The status of the otter (Lutra lutra L.) in Norfolk

The county of Norfolk was surveyed for otters between December 1974 and June 1975 inclusive. Only 32 sites out of a total of 233 sites visited had signs of otters and a further 8 records were received. A total population of 17 pairs was estimated, considerably below the carrying capacity of the area.     

The Otter Lutra lutra in central Portugal

In a survey of central Portugal during August 1980, otters were found to be widespread with signs of animals 70% of the 90 stations visited. Otters were present on major rivers and their tributaries, on small streams connecting pools and at fetid pools in semi-dry river beds. The greatest densities of marking sites and signs were found around fetid pools. Snakes, as well as fish, were found to be important prey items. The survival, in good numbers, of the otter in Portugal may be due in part to the limited use of agricultural chemicals.     

Factors affecting the success of an otter (Lutra lutra) reinforcement programme, as identified by post-translocation monitoring

Monitoring is essential to evaluate the success of translocations, but is frequently neglected. One exception has been the reinforcement of the otter (Lutra lutra) population in the Derwent and Esk catchments in North East England, UK, between 1990 and 1993. Here, we use data on otter sprainting activity collected before, during and after translocations to identify relationships with vegetation, food resources and physical river characteristics. Sprainting activity increased significantly with trout density, stream order, and surrounding cover by woodland and semi-natural grassland vegetation, and decreased significantly with stream gradient. The form of these relationships was unimodal, sprainting activity peaking at intermediate levels of environmental variables. A logistic regression model including variables relating to fish density, the physical characteristics of the river and surrounding vegetation cover was able to predict the presence or absence of otter sprainting at different survey sites with an accuracy of 92%. Fish density and the physical characteristics of the river were the most important factors in the model. Models such as this are of practical use for assessing the likely success of future otter translocations, both in North East England and other regions of the UK and Europe.     

Ecology of otters in Northern Scotland IV. A model scheme for otter Lutra lutra L. conservation in a freshwater system in aberdeenshire

Habitats for inclusion within otter havens are illustrated from a case-history study on the middle part of the Aberdeenshire River Dee. The environment is divided into breeding and rearing areas and places for non-breeding otters. One good location for a haven incorporating all three habitats includes 12–13 km of river and two nearly lochs. In this area, part of the river bank is inaccessible, and there are secluded islands and deep woods. Havens should include tiny tributaries leading to shelter where otters are likely to have their young. An otter haven in mid-Deeside planned to incorporate all these habitats may be regarded as a model for conservation that could be followed in other similar environments elsewhere.     

Otter (Lutra lutra) distribution modeling at two resolution scales suited to conservation planning in the Iberian Peninsula

We used the results of the Spanish Otter Survey of 1994-1996, a Geographic Information System and stepwise multiple logistic regression to model otter presence/absence data in the continental Spanish UTM 10×10-km squares. Geographic situation, indicators of human activity such as highways and major urban centers, and environmental variables related with productivity, water availability, altitude, and environmental energy were included in a logistic model that correctly classified about 73% of otter presences and absences. We extrapolated the model to the adjacent territory of Portugal, and increased the model's spatial resolution by extrapolating it to 1×1-km squares in the whole Iberian Peninsula. The model turned out to be rather flexible, predicting, for instance, the species to be very restricted to the courses of rivers in some areas, and more widespread in others. This allowed us to determine areas where otter populations may be more vulnerable to habitat changes or harmful human interventions.     

The otter Lutra lutra in Albania

During a survey in Albania we found signs of otters at 17 (54·8%) of the 31 stations investigated. Otters were widespread in much of the country, and healthy populations were localised in rivers and marshes in the north-west and in the south. Average sprainting activity was 1·7 positive sites per 200 m and 3–6 spraints per 200 m. Frogs, probably Rana ridibunda, as well as fish, appeared to be important prey for otters. In the coastal plains, several rivers were grossly polluted and the growing agricultural and industrial development may endanger the survival of otters.     

Otter Lutra lutra L. mortality and marine oil pollution

Following an oil spill at Sullom Voe Oil Terminal, Shetland, at least 13 otters died. Post-mortems on five corpses showed that they had died of haemorrhagic gastroenteropathy, associated with ingested oil. The primary cause of oil ingestion seems to have been grooming of the fur. A survey of the polluted coasts revealed that otters were still present throughout most of the area.     

A survey of the southern river otter Lutra provocax Thomas in Nahuel Huapi National Park,Argentina

A survey of the huillin or southern river otter Lutra provocax distribution in Nahuel Huapi National Park was made. This amphibious mustelid is included in the International Union for the Conservation of Nature Red Data Book, and as endangered in the Argentine National Wildlife List.One hundred sites were visited for signs of activity, particularly scats. Twenty-eight sites were positive, all of them in Nahuel Huapi Lake system and tributary water-bodies, where they represent 48·3% of 58 sites. No positive sites were found in the Rio Manso basin, where 13 sites with signs of American mink Mustela vison were recorded. However, it seems improbable that there is significant competitive interference between mink and otter.Although the huillin is not common, there is an apparently viable population in the Nahuel Huapi Lake system, where a high density of signs was found in several places.No significant relation was found between the otter's presence and frequency of human visitors, human settlements, domestic dogs or occurrence of introduced salmonids.Special protection areas and a monitoring programme of otter populations in the National Park are proposed.     

Habitat selection by the Mediterranean horseshoe bat, Rhinolophus euryale (Chiroptera: Rhinolophidae) in a rural area of southern Italy and implications for conservation

We studied habitat selection by Rhinolophus euryale in a rural area of southern Italy in 1998-2000 by radio-tracking. Two comparisons were carried out, one between habitat occurrence within individual home ranges and within the study area, the other between time spent in each foraging habitat and habitat occurrence within the home range. The first analysis showed that olive groves and conifer plantations were, respectively, the most and the least important habitats. The second analysis highlighted the importance of woodland for R. euryale, while urban sites, open areas and conifer plantations were avoided. We recommend that clearing of continuous, large areas of woodland for tree harvesting should be avoided. Conifers should not be used for reforestation. Urbanisation should be limited in the areas of greatest importance for the species, and linear landscape elements such as tree lines and hedgerows should be maintained.     

Rhizobia nodulating African Acacia spp. and Sesbania sesban trees in southern Ethiopian soils are metabolically and genomically diverse

The diversity of 110 rhizobial strains isolated from Acacia abyssinica, A. seyal, A. tortilis, Faidherbia albida, Sesbania sesban, Phaseolus vulgaris, and Vigna unguiculata grown in soils across diverse agro-ecological zones in southern Ethiopia was assessed using the Biolog™ system and amplified fragment length polymorphism (AFLP) fingerprinting technique. By cluster analysis of the metabolic and genomic fingerprints, the test strains were grouped into 13 Biolog and 11 AFLP clusters. Twenty-two strains in the Biolog method and 15 strains in the AFLP analysis were linked to eight and four reference species, respectively, out of the 28 included in the study. Most of the test strains (more than 80% of 110) were not related to any of the reference species by both methods. Forty-six test strains (42% of 110) were grouped into seven corresponding Biolog and AFLP clusters, suggesting that these groups represented the same strains, or in some cases clonal descendants of the same organisms. In contrast to the strains from S. sesban, isolates from Acacia spp. were represented in several Biolog and AFLP clusters indicating the promiscuous nature of the latter and widespread occurrence of compatible rhizobia in most of the soil sampling locations. The results showed that indigenous rhizobia nodulating native woody species in Ethiopian soils constituted metabolically and genomically diverse groups that are not linked to reference species.     

Polypore diversity in managed and old-growth boreal Picea abies forests in southern Finland

Polypore communities were compared between mature managed, overmature managed, and old-growth spruce-dominated forests in southern Finland. A total of 85 polypore species, with 6000 records, were found in 16 sample plots, each 4 ha in size. Old-growth stands had on average 80% more species than mature stands, and 38% more species than overmature managed stands. Variation in polypore species richness was best explained by diversity of dead wood and the number and volume of dead trees. The best predictor for the number of threatened polypore species was the number of cut stumps. Threatened species were practically confined to old-growth forests and to stands in which the amount of dead wood exceeded 20 m³/ha. This figure appears to represent a stand-level threshold value for the amount of dead wood, below which the persistence of threatened species becomes unlikely. Our results suggest that a significant increase in the amount of dead wood (e.g. by leaving large retention trees and even by killing trees) is needed in managed forests before they become suitable habitats for threatened polypores.     

The size and status of the population of southern sea lions Otaria flavescens in the Falkland Islands

Pup production of southern sea lions in the Falkland Islands was estimated to be 80,550 (total population ca. 380,000) in 1937, but by 1965 it had fallen to around 6000; a 93% reduction in under 30 years. We describe the results of an aerial survey of part of the breeding population in 1990 and comprehensive ground counts of the entire population in 1995 and 2003. Results indicate that the decline continued. In 1995, 63 breeding and 42 non-breeding groups were found. Pup production was estimated at 2034 pups; less than 2.7% of the 1930s estimate. All known and potential sites were revisited in 2003. 2747 pups were counted at 68 breeding sites, seven of which were new since 1995. Results indicate that between 1965 and 1990 the population reached a minimum of less than 1.5% of the 1937 population. Since then, pup production has increased at a rate of 8.5% p.a. between 1990 and 1995 and at 3.8% p.a. between 1995 and 2003.The Falklands' trajectory is similar to that of the adjacent Argentinian population. The causes of these declines are not clear. Around 44,000 sea lions were killed in the Falklands between 1935 and 1962, more than 500,000 were taken in Argentina in the same period. We present the results of a simple population model which suggests that, if sea lions migrated between the two areas, the combined hunt may explain the initial decline in the Falklands population. However, the continued decline after 1965 is as yet unexplained.     

Population recovery following differential harvesting of Allium tricoccum Ait. in the southern Appalachians

Over 100 native herbaceous forest perennials are harvested in the United States. Management of these populations for continued survival requires information on the long-term effects of varied harvesting levels on populations of forest perennials. Allium tricoccum Ait. is a species that is harvested throughout its range for its edible bulb. We examined the recovery of A. tricoccum populations over a 5-year period following experimental harvests of different intensity to predict the number of years required to return to pre-harvest levels and to establish guidelines for sustainable harvesting. Our harvest treatments included removal of 0, 25, 50, 75, and 100% of plants within experimental plots. Treatments were repeated at three sites. Population recovery was monitored for 4 years at two sites and 7 years at one site. We found a relationship between the level of harvest and the negative impacts on populations of A. tricoccum, with limited population recovery in the 4 years following harvesting. We projected recovery times as a function of harvest level using a population projection model. Deterministic projections of recovery time ranged from 148 years for a 95% harvest to 2.5 years for a 5% harvest. Incorporating stochasticity into our projections increased the uncertainty in our estimates of recovery time. For example the recovery time from a 5% harvest ranged from 1 to 89 years (95% confidence limit). Based on our results, a 10% harvest once every 10 years would, on average, be a sustainable level of harvest for A. tricoccum in southern Appalachian forests.     

Distribution and conservation of the shoebill (Balaeniceps rex) in the southern Sudan

The report deals with the distribution of the shoebill stork (Balaeniceps rex) in wetlands in the southern Sudan. The shoebill is a highly specialised bird requiring resources which are limited and which are discontinuously distributed in time and space. The bird's habitat is affected by a variety of artificial factors which are contributing to increasingly widespread ecological degradation of the natural wetlands. The survival of the shoebill is threatened, and the declining status of the species merits international recognition and conservation attention.     

The impact of land use on the credibility of dispersive clay soils in central and southern Italy

Abstract. Tracts of dispersive Plio-Pleistocene clays in central and southern Italy suffer from severe erosion, which has led to the creation of badlands characterized by 'calanchi'(unvegetated knife-edge ridges) and 'bian-cane'(cone-shaped hummocks). In recent decades, large areas of this eroded land have been reclaimed for arable cultivation by remodelling the landscape with heavy earth moving equipment. This exposes the clay to erosive rainfall. Wet aggregate strength was used to assess those physical and chemical properties that govern the erodibility of the clays. Regression analysis demonstrated that the most significant variables in predicting soil erodibility were the % organic matter and the exchangeable sodium percentage (ESP). Threshold values of 1–2% and 3–4% organic matter were obtained, dependent on the method of pre-wetting. Reclaimed land is on the borderline of these thresholds and therefore at risk of erosion. Nevertheless, the stability of reclaimed land is significantly higher than that of the badland parent material, ascribable to a lower ESP. Careful land management is required to avoid a recurrence of erosion and the reestablishment of badlands.     

The regional distribution of large gliding possums in southern Queensland, Australia. I. The yellow-bellied glider (Petaurus australis)

Generalised linear modelling (logistic regression) was used to predict habitat suitability for the yellow-bellied glider (Petaurus australis) from data collected from 620 sites throughout southern Queensland, Australia. Of 42 potential explanatory biotic and abiotic variables, 12 were selected in the final model including an index describing bark characteristics of the overstorey, five climatic variables, three topographic/lithological variables, two landscape metrics and one survey covariate. The predictive capacity of the final model was evaluated using Receiver Operating Characteristic curves and an independent validation dataset (ROC = 0.75; n = 180). Of the extant forest and woodlands of the southern Queensland study region, the interpolated model predicted that approximately 19% was yellow-bellied glider habitat. The majority of predicted habitat occurred within public-owned forests, which are managed under a set of prescribed standards in a Code of Practice for commercial forest management. An important issue for conservation management of the yellow-bellied glider will be management of habitat on privately owned land, which incorporates over 27% of potential glider habitat.     

Ecology of the native and introduced crayfishes Austropotamobius pallipes and Procambarus clarkii in southern Spain and implications for conservation of the native species

The former and present distribution of white clawed crayfish (Austropotamobius pallipes) in the province of Granada (southern Spain) is studied. Before 1980 it was widely distributed but at present only 16 populations exist. The decline is related to the presence of the freshwater red-swamp crayfish (Procambarus clarkii), an American species, vector of the aphanomycosis disease, introduced to the Iberian Peninsula in 1974 and now widely distributed in the watercourses and marshes of southern Spain. To establish an appropriate conservation policy for A. pallipes at its southernmost distribution limit, we studied watercourses from two river basins, Genil and Guadiana Menor, (tributaries of the Guadalquivir River). P. clarkii inhabits the medium to lower reaches of these two river basins (with its upper limit at 820 m a.s.l.). The distribution of this species was best explained by the effect of three of the 12 analyzed variables: altitude, water-current and minimum winter temperatures. From our results, the repopulation of the native crayfish is almost impossible in those reaches inhabited by P. clarkii. However, based on the habitat selection study, it is clear that upper reaches are unsuitable for the red-swamp crayfish, where the native white-clawed crayfish may have greater survival possibilities, and these sites can be used for future restocking projects.     

Spread and attempted eradication of the grey squirrel (Sciurus carolinensis) in Italy, and consequences for the red squirrel (Sciurus vulgaris) in Eurasia

In 1997, the National Wildlife Institute, in co-operation with the University of Turin, produced an action plan to eradicate the American grey squirrel from Italy, as this introduced species replaces the native red squirrel through competitive exclusion and damages trees through de-barking. The first step, a trial eradication of a small population of grey squirrels at Racconigi (Turin) to evaluate the efficiency of the removal techniques, started in May 1997. Preliminary results showed that eradication was feasible, but the project was opposed by radical animal rights groups which took the National Wildlife Institute to court in June 1997. This legal action caused a suspension of the project and led to a lengthy judicial enquiry that ended in July 2000 with the acquittal of the Institute. Nevertheless, the 3-year suspension of all actions led to a significant expansion of the grey squirrel's range and thus eradication is no longer considered practical. Therefore, in the medium to long term, grey squirrels are likely to expand through continental Eurasia. This constitutes a major threat to the survival of the red squirrel over a large portion of its distribution range and will have a significant impact on forests, with economic damage to timber crops.     

The incidence of Gaeumannomyces graminis var. Tritici and Phialophora radicicola var. Graminicola on wheat grown after different cropping sequences

The effects of three treatment cropping sequences (fallow, lucerne or grass-clover ley) on the incidence of Gaeumannomyces graminis var. tritici and Phialophora radicicola var. graminicola were measured in a field experiment. Increases in G. g. tritici population in the soils of the first wheat crop and the incidence of take-all in the second wheat crop were greater after fallow or lucerne than after grass-clover. These differential increases were not associated with differences in survival of G. g. tritici during the treatment cropping but were correlated negatively with the population of P.r. graminicola in the soil. After the third wheat crop the P. r. graminicola population after grass-clover had decreased and take-all was as prevalent as after fallow or lucerne.