Effects of the risk of competition and predation on large secondary cavity breeders

The effects of competition and risk of predation on secondary cavity breeders were examined between the 2008 and 2009 breeding seasons using an experimental design manipulating two nest entrance sizes (large entrances allowed Barn Owls (Tyto alba) to enter, while the small entrances excluded them). During the 2009 breeding season, the entrance sizes of nest boxes were exchanged, so that if during one year a nest box in a particular location had a small entrance, the second year it had a large entrance and vice versa. Barn Owls and Eurasian Kestrels (Falco tinnunculus) occupied 67.3 and 17.3%, respectively, of large entrance nest boxes. Significantly more Jackdaws (Corvus monedula), House Sparrows (Passer domesticus) and Scops Owls (Otus scops) bred in nest boxes with small than with large entrances. After nest box entrance sizes were exchanged, Barn Owls and smaller species did not breed in the same nest boxes with the new entrance size. Jackdaws probably did not breed in large entrance nest boxes due both to exploitation competition (Barn Owls and Eurasian Kestrels occupied the majority of large entrance nest boxes), and may also have avoided empty nest boxes because of the risk of interference competition; whereas smaller species may have also avoided large entrance nest boxes due to risk of predation.     

Wildflower areas within revitalized agricultural matrices boost small mammal populations but not breeding Barn Owls

Agro-ecosystems have recently experienced dramatic losses of biodiversity due to more intensive production methods. In order to increase species diversity, agri-environment schemes provide subsidies to farmers who devote a fraction of their land to ecological compensation areas (ECAs). Several studies have shown that invertebrate biodiversity is actually higher in ECAs than in nearby intensively cultivated farmland. It remains poorly understood, however, to what extent ECAs also favour vertebrates, such as small mammals and their predators, which would contribute to restoring functional food chains within revitalised agricultural matrices. We studied small mammal populations among eight habitat types—including wildflower areas, a specific ECA in Switzerland—and habitat selection (radiotracking) by the Barn Owl Tyto alba, one of their principal predators. Our prediction was that habitats with higher abundances of small mammals would be more visited by foraging Barn Owls during the period of chicks’ provisioning. Small mammal abundance tended to be higher in wildflower areas than in any other habitat type. Barn Owls, however, preferred to forage in cereal fields and grassland. They avoided all types of crops other than cereals, as well as wildflower areas, which suggests that they do not select their hunting habitat primarily with respect to prey density. Instead of prey abundance, prey accessibility may play a more crucial role: wildflower areas have a dense vegetation cover, which may impede access to prey for foraging owls. The exploitation of wildflower areas by the owls might be enhanced by creating open foraging corridors within or around wildflower areas. Wildflower areas managed in that way might contribute to restore functional links in food webs within agro-ecosystems.     

Adaptive habitat preferences in the Tawny Owl Strix aluco

Capsule: Tawny Owls Strix aluco occupying nest boxes preferred habitats which were positively associated with the probability of nesting success.

Aims: We aimed to determine whether or not: (1) Tawny Owls showed habitat preferences when occupying nest boxes; (2) nesting performance was related to the habitats around occupied nest boxes and (3) habitat availability had changed around available and occupied nest boxes between 1995–2004 and 2005–14.

Methods: Tawny Owls were studied using nest boxes erected in a commercial forest. During nest boxes checks (724 cases), data on occupancy and nesting performance (88 cases) were recorded, and habitat within a 0.4?km radius around nest boxes was analysed.

Results: Tawny Owls had preferences for clearings within forests, mature forests and grasslands but avoided young forests. We found a positive relationship between nesting success and abundance of clearings within the forest, and a negative relationship between nesting success and abundance of young forests. A change in habitat preferences over the two decades was evident, but habitat availabilities remained similar.

Conclusions: Findings indicate adaptive habitat selection in Tawny Owls because preferred habitats were associated with higher fitness and this type of habitat became more frequently selected over time.     

Food partitioning between breeding White-tailed Kites (Elanus leucurus; Aves; Accipitridae) and Barn Owls (Tyto alba; Aves; Tytonidae) in southern Brazil.

I examined the diet of breeding White-tailed Kites (Elanus leucurus; Aves; Accipitridae) and Barn Owls (Tyto alba; Aves; Tytonidae) in an agrarian area of southern Brazil by analyzing regurgitated prey remains. The objective was to evaluate how these raptors, which differ markedly in their hunting activity periods (owls are nocturnal and kites diurnal), share their mammalian food component. 2,087 prey consumed by Barn Owls and 1,276 by White-tailed Kites were identified. They presented a high overlap of food-niches (Piankas index was 0.98). Based on the daily activity period of their main small mammal prey, a lower overlap would be expected. The crepuscular/nocturnal Mus musculus was the main prey for the diet of breeding Barn Owls (81%) and White-tailed Kites (63%). This small exotic rodent provided 63% of the small mammal biomass ingested by owls and 44% by kites. Larger native small mammals were also considered important for the diet of kites, mainly because of their biomass contribution. Although these raptors differ markedly in their hunting activity periods, Barn Owls and White-tailed Kites are very similar predators in southern Brazil, overlapping their diets.     

Avian Nest Box Selection and Nest Success in Burned and Unburned Southwestern Riparian Forest

ABSTRACT Riparian forest communities in the southwestern United States were historically structured by a disturbance regime of annual flooding. In recent decades, however, frequency of flooding has decreased and frequency of wildfires has increased. Riparian forests provide important breeding habitat for a large variety of bird species, and the effects of this altered disturbance regime on birds and their breeding habitat is largely unknown. To evaluate effects of high-intensity spring and summer wildfire on the quality of breeding bird habitat in the Middle Rio Grande valley, we measured vegetation structure and composition, avian nest use, and nest success at 4 unburned plots and 4 wildfire plots over a 3-year period. We measured avian nest use and success at nest boxes located in unburned riparian forest plots and plots recently burned by wildfire. Recent wildfire plots (<7 yr after fire) had a much different vegetation structure than unburned plots; an older (>7 yr after fire) wildfire plot more closely resembled its paired unburned plot than did recently burned plots. Ash-throated flycatchers (Myiarchus cinerascens) and Bewick's wrens (Thryomanes bewickii; hereafter, flycatchers and wrens, respectively) used nest boxes in most of the plots. A model selection procedure applied to logistic regressions showed that frequency of nest box use by flycatchers was positively associated with wildfire, although flycatchers used boxes in unburned plots as well. Wrens showed a preferential use of nest boxes that were in unburned sites and in close proximity to vegetative cover. Growth rates, feeding rates, and fledging mass of flycatchers were similar in wildfire and unburned plots. Growth rates for wrens were slower in wildfire plots, while feeding rates and fledging mass were similar. Nest predation varied between years, was higher for flycatchers than for wrens, and was not directly influenced by wildfire. Model selection showed that predation increased with grass cover, an indicator of forest openness, and decreased with distance to habitat edge. Recovery of dense vegetation appears important in maintaining populations of Bewick's wrens, whereas ash-throated flycatchers were less sensitive to vegetative structure and composition of postfire succession. Postfire management that maintains nest sites in large forest strips would enhance nesting density and success of these cavity-nesting birds in riparian zones.     

Habitat associations of small mammals in southern Brazil and use of regurgitated pellets of birds of prey for inventorying a local fauna.

We inventoried terrestrial small mammals in an agricultural area in southern Brazil by using trapping and prey consumed by Barn Owls (Tyto alba) and White-tailed Kites (Elanus leucurus). Small mammals were trapped in three habitat types: corn fields, uncultivated fields ("capoeiras"), and native forest fragments. A total of 1,975 small mammal specimens were trapped, another 2,062 identified from the diet of Barn Owls, and 2,066 from the diet of White-tailed Kites. Both trapping and prey in the predators' diet yielded 18 small mammal species: three marsupials (Didelphis albiventris, Gracilinanus agilis, and Monodelphis dimidiata) and 15 rodents (Akodon paranaensis, Bruceppatersonius iheringi, Calomys sp., Cavia aperea, Euryzygomatomys spinosus, Holochilus brasiliensis, Mus musculus, Necromys lasiurus, Nectomys squamipes, Oligoryzomys nigripes, Oryzomys angouya, Oxymycterus sp.1, Oxymycterus sp.2, Rattus norvegicus, and Rattus rattus (Linnaeus, 1758)). The greatest richness was found in the uncultivated habitat. We concluded that the three methods studied for inventorying small mammals (prey in the diet of Barn Owls, White-tailed Kites, and trapping) were complementary, since together, rather than separately, they produced a better picture of local richness.     

Autumn resource selection by female elk in a recently burned landscape in western Montana

Wildfire activity across the western United States has increased in recent decades, with wildfires burning at a higher severity and larger scale. The effect of wildfires on forest structure and wildlife habitat is largely influenced by wildfire severity; however, few studies have evaluated the effects of wildfire severity on resource selection of ungulates, particularly during hunting seasons, when knowledge of resource selection is essential for making informed management decisions. To fill this knowledge gap, we fit resource selection probability functions for female elk (Cervus canadensis) in years 2 and 3 post-wildfire to evaluate the effects of wildfire severity and other environmental and anthropogenic factors on elk resource selection during 4 autumn periods with varying levels of hunter pressure (prehunt, archery-only, backcountry rifle, and rifle). The probability of female elk selecting low-severity burned forests during the prehunt, archery-only, backcountry rifle, and rifle periods was 0.99 (95% credible interval [CrI] = 0.98–1.00), 0.99 (CrI = 0.97–1.00), 0.99 (CrI = 0.99–1.00), and 0.0010 (CrI = 0.00067–0.0015]), respectively, and did not strongly differ from the probability of selecting high-severity burned forests. During the prehunt period, elk also selected areas with greater forage quality and areas farther from open roads. Elk selected similar resources during the archery period, and selected areas with higher hunter pressure. Elk started leaving hunting districts that had higher snowpack (i.e., snow water equivalent; β = −0.84, CrI = −0.96–−0.72) and allowed rifle hunting (β = −5.39, CrI = −5.80–−4.97) but still selected areas with higher hunter pressure (β = 0.92, CrI = 0.78–1.07) during the backcountry rifle period. During the rifle period, elk continued avoiding areas with high snowpack (β = −3.96, CrI = −4.22–−3.71) and started selecting areas with lower hunter pressure (β = −1.71, CrI = −1.79–−1.64) and lower canopy cover. Overall, wildfire affected elk distributions in early autumn 2 and 3 years after fire in our study area, with limited differences in resource selection between wildfire severity categories. By late autumn, hunter pressure and snowpack were the primary factors influencing elk distribution, and wildfire had little influence on selection. When estimating wildfire effects on elk movements during autumn and establishing appropriate hunting regulations, managers should consider the hunting season, hunter pressure, timing and amount of snowpack, location of traditional winter range, and the seasonal elk range burned, as all these factors may contribute to how elk use the landscape in autumn.     

Habitat does not influence breeding performance in a long‐term Barn Owl Tyto alba study

Capsule This study examines the relationship between habitat variables and various aspects of breeding and foraging performance for 257 Barn Owl breeding attempts involving both released and wild birds, at 86 different nest‐sites over a 14‐year period.

Aims The study aimed to: (1) provide evidence for or against the importance of foraging habitat in Barn Owl breeding performance; (2) enable identification of areas which can, and those which cannot, be expected to sustain Barn Owl populations; (3) inform the compilation of any future guidelines such that Barn Owl release schemes are more likely to succeed; and (4) allow the revision of untested concerns in terms of the likely survival or otherwise of Barn Owls in a given area.

Methods Three data sources are used to assess the proportions of various habitat types and lengths of linear features in the vicinity of each nest: (1) The Centre for Ecology and Hydrology Land Cover Map; (2) Ordnance Survey Strategi dataset; and (3) Agricultural Census data. These are linked to various aspects of breeding performance.

Results Despite the size of the dataset, the number of significant correlations between habitat type and aspects of Barn Owl breeding success was similar to that expected by chance. Sites with more unimproved grassland within 1 km of the nest did not differ from those with less, except by a significant advancement of first‐egg date.

Conclusion The paucity of significant results may be evidence that Barn Owls are in fact rather catholic and adaptable in their habitat requirements, and not as dependent upon large areas of Field Vole (or other) habitat as has often been stated.     

Diversity patterns of plant functional types in relation to fire regime and previous land use in Mediterranean woodlands

Abstract. We explore patterns of diversity of plant functional types (PFTs) in Mediterranean communities subjected to landscape‐scale fire disturbances in a mosaic of uncultivated and old fields stands. We use regenerative and growth form attributes to establish two sets of PFTs of perennial species living in shrublands and pine forests of NE Spain. We test the following hypotheses: 1. Fire frequency decreases regenerative PFTs diversity by negatively selecting attributes with low regenerative efficiency. 2. Fire history has more influence on regenerative than on growth form PFTs. 3. The lowest diversity of growth form PFTs will be in old fields without recent fires. We surveyed stands of different combinations of fire and land use histories. Fire history included areas without fires in the last twenty years (unburned), sites burned in 1982 (1‐burned), and sites burned in 1982 and 1994 (2‐burned). Land use histories considered terraced old fields, and uncultivated stands on stony soils. We analysed patterns of PFT abundance and diversity at the stand level, and across the landscape (among stands absolute deviations from sample medians of the relative cover of PFTs). At the stand level, fire had more influence on the diversity patterns of regenerative PFTs than on growth form PFTs. Fire decreased the diversity of regenerative PFTs, due to the elimination of the species without effective mechanisms to post‐fire regeneration. This effect was not observed across the landscape, but seeders showed more variation in stands with longer history without fire. Land use contributed to explain the diversity patterns of growth form PFT (i.e. the number of growth form PFTs was lower in uncultivated, unburned sites), but it did not influence regenerative PFTs diversity. Patterns of PFTs diversity reflect the response to ecological processes operating at the landscape level. Overall, regenerative and growth form PFTs appear to be more sensitive to the fire history than to the past land use.     

High resilience of Mediterranean land snail communities to wildfires

In the Mediterranean region, wildfires have devastating effects on animals with limited mobility. With their poor dispersal abilities, their habitats on vegetation and in litter, and their sensitivity to humidity and shade, we expected land snails to be an interesting model to assess short, medium and long-term impact of fires on fauna biodiversity and their resilience. Stratified sampling was carried out on 12 sampling sites in garrigues and forests of Provence (southeastern France), according to fire regime (number of fires, fire intervals and age of the last fire) over the past 30 years. Data were investigated using diversity indexes, Kruskal–Wallis test, dendrogram of affinities and Correspondence Analysis (CA). We found, however, that Mediterranean land snail communities are particularly resilient to fires. Although abundance is drastically reduced in the short-term, species richness and community diversity are preserved provided that the time lapse between two successive fires is longer than the time required for recovery (i.e. around 5 years). This high community resilience in the short-term may be partly due to ecological and ethological aptitudes of land snails. However, these astonishing results, which have implications for conservation biology, are mainly due to the presence, within burned areas, of cryptic refuges that allow initial land snail survival, malacofauna persistence after successive fires and consistent biogeographical patterns in the long-term.     

Preburn Characteristics and Woodpecker Use of Burned Coniferous Forests

ABSTRACT Large wildfires are common in many western coniferous forests, and these fires can affect woodpecker reproduction and habitat use. Our objectives were to examine nesting densities, reproductive parameters, and species-specific habitat selection of woodpeckers in a recently burned region of the Black Hills in South Dakota, USA, between 2001 and 2004. Postfire nesting densities were greatest in areas dominated by high prefire canopy cover, and reproductive success averaged >70%. For some species of woodpeckers, factors such as diameter at breast height, burn severity, and distance to unburned patches were important for nest-site selection. Our data indicated that nesting densities of many woodpeckers in the Black Hills were lower than what has been recorded elsewhere following recent, large wildfires in ponderosa pine (Pinus ponderosa) forests. Management activities that simulate mixed-severity fire effects and retain higher numbers of large snags are likely to benefit cavity nesters in this region.     

FIRST ANNUAL REPORT ON THE RHODESIAN ORNITHOLOGICAL SOCIETY'S NEST RECORD SCHEME FOR THE YEAR ENDED 30 JUNE, 1956

MENDELSOHN, J. M. 1989. Habitat preferences, population size, food and breeding of six owl species in the Springbok Flats, South Africa. Ostrich 60:183-190.

Information on the habitat preferences, population size, food and breeding of Barn, Grass, Whitefaced, Marsh, Pearlspotted and Spotted Eagle Owls was obtained in a 6900-ha area in the Springbok Flats, South Africa. Seventy-two per cent of the area consisted of cultivated fields not usually used by owls. Hunting, roosting and nesting requirements were largely met in 1930 ha of verges, farmyards and patches of wood land ant grassland, here was an estimated total population of 303 owls in the area, giving an overall density of 22,7 ho/owl for the whole area or 6.4 ha/owl for those areas used by owls. These high densities were attributed to an abundance of Mastomys natalensis, the most important prey item for all except Pearlspotted Owls. Rates of predation on M. natalensis varied in relation to their population density, as indicated by rodent trapping results. Marsh Owls ate more insects in summer than at other times. Barn and Marsh Owls usuall laid in March-April and August-September, while other species started breeding in July-October. de timing of breeding of some owls may be related to changes in rates of recruitment of juvenile M. natalensis. Most Marsh Owl nests were placed on the southwestern sides of grass clumps or shrubs.     

Spatial,road geometric and biotic factors associated with Barn Owl mortality along an interstate highway

Highway programmes typically focus on reducing vehicle collisions with large mammals because of economic or safety reasons, while overlooking the millions of birds that die annually from traffic. We studied wildlife–vehicle collisions along an interstate highway in southern Idaho, USA, with among the highest reported rates of American Barn Owl Tyto furcata road mortality. Carcass data from systematic and ad hoc surveys conducted in 2004–2006 and 2013–2015 were used to explore the extent to which spatial, road geometric and biotic factors explained Barn Owl–vehicle collisions. Barn Owls outnumbered all other identified vertebrate species of roadkill and represented > 25% of individuals and 73.6% of road‐killed birds. At a 1‐km highway segment scale, the number of dead Barn Owls decreased with increasing numbers of human structures, cumulative length of secondary roads near the highway and width of the highway median. The number of dead Barn Owls increased with higher commercial average annual daily traffic (CAADT), small mammal abundance index and grass rather than shrubs in the roadside verge. The small mammal abundance index was also greater in roadsides with grass vs. mixed shrubs, suggesting that Barn Owls may be attracted to grassy portions of the highway with more abundant small mammals for hunting prey. When assessed at a 3‐km highway segment scale, the number of dead Barn Owls again increased, with higher CAADT as well as with greater numbers of dairy farms. At a 5‐km scale, the number of dead Barn Owls increased with a greater percentage of cropland near the highway. Although human conversion of the environment from natural shrub‐steppe to irrigated agriculture in this region of Idaho has probably enhanced habitat for Barns Owls, it simultaneously has increased risk for owl–vehicle collisions where an interstate highway traverses the altered landscape. We review some approaches for highway mitigation and suggest that reducing wildlife–vehicle collisions involving Barn Owls may contribute to the persistence of this species.     

Return of Fire as a Restoration Tool: Long‐Term Effects of Burn Severity on Habitat Use by Mexican Fox Squirrels

After decades of suppression, fire is returning to forests of the western United States through wildfires and prescribed burns. These fires may aid restoration of vegetation structure and processes, which could improve conditions for wildlife species and reduce severe wildfire risk. Understanding response of wildlife species to fires is essential to forest restoration because contemporary fires may not have the same effects as historical fires. Recent fires in the Chiricahua Mountains of southeastern Arizona provided opportunity to investigate long‐term effects of burn severity on habitat selection of a native wildlife species. We surveyed burned forest for squirrel feeding sign and related vegetation characteristics to frequency of feeding sign occurrence. We used radio‐telemetry within fire‐influenced forest to determine home ranges of Mexican fox squirrels, Sciurus nayaritensis chiricahuae, and compared vegetation characteristics within home ranges to random areas available to squirrels throughout burned conifer forest. Squirrels fed in forest with open understory and closed canopy cover. Vegetation within home ranges was characterized by lower understory density, consistent with the effects of low‐severity fire, and larger trees than random locations. Our results suggest that return of low‐severity fire can help restore habitat for Mexican fox squirrels and other native wildlife species with similar habitat affiliations in forests with a historical regime of frequent, low‐severity fire. Our study contributes to an understanding of the role and impact of fire in forest ecosystems and the implications for forest restoration as fire returns to the region.     

Breeding habitat and nest‐site selection by an obligatory “nest‐cleptoparasite”, the Amur Falcon Falco amurensis

The selection of a nest site is crucial for successful reproduction of birds. Animals which re‐use or occupy nest sites constructed by other species often have limited choice. Little is known about the criteria of nest‐stealing species to choose suitable nesting sites and habitats. Here, we analyze breeding‐site selection of an obligatory “nest‐cleptoparasite”, the Amur Falcon Falco amurensis. We collected data on nest sites at Muraviovka Park in the Russian Far East, where the species breeds exclusively in nests of the Eurasian Magpie Pica pica. We sampled 117 Eurasian Magpie nests, 38 of which were occupied by Amur Falcons. Nest‐specific variables were assessed, and a recently developed habitat classification map was used to derive landscape metrics. We found that Amur Falcons chose a wide range of nesting sites, but significantly preferred nests with a domed roof. Breeding pairs of Eurasian Hobby Falco subbuteo and Eurasian Magpie were often found to breed near the nest in about the same distance as neighboring Amur Falcon pairs. Additionally, the occurrence of the species was positively associated with bare soil cover, forest cover, and shrub patches within their home range and negatively with the distance to wetlands. Areas of wetlands and fallow land might be used for foraging since Amur Falcons mostly depend on an insect diet. Additionally, we found that rarely burned habitats were preferred. Overall, the effect of landscape variables on the choice of actual nest sites appeared to be rather small. We used different classification methods to predict the probability of occurrence, of which the Random forest method showed the highest accuracy. The areas determined as suitable habitat showed a high concordance with the actual nest locations. We conclude that Amur Falcons prefer to occupy newly built (domed) nests to ensure high nest quality, as well as nests surrounded by available feeding habitats.     

Landscape and anti-predation determinants of nest-site selection, nest distribution and productivity in a Mediterranean population of Long-eared Owls Asio otus

Nest predation is an important determinant of owl breeding success. We studied Long-eared Owl Asio otus productivity and attributes of nest-sites at the microhabitat and landscape scales in a Mediterranean locality over an 8-year period. We examined the effect on nest location and productivity of protective cover in concealing the nest from aerial and terrestrial predators. A dense cover of ivy and tree-foliage at canopy level favoured nest location but not productivity. By contrast, high shrub cover beneath the nest was selected by Owls and was positively related to both the site reoccupancy rate and the overall number of young fledged. Pre-fledging Owls use the ground, where they are exposed to terrestrial predators, which are much more abundant in the study area than are aerial predators. Our results therefore support the hypothesis that Owls adapt nest-site choice to local sources of predation risk. As reported elsewhere, Long-eared Owls in our study area showed restricted territoriality and nested in clusters. As active nest-sites during the same breeding season were more than 1 km apart on average, and their productivity was never greater for clustered nests than for more isolated nests, nest aggregation could not be interpreted as a case of facultative colonial breeding, which has been reported for this species in other areas. Neither landscape variables indicative of the availability of foraging areas nor structural attributes that protect young from predators explained the remarkable scarcity of nests in half of the study area. Unmeasured factors such as human disturbance could explain the pattern of distribution of Long-eared Owl nests.     

The feeding and breeding ecology of Barn Owls Tyto alba in Peninsular Malaysia

Barn Owls have only recently colonized Peninsular Malaysia, nesting in the roof spaces of houses in oil palm estates and feeding on the rats which inhabit these plantations. Pellet analysis showed that the prey spectrum was confined almost entirely to three species of the genus Rattus which are the major pests of oil palm. There was no annual variation in diet. Breeding showed a broad seasonality but occurred in all months of the year. Mean clutch and brood sizes of 6.6 and 4.6 respectively were recorded, most pairs producing two broods a year although on two occasions three were raised. Overall hatching success was 69.0% with first clutches more successful (79.9%) than second (57.3%). First broods fledged 86.1% and second broods 69.1% of young fledged. Comparison of growth rates of different sized broods suggested that there is a physiological maximum at which all broods proceed irrespective of brood size. The behaviour al changes needed in hunting techniques when colonizing dense plantations rather than the more usual open habitat of Barn Owls is discussed. The breeding strategy seems to be one of producing large clutches and broods, and frequent breeding attempts in a habitat with a high potential carrying capacity.     

Behavioural and body mass changes before egg laying in the Barn Owl: cues for clutch size determination?

To investigate laying decision and clutch size determination in indeterminate layers, we analysed in-nest activity (nest presence, and copulation, prey deliveries, and entrance frequencies) and female body mass change, as well as their relation to clutch size variation in five Barn Owl pairs (Tyto alba) nesting in eastern France. Body mass of the female and behaviour [copulation frequency, entrance frequency, and prey delivery to the nest by the male (in number and mass)] were monitored using an automated weighing system and a video camera. There was a consistent change of behaviour and foraging activity among pairs ca. 18 days before laying indicating that the females may be tied to the nest at this time. Barn Owls being indeterminate layers have their clutch size determined at the oviposition of the first egg of the clutch. Window correlation analyses between the clutch size and the female body mass gain indicate that the clutch size might be determined no later than a few days before the laying of the first egg. Our results suggest that female Barn Owls may use the pre-laying period to determine the clutch size using cues such as the male food deliveries (a proxy for male quality).     

Human Impacts on the Fire Regime of Interior Alaska: Interactions among Fuels, Ignition Sources, and Fire Suppression

Wildfire is the major natural agent of disturbance in interior Alaska. We examined the magnitude of human impact on fire by comparing fire regime between individual 1-km² grid cells designated for fire suppression with lands where fires are allowed to burn naturally. Two-thirds of interior Alaska has an essentially natural fire regime, with few human ignitions, negligible suppression activity, and many large lightning-caused fires. In the 17% of land that is designated for fire suppression due to its proximity to communities and roads, there was a 50% reduction in the proportion of area burned from 1992–2001, relative to areas without suppression. The remaining 16% of land serves as a buffer, receives some suppression, and has an intermediate fire regime. Even though there were 50 times more fires and the fire season began two months earlier in lands designated for suppression, most of these fires were lit by people and remained small because fires tended to occur at times and places less favorable for fire spread and were more accessible to fire fighters compared to lands not designated for suppression. Even in the absence of fire suppression, human-caused fires were less likely to exceed 400 ha compared to lightning-caused fires. Fire suppression reduced area burned in all fuel types but was somewhat more effective in less flammable (non-forest) vegetation. Alaska’s fire policy of focusing suppression efforts on a small proportion of the fire-prone region maximizes the ecological and social benefits associated with fire-dependent ecosystem services, while minimizing the social and ecological costs of suppression. Application of this policy to other areas would require well-informed managers and stakeholders to make difficult decisions about the relative costs and benefits of fire across ecologically and culturally variable landscapes.     

Wildfires modify the parasite loads of invasive cane toads

The frequency and severity of wildfires are increasing due to anthropogenic modifications to habitats and to climate. Post-fire landscapes may advantage invasive species via multiple mechanisms, including changes to host–parasite interactions. We surveyed the incidence of endoparasitic lungworms (Rhabdias pseudosphaerocephala) in invasive cane toads (Rhinella marina) in near-coastal sites of eastern Australia, a year after extensive fires in this region. Both the prevalence of infection and number of worms in infected toads increased with toad body size in unburned areas. By contrast, parasite load decreased with toad body size in burned areas. By killing moisture-dependent free-living lungworm larvae, the intense fires may have liberated adult cane toads from a parasite that can substantially reduce the viability of its host. Smaller toads, which are restricted to moist environments, did not receive this benefit from fires.