Sewage works as bird habitats in Britain

The bird communities associated with different systems of sewage disposal are described in relation to the components of each system. The data were drawn from published studies and from British Trust for Ornithology data in the Common Birds Census and Register of Ornithological Sites. The bird communities were considered under four divisions: breeding, summer feeding, spring and autumn, winter. The ornithological gains and losses associated with recent changes in methods of sewage treatment are discussed, particularly in relation to the decline of sewage farms. It is concluded that modern works, which are on average smaller in area than sewage farms, support lower populations of wetland species. The variety of ornithological interest is also lower but it is suggested that modern works can be important bird habitats, particularly as feeding sites for several passerine species. Those systems with percolating filters and tertiary treatment by surface irrigation are likely to support the most varied bird communities. Works using other oxidation methods, and no tertiary treatment, are of the least value as bird habitats.     

Proposal for a new classification of Norwegian bird communities

Cartographic methods for the presentation of zoological data have been much neglected, mainly because there is a lack of classification systems relating to different animal communities. A classification system for bird communities in Norway, based on a hierarchical structure as used by the phytosociologists, is described. Five main communities are proposed at the class level. As an example, the forest community (Fringilla) is described down to the association level. Indices of preference are formulated for particular bird species in specified vegetation units and communities, together with a general knowledge of avian distribution and ecology. The ‘complete’ system will make it possible to read the corresponding bird community from the vegetation units in a vegetation map and to compare one bird community with another when assessing relative conservation values. The new system is intended to aid planning authorities who need up-to-date biological data for nature conservation and resource legislation.     

Linking cost efficiency evaluation with population viability analysis to prioritize wetland bird conservation actions

Prioritizing management actions for wildlife conservation is a difficult task due to the large number of problems relative to available conservation resources and uncertainty about the benefits arising from numerous potential management actions. In this study we use a cost-efficiency protocol to evaluate and prioritize eight different management actions for waterbird community in wetlands throughout southeastern Spain. The protocol generated an action priority ranking based on the costs and predicted benefits of the actions in terms of waterbird carrying capacity. Action prioritization outcomes were also evaluated using population viability analysis models for two of the study species. Removal of dead bird carcasses to prevent disease outbreaks was identified as the most cost efficient action. Removing lead pellets from the sediment was the least efficient strategy. Our approach highlights the role of detailed risk assessment as a form of quality control on the simpler prioritization protocols. We recommend a two-step prioritization protocol based on (i) a rapid, usually simpler prioritization approach for the bulk of species or values being managed, and (ii) a more sophisticated risk assessment for a subset of the species of interest for which detailed risk assessments are tractable. This process strikes a balance between sophistication and practicality.     

Remnant grassland habitats as source communities for plant diversification in agricultural landscapes

Lately there has been a shift in Sweden from grazing species-rich semi-natural grasslands towards grazing ex-arable fields in the modern agricultural landscape. These fields normally contain a fraction of the plant species richness compared to semi-natural grasslands. However, small remnant habitats have been suggested as important for plant species diversity and conservation as they may function as refugia for grassland specialists in fragmented and highly modified agricultural landscapes. In this study, we examined whether plant communities on small remnant habitats, i.e. midfield islets, can function as sources for grassland species to disperse out into surrounding grazed ex-fields (former arable fields). We examined species richness and grassland specialists (species favoured by grazing) and their ability to colonize fields after 5 and 11 years of grazing. The fields that had been grazed for a shorter time were fairly species-poor with few grassland specialists. A longer period of grazing had a positive effect on total and small-scale species diversity in both islets and fields. Species composition became more similar with time, and the number of grassland specialists in both habitats increased. We found that grassland specialists dispersed step-wise into the fields, and the number of grassland specialists decreased with distance from the source. Our study suggests that remnant habitats, such as midfield islets, do function as a source community for grassland specialists and enhance diversification of grassland species when grazing is introduced. For long-term conservation of plant species, incorporating small refugia into larger grazing complexes may thus enhance species richness.     

Influence of land-use and conservation programs on wetland plant communities of the semiarid United States Great Plains

Depressional wetlands are predominant surface hydrological features providing critical societal ecosystem services in the semiarid United States High Plains. Critical wetland properties may be threatened because this 30 million ha short-grass prairie largely was converted from grassland to cropland. Further, the United States Department of Agriculture enrolled marginal cropland into the Conservation Reserve Program (CRP). CRP reduces topsoil erosion by planting permanent cover on croplands. In the High Plains, introduced tall-grasses primarily were planted in CRP, possibly reducing precipitation runoff, an important hydroperiod driver in wetlands. We assessed land-use influence on important wetland processes (wetland area, inundation, and plant composition) in 261 depressional wetlands called playas (87 each in native grassland, CRP, and cropland). Surveys spanned six states within three High Plains sub-regions (southern, central and northern). Playas averaged 8 ha in cropland and 16 ha in other land-uses. Plant composition in grassland playas was predominately native perennials, and upland plant cover equaled wetland plant cover. Cropland playas had fewer species/ha, generally more annuals than perennials and 80% greater exposed ground than other land-uses. CRP playas had 400% greater cover of introduced species (mostly upland perennial tall-grasses), which possibly inhibited catchment runoff, as CRP playas were inundated 56% less often than other land-uses. Therefore, tall grasses should not be planted in short-grass prairie CRP catchments, as they alter inundation frequency and vegetation communities in embedded wetlands. Conservation programs containing provisions to protect playas, including planting common native species and using grass buffers to control erosion into wetlands, should be promoted.     

Comparison of breeding bird and vegetation communities in primary and secondary forests of Great Smoky Mountains National Park

We compared breeding bird communities and vegetation characteristics at paired point locations in primary (undisturbed) and mature secondary forest (70-100 years old) sites in Great Smoky Mountains National Park, USA to understand how sites logged prior to creation of the park compare to undisturbed sites following 70 years of protection from human disturbance. We found that bird and vegetation communities are currently similar, but retain some differences in species composition. Rank abundance curves for primary and secondary forest bird communities showed very similar patterns of species dominance. Species composition was also similar on the two sites which shared 24 of the 25 most frequently recorded species. Nonetheless, comparisons of density estimates derived from distance sampling showed three bird species were more abundant on primary forest sites and that one bird species was significantly more abundant on secondary forest sites. Notably, comparisons based on raw counts (unadjusted for potential differences in detectability) produced somewhat different results. Analyses of vegetation samples for the paired sites also showed relative similarity, but with some differences between primary and secondary forests. Primary forest sites had more large trees (trees greater than 50 cm diameter at breast height) and late successional species. Primary forest sites had a denser tall shrub layer while secondary forest sites had a denser canopy layer. Nonetheless, tree species richness, basal area of live trees and number of standing snags did not differ between primary and secondary forest sites. Results indicate that breeding bird communities on sites within the park that were logged commercially 70 years ago are currently quite similar to bird communities on sites with no history of human disturbance. Similarities between the bird communities on previously disturbed and undisturbed sites in Great Smoky Mountains National Park may exceed those on more fragmented landscapes because large patches of primary forest, adjacent to commercially logged sites, remained in the park when it was established in 1935. These patches of primary forest may have served as source areas for commercially logged sites.     

Satellite tracking of breeding black storks Ciconia nigra: new incomes for spatial conservation issues

Satellite tracking of black storks was used to estimate home range sizes and to study habitat selection during the breeding season. Breeding and non-breeding adults foraged over very large areas (ca. 54 000 ha for 12 territories), preferentially in woodlands with high number of river sources, mirroring the species needs for high quality water resource. Rearing and post-fledging ranges of breeding partners largely overlapped. Home ranges of non-breeding adults largely overlapped ranges of breeding birds, so that assessing home range size of breeding pairs from observed densities is not reliable. Protection and management of breeding and feeding habitats appear to be the most important conservation measures to be considered. This study allowed to evaluate how large these protected areas should be, and which habitat types they should encompass. Conservation measures for the species in western Europe should include protection of very large forest areas and also focus on managing river networks to ensure a high water quality as far as 20 km away from nests.     

Breeding bird communities in southern Tunisian oases: the importance of traditional agricultural practices for bird diversity in a semi-natural system

We investigated the diversity of breeding bird communities in 53 oases in southern Tunisia. In particular, we examined the similarity of bird communities among oases in relation to vegetation structure and geographic location. We found that oases close to each other supported similar bird communities, suggesting that the spatial distribution of oases has played an important role in shaping local communities. Accounting for oasis location, bird richness was related to oasis size and to vegetation traits, namely to the diversity of trees and herbaceous plants. Oases within which traditional practices are used to diversify the agricultural products were found to provide more suitable habitat conditions for birds than modern plantations created to maximize the production of dates. Traditional oases represent semi-natural habitats within which traditional human activities may be essential for maintaining their biodiversity, and we think that more attention to the conservation of these systems is to be paid.     

Influences of roads and development on bird communities in

Our objective was to improve knowledge about effects of broad-scale road and development variables on bird communities in protected desert landscapes. Bird species richness and the relative abundance or probability of occurrence of many species were significantly associated with total length of roads within each of two spatial extents (1- and 2-km radii), distance to the nearest road, distance to the nearest development, or the two-way interactions of these variables. Regression models reflected non-linear relations, interaction effects, spatial-extent effects, and interannual variation. Road and development effects warrant special attention in protected areas because such places may be important sources of indigenous bird communities in a region.     

Research effort allocation and the conservation of restricted-range island bird species

Knowledge gap analyses can be useful to highlight imbalances in research and to improve the distribution of conservation research efforts. We used ISI’s Web of Knowledge (WoK) and BirdLife International’s library catalogue (BLI) to examine the allocation of research effort amongst the extinction-prone island restricted-range birds (RRSs, n = 1321) and the island endemic bird areas and secondary areas (EBAs, n = 108; SAs, n = 58) previously identified by BirdLife International. We found that the distribution of research effort was very uneven across both species and areas. Half of the number of outputs obtained from WoK referred to 3.1% of the island restricted-range bird species and to 4.8% of the endemic bird areas and secondary areas, whereas 52.2% of the species and 34.3% of the areas had no output. The global distribution of research had a strong spatial component, with a limited number of places receiving most of the research efforts (Hawaii, New Zealand, Central America), while many species rich areas were very poorly studied (South East Asia, South Pacific, most Atlantic islands). Research amongst the most threatened RRSs tended to be less biased, with these species having a higher probability of having at least one output from WoK than less threatened species. Given that threats to the conservation of biodiversity are often highly context-dependent, we advocate prioriting the study of poorly known species and regions. Finally, we integrate the knowledge gaps we identify with previously established conservation priorities, in order to prioritize for future conservation research on RRS, EBAs and SAs.     

Trends associated with residential development in riparian breeding bird habitat along the Snake River in Jackson Hole, WY, USA: Implications for conservation planning

Throughout North America, bird population declines may be attributable to loss of habitat on the breeding grounds. Human land uses such as residential development, greatly impact landscapes and biota, particularly breeding birds. Riparian areas, which are essential to breeding birds, are particularly vulnerable to development pressures. In North America, most studies have focused on eastern birds and it is unclear how western bird assemblages respond to the effects of residential development. We sampled bird community parameters and habitat variables at three spatial scales (microhabitat, macrohabitat, and landscape) along a residential development gradient within the Snake River riparian corridor in Jackson Hole, WY, USA. Principal component analysis and multiple linear regression statistical tests were used to determine the effects of housing densities on avian community parameters, guilds, individual species distributions, and environmental variables. Landscape-level features were most affected by residential development and trends associated with increasing housing densities, such as anthropogenic habitat fragmentation primarily structured local bird communities. Overall species richness and diversity declined with increasing residential development. Neotropical migrant species were most negatively impacted and consistently declined in proportional representation on forested plots as residential development densities increased. Food generalists, ground gleaners, and avian nest predators all increased with increasing residential development. Brood parasites, on the other hand, did not increase with increasing housing densities and their distribution may reflect the availability of nest host species. These results suggest that residential development within riparian habitats may be exerting a strong negative influence on western bird communities and at high densities may lead to a depauperate avian biota. The results of our study indicate that preserving forest structure may benefit certain species but will not likely conserve as diverse and rich an avian assemblage as minimizing fragmentation associated with residential development.     

Effect of forest management on the breeding bird community in southern Sweden

A natural and a managed forest of similar age were compared. Total bird density was three times higher in the natural forest. All species groups had higher population densities in the natural forest, but woodpeckers and warblers much more so than other groups. Hole-nesting species made up about the same proportion of the bird communities in the natural and the managed forests.Bird density in a young spruce plantation was one-ninth of that in the natural forest. Species number was higher in the natural than in the managed forest.     

Butterfly conservation—The need for a captive breeding institute

There is increasing evidence that local invertebrate populations persist only because of occasional immigration. Demands on land are so great that suites of reserves within the natural dispersal abilities of most species are unlikely to be obtained. Thus there may be little alternative to occasional reintroduction of stock if some species are to be preserved. Moreover, there may be occasions when a species is threatened with extinction due to destruction of its last habitats, and the absence of other suitable sites to which it could be transferred. In such cases there is a need to maintain stocks in captivity for use in future reintroductions. Indeed, this has been the approach followed by vertebrate conservationists, where the ideal of habitat conservation is often prohibitively expensive. Recent methods of rearing butterflies on artificial diets have allowed cost-effective production of large populations of butterflies and moths, even when their natural foodplant is unavailable. These populations may be considerably larger than their natural counterparts. Since it is more efficient to use resources to produce a number of species on one site, it is proposed that the maintenance of stocks of rare species be entrusted to a Captive Breeding Institute established for this purpose. Since the techniques employed have commercial potential in mass-production of species of economic importance, it is hoped that the Institute will be largely self-financing after its initial foundation. In this manner resources will not be diverted from the essential work of habitat conservation.     

Landscape-level processes and wetland conservation in the Southern Appalachian Mountains

The function of wetland ecosystems is not independent of the landscapes in which they are embedded. They have strong physical and biotic linkages to the surrounding landscape. Therefore, incorporating a broad-scale perspective in our study of wetland ecology will promote our understanding of these habitats in the Southern Appalachians. Changes in the surrounding landscape will likely affect wetlands. Broad-scale changes that are likely to affect wetlands include: 1) climate change, 2) land use and land cover change, 3) water and air-borne pollution, 4) a shift in disturbance/recovery regimes, and 5) habitat loss and fragmentation. Changes in climate and land cover can affect the hydrology of the landscape and, therefore, the water balance of wetlands. Excessive nutrients and toxin transported by air and water to wetlands can disrupt natural patterns of nutrient cycling. Periodic disturbances, like flooding in riparian zones, is required to maintain some wetlands. A change in disturbance regimes, such as an increase in fire frequency, could alter species composition and nutrient cycles in certain wetlands. Many plant and animal species that found in small, isolated wetlands have populations that are dependent on complementary habitats found in the surrounding landscape. Loss or fragmentation of these complementary habitats could result in the collapse of wetland populations.     

Influence of matrix habitats on the occurrence of insectivorous bird species in Amazonian forest fragments

The influence of matrix habitats on the occurrence of seven understory insectivorous bird species in forest fragments was examined at the Biological Dynamics of Forest Fragments Project, Manaus, Amazonia. Playback techniques were used to detect individuals in the continuous primary forest, fragments of 1, 10 and 100 ha, and in two matrix habitats of secondary forest dominated by Vismia spp. and Cecropia spp. Sampling points in secondary forest areas were distributed at 50, 250 and 500 m from the continuous forest. Using G-tests of frequency distribution, species occurrences were compared in the following ways: (a) continuous forest vs. fragments; (b) continuous forest vs. second growth forest; (c) in second growth at different distances from continuous forest. Species were divided into three categories according to their sensitivity to the fragmentation process. Highly sensitive species (Cyphorhinus arada, Hylophilus ochraceiceps and Thamnomanes ardesiacus) did not occur in small fragments or in matrix habitats. Moderately sensitive species (Formicarius colma and T. caesius) occurred in small fragments and utilized infrequently matrix habitats. Positively affected species (Percnostola rufifrons and Hypocnemis cantator) were frequently detected in small fragments and all matrix habitats. Distances from the continuous forest did not influence the frequency of species occurrences in the secondary forest areas. Species were more frequent in small fragments surrounded by Cecropia spp. than by Vismia spp. Our results support the idea that the maintenance of species in small fragments may depend on their ability to use the matrix, and that increasing the permeability of the matrix may be an option to lessen the effects of forest fragmentation.     

Case studies on breeding systems and its consequences for germplasm conservation

Summary This study gives the results of allozyme diversity within and among 20 wild Lima bean populations uniformly distributed throughout the Central Valley of Costa Rica. The electrophoretic analysis of seven enzyme systems show five monomorphic loci and a relatively low level of polymorphism for the other loci. This moderate level of polymorphism is unexpected for a species for which a fair amount of allogamy rates has been reported, at least among the cultivated forms. The genetic parameters (mainly percentage of polymorphic loci, mean genetic diversity, percentage of heterozygotes and fixation index) indicate a tendency for a predominantly selfing breeding system in the wild Lima beans although some values range between selfing and mixed-animal breeding systems. Very low within-population diversity is observed while a good diversity is found among populations. Results also show a departure from Hardy-Weinberg equilibrium on most analyzed populations in the target site This might be due to populations divided into subpopulations among which no natural crosses occur randomly, to weeding practices or to overlap of generations within some populations. All the results obtained in this work are discussed in view of further studies for the planning of in situ conservation in a quickly evolving tropical environment.     

Case studies on breeding systems and its consequences for germplasm conservation

The first results of a study relative to the demography of wild Lima bean (Phaseolus lunatus L.) populations in the Central Valley of Costa Rica are presented. Six wild populations were selected in the four mainly representative ecological zones of this region and several 1 m₂ quadrats were demarcated in order to determine the vital rates (fecundity, survival, growth and mortality) of the individuals within each population. These data were collected during two years from 3000 labelled individuals and combined with those relative to the soil seed bank and the seed dormancy to propose a demographic model for a hypothetical mean wild population based on the projection matrix theory. This model helps to determine the growth rate of the population, the stability of its structure and, by using a sensitivity analysis, reveals also the factors most constraining for the population survival. Population behaviour under natural conditions and human pressure are simulated, which allow to propose management practices for in situ conservation.     

Geographic associations of breeding bird distribution in an urban open space

The Puente-Chino Hills, extending west into the highly urbanized Los Angeles Basin, represent one of the largest expanses of lowland habitats in the region. During spring and early summer of 1997 and 1998, birds and vegetation surveys were conducted to clarify the influence of geographical position in the distribution of birds in the hills. Using logistic regression, the inclusion of longitudinal position as a variable is shown to make a statistically significant contribution to bird species presence beyond that of habitat alone for 12 of the 49 most commonly detected species. Species more common than would be expected based on habitat in the east were typical of grassland and open habitats, whereas those more common in the west were characteristic of tall scrub or urban habitats. Thus, species’ distributions in the hills are likely influenced by landscape-scale vegetation patterns and by the aggregate amount of urbanized areas in the west. This emphasizes the importance of using geographical position as a variable when analyzing patterns in bird distribution and siting conservation areas.     

Grazing management of calcareous grasslands and its implications for the conservation of beetle communities

Calcareous grasslands are an important habitat for floral and faunal communities in the UK and Europe. Declines due to changes in management, scrub invasion and agricultural improvement have left much of the remnants of this habitat in a degraded and fragmented state. Grazing, by cattle or sheep, is one of the main management practices used to maintain and improve the floral and faunal quality of calcareous grassland. The long-term impacts of different grazing regimes, however, are poorly understood, particularly in terms of the invertebrate communities. This study contrasted the impacts of recently introduced and long-term sheep or cattle grazing on beetle communities present on one of the largest areas of calcareous grassland in Europe, the Salisbury Plain military training Area, UK. No effects of grazing management on beetle abundance, species richness or evenness were found, but plant diversity and overall percentage cover of grasses did influence beetle diversity. Proportions of the total number of individuals and overall species richness within beetle guilds (predatory, phytophagous, flower/seed feeders, root feeders and foliage feeders) were strongly influenced by both the duration and type of grazing animal. At the species level, beetle community structure showed significant differences between ungrazed, long-term cattle and long-term sheep grazing treatments. Changes in plant community structure were found to influence beetle community structure. The significance of these results is discussed in terms of the long-term impacts of grazing on beetle community structure, and the benefits of different grazing regimes for the conservation management of calcareous grasslands.     

Bacterial communities in the rhizosphere of Phragmites australis from an oil-polluted wetland

Although Phragmites australis is commonly planted in constructed wetlands, very little is known about its roots-associated bacterial communities, especially in wetlands used for the remediation of oil produced waters. Here, we describe the bacterial diversity, using molecular (illumina MiSeq sequencing) and cultivation techniques, in the rhizosphere soils of P. australis from an oil-polluted wetland in Oman. The obtained isolates were tested for their plant-growth promoting properties. Most sequences belonged to Proteobacteria, Bacteriodetes and Firmicutes. Sequences of potential hydrocarbon-degrading bacteria (e.g. Ochrobactrum, and Pseudomonas) were frequently encountered. All soils contained sequences of known sulfur-oxidizing (e.g. Thiobacillus, Thiofaba, Rhodobacter and Sulfurovum) and sulfate-reducing bacteria, although the latter group made up only 0.1% to 3% of total sequences. The obtained isolates from the rhizosphere soils were phylogenetically affiliated to Serratia, Acinetobacter, Xenorhabdus, Escherichia and Salmonella. All strains were able to solubilize phosphate and about half were capable of producing organic acids and 1-aminocyclopropane-1-carboxylate (ACC) deaminase. Around 42% of the strains had the ability to produce indole acetic acid and siderophores. We conclude that the rhizosphere soils of P. australis in oil polluted wetlands harbor diverse bacterial communities that could enhance the wetland performance through hydrocarbon degradation, nutrient cycling and supporting plant growth.