bluuebunny/crossref_metadata_2025 huggingface dataset:
Ontogenetic patterns of relative growth in young roach Rutilus rutilus: within‐river basin comparisons
Authors: Kováč Vladimir , Copp Gordon H.
Published: July 2006

To address the lack of information on the ecomorphology of young of the year juveniles (0 +) freshwater fishes, despite its importance to understanding geographical variation in life history, we compared the morphology of 0+ juvenile roach Rutilus rutilus from eight sub‐regions of the River Great Ouse basin (U.K.). We tested for variation due to water retention structures, which could act to isolate upstream stocks from the general population. Differences in mensural characters between the eight different regions appeared in ventral fin length and eye diameter only, which both were strongly affected by variable relative growth during early juvenile development; thus the discrepancies between regions were not due to geographical location. Morphological development in roach ≥ 15 mm standard length (SL) consists of two different intervals: during the first (≅ 15–40 mm SL), in contrast to adults, several mensural characters continue to develop allometrically, either positively or negatively, suggesting a continuance of the larval period. Whereas, in the second interval (> ≅ 40 mm SL), all the mensural characters except head length and eye diameter grew close to isometrically with body length, and the rate of variation in relative growth became as strongly limited as that previously reported for adults. In contrast to previous studies, which are based on few specimens, we suggest this second interval to be the true start of the juvenile period.
Benthic invertebrate communities in six Danish forest streams: Impact of forest type on structure and function
Authors: Friberg Nikolai
Published: July 2006

I investigated the impact of riparian vegetation type on stream invertebrate communities in SIX Danish forest streams during the period 1992–1993 Two of the streams ran through beech forest Fagus sylvatica, two through mixed, mainly deciduous forest, and two through conifer plantations Algal biomass and detritus standing stock differed significantly depending on forest type In mixed deciduous forest streams algal biomass was higher and detritus standing stock lower than in beech and conifer forest streams Benthic invertebrate community composition was functionally similar in all streams, with detritivores comprising >80% by numbers of the community Grazer abundance was low in all streams Shredder abundance in the four deciduous streams was significantly correlated to coarse detritus standing stock When taking into account both quantitative and qualitative POM parameters for all six streams combined, shredder abundance correlated significantly to the amount of CPOM There were significantly more invertebrates with a ≥ 2 yr life cycle in the conifer and beech forest streams than m the mixed forest streams, probably reflecting the larger and more stable food resource For all streams combined there was a significant correlation between predator abundance and the abundance of potential prey My findings suggest that Danish forest streams are regulated by “bottom‐up control” at all trophic levels within the invertebrate community, and hence that forest type can structure benthic communities in forest streams
Influence of gut parasites on growth performance in the water strider Gerris buenoi (Hemiptera: Gerridae)
Authors: Klingenberg Christian Peter , Leigh Rosalind H. Barrington , Keddie B. Andrew , Spence John R.
Published: July 2006

Water striders harbor a diverse assemblage of symbionts in their digestive tract We used a field experiment, in which water striders were reared in enclosures in their natural pond habitat, to assess the effects of gut symbionts on growth Trypanosomatid flagellates had significant adverse effects on both development time and adult size, and therefore are clearly parasitic Yet because of their low prevalences (2% or less), trypanosomatids cannot be a major factor in the dynamics of our study population Gregannes occurred in 36% of the water striders, often in high numbers, and filling the entire midgut of some bugs Nevertheless, infected and uninfected gerrids did not differ in their growth, and gregarine loads were uncorrelated with development time and adult size attained We also did not find effects of gregarines in a second experiment with different rearing conditions, including a treatment with food stress We used a quantitative genetic approach to test if resistance against gregarines has a heritable component There was no evidence for any genetic variation, suggesting that variability in gregarine loads is the result of environmental heterogeneity Comparison with published reports from water striders shows that there is a great variability in the diversity and prevalence of symbionts among different populations and species, of gerrids
Delayed and inverse density dependence in a chamois population of the Italian Alps
Authors: Capurro Angel F. , Gatto Marino , Tosi Guido
Published: July 2006

Both density dependent and density independent factors have been considered important determinants of the dynamics of ungulate populations Intraspecific competition for food and the amount of snow cover were suggested in the past as factors that influence the demographic parameters of the chamois Rupicapra rupicapra We present a 10 yr study on a closed population of the Italian Alps Animals, divided by sex and age class (kid, yearling, subadult, adult, old), were counted over the period 1981–1990 The number of chamois hunted and the number of carcasses found each year and the daily snow height were also available We investigated possible correlations between several demographic parameters and both snow cover and chamois density, accounting for sex‐ and age‐differential mortality and a possible delay in density dependence Results are as follows a) there is no statistically significant correlation between snow cover and demographic rates, b) there is no detectable compensation between natural and hunting‐related mortality, c) birth rate is density independent for any time delay, d) when calculated from carcasses, total mortality, mortality of 1‐yr‐old and older males and females significantly depend on total density with 2 years' lag, while kid mortality is not related to density for any time delay, e) when calculated from censuses, all mortality rates significantly depend on total density with 2 years' lag, although the variance explained by delayed density is definitely smaller for kids, f) nonlinear regression of kid mortality from censuses against density of kids in the same year yields a much higher coefficient of determination and inverse density dependence is evidenced However, determination between delayed and inverse density dependence in kid mortality is impossible, given our dataset In general, results support the hypothesis that intraspecific competition, epidemics and predation, rather than weather, play a role in the dynamics of this ungulate population
Distribution and abundance patterns of bird community and raptor populations in the Andaman archipelago
Authors: Thiollay Jean‐Marc
Published: July 2006

A qualitative survey of the terrestrial bird community (sixty‐five species) and a quantitative analysis of the five‐diurnal raptor assemblage were earned out on 33 islands of the oceanic Andaman archipelago in the Bay of Bengal Among seven geographical parameters, island area was the main determinant of species richness for both the whole bird community and each category of species associated with four habitat types Species richness decreased most markedly with island size in the smallest islands and in open habitat species The rarest forest species were the most extinction prone with decreasing island size Specific habitat selection was the most prominent ecological correlate of inter island species distribution Observed species distribution patterns did not fit the random species placement or equprobable occurrence hypotheses

Raptors were primarily forest species, two of them restricted to forest interior, two more tolerant of fragmentation and one naturally associated with mangroves Unexpectedly, the two rarest and most area sensitive raptors were the two smallest species with a strong active flight, whereas the most abundant and widespread species was the most forest interior and endemic taxon Both raptor species richness, species frequency of occurrence and abundance indices decreased with island area, which was consistently the most significant determinant of every species' occurrence and abundance There was a significant correlation between abundance or frequency of occurrence of every raptor species and the proportion of their preferred habitat type No relationship was found between habitat niche breadth or local abundance of any species and their distribution range among islands The hypothesis of random composition of species assemblages on islands was not supported because of species specific habitat selection Any evidence of interspecific competitive exclusion was limited to the striking habitat segregation of the two congeneric serpent eagles A metapopulation structure was suggested by small population distribution patterns, observed sea crossing and the circumstances of an apparent extinction
Palatability of silver birch seedlings to root voles Microtus oeconomus
Authors: Harju Anu , Tahvanainen Jorma
Published: July 2006

We used laboratory feeding trials to test the palatability of silver birch Betula pendula seedlings to root voles Microius oeconomus Seedlings of two B pendula families (A and B) were grown in growth chambers on three soil types and under two light intensities. Seedlings from family A grew taller and had more resin droplets on their bark than seedlings from family B The more light or nutrients the seedlings received the taller they grew and the more resm droplets they had on their bark We offered 10 root voles both basal and top 5–10 cm segments of winter‐dormant seedlings one treatment at a time (no‐choice arrangement) in a random order The seedlings grown on low‐fertility soil were eaten more than those grown on non‐fertilized or fertilized peat The top segments of seedlings grown in low light were slightly more eaten than those grown in high light Birch family did not have any effect on the consumption Consumption correlated negatively with the amount of resin droplets on the bark when the seedling material was compared over different treatments These results indicate that root voles would prefer young birch seedlings that have low amount of resin droplets on the bark and that grow in poor soils or under low light conditions
Regional patterns of mussel species distributions in North American rivers
Authors: Vaughn Caryn C.
Published: July 2006

North American freshwater mussels are a highly threatened group with half of the fauna already federally listed as threatened or endangered candidates for listing, or believed extinct Using data from 16 river systems I examined distributional attributes of mussel species to gain insight into the importance of regional‐scale processes vs local‐scale processes to species distribution patterns There was no evidence of density compensation or saturation which would have indirectly indicated that competition was important in structuring mussel communities Rather there was a positive correlation between summed species densities and regional richness, indicating that regional forces may be strongly contributing to community structure Incidence, abundance and nestedness patterns all indicated a hierarchical niche structure for these mussel assemblages I hypothesize that these hierarchical patterns may be the result of differences in colonization potentials among mussel species as a result of different fish‐host requirements among mussels, and of the abundance and distribution of those host fishes
The spatial variability of rare and common species in a gall‐inhabiting Lepidoptera community
Authors: McGeoch Melodie A. , Chown Steven L.
Published: July 2006

Determining the spatial variability in abundance structure of rare species is necessary to assess the validity of the often clarmed properties of rare species, I e as being both vulnerable to extinction and good indicators of environmental change The spatial concordance of the Lepidoptera species that inhabit a fungus‐induced gall on Acacia karroo was examined across South Africa A positive relationship was found between species distribution and abundance The common and moderately common species in the community were highly concordant, although the rare species were diffusive As such, the vulnerability of the rare species in this community is difficult to assess and they are unlikely to make useful indicators of environmental change Although preliminary results suggest that the community is temporally concordant, establishing the level of temporal, in addition to spaual, concordance of rarity is necessary to determine the mechanisms responsible for the abundance structure of rare species in communities
Growth and survivorship in juvenile woodlice: is birth mass important?
Authors: Dangerfield J. Mark
Published: July 2006

Growth and survivorship of individually reared offspring of the woodlice (Isopoda Oniscidae) Porcellionides pruinosus (Brandt) and Aphiloscia vilis (Budde‐Lund) were measured under laboratory conditions These measures of offspring fitness were compared to birth mass, which is a realistic measure of parental investment in offspring for these species, to test a key assumption of life history theory that an increase in resource allocation to offspring will increase offspring fitness In both species birth mass had no significant effect on survivorship to 60 days and in P pruinosus birth mass did not correlate with mass at 15, 30 or 45 days after birth In A vilis larger young at birth had a slight growth advantage to 15 days but not thereafter There appears to be little effect of birth mass on offspring fitness despite a considerable range in birth mass within broods In these species high variance in juvenile growth may spread subsequent reproductive effort and avoid risks of total reproductive failure
The relative share of graminoid and forb life‐forms in a natural gradient of herb layer productivity
Authors: Kull Olevi , Aan Anne
Published: July 2006

The proportional share of graminoid and forb life‐form in the herbaceous layer was investigated along a productivity gradient at Laelatu, western Estonia With an increase in the herbaceous layer standing crop from 43 5 to 723 7 g m−2 the graminoid life‐form became dominant in total above‐ground mass and in species number Three hypotheses to better explain competitive ability of graminoids were tested 1) graminoids are able to form higher foliage, 2) they are able to distribute foliage nitrogen in a more beneficial way, 3) they have better nitrogen use efficiency 21 sample plots 50 × 50 cm were harvested All above‐ground parts of vascular plants were removed by two canopy layers Vertical separation of layers were made according to the height of half light interception A species list was compiled, total and leaf masses and leaf nitrogen content of both life‐forms were measured by layer ANOVA showed that there were no significant differences in vertical distribution of foliage or foliage nitrogen between life‐forms in the productivity gradient, and hypotheses 1) and 2) are not supported by our data‐set Hypothesis 3) is approved partly as the nitrogen concentration in graminoid foliage was 20% less than in forbs If one supposes that nitrogen retention time is equal in both life‐forms then graminoids must have higher nitrogen use efficiency when compared to forbs Although the influence of life‐form x productivity interaction on leaf nitrogen concentration was not significant, there was a tendency that difference in leaf mass to nitrogen ratio of the two life‐forms increased with increasing incident light Thus, we can hypothesize that graminoid species dominate in high productive plots where the incident light intensity is also higher due to their better nitrogen use efficiency when compared to forb species
The effects of elk on aspen in the winter range in Rocky Mountain National Park
Authors: Baker William L. , Munroe Jennifer A. , Hessl Amy E.
Published: July 2006

National parks face problems in managing wild ungulates and their forage resources, including small park sizes and incomplete protection of winter ranges, absence of major predators, and influences from exterior management activities Our study focuses on the effects of elk Cervus elaphus browsing on aspen Populus tremuloides in the elk winter range of Rocky Mountain National Park Elk can prevent successful regeneration of aspen by suckers, and increase the mortality of established trees Here we quantify the effect of elk on aspen in the elk winter range of the park particularly since the adoption of a policy of “natural regulation” in 1968 We collected a stratified‐random sample of aspen cohorts in the elk winter range, and also inside two long‐term exclosures In each cohort we tallied live and dead trees by diameter, recorded the height and percentage of stem surface covered by bark‐stripping, and estimated the date of regeneration of the cohort using increment cores We also tallied live and dead aspen suckers (young trees < 2 5 in tall) by height and the number of live and dead branches on each sucker Aspen outside the exclosures are declining as evidenced by 1) high mortality among established trees, including entire stands that are dead, 2) low density of live suckers, insufficient to regenerate the stand, 3) suckers that are excessively branched and seldom surviving to reach tree height, and 4) almost no cohort regeneration since adoption of natural regulation Exclosures and early photos of the elk winter range suggest these are anomalous conditions Over the last century, aspen cohorts regenerated only when there were fewer than ca 600 elk on the park's elk winter range, far fewer than the present estimated 1600 head Fire suppression, natural succession, fluctuations in beaver populations, climatic fluctuations, and other factors are of no or lesser importance than elk in the regeneration and survival of aspen cohorts on the elk winter range The decline of aspen is a concern when management is focused on the ecosystem scale rather than simply the scale of wildlife and their primary forage resources
Effects of predator interactions, prey palatability and habitat structure on survival of natterjack toad Bufo calamita larvae in replicated semi‐natural ponds
Authors: Denton Jonathan S. , Beebee Trevor J. C.
Published: July 2006

The significance of predation and aquatic habitat structures to the survivorship of natterjack toad Bufo calamita larvae was investigated by manipulating predator numbers and pond characteristics in a series of replicated semi‐natural pools over three consecutive years Two species of fish (common carp Cyprinus carpio and perch Perca fluviatilis) increased the survival of small tadpoles severalfold by selectively consuming predatory invertebrates, but a third species of fish (rudd Scardinius erythrophthalmus) devoured tadpoles and invertebrates indiscriminately Survival of larger tadpoles later in larval development was less affected by the reduction of invertebrate predation pressure from carp and perch, probably because abiotic factors (pond desiccation and anoxia) were stronger agents of tadpole mortality In ponds of low pH (ca 4 5) there was greatly increased spawn mortality and reduced tadpole growth rates but no significant change in tadpole predation compared with circumneutral controls Neutralisation of acid ponds to pH 7 by addition of Ca(OH)2 restored spawn viability and tadpole growth rates to control levels without affecting predation level Addition of organic nutrients stimulated tadpole growth rates significantly m ohgotrophic ponds but not sufficiently to improve survival of small larvae in the face of predation Extensive growths of macrophytes increased predator numbers up to more than twofold but effects on tadpole mortality rates differed between experiments Replacement of natural substrates by concrete basins substantially increased tadpole survival throughout development, probably because both predation by invertebrates and abiotic mortality factors were ameliorated Predation was a strong force early in natterjack tadpole development irrespective of chemical and biological conditions within ponds, but became much less important compared with abiotic factors as an agent of mortality at later tunes
The evolution of ant‐dispersal in a spring‐ephemeralCorydalis ambigua(Papaveraceae): timing of seed‐fall and effects of ants and ground beetles
Authors: Ohkawara Kyohsuke , Ohara Masashi , Higashi Seigo
Published: July 2006

Corydalis ambiguais one of major spring‐ephemerals exhibiting ant‐dispersal in Hokkaido, northern Japan Seed dispersal in this herb species was observed in a field To attract ants, Cambiguahas small spherical seeds with large elaiosomes containing lipids In the quadrat census, 284 (11%) of 2560 seeds were moved away from their mother plants and 131 (46%) of them were recovered into ant nests The mean dispersal distance was 48 3 ± SD 34 4 cm Also the spatial distribution of Cambiguaseedlings suggested that the seeds were frequently dispersed by ants The direct observations revealed that the main dispersal ant species wereMyrmica kotokuiandLastus japomcusAdditionally some ground beetles includingPlerostichusspp often devoured elaiosomes and seedsCorydalis ambiguaseeds were dropped for about two weeks in late May The collecting by pitfall trap revealed that, in this short period, the frequency of ant foraging on the ground was high and ground beetles were a little yet Moreover, in the seed removal experiments, seeds were more frequently removed in this seed‐fall period while seed predation by ground beetles was intensive after the period
Predation on artificial nests in relation to forest type: contrasting the use of quail and plasticine eggs
Authors: Bayne Erin M. , Hobson Keith A. , Fargey Pat
Published: July 2006

Previous studies of avian nest predation have focused on how human‐induced changes in the landscape influence the frequency of predation However, natural variation in the abundance of predators due to their choice of habitat can also influence predation rate To determine if predation on artificial nests was influenced by forest stand type, we placed ground and shrub nests containing quail and plasticine eggs in contiguous coniferous, mixedwood and deciduous stands in the southern boreal mixedwood forest of central Canada Nest predators were identified using remotely triggered cameras and marks left in plasticine eggs, while the relative abundance of nest predators such as squirrels and corvids were estimated using acoustic‐visual surveys Using the fate of quail eggs to calculate predation rate, we found that predation was significantly higher in coniferous (67%) than in deciduous (17%) or mixedwood (25%) forest, with similar predation on ground (37%) and shrub (29%) nests Using plasticine eggs to calculate predation rate, nests in coniferous forest still suffered higher rates of predation, although predation rates were 15–20% higher, and ground nests suffered significantly higher rates of predation than shrub nests Quail eggs seemed to suffer lower rates of predation because small mammals were unable to penetrate the shell, but could leave marks on plasticine eggs The higher predation rate in coniferous forest was likely caused by higher abundance of red squirrels Tamiasciurus hudsonicus, the presence of fishers Martes pennanti and a simplified understory which may have made it easier for predators to find nests relative to the deciduous and mixedwood forest Plasucine eggs provide new insights into nest predation by identifying predation events by smaller predators such as mice that are missed when using quail eggs
Biogeography of Lacerta (Zootoca) vivipara: reproductive mode and enzyme phenotypes in Bulgaria
Authors: Guillaume Claude‐Pierre , Heulin Benoît , Beshkov Vladimir
Published: July 2006

Lacerta (Zootoca) vivipara, has allopatric oviparous and viviparous populations viviparity is observed from central France and the British Isles to Scandinavia and Russia, while oviparity is restricted to northern Spain and southwestern France, i e the extreme southwestern part of the range Recent observations in the Rila, Balkan, Vitocha, Pirin and Rhodopes mountains indicate that Bulgarian populations of Lacerta (Zootoca) vivipara are indeed viviparous The electrophoretic study of allozymes and the estimation of genetic distances indicate that viviparous lizards from northwest and central France are more closely related to those of Bulgaria, than to the oviparous lizards of southwest France and northwest Spain Variations in reproductive mode and allozymes are not directly related to geographic distances between populations, nor to their latitude populations located at the southwest limit of distribution are oviparous and exhibit alleles ATA‐150 or ATA‐200, whereas, at a comparable latitude, the Bulgarian populations are viviparous and exhibit allele ATA‐100 characteristic of other distant viviparous populations These findings underline the orginality of the oviparous southwestern populations They do not contradict our previous biogeographic scenario
Distribution of an increasing roe deer population in a fragmented Mediterranean landscape
Authors: Tellería José Luis , Virgós Emilio
Published: July 2006

This paper describes roe deer Capreolus capreolus distribution in central Spain, where the species has spread from the mountains into peripheral agricultural areas In this region, it is more abundant in forest fragments near the mountains than in those further away, in pine and oak woodlands than in sclerophyllous forests, and in forests with open water than in those lacking this resource The paper also analyzes whether habitat quality and geographic location of forests with respect to roe deer source areas are the two basic causes of its distribution, as predicted by some models of the species distribution in fragmented landscapes The results corroborate this hypothesis revealing that roe deer abundance is linked negatively to sclerophyllous forest cover and distance from mountains We conclude that this type of farmland seems to be sub‐optimal for roe deer in comparison with forested, moist mountains
Home range size, habitat utilisation and movement patterns of suburban and farm cats Felis catus
Authors: Barratt David G.
Published: July 2006

The movements of 10 house cats (4 desexed females, 5 desexed males and 1 intact male) living on the edge of a suburb adjoining grassland and forest/woodland habitat, and a neighbouring colony of seven farm cats, were examined using radio‐telemetry over nine months Nocturnal home range areas of the suburban cats varied between 0 02 and 27 93 ha (mean 7 89 ha), and were larger than diurnal home range areas (range 0 02 to 17 19 ha – mean 2 73 ha) Nocturnal home range areas of cats from the farm cat colony varied between 1 38 and 4 46 ha (mean 2 54 ha), and were also larger than diurnal home range areas (range 0 77 to 3 70 ha – mean 1 70 ha) Home ranges of cats in the farm cat colony overlapped extensively, as did those of cats living at the same suburban residence There was no overlap of home ranges of female cats from different residences, and little overlap between males and females from different residences Four of the suburban house cats moved between 390 m and 900 m into habitat adjoining the suburb Polygons describing the home ranges of these animals were strongly spatially biased away from the suburban environment, though the cats spent the majority of their time within the bounds of the suburb Movements further than 100–200 m beyond the suburb edge were always made at night There is evidence that home range sizes and spatial movement patterns of house cats are largely determined by a) the density and spatial distribution of cats utilising separate food resources, b) the personality and social dominance of individual cats, c) the location of favoured hunting and resting/sunning sites, and, d) barriers such as busy roads
Factors affecting crossing of red foxes and wildcats through non‐wildlife passages across a high‐speed railway
Authors: Rodriguez Alejandro , Crema Giulia , Delibes Miguel
Published: July 2006

We used trail records on sand surface within non‐wildlife passages to test whether foxes and wildcats used them regularly, and to identify passage features which may favour crossing across a railway and, therefore, may alleviate possible banner effects Both species crossed more in places and periods corresponding with assumed peaks in abundance and mobility, thus supporting the regular use hypothesis The vicinity of cover favoured crossing, but both species used infrequently passages near permanent sources of human perturbation (especially intense traffic) even in suitable habitats with abundant cover The presence of cover in the passage entrances further favoured fox and wildcat crossing Cover near entrances may be particularly important to improve carnivore crossing chances in open habitats and when human activity levels are high Passage design and dimensions had little effect on crossing rates Location of passages within or close to suitable habitats explained a greater amount of variance in crossing rates than favourable passage features There was a remarkable similarity in the behaviour of foxes and wildcats, possibly representing the rule for other carnivore species
Landscape composition models for breeding bird populations in lowland English farmland over a 20 year period
Authors: Fuller R. J. , Trevelyan R. J. , Hudson R. W.
Published: July 2006

The aim of this paper was to assess which components of landscape structure in lowland English farmland could best predict patterns m bird community composition, total bird density and densities of 12 bird species As far as possible, predictors were sought that were consistent m their effects over a 20 yr period The data were derived from mapping censuses in 1966, 1970, 1974, 1978, 1982 and 1986 with yearly sample sizes ranging from 41 to 51 plots, of minimum size 50 ha Landscape composition was quantified in terms of 10 landscape variables representing broad structural (e g density of woodland) and crop attributes (e g proportion of area under cereals) plus altitude Gradients in bird community composition were defined as plot scores on axis 1 of a detrended correspondence analysis (AXIS1) This gradient consistently represented a gradient from plots rich in woodland bird species to ones rich in field‐feeding and wetland species Multiple regression was used to build models containing 2‐, 3‐ and 4‐vanables Two approaches were used to combine data from the six years and models based on the single best subset in each year were found to be most consistent with respect to predictor selection Predictors were tested by building models based on each combination of five years and assessing how well the predictors explained variation in the bird variables for the sixth, independent year The predictors were relatively successful in explaining variations in densities of wren, robin, willow warbler, blue tit, great tit and chaffinch but especially AXIS1 which was explained in terms of woodland density, field size and altitude The predictors were unsuccessful in explaining total bird density, song thrush density and whitethroat density Structural attributes of landscape (especially density of hedgerow and woodland, but also rivers and ponds) were frequent predictors of species densities, but variables relating to farming system were not, with the exception of skylark and yellowhammer which were positively associated with extent of cereal crops Implications for landscape design and management, and the relative contribution of woodland and hedgerows to bird communities m farmland landscapes are discussed There was considerable variation between individual years which suggests that models of bird‐habitat relationships based on single years may have limited general application
The effect of evergreen and deciduous coniferous plantations on the field layer and seed bank of native woodlands
Authors: Amezaga I. , Onaindia M.
Published: July 2006

Vegetation and seed bank changes due to the replacement of a native woodland 29 yr ago by coniferous plantations (evergreen coniferous Pinus: radiata and deciduous coniferous Larix kaempferi) were studied in a replicated experiment in the Basque Country, northern Spain In the vegetation the species richness was lower in both coniferous plantations than in the native woodland but there was no significant difference in species richness between the two coniferous plantations The highest similanty between the vegetation and the seed bank was in the P radiata plantations (0 51) There was higher vegetation similarity between the native woodland and the larch plantation (0 65) than that with the pine plantation (0 58) Seed bank species richness was higher in the larch plantation than in the native woodland but species richness in the seed bank did not differ between the coniferous plantations The seed bank showed no difference in the species similarity between the plantations and the native woodland This was mainly due to the similanty between the broad ranged species In the coniferous plantations the vegetation diversity was lower than in the native woodland, however, in the seed bank the diversity was higher Coniferous plantations affected mainly the shade‐tolerant and shade‐intolerant vernals (Caltha palustris, Galium odoratum, Heleborus viridis and Saxifraga hirsula), which disappeared from the field layer of plantations while the shade‐intolerant not vemals were favoured by the plantations (Blackstonia perfoliata, Danthonia decumbens, Deschampsia flexuosa, Hypericum androsaemum, Holcus lanatus, Lotus cormiculatus and Plantago lanceolata) There was no significant difference in vegetation or seed bank between the two types of coniferous plantations
Stand age‐structure influence in a low population peak of Epirrita autumnata in a mountain birch forest
Authors: Bylund Helena
Published: July 2006

Population densities of Epirrita autumnata caterpillars were recorded from 1984 to 1990 m four mountain birch stands of two age categories, young and old Caterpillar populations peaked m 1986–87, and peak densities were higher in the old than in the young stands Recorded peak densities were low compared with synchronous populations with outbreak densities in neighbouring areas Differences in caterpillar densities between young and old stands could not be explained by differences in survival of early instar caterpillars or in parasitoid‐caused larval mortality Instead, tree‐age related differences in amounts of suitable oviposition sites and possible changes in food quality due to ageing and lower vigour of mature trees are suggested to explain why E autumnata populations tend to be higher in old stands
Ontogenetic variation in the autecology of the greater earless lizard Cophosaurus texanus
Authors: Durtsche Richard D. , Gier Paul J. , Fuller Michael M. , Lutterschmidt William I. , Bradley Rosemary , Meier C. Kate , Hardy Steven C.
Published: July 2006

We investigated the potential for ontogenetic resource partitioning within a population of the Texas earless lizard Cophosaurus texanus Results from focal samples, line transects, haphazard observations, and stomach flushes compiled in summer (July 1993) and autumn (September 1995) revealed differences in microhabitat use and diet between adults and juveniles Juveniles use rock perches more frequently than adult males, and consume smaller prey than adults No ontogenetic differences in thermal ecology were observed Diet differences between juveniles and adults may be attributed to the inability of juveniles to handle large prey items Differences between juveniles and adults in prey size and microhabitat use suggest ontogenetic variation in foraging, predator avoidance, and territory defense
The effect of spring temperature on the appearance dates of British butterflies 1883–1993
Authors: Sparks T. H. , Yates T. J.
Published: July 2006

This paper examines the first appearance of butterflies using two sources, historical data from the former phenologieal reports of the Royal Meteorological Society and recent data from the extant Butterfly Monitoring Scheme Using regression techniques mean dates of appearance are related to Manley's central England temperatures and are then examined for other, unexplained, trends over time The observed relationships suggest that, in the absence of evolutionary change, climate warming of the order of 3°C could advance butterfly appearance by two to three weeks The flowering of two of the larval foodplants of the orange tip butterfly is also examined, with the conclusion that synchrony is likely to be maintained by a similar advance in timing The consequences of such changes to the phenology of British butterflies are discussed
Interspecific abundance‐range size relationships: range position and phylogeny
Authors: Gaston Kevin J. , Blackburn Tim M. , Gregory Richard D.
Published: July 2006

A number of mechanisms have been proposed to explain the widely observed positive interspecific relationship between local abundance and extent of geographic distribution in animals Here, we use data on British birds to assess two of these hypotheses that the relationship results from the relative position of a study area with respect to the geographic ranges of the species which occur there, and that the relationship results from a simple difference between taxonomic groups, rather than any general tendency for more abundant species to have larger range sizes We find support for neither hypothesis Phylogenetically controlled comparative analyses reveal that the positive abundance‐range size relationship is consistently found within taxa, even when abundance and range size are calculated at a variety of spatial and temporal scales Analyses both across species and within taxa show that bird species for which Britain is near to the centre of their distribution in Europe tend to have larger British range sizes and higher abundances than do species where Britain is close to the edge of their range in Europe However, these relationships do not cause that between abundance and range size, because this latter relationship persists within different range position categories Whether a species is near the centre or edge of its geographic range in Britain may affect its position on the abundance‐range size relationship, but does not produce the relationship Range position in Britain does, however, seem to be related to the magnitude of temporal changes in the range sizes of British birds There is some evidence to suggest that species for which Britain is nearer to their European range centre have shown smaller changes in distribution over the period 1970–1990 than have species for which Britain is close to their European range edge
Breeding bird dynamics in a primaeval temperate forest: long–term trends in Biatowieza National Park (Poland)
Authors: Wesolowski Tomasz , TomiaJojć Ludwik
Published: July 2006

Numerical vanation of the breeding bird community, its ecological subunits (guilds) and the 26 most numerous constituent species is analysed over 20 yr period (1975–1994), and related to variation in supply of defoliating caterpillars, tree seed crop, numbers of rodents and winter weather Maximum rates of increase between two years were less than twofold in most species Changes in numbers of individual species/guilds were either independent of each other or in parallel The pattern of numerical vanation was not related to taxonomic affinities, type of nest site, food types, or migratory habits Whole bird community and 13 of 26 species showed long–term increasing trends, only three species declined Numbers remained basically stable during the first decade, increases were concentrated to the second decade Except tropical migrants (no long–term change) other migratory groups increased in numbers None of the measured environmental vanables showed parallel trends, which could account for the recorded trends Long–term trends and year–to–year fluctuations were not correlated The short–term variation in bird numbers was to some extent correlated with (in decreasing order of importance) abundance of defoliating caterpillars, winter seventy, and changes in rodent numbers No correlation with tree seed crop was found Overall, a substantial part of the vanation in breeding bird numbers could not be explained by that set of factors This could be due to birds using wider spectrum of food sources than those measured, varying predator pressure and/or strong influences from outside the forest, swamping local relationships
Dynamics of Canadian lynx populations in space and time1
Authors: Ranta Esa , Kaitala Veijo , Lindström Jan
Published: July 2006

The records of Canadian lynx fur returns indicate rather regular self‐repeating pattern with 9–11 yr cycles That the lynx populations over a vast geographical range fluctuate in synchrony appears to be well established The finding that the degree of synchrony levels off with increasing distance among provinces compared to increase again between the furthest–away provinces (O–shape) has largely escaped notice in previous analyses Moreover, the pattern of synchrony against distance varies depending on the period of time used m the analysis, sometimes there is O–shape, sometimes mere negative correlation, and sometimes no relationship whatsoever The entire rich pattern of lynx dynamics in space and time can be emulated by sets of local subpopulations acknowledging dispersal among populations This all suggest that local dynamics of populations cannot be fully understood unless the significance of spatial linkage of subpopulations via dispersal of individuals is acknowledged
Abundance‐range size relationships in British birds: is unexplained variation a product of life history?
Authors: Blackburn Tim M. , Gaston Kevin. J. , Gregory Richard D.
Published: July 2006

Positive interspecific relationships between local abundance and geographic range size are a common feature of animal assemblages However, range size typically explains only a moderate proportion of the variation m abundance, begging the question of whether species of differing life history deviate from the underlying relationship in any systematic fashion Using data for the avifauna of Britain, and applying a comparative method to control for the effects of phylogenetic association, we demonstrate that this does not appear to be the case Only adult survivorship, age at independence and incubation period explain significant variation in abundance once range size is controlled for statistically, and then only a few percent There are two probable reasons why this result is contrary to general expectation First, although many life history variables are expected to show simple correlations with abundance or range size It is not obvious how these might relate to variation about the abundance–range size relationship Second, intuitive ideas about the form such variation might take may be seriously confounded by phylogenetic non–independence
Clonal diversity of populations of Calamagrostis epigejos in relation to environmental stress and habitat heterogeneity
Authors: Lehmann Cornelia
Published: July 2006

The clonal diversity of four populations of the vegetatively propagating grass Calamagrostis epigejos was studied with isozyme markers From each population, 100 individuals were sampled within a 10 × 10 m gnd In two populations of unpolluted sites 5 and 10 clones were distinguished, respectively Higher levels of clonal diversity were found m the populations at an abandoned sewage farm (59 clones) and around a copper smelter (92 clones) The level of clonal diversity observed suggests that sexual recruitment is important for the genetic structure in this species On the unpolluted, presumably more suitable habitats, the clonal diversity was lower than on the habitats polluted with heavy metals The results are discussed in relation to environmental stress and habitat heterogeneity, with the conclusion that in the unpolluted habitats intraspecific competition results in low clonal diversity On the other hand, stressful conditions decrease the importance of competition and facilitate the coexistence of a great number of clones
Habitat predictability and the occurrence of wood beetles in old‐growth beech forests
Authors: Nilsson Sven G. , Baranowski Rickard
Published: July 2006

We sampled the wood beetle fauna in 1) living hollow, 2) standing dead and 3) downed dead beech Fagus svlvatica logs in fragmented old–growth forests in southern Sweden In nearly primaeval stands, species richness was similar in the three types of microhabitat, but m previously (50–100 yr ago) managed stands species richness was lower in living hollow trees The number of red–listed beetle species per sample was higher in living hollow beeches in nearly primaeval stands than in formerly managed stands, but there was no difference in downed dead beeches This agrees with our expectation, based on the relative stability of the microhabitats, that species living in hollow trees would have a lower dispersal propensity than those that depend on dead, downed logs Among 55 red–listed species found, 69% had a higher frequency in nearly primaeval stands than in previously managed stands For 22 endangered plus vulnerable species the figure was 77% Most red–listed species had occurrence frequencies of 5%, or less
Banksia pollen in the diet of Australian mammals
Authors: van Tets Ian G. , Whelan Robert J.
Published: July 2006

Mammals are frequent visitors to flowers in some Australian plant communities Nectar is usually considered to be the food sought, because pollen is thought to be of low digestibility This study compared the abilities of four non‐flying mammal species to extract the protoplasts fromBanksiapollen grains and quantified the amount of pollen in the diets of the species over 16 months All four species were capable of extracting the protoplast from a large proportion of the pollen grains that they ingested the mean percentage of emptyBanksiapollen grains in the faeces ranged from 37% to 66%Banksiapollen was a major component in the faecal samples from two species,Cercartetus nanusandPetaurus breviceps, between March and October It occasionally comprised a large proportion ofAmechmus stuarttifaeces but was rare in the faeces ofRattus fuscipesOther major components of faeces included invertebrates and plant material other than pollen and fungal spores As the four mammal species tested were all from separate families and all capable of extracting the protoplast from a large proportion of the pollen grains, it is concluded that the extraction of pollen protoplasts by mammals may be widespread and may require no special adaptations