Burrowing Owl Research Articles

Behavioral Correlations Associated with Fear of Humans Differ between Rural and Urban Burrowing Owls

Behavioral studies are fundamental to understanding how animal populations face global change. Although much research has centered upon the idea that individuals can adaptively modify their behaviors to cope with environmental changes, recent evidence supports the existence of individual differences in suites of correlated behaviors. However, little is known about how selection can change these behavioral structures in populations subject to different environmental constraints. The colonization of urban environments by birds has been related to their inter-individual variability in their fear of humans, measured as their flight initiation distance to an approaching human, such that urban life would select for fearless individuals. This behavior has been demonstrated to be heritable and highly consistent throughout the adult lifespan of burrowing owls (Athene cunicularia). Here, we experimentally assessed, in field conditions, whether urban life involves changes in other behaviors such as exploration and antipredatory response through their correlation with fear of humans. Breeding urban birds were more fearless toward humans and were quicker to explore a new food resource and defend their nests from predators than their rural counterparts. However, while fear of humans positively correlated with exploration and antipredatory response in the rural population, it only correlated with exploration in the urban one. Predator release in urban environments could relax - and even counterselect - antipredator behaviors, thus dismantling the behavioral correlation existent in natural populations. Altogether, our results suggest that rural and urban animals may differ in some behavioral aspects, may be as a consequence of the selection processes acting during the colonization of urban areas as well as the different ecological environments encountered by individuals.

Microscale nest-site selection by the Burrowing Owl (Athene cunicularia) in the pampas of Argentina

Habitat modifications have led many bird species to occupy areas with different characteristics, including human-altered landscapes. In this study, we analyzed how land use influences the nest-site selection at the microscale level by Burrowing Owls (Athene cunicularia) breeding in vegetated sand dunes, periurban areas, and agroecosystems in the Pampas of Argentina. We compared the characteristics of the nest site (percentage of open space) and the nest patch (distance to conspecific nests, tall vegetation and perches and number of perches) within and among the three land-cover types. In addition, we evaluated the breeding performance (nesting success and productivity) of owls nesting in these land-cover types. We found that nest microsite variables did not vary between owl-occupied and owl-unoccupied sites within nest patches, but they differed among land-cover types. Although nest patches differed in their availability of perches at each land-cover type, distance from the nest to the nearest perch did not vary between them. Distances to tall vegetation and to conspecific nests were highly variable and did not differ among land-cover types. Our results indicate that Burrowing Owls that inhabit the Pampas used a variety of land-cover types for nesting and showed little selectivity of nest sites and nest patches, thus reinforcing the idea that they are habitat generalists.

The presence of conspecific females influences male-mobbing behavior

Many prey species mob predators to drive them away, thereby reducing their immediate and future predation risk. Given that mobbing is risky, it may also serve as an opportunity for males to advertise their phenotypic quality to females; however, this idea remains untested. We tested this hypothesis with a field experiment in south-eastern Brazil that assessed the response of sexually dimorphic bird species to models of two diurnal owls: a ferruginous pygmy owl (Glaucidium brasilianum), which mainly eats small birds, and a burrowing owl (Athene cunicularia), which mainly eats invertebrates and thus poses a low risk to birds. Across 19 bird species, the mobbing intensity was higher when facing the less-dangerous owl, and more males engaged in predator mobbing than females. The mobbing intensity of males was higher with a larger number of conspecific females present. This finding indicates that males may use mobbing to display their phenotypic quality to females, suggesting that predator mobbing may be influenced by sexual selection.

Anthropogenic Influence on Blood Biomarkers of Stress and Genotoxicity of the Burrowing Owl (Athene Cunicularia)

Anthropogenic activities are putting increasing pressure on ecosystems and raising the need to assess environmental health quickly and accurately. Heterophile/lymphocyte index is accepted as a response to stress factors and the micronucleus test is used as a biomarker to estimate genotoxic damage. To evaluate a model of environmental quality, healthy Burrowing owl (Athene cunicularia) were sampled, and the heterophile/lymphocyte ratio was determined, as well as the frequency of micronucleated erythrocytes and nuclear abnormalities, determined with the Wright-Giemsa and acridine orange technique. The sites with the greatest antropic disturbance recorded the highest frequencies of micronuclei and heterophile/lymphocyte index. The combination of both tests allows the detection of possible acute or chronic exposure to stressors and genotoxic contaminants, both in healthy or altered ecosystems.

Protozoal hepatitis in a western burrowing owl (Athene cunicularia hypugaea)

Abstract A western burrowing owl (Athene cunicularia hypugaea) found dead in southern California had many light-colored lesions visible grossly on its liver, and histopathology revealed extensive necrosis throughout the hepatic parenchyma. Single-celled organisms were seen in clear spaces within the areas of necrosis. The owl was diagnosed with protozoal hepatitis.

Habitat Selection by Burrowing OwlsAthene cuniculariain the Pampas of Argentina: A Multiple-Scale Assessment

Fil: Baladron Felix, Alejandro Victor. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Centro Cientifico Tecnologico Conicet - Mar del Plata. Instituto de Investigaciones Marinas y Costeras. Universidad Nacional de Mar del Plata. Facultad de Ciencia Exactas y Naturales. Instituto de Investigaciones Marinas y Costeras; Argentina

Burrowing Owl Diet at a Migratory Stopover Site and Wintering Ground on Southeast Farallon Island, California

Abstract On the Farallon Islands, 48 km west of the coast of central California, Burrowing Owls (Athene cunicularia) are a native migrant and a predator of the nonnative house mouse (Mus musculus) and the native Ashy Storm-Petrel (Oceanodroma homochroa). Previous research showed that Burrowing Owl predation on Ashy Storm-Petrels is likely unnaturally exacerbated by the abundance of house mouse prey in the fall, which may encourage more owls to overwinter. When the cyclic mouse population crashes in winter, the owls switch to preying upon the storm-petrels, a species of conservation concern. From September 2010 to May 2011, we conducted daily owl surveys and a diet study of Burrowing Owls on Southeast Farallon Island. One goal was to document seasonal changes in Burrowing Owl diet composition through collection and assessment of pellets. During our study period, 12 banded owls overwintered for an average of 118 d and contributed 64% of the 679 analyzed owl pellets. Insects were the most numerous prey item ...

Diet and behavior of extralimital Western burrowing owls (Athene cunicularia hypogea) in tallgrass prairie

Abstract Species geographic limits can be shaped by unfavorable conditions beyond range edges, and observations from peripheral habitats provide opportunities to assess individuals' capacity to tolerate environmental change. I monitored an extralimital breeding pair of Western burrowing owls (Athene cunicularia hypogea) in an eastern Kansas tallgrass prairie in 2013 using still and video photography. I quantified (1) the relative importance of different prey types in their diet, and (2) the timing and prevalence of a novel sunbathing behavior and discuss its possible adaptive significance. Owls in tallgrass prairie consumed more arthropods than vertebrates, with the latter contributing the most biomass in their diet. However, arthropods contributed more biomass than reported in studies that used indirect prey remains analyses. Owls sunbathed during midday when conditions were hot and dry, but never during cool periods or following rain events. I suggest owls in tallgrass prairie may sunbathe to shed ectop...

Mortality of Western Burrowing Owls ( Athene cunicularia hypugaea) Associated with Brodifacoum Exposure.

Western Burrowing Owls ( Athene cunicularia hypugaea) frequently occupy periurban areas, where they may be exposed to pest control agents. This short communication describes necropsy findings and detected brodifacoum rodenticide levels for four Western Burrowing Owls in Lake Havasu City, Arizona, US, 2013-15. Levels detected ranged from 0.077 mg/kg to 0.497 mg/kg. Brodifacoum, one of several second-generation anticoagulant rodenticides recently removed from the general consumer market, is still available for use by licensed pesticide applicators. Despite recent regulatory actions, second-generation anticoagulant pesticides continue to threaten predatory species in periurban areas.

New records of three hippoboscid species on newly captured birds from nature in Paraná, Brazil.

The aims of this study was to provide new records of hippoboscid flies collected over an one-year period on newly captured birds from nature in the state of Paraná, Brazil. The birds were received by a wildlife center in Tijucas do Sul and the hippoboscid flies were collect by hand or by tweezers, generating a prevalence of 0.7% (16/2232) of parasitized birds. New information about distribution of hippoboscid flies on Asio clamator, Rupornis magnirostris and Athene cunicularia was reported in the state of Paraná. The Caracara plancus, Falco peregrinus and Penelope obscura are new host species for Ornithoctona erythrocephala in the state of Paraná, and the Asio stygius for Icosta rufiventris and Ornithoica vicina in Brazil. This study provided new information about hosts and distribution of hippoboscid flies in Brazilian birds.

Influence of human footprint and sensory disturbances on night-time space use of an owl

ESR Endangered Species Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials ESR 31:75-87 (2016) - DOI: https://doi.org/10.3354/esr00756 Influence of human footprint and sensory disturbances on night-time space use of an owl C. A. Scobie1,3,*, E. M. Bayne1, T. I. Wellicome1,2 1Department of Biological Sciences, University of Alberta, Edmonton, Alberta T6G 2E9, Canada 2Canadian Wildlife Service, Environment Canada, 9250 49 Street NW, Edmonton, Alberta T6B 1K5, Canada 3Present address: Royal Alberta Museum, 12845 102 Avenue, Edmonton, Alberta T5N 0M6, Canada *Corresponding author: corey.scobie@gov.ab.ca ABSTRACT: Artificial sensory disturbances (sound and light) can extend far beyond the physical footprint of human development. Nocturnal predators such as owls may be influenced by artificial sound and light, as they depend on aural and visual cues when hunting. Owl nocturnal movements may also be altered by physical changes to the landscape, as these can affect prey availability. The burrowing owl population in Canada has declined by 90% and was classified as endangered in 1995. We tracked adult male burrowing owls Athene cunicularia with GPS dataloggers, and used resource selection models to examine their night-time movement patterns in relation to human infrastructure and associated artificial light and sound. The amount of sound and light from compressor stations, oil wells, traffic, towns and buildings was calculated for each owl and random location. We found that owl night-time space use was better predicted by distance to infrastructure on the landscape than by intensity of sensory disturbance. Burrowing owls did not show a pronounced avoidance of artificial sound. Infrastructure best predicts owl space use, perhaps because associated changes to vegetation alter prey abundance and availability. While human infrastructure most influenced owl nocturnal space use, the extent to which ecosystems are impacted by artificial sound and light is becoming clearer and needs to be considered when assessing the total effect of human development on species. KEY WORDS: Sensory disturbance · Human development · Light · Sound · Resource selection · Burrowing owl · Athene cunicularia Full text in pdf format PreviousNextCite this article as: Scobie CA, Bayne EM, Wellicome TI (2016) Influence of human footprint and sensory disturbances on night-time space use of an owl. Endang Species Res 31:75-87. https://doi.org/10.3354/esr00756 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in ESR Vol. 31. Online publication date: October 06, 2016 Print ISSN: 1863-5407; Online ISSN: 1613-4796 Copyright © 2016 Inter-Research.

Histological analysis of the eyeball of Neotropical birds of prey Caracara plancus, Falco sparverius, Rupornis magnirostris, Megascops choliba and Athene cunicularia

Nos últimos anos a oftalmologia aviária se tornou um instrumento de grande relevância para a conservação de aves de vida livre e de cativeiro, principalmente pela crescente utilização do exame oftalmológico para a triagem de indivíduos designados para reintrodução em ambientes naturais. Os olhos das aves de rapina são estruturas imprescindíveis para detectar e capturar suas presas, e a sua notável capacidade visual torna o seu sistema de visão assunto de grande interesse para o estudo anatômico e histológico. Neste contexto, no presente trabalho foi realizada a análise histológica do bulbo ocular de aves de rapina representadas por espécies pertencentes às ordens Falconiformes, Accipitriformes e Strigiformes presentes em território brasileiro. Para realização do estudo foram utilizados vinte bulbos oculares obtidos de animais mortos por causas naturais, das espécies Caracara plancus, Falco sparverius, Rupornis magnirostris, Megascops choliba e Athene cunicularia.. As lâminas histológicas foram coradas pela técnica de hematoxilina e eosina e, analisadas por microscopia óptica. Foi constatada a existência de um padrão histológico com discreta variação entre as estruturas oculares nas diferentes espécies avaliadas, com destaque para o cristalino e a retina. Este estudo salienta a importância da determinação do padrão histológico ocular das espécies, e seus resultados atribuem informações histológicas basais auxiliares na determinação de diagnósticos histopatológicos oculares.

Population density of the western burrowing owl (Athene cunicularia hypugaea) in Mexican prairie dog (Cynomys mexicanus) colonies in northeastern Mexico.

BackgroundThe western burrowing owl (Athene cunicularia hypugaea) occurs throughout western North America in various habitats such as desert, short-grass prairie and shrub-steppe, among others, where the main threat for this species is habitat loss. Range-wide declines have prompted a need for reliable estimates of its populations in Mexico, where the size of resident and migratory populations remain unknown.ResultsOur objective was to estimate the abundance and density of breeding western burrowing owl populations in Mexican prairie dog (Cynomys mexicanus) colonies in two sites located within the Chihuahuan Desert ecoregion in the states of Nuevo Leon and San Luis Potosi, Mexico. Line transect surveys were conducted from February to April of 2010 and 2011. Fifty 60 ha transects were analyzed using distance sampling to estimate owl and Mexican prairie dog populations. We estimated a population of 2026 owls (95 % CI 1756–2336) in 2010 and 2015 owls (95 % CI 1573–2317) in 2011 across 50 Mexican prairie dog colonies (20,529 ha).ConclusionsThe results represent the first systematic attempt to provide reliable evidence related to the size of the adult owl populations, within the largest and best preserved Mexican prairie dog colonies in Mexico.

Heritability of fear of humans in urban and rural populations of a bird species.

Flight initiation distance (FID), a measure of an animal’s tolerance to human disturbance and a descriptor of its fear of humans, is increasingly employed for conservation purposes and to predict the response of species to urbanization. However, most work devoted to understanding variability in FID has been conducted at the population level and little is still known about inter-individual variability in this behaviour. We estimated the heritability of FID, a factor fundamental to understanding the strength and evolutionary consequences of selection of particular phenotypes associated with human disturbances. We used a population of burrowing owls (Athene cunicularia) monitored long-term and for which FID was previously shown to be highly consistent across an individual’s lifespan. Heritability estimates varied between 0.37 and 0.80, depending on the habitat considered (urban-rural) and method used (parent-offspring regressions or animal models). These values are unusually high compared with those previously reported for other behavioural traits. Although more research is needed to fully understand the underlying causes of this resemblance between relatives, selection pressures acting on this behaviour should be seriously considered as an important evolutionary force in animal populations increasingly exposed to human disturbance worldwide.

Contrast response functions in the visual wulst of the alert burrowing owl: a single-unit study.

The neuronal representation of luminance contrast has not been thoroughly studied in birds. Here we present a detailed quantitative analysis of the contrast response of 120 individual neurons recorded from the visual wulst of awake burrowing owls (Athene cunicularia). Stimuli were sine-wave gratings presented within the cell classical receptive field and optimized in terms of eye preference, direction of drift, and spatiotemporal frequency. As contrast intensity was increased from zero to near 100%, most cells exhibited a monotonic response profile with a compressive, at times saturating, nonlinearity at higher contrasts. However, contrast response functions were found to have a highly variable shape across cells. With the view to capture a systematic trend in the data, we assessed the performance of four plausible models (linear, power, logarithmic, and hyperbolic ratio) using classical goodness-of-fit measures and more rigorous statistical tools for multimodel inferences based on the Akaike information criterion. From this analysis, we conclude that a high degree of model uncertainty is present in our data, meaning that no single descriptor is able on its own to capture the heterogeneous nature of single-unit contrast responses in the wulst. We further show that the generalizability of the hyperbolic ratio model established, for example, in the primary visual cortex of cats and monkeys is not tenable in the owl wulst mainly because most neurons in this area have a much wider dynamic range that starts at low contrast. The challenge for future research will be to understand the functional implications of these findings.

Factors Influencing Burrowing Owl Abundance in Prairie Dog Colonies on the Southern High Plains of Texas

Large numbers of Western Burrowing Owls (Athene cunicularia hypugaea) nest in black-tailed prairie dog (Cynomys ludovicianus) colonies in the southern high plains of Texas. Because the Western Burrowing Owl is a species of concern with an uncertain future due to widespread extirpation of prairie dogs, we examined the roles of prairie dog colony size, burrow density, proxies of prey availability, and vegetative composition and structure on owl abundance and reproductive rate. The number of nesting Burrowing Owl pairs was positively correlated to colony area (r2 = 0.550, P = 0.006) and to number of prairie dog burrows in a colony (r2 = 0.733, P = 0.0230). Burrowing Owl numbers and reproductive rate (maximum number of young seen per successful pair) were not related to our measures of vegetative composition and structure in prairie dog colonies, nor to indices of prey availability.

Diet of the Burrowing Owl Athene cunicularia, in two locations of the inter-Andean valley Ecuador

We provide the first detailed description of the diet of Burrowing Owls ( Athene cunicularia ) for Ecuador, based on an analysis of 408 pellets collected from one locality in the north and one in the south of the central dry Andean Valley. Our results are consistent with previous studies in the Neotropics that document the importance of insects in the diet. Rodents made up 78.8% of the biomass in our sample. Additionally, we highlight the first record of the Andean eared mouse Phyllotis andium in a xeric environment, which was identified in the pellets.

Diversity of Quill Mites of the Family Syringophilidae (Acari: Prostigmata) Parasitizing Owls (Aves: Strigiformes) With Remarks on the Host-Parasite Relationships.

The quill mite fauna of the family Syringophilidae (Acari: Prostigmata: Cheyletoidea) associated with owls (Aves: Strigiformes) is reviewed. A new genus is proposed, Neobubophilus Skoracki & Unsoeld gen. nov. It differs from closely related Bubophilus (Bubophilus Philips and Norton, 1978) by the absence of leg setae vsII in the both sexes. In addition, four new species are described: (1) Neobubophilus cunicularius Skoracki & Unsoeld sp. nov. from Athene cunicularia (Molina, 1782) (Strigidae) from Paraguay; (2) Neobubophilus atheneus Skoracki & Unsoeld sp. nov. from Athene noctua (Scopoli, 1769) and Athene brama (Temminck, 1821) (Strigidae), both from India; (3) Bubophilus tytonus Skoracki & Unsoeld sp. nov. from Tyto alba affinis (Blyth, 1862) (Tytonidae) from Cameroon, and (4) Megasyringophilus dalmas Skoracki & Unsoeld sp. nov. from Megascops choliba (Vieillot, 1817) (Strigidae) from Venezuela. The following new host species are given: Bubo bubo (Linnaeus, 1758) (Strigidae) from Nepal for Bubophilus ascalaphus (Philips and Norton 1978) and Strix woodfordii (Smith, 1834) (Strigidae) from Tanzania for Bubophilus aluconis (aluconis Nattress and Skoracki 2009). A key for syringophilid genera and species associated with owls is constructed. The host-parasite relationships of syringophilid mites and owls are discussed.

Burrowing Owls Athene cunicularia (Strigidae) respond with increased vigilance to calls of the Curl-crested Jay Cyanocorax cristatellus (Corvidae) in the Paraguayan Cerrado

Nesting Burrowing Owls ( Athene cunicularia) in the Cerrado of northeastern Paraguay were observed to show increased vigilance in response to Curl-crested Jay ( Cyanocorax cristatellus ) calls. To test whether this reaction was species specific, a playback experiment was conducted using jay calls, a native passerine and three exotic passerines, and responses of the owls to the recordings were measured. The results indicated that the owls responded with increased vigilance only to calls of the Curl-crested Jay. It is hypothesized that the interaction between the two species may be related to competition for dietary resources initiating a greater aggressive response in the diurnal jay due to its more limited foraging time, compared to the nocturnal and diurnal owls. The vigilant response of the owls may thus be related to avoidance of potentially costly aggressive interactions with jays.

Experimental habitat restoration for conserved species using ecosystem engineers and vegetation management

AbstractWe experimentally address the theoretical potential for managing ecosystem engineer species to support suites of species in degraded habitats. Historically, the ecosystem engineer California ground squirrel Otospermophilus beecheyi supported a grassland food web through widespread burrowing activity. Currently, ground squirrels are not a threatened species, but like many other ecosystem engineers, they exist at densities too low to fulfill their engineering role in many locations. Our objective was to implement short‐term treatments, including squirrel translocation, to re‐establish key ecological processes on protected reserve lands. We manipulated vegetation and squirrels in a replicated, large‐scale field experiment for 2 years, and monitored through a third year. Vegetation mowing and soil decompaction treatments reduced grass density and thatch depth. Squirrel translocation accelerated squirrel settlement and activity in target sites. Of the more than 1000 burrow entrances remaining through the third year, nearly all burrows were concentrated in the plots that received squirrel translocation. We found significant additive effects of squirrel translocation and vegetation management on the spatial footprint of squirrel activity. Noteworthy and persistent engineering effects were achieved through squirrel activity, and both vegetation management and squirrel re‐establishment were needed to stimulate squirrel activity. The overarching goal of this experiment was to provide conservation managers with a cost‐effective tool for restoring degraded habitats to a hybrid ecosystem state with improved suitability for species of conservation concern, in this case, the western burrowing owl Athene cunicularia hypugaea.