area (NE Spain). Owl pellets provided 17 small mammal species (17,232 individuals), genet scats 14 species (2,145 individuals), and livetrapping 9 species (1,488 individuals). Owl pellets oversampled insectivores and grassland rodents and undersampled tree-dwelling and woodland rodents. Genet scats and livetrapping overs amp led woodland rodents and undersampled insectivores and grassland rodents. After controlling for sample size and elevation differences between methods by means of analysis of covariance (ANCOV A) and rarefaction, owl pellets contained higher richness for small samples(<50 individuals), and scats contained higher richness for large samples (> 100 individuals), both having higher richness than livetrapping regardless of sample size. We concluded that both indirect methods provided complementary infonnation of small mammal communities, detecting the 19 small mammal species known to be present in the study area.

Post-burial fragmentation of microvertebrate skeletons

An experiment designed to assess the effect of post-burial compaction on microvertebrate skeletons was achieved by compacting an owl pellet assemblage and a simulated natural death assemblage under increasing pressure in sediments of differing grain size. Observations of the compacted assemblages suggest that the distinct signatures associated with dissimilar agents of accumulation can maintain their integrity after tertiary modification in buried substrates.