Forest fragmentation is associated with primary brood sex ratio in the treecreeper (Certhia familiaris)

We studied the primary brood sex ratio of an old-growth forest passerine, the Eurasian treecreeper (Certhia familiaris), along a gradient of forest fragmentation. We found evidence that male nestlings were more costly to produce, since they suffered twofold higher nestling mortality and were larger in body size than females. Furthermore, the proportion of males in the brood was positively associated with the provisioning rate and the amount of food delivered to the nestlings. During the first broods, a high edge density and a high proportion of pine forests around the nests were related to a decreased production of males. The densities of spiders, the main food of the treecreeper, were 38% higher on spruce trunks than on pine trunks. This suggests that pine-dominated territories with female-biased broods may have contained less food during the first broods. The observation was further supported by the fact that the feeding frequencies were lower in territories with high proportions of pines. In the second broods, territories with a high forest patch density produced female-biased broods, whereas high-quality territories with a large amount of deciduous trees and mixed forests produced male-biased broods. Our results suggest that habitat quality as measured by habitat characteristics is associated with sex allocation in free-living birds.     

Predation risk effects on fitness related measures in a resident bird

Predation risk is thought to be highly variable in space and time. However, breeding avian predators may create locally fixed and spatially fairly predictable predation risk determined by the distance to their nest. From the prey perspective, this creates predation risk gradients that potentially have an effect on fitness and behavioural decisions of prey. We studied how breeding avian predators affect habitat selection (nest location) and the resulting fitness consequences in a northern population of resident willow tit ( Parus montanus ). Data included 429 willow tit nests over a four year period in a landscape containing a total of 33 avian predator nests. Willow tit nests were located randomly in the landscape and no predator avoidance in habitat selection or emptying of territories in proximity to predators was observed. Nestling size, however, was positively associated with distance from predator nests (n=252). Nestling mass and wing length were about 4.5% smaller close to predator nests compared to nestlings raised far from predator nests. Tarsus length also exhibited a positive relationship with increasing distance from predator nest but this was limited to habitats of young forests and pine bogs or dense mixed forests (4% increase). It is likely that habitat structural complexity influenced the perception of predation risk in different habitats. Our results indicate that willow tits do not provide reliable cues of predator free habitats for settling migrants. Nonetheless, breeding avian predators may create predictable predation risk in the landscape which is an important factor affecting reproductive success and potentially the demography of prey populations.     

Consequences of forest fragmentation for polyporous fungi at two spatial scales

Greatly reduced area of old-growth forests and the very low amount of dead wood in managed forests in northern Europe have caused a marked decline in the populations of saproxylic species. It is less clear at which spatial and temporal scales these adverse changes are taking place, and more information is needed to reliably predict which species are especially sensitive to loss and fragmentation of habitat. Here we compare species richness, incidence of occurrence in forest fragments, and abundance of polyporous fungal species and species groups between two regions in Finland with contrasting histories of forestry and a marked difference in the amount and spatial configuration of old-growth forests. We also analyse the consequences of increasing loss of connectivity on the presence and abundance of polypores in a study region with a documented short-term history of old-growth fragmentation. Our results show that the species number, incidence of occurrence, and abundance of especially the rare, threatened, and near-threatened species are much lower in the old-growth fragments in Häme in southern Finland in comparison with Kuhmo in eastern Finland, most probably because of the longer history of intensive forestry in Häme. Among the rare species, the species that show the greatest difference between the two regions (at the scale of 500 km) also tended to respond most strongly to the more recent forest fragmentation within the study region in Kuhmo (at the scale of 50 km). Polypores associated with spruce seem to be more strongly affected by forestry than species associated with pine, possibly reflecting the differences in the natural dynamics of spruce-dominated and pine-dominated forests.     

Marten space use and habitat selection in managed coniferous boreal forests of eastern Canada

Effects of habitat loss and fragmentation on the behavior of individual organisms may have direct consequences on population viability in altered forest ecosystems. The American marten (Martes americana) is a forest specialist considered as one of the most sensitive species to human-induced disturbances. As some studies have shown that martens cannot tolerate >30–40% clear-cuts within their home range, we investigated marten space use (home range size and overlap) and habitat selection in landscapes fragmented by 2 different patterns of timber harvesting in the black spruce boreal forest: dispersed-cut landscapes (10–80 ha cut-blocks) and clustered-cut landscapes (50–200 ha cut-blocks). We installed radio-collars on female martens and determined 20 winter home ranges (100% minimum convex polygons and 60–90% kernels) in dispersed-cut (n = 8) and clustered-cut (n = 12) landscapes. Home range size was not related to the proportion of clear-cuts (i.e., habitat loss), but rather to the proportion of mixedwood stands 70–120 years old. However, female body condition was correlated to habitat condition inside their home ranges (i.e., amount of residual forest and recent clear-cuts). At the home range scale, we determined that mixedwood forests were also among the most used forest stands and the least used were recent clear-cuts and forested bogs, using resource selection functions. At the landscape scale, home ranges included more mixedwood forests than random polygons and marten high activity zones were composed of more residual forest and less human-induced disturbances (clear-cuts, edges, and roads). These results suggest that mixedwood forests, which occupy approximately 10% of the study area, play a critical role for martens in this conifer-dominated boreal landscape. We recommend permanent retention or special management considerations for these isolated stands, as harvesting mixedwood often leads to forest composition conversion that would reduce the availability of this highly used habitat. © The Wildlife Society, 2013     

Effects of habitat transitions on rainforest bird communities across an anthropogenic landscape mosaic

We compared bird community responses to the habitat transitions of rainforest‐to‐pasture conversion, consequent habitat fragmentation, and post‐agricultural regeneration, across a landscape mosaic of about 600 km² in the eastern Australian subtropics. Birds were surveyed in seven habitats: continuous mature rainforest; two size classes of mature rainforest fragment (4–21 ha and 1–3 ha); regrowth forest patches dominated by a non‐native tree (2–20 ha, 30–50 years old); two types of isolated mature trees in pasture; and treeless pasture, with six sites per habitat. We compared the avifauna among habitats and among sites, at the levels of species, functional guilds, and community‐wide. Community‐wide species richness and abundance of birds in pasture sites were about one‐fifth and one‐third, respectively, of their values in mature rainforest (irrespective of patch size). Many measured attributes changed progressively across a gradient of increased habitat simplification. Rainforest specialists became less common and less diverse with decreased habitat patch size and vegetation maturity. However, even rainforest fragments of 1–3 ha supported about half of these species. Forest generalist species were largely insensitive to patch size and successional stage. Few species reached their greatest abundance in either small rainforest fragments or regrowth. All pastures were dominated by bird species whose typical native habitats were grassland, wetland, and open eucalypt forest, while pasture trees modestly enhanced local bird communities. Overall, even small scattered patches of mature and regrowth forest contributed substantial bird diversity to local landscapes. Therefore, maximizing the aggregate rainforest area is a useful regional conservation strategy.     

Survival of male Tengmalm’s owls increases with cover of old forest in their territory

The loss and fragmentation of forest habitats have been considered to pose a worldwide threat to the viability of forest-dwelling animals, especially to species that occupy old forests. We investigated whether the annual survival of sedentary male Tengmalm’s owls Aegolius funereus was associated with the cover of old coniferous forests in Finland. Survival and recapture probabilities varied annually with density changes in populations of the main prey (Microtus voles). When this variation was controlled for, and relationships between survival and proportions of the three different forest age classes (old-growth, middle-aged, and young) were modeled separately, the old-growth model was the most parsimonious. Survival increased with the cover of old forest, although the extent of old forest within owl territories was relatively small (mean ∼12%, range 2–37%). This association, however, varied among years and appeared especially in years of increasing vole abundance. At such times, old forests may sustain high populations of bank voles Clethrionomys glareolus, shrews and small passerines. In addition, old forests may serve as refuges against large avian predator species, such as Ural owls Strix uralensis and goshawks Accipiter gentilis. Our results suggest that changes in habitat quality created by agriculture and forestry may have the potential to reduce adult survival, an essential component of fitness and population viability.     

Behavioural responses to changing landscapes: flock structure and anti-predator strategies of tits wintering in fragmented forests

We analysed the effects of forest fragmentation on the flock structure of insectivorous forest passerines (Parus, Aegithalos, Certhia, Regulus, etc.), and on the anti‐predator behaviour and energy management of blue tits in these flocks. We surveyed flocks in Central Spain during two winters. Flocks in fragments comprised fewer individuals and species than flocks in unfragmented forests. The most abundant species in forest flocks (blue tit, Parus caeruleus, and firecrest, Regulus ignicapillus) were also the most abundant in fragments, while the rarest species in the area never occurred in small woodlots. We investigated how fragmentation and related changes in flock structure affect anti‐predator behaviour of blue tits, a widely distributed species in the area. In fragments but not in forests, blue tits increased scanning rates with decreasing flock size. Vigilance was relaxed when great tits, Parus major, were abundant as flock mates, suggesting that the absence of this dominant species in fragments could intensify anti‐predator behaviour of blue tits. Blue tits enhanced anti‐predator behaviour in the second winter parallel to an increase in the abundance of raptors. This behavioural change was stronger in fragments, where blue tits foraged deeper in the canopy and increased scanning and hopping rates. Under increased predation risk, birds are expected to reduce body mass to improve predator avoidance. On average, blue tits weighed similar in fragments and forests the second winter. However, they accumulated fat along the day in fragments only, and adjusted body mass to body size more closely in that habitat type. This suggests that blue tits perceived fragments as unpredictable habitats where fattening would help avoid starvation, but also as dangerous sites where overweight would further increase the risk of predation. In summary, our results support that fragmentation affects individual behaviour of blue tits, and show the potential of behavioural approaches to unravel how different species face the advancing fragmentation of their habitats.     

Abundance and Movement of Understory Birds in a Maulino Forest Fragmented by Pine Plantations

Understory birds are especially vulnerable to habitat fragmentation because of the reduction in habitat quality and bird movement. We study the separate effects of understory, overstory and landscape on four understory birds (tapaculos), in Central Chile, comprising a landscape mosaic of pine (Pinus radiata D. Don) plantations and native Maulino forest fragments. We also determined whether habitats with poor understory could be barrier to tapaculos movements. Abundance was measured using stationary playbacks and habitat barrier through playbacks. Understory structure was the main factor that predicted tapaculos presence and abundance. Two species, the Andean Tapaculo (Scytalopus magellanicus fuscus Gmelin) and the Ochre-flanked Tapaculo (Eugralla paradoxa Kittlitz), were positively associated with dead pine branches and negatively to forest fragment size. Tapaculos were less abundant in mature native forest, but appeared willing to cross between different habitat types. However, the Chestnut-throated Huet-huet (Pteroptochos castaneus Philippi and Landbeck), did not move from forest fragments to pine with poor understory. Overall, tapaculos species varied in their response to fragmentation depending on their habitat selection and movement capacities.     

REPRODUCTIVE COST,AGE-SPECIFIC SURVIVAL AND A COMPARISON OF THE REPRODUCTIVE STRATEGY IN TWO EUROPEAN TITS (GENUS PARUS)

Theoretical analyses of optimal reproductive rates usually assume a trade-off between offspring production and parental survival. This study verified a survival cost for willow tit males; nonbreeding males survived better than males attending a brood. Theory also predicts a smaller clutch size in birds that are less successful in transforming reproductive investments into mature offspring. As predicted, we found that crested tits, suffering a higher nest predation rate, laid smaller clutches than willow tits. The generally lower survival rate of willow tit adults may largely be attributed to their higher reproductive commitment (larger willow tit clutch size), because no significant interspecific survival difference remained between nonbreeding males. Finally, in willow tits we found a positive correlation between average clutch size and juvenile survival rate (density-dependent) the ensuing year, suggesting that willow tits may adjust clutch size in response to changing survival prospects for their young by using the breeding density as a cue.     

Habitat-mediated predation risk and decision making of small birds at forest edges

We studied the effect of four components of predation risk, namely predation pressure, spatial variation in woody cover, visibility, and flock size, on the behaviour of four species of the Parus guild (crested tit, P. cristatus , willow tit, P. montanus , coal tit, P. ater , and goldcrest, Regulus regulus ) at the edge of patches of mature boreal forest. Birds used the exposed side of the edge (matrix) mainly during periods with low levels of predation pressure by pygmy owls ( Glaucidium passerinum ). Some species avoided edges under low light conditions. Birds in large groups were more prone to cross the edge, whereas group cohesion increased in risky situations, especially in the most vulnerable species (coal tit and goldcrest). The effects of these three components of predation risk were not general in that only some species responded to them, and in that intra-specific responses were not always consistent. In contrast, all behaviours examined in all four bird species (occurrence, matrix crossing, edge crossing, and group cohesion) appeared to be strongly affected by habitat-mediated predation risk. Mature boreal forests appeared to be qualitatively superior to any type of matrix in terms of protection against predators. Birds generally avoided open matrix, and seemed to move towards and across more developed stages in forest regeneration according to the ratio between food intake and predation risk attributable to a given matrix type. Open matrix (farmland and clearcuts) and very young plantations strongly restricted the rate of bird movement between old forest patches. Our results contrast with the widespread thought that birds have a great potential to use fragmented landscapes in a fine-grained manner. These limited movements across the landscape during winter might have important repercussions on the occupation of some forest patches by tits, their subsequent reproduction, and in turn their population dynamics.     

Habitat selection by capercaillie in summer and autumn: Is bilberry important?

The use of habitat by female and male adult capercaillie Tetrao urogallus during summer and autumn was studied by comparing the distribution of radio locations of birds with the availability of habitat at forest stand, home range and landscape level in an area of the Bavarian Alps, Germany. Capercaillie preferred forests with structural features typical of their main distribution range, the boreal forest: they selected large patches of old forest with moderate canopy cover of about 50%, and a well developed field layer with high proportions of bilberry Vaccinium myrtillus. Hens selected both home ranges and sites within home ranges in old forest. Ranges selected by cocks did not differ from availability in the study area, but they preferred old forest within their ranges. The size of home ranges was negatively related to bilberry cover both in hens and cocks. The distribution of bilberry also determined habitat use by capercaillie at the landscape scale. The study demonstrated that bilberry is the major determinant of the selection of habitat by capercaillie in landscapes with sparse and fragmentary cover of ericaceous shrubs, such as central Europe.     

Forest bird diversity in Mediterranean areas affected by wildfires: a multi-scale approach

Fire is a key mechanism creating and maintaining habitat heterogeneity in Mediterranean landscapes by turning continuous woody landscapes into mosaics of forests and shrublands. Due to the long historical role of fires in the Mediterranean, we hypothesised a moderate negative effect of this type of perturbation on forest bird distribution at a landscape level. We conducted point bird censuses in Aleppo pine forest patches surrounded by burnt shrublands and studied the relationships between three ecological groups of bird species (forest canopy species, forest understorey species, and ubiquitous species) and the features of local habitat, whole patch and surrounding landscape. We used a multi-scale approach to assess the effects of landscape variables at increasing spatial scales on point bird richness. Regarding local habitat components, canopy species were positively associated with tall pines while understorey species with the cover of shrubs and plants from holm-oak forests. Forest birds were positively related to patch size and irregular forest shapes, that is, with high perimeter/size ratios. Thus, these species did not seem to perceive edges as low quality but rather favourable microhabitats. We did not detect any negative effect of isolation or cover of woodlands in the landscape on the presence of forest species after local habitat factors had been accounted for. Finally, only local habitat factors entered the model for ubiquitous species. We suggest that mosaic-like landscapes shaped by fires in the Mediterranean basin are not strongly associated with negative effects fragmentation on forest birds other than those related with habitat loss.     

Species‐habitat associations change in a subtropical forest of China

Question: Do tree and shrub species in an evergreen broadleaf forest show similar habitat associations across different life stages? Location: A 24‐ha evergreen broadleaf forest plot in a heterogeneous landscape in Gutianshan National Nature Reserve, Zhejiang Province, Eastern China. Methods: Species having positive associations with four habitat types (low valley, low ridge, upper valley, and upper ridge) at three life stages (sapling, juvenile, and mature stages) were compared for 60 tree and shrub species using torus‐translation tests. Results: A total of 117 significant positive associations with the four habitats were observed at the three life stages (43, 41, and 33 at the sapling, juvenile, and mature stages, respectively). For the 52 species significantly associated with habitats, only 16 were associated with the same habitat across all three stages. The majority of associated species at the juvenile stage (34 out of 40) were associated with the same habitat at their sapling stage, whereas half of species at the mature stage had consistent associations with the same habitat at their sapling stage. More species were associated with the upper ridge at the sapling and juvenile stages compared to the mature stage. Conversely, more species were associated with the low valley at the mature stage compared to the sapling and juvenile stages. Conclusions: Our results indicate that species ecological habitat associations can differ between developmental stages beyond 1 cm DBH, as most species habitat preferences were consistent from the sapling stage to the juvenile stage but changed at the mature stage.     

黑龙江省不同地点蒙古栎林生态特点研究

通过对黑龙江省６个地点的天然蒙古栎林的结构和更新特点的分析,蒙古栎林可划分为不同特点的蒙古栎群落,即纯蒙古栎群落、蒙古栎桦树群落、蒙古栎槭树群落、蒙古栎红松群落和蒙古栎松混交林群落,其演替趋势如下：红蒙古栎群落、蒙古栎桦树群落至蒙古栎槭树落、蒙古栎红松群落,再至蒙古栎红松混交林群落,蒙古栎群落类型的多样性主要反应群落不同的演替阶段,造成蒙古栎群落多样的原因是人类活动和自然因素作用的结果,随着群落的演替,蒙古栎的优势地位逐渐被消弱,乔木种类丰富度增多,草本种类丰富度增多;蒙栎的相对密度下降,林内环境由于干燥逐渐变中性至较湿润,蒙古栎幼苗和幼树在总幼苗和幼树中所占的比例下降,耐荫物中色木槭等的幼苗和幼树所占比例上升;在演替过程中,蒙古栎分布格局－聚集分布的聚集程度逐渐降低,并向随机分布的方向发展。     

Spacing behaviour and habitat use of rock ptarmigan (Lagopus mutus) at low density in the Italian Alps

Studies of rock ptarmigan Lagopus mutus in northern latitudes have shown that, in the breeding season, the majority of cocks pair monogamously and defend small territories, whilst in most populations, a small proportion of cocks are polygynous or remain unmated. Little is known, however, on spacing behaviour and habitat use of alpine rock ptarmigan populations occurring at low densities at the southern edge of the species’ range. From 1995 to 1997, we trapped, radio-tracked and observed birds in the Central Italian Alps (elevation 2,000–3,000 m) in order to investigate spacing behaviour and habitat use in alpine landscapes where habitats offering rich food and cover are patchy. Both sexes were selective in their habitat use, and cocks did not establish territories on bare ground, artificial or nutrient rich grasslands or bogs. In the breeding season, cocks had larger home ranges than hens (cocks 99 ± 57 ha, hens 50 ± 25 ha) that overlapped with the ranges of neighbouring cocks and hens. Cocks were monogamous and defended relatively large territories (core areas of home ranges: cocks 37 ± 26 ha, hens 24 ± 12 ha), which corresponded with low spring densities (0.47–2.29 cocks km⁻² and 0.35–1.60 pairs km⁻²). Territory size of individual cocks was negatively correlated with the amount of high quality habitat in the core-area. Our results suggest increased home ranges and large breeding territories in low density alpine rock ptarmigan populations, compared to populations occurring at higher densities in the central and northern alps, and on subarctic and arctic grounds at northern latitudes, confirming the predictions of models on food-based territoriality.     

Diurnal Habitat Relationships of Canada Lynx in an Intensively Managed Private Forest Landscape in Northern Maine

Abstract In March 2000, Canada lynx (Lynx canadensis) were listed as a federally threatened species in 14 states at the southern periphery of their range, where lynx habitat is disjunct and snowshoe hare (Lepus americanus) densities are low. Forest conditions vary across lynx range; thus, region-specific data on the habitat requirements of lynx are needed. We studied lynx in northern Maine, USA, from 1999 to 2004 to assess quality and potential for forests in Maine to sustain lynx populations. We trapped and radiocollared 43 lynx (21 M, 22 F) during this period and evaluated diurnal habitat selection by 16 resident adult lynx (9 M, 7 F) monitored in 2002. We evaluated lynx selection of 8 habitats at multiple spatial scales, and related lynx habitat selection to snowshoe hare abundance. Lynx preferred conifer-dominated sapling stands, which supported the highest hare densities on our study site (x̄ = 2.4 hares/ha), over all other habitats. The habitats where lynx placed their home ranges did not differ by sex. However, within their home ranges, males not only preferred conifer-dominated sapling stands, but also preferred mature conifer, whereas females singularly preferred conifer-dominated sapling stands. Approximately one-third of Maine's spruce-fir forest and nearly 50% of our study area was regenerating conifer or mixed-sapling forest, resulting from a disease event and intensive forest management (e.g., large clear-cuts). Our findings suggest that current habitat conditions in Maine are better than western montane regions and approach conditions in boreal forests during periods of hare abundance. We recommend that forest landowners maintain a mosaic of different-aged conifer stands to ensure a component of regenerating conifer-dominated forest on the landscape.     

Space use of the Siberian flying squirrel Ptevomys volans in fragmented forest landscapes

We studied the space use of the Siberian flying squirrel in fragmented forest landscapes in southern Finland in 1996- 1999. Twenty-four adult males and 23 adult females were radio trucked in three different study areas. The use of different landscape elements by flying squirrels was compared to their availability using compositional analysis. Effects of fragmentation on flying squirrels were studied by comparing the use of different habitat types, number of used patches, and size of home range to the principal components formed from the landscape variables patch size, patch isolation, area of spruce-dominated forests, and area of other habitats with trees.
Flying squirrels preferred spruce- and deciduous-dominated forests, but other habitats with trees were also used for moving and foraging. These less preferred habitats connected spruce and deciduous forest patches in a matrix of open areas. Males used several separate patches of preferred habitat, but females usually stayed in one patch. The spacing behaviour of males was affected by the structure of the landscape in a way that home ranges were larger and males used more spruce patches in the more highly fragmented landscape. Home-range size of females was not affected by the landscape structure. Basically, the space use of males seemed lo be reflected by the location and number of female home ranges. In the study area where female density was high, the home ranges of males were small. Our results give empirical evidence of the effects of habitat loss and landscape connectivity for the Siberian flying squirrel and the implications of these for the conservation of the species.     

Effects of habitat quality and landscape structure on saproxylic species dwelling in boreal spruce-swamp forests

Intensive forest management has caused loss and fragmentation of old‐growth forests and reduced the amount of dead wood throughout northwest Europe. Changes in habitat availability are reflected in occurrence patterns of habitat‐specialist species only after a certain time lag. Here we analyse the responses of wood‐decomposing fungi and saproxylic beetles inhabiting patches of spruce‐swamp forest to habitat quality, loss and isolation at three different spatial scales in eastern Finland and adjacent Russian Karelia, where forestry has been very marginal until recently. Both rare specialist species and common generalist species were included in the study to reveal whether their occurrence patterns differ. Variables describing habitat quality (density and continuity of host trees, patch area) turned out significant in explaining species' incidences (proportion of occupied host trees) in only a few cases, probably because of the relatively high quality of all study patches. Despite this fact, and consistent with our hypothesis, incidences of all the eight specialist species were higher in Russia than Finland, and the difference was significant in the two most strict habitat specialists, Pytho kolwensis and Phlebia centrifuga. In contrast, incidences of three out of four generalist species were higher in Finland than in Russia, and the difference was significant in Rhagium inquisitor. In a subset of 21 patches in Finland, we used a metapopulation model to predict the probability of each patch to be currently occupied by a species given the known spatiotemporal distribution of suitable forest stands during the last 50 years. The degree of isolation alone explained significantly the incidences of five species. However, including habitat variables into the models altered some of the effects. Moreover, inconsistent with our hypothesis, isolation appeared to also negatively affect some very common generalist species. Inclusion of these species in the study disclosed that apparently significant effects of spatiotemporal isolation should be interpreted cautiously.     

Habitat fragmentation rather than habitat amount or habitat split reduces the diversity and abundance of ground-dwelling anurans within forest remnants of the Brazilian Cerrado

Rampant deforestation has caused the loss and fragmentation of natural habitats, which has precipitated a global biodiversity crisis. Research on how land-use change contributes to a loss of biodiversity is urgently needed, especially in ecosystems that have undergone rapid anthropogenic changes. We sought to investigate the extent to which habitat loss, fragmentation, and habitat split (the separation of forest and aquatic habitats) negatively influenced taxonomic diversity, functional diversity, total abundance, and the individual abundances of five anuran species in the Brazilian Cerrado. We sampled anurans between December 2017 and March 2018 using pitfall traps at sites distributed along a gradient of habitat fragmentation/habitat split: unfragmented forest, forest fragments without habitat split, and forest fragments with habitat split. Forest cover was measured within a 1-km radius of each site. Sites within unfragmented forests had higher taxonomic and functional diversities than either fragment type. Taxonomic diversity was highly correlated with functional diversity, but we did not find a pattern to the loss of functional traits. Total anuran abundance and the abundances of Chiasmocleis albopunctata, Physalaemus cuvieri, and Rhinella diptycha were higher in unfragmented forests compared to forest fragments. No species was more abundant in fragments than in unfragmented forests. Our results indicate that the fragmentation of forests by agricultural land use is directly and indirectly responsible for the loss of taxonomic and functional diversity, as well as for reducing population sizes of ground-dwelling anurans. Although we did not find a distinct effect of habitat split on ground-dwelling anurans, our study underscores the importance of preserving continuous forest habitats for the maintenance of anuran diversity in the Cerrado.     

Home range and habitat selection of spotted owls in the central Sierra Nevada

We studied home range and habitat selection of radio-marked adult California spotted owls (Strix occidentalis occidentalis) randomly selected from among the breeding population of owls in the central Sierra Nevada, California from June to October 2006. The most parsimonious home-range estimate for our data was 555 ha (SE = 100 ha). Home-range size was positively correlated with the number of vegetation patches in the home range (habitat heterogeneity). We used resource selection ratios to examine selection of vegetation types by owls within our study area. Owl home ranges contained a high proportion of mature conifer forest, relative to its availability, although the confidence interval for this estimate overlapped one. We also used resource selection functions (RSF) to examine owl foraging habitat selection. Relative probability of selection of foraging habitat was correlated with vegetation classes, patch size, and their interaction. Owls showed highest selection rates for large patches (>10 ha) of pole-sized coniferous forest. Our results suggested that spotted owls in the central Sierra Nevada used habitat that contained a high proportion of mature conifer forest at the home-range scale, but at a finer scale (foraging site selection) owls used other vegetation classes interspersed among mature forest patches, consistent with our hypothesis that spotted owls may use other forest types besides old growth and mature forests when foraging. Our study provides an unbiased estimate of habitat use by spotted owls in the central Sierra Nevada. Our results suggest that forest managers continue to protect remaining mature and old-growth forests in the central Sierra Nevada because owl home ranges contain high proportions of these habitats. However, our results also showed that owls used younger stands as foraging habitat so that landscape heterogeneity, with respect to cover types, may be an important consideration for management but we did not attempt to relate our findings to fitness of owls. Thus management for some level of landscape heterogeneity for the benefit of owls should proceed with caution or under an adaptive management framework. © 2011 The Wildlife Society.