Contemporary conservationist (12)

Outdoor recreation is often supposed to have an important impact on wildlife, although this assumption has not been tested very often. The resulting lack of knowledge becomes apparent in situations where parties with conflicting interests disagree on the number of visitors an area can sustain without major repercussions.In 1980 the possible effects of recreation intensity upon bird densities were studied in seven study plots adjacent to urban residential areas in The Netherlands. Of the 31 bird species found, only 13 could be studied in detail, being present in at least 20 territories. Significant negative correlations between recreation intensities and bird densities were found for 8 of these 13 species.The slopes of the regression lines enabled us to rank the 8 species in a sequence of decreasing susceptibility. The results indicate that the disturbance is caused rather by the recreation intensity during the week than by the recreation intensity at weekends.     

Gaps in the protected area network for threatened Afrotropical birds

Protected areas established for wildlife conservation (IUCN category I-VI protected areas) or for forest and watershed conservation (forest reserves) across mainland sub-Saharan Africa have high biodiversity values. However, they fail to cover over half of the 106 threatened bird species, and thus leave these vulnerable to extinction. An analysis of Red List bird species that are not represented in existing reserves indicates gaps in the current network of protected areas, namely: Mt. Cameroon-Bamenda highlands (Cameroon), the Angolan scarp (Angola), the Drakensberg Highlands (South Africa), the Highveld (South Africa), the Eastern Arc Mountains (Tanzania), the eastern African coastal forest mosaic (Kenya and Tanzania), the Albertine Rift (Uganda, Rwanda, Burundi, eastern Democratic Republic of Congo and western Tanzania), and the Ethiopian Highlands. The addition of Forest Reserves to the existing protected areas closes some of the reservation gaps for threatened birds in Africa. We suggest that these Forest Reserves should be included within official lists of protected areas, and that National forestry authorities be encouraged to manage these areas. Publication of scientific articles showing the conservation value of Forest Reserves is needed to raise local and international support and funding.     

Nature-based tourism impacts on yellow-eyed penguins Megadyptes antipodes: does unregulated visitor access affect fledging weight and juvenile survival?

The Otago Peninsula, South Island, New Zealand offers tourists opportunities for unregulated access to breeding sites of the yellow-eyed penguin (Megadyptes antipodes). The presence of people on beaches delays post-foraging landing by penguins, which in turn may affect the amount of food delivered by parents to their chicks, with consequences for chick growth and fledging mass. This study explored the relationship between human disturbance and yellow-eyed penguin chick fledging weight and survival by comparing five yellow-eyed penguin breeding areas with different levels of visitor frequency. We investigated whether chick fledging weights vary between breeding areas, and whether fledging weight is a predictor of juvenile survival. In 2002, chicks at Sandfly Bay, an area with high numbers of tourists, had significantly lower fledging weights than chicks at Highcliff, an area with no tourist visitors. An analysis of sightings of 2125 yellow-eyed penguin chicks banded between 1981 and 2000 indicated probability of survival was positively associated with mass at fledging. Thus lower fledging weights may have long-term population consequences. Fledging weight is influenced by many factors, however the results suggest the possibility of an effect of tourist numbers on chick fledging weight. This is noteworthy, especially in light of the rapid rate at which wildlife tourism is increasing in coastal areas of southern New Zealand.     

Resource use and rarity among frugivorous birds in a tropical rain forest on Sulawesi

Relatively few studies have focussed on the relationship between resource use and rarity. Rare species could differ from common species in two ways: rare species may utilise resources that are themselves rarer or rare species may utilise a narrower range of resources than common species (i.e., they are more specialised). I investigated the relationship between local abundance and patterns of food resource use for an assemblage of 19 frugivorous birds in the tropical lowland rain forest of Sulawesi, Indonesia. Over a 10-month period I collected data on two measures of rarity, the local abundance and monthly variability in local abundance of each bird species, together with data on their feeding ecology including dietary specialisation, resource availability, resource overlap and habitat use. These measures produced 18 ecological variables, 17 of which I correlated with the two measures of rarity using univariate correlations and minimum adequate multiple regression models. These were carried out using the original data and independent contrasts that controlled for potential phylogenetic bias. Both measures of rarity were most strongly correlated with measures of resource availability. In both the original data and independent contrasts regression models of the temporal variability in bird abundance, only temporal fruit availability was included as a significant predictor. In the regression models of bird abundance, the strongest significant predictor was the amount of rare fruit in the diet (a negative relationship). Both models also included measures of resource specialisation, however, these were not significant in the absence of the measure of resource availability. On Sulawesi, rare frugivorous birds utilise rare resources. Specialisation, however, might be an important factor in species persistence once they become rare. The generality of the findings need to be tested.     

Gravel pits as new wetland habitats for the conservation of breeding bird communities

Gravel pit wetland habitats are a new and rapidly expanding feature of the contemporary environment in Britain. This paper investigates and emphasises their value as potential conservation areas for breeding bird communities. Most gravel pits are characterised by close proximity to man in an urban-agricultural environment, but contain a variety of aquatic, marshland and terrestrial habitats. Their breeding bird communities contain a wide variety of species, often at high breeding densities. As natural wetlands come under increasing pressure, it is suggested that these new wetlands are important for the future conservation of marshland and aquatic species, and may also act as reservoirs of diversity and abundance in a rapidly changing environment. Conservation of some gravel pits should be based on their overall value as conservation, education and recreation areas near urban centres, and others could relieve the increasing public pressure on natural wetlands. Present trends in the utilisation of gravel pits for recreation are discussed and ultimately it is hoped to show how conservation and recreation may or may not co-exist in the new wetlands of the future.     

Using community observations to predict the occurrence of malleefowl (Leipoa ocellata) in the Western Australian wheatbelt

The Malleefowl is a ground-dwelling bird species that has declined in distribution and abundance in Australia since European settlement. These declines have been exacerbated in the Western Australian wheatbelt by the extensive clearing of native vegetation for agricultural development. A wealth of opportunistic, presence-only data exists for this species but absence data required for distribution modelling is lacking. This situation is typical of many species distribution datasets. We sought to establish the distribution of malleefowl within the Western Australian wheatbelt (210 000 km²) and their choice of habitat within this broad region. We supplemented a large presence-only dataset of malleefowl sightings with absence data derived from a bird atlas scheme and used these data to effectively predict the distribution of the species for the wheatbelt using a combined GAM/GLM approach. Both datasets were derived largely from community sightings. The distribution of malleefowl within the Western Australian wheatbelt was associated with landscapes that had lower rainfall, greater amounts of mallee and shrubland that occur as large remnants, and, lighter soil surface textures. This study illustrates how community knowledge, coupled with solid ecological understanding, can play a key role in developing the knowledge base to inform conservation and management of species in agricultural landscapes.     

Identifying areas of high-value vertebrate diversity for strengthening conservation

Identifying areas with relevant features of biodiversity is useful to rank priorities for strengthening the design of well-sited natural protected areas and to optimize resource investment in conservation. This study provides decision makers critical tools for highlighting pieces of land worthy of conservation in Spain. We studied four taxa—amphibians, reptiles, nesting birds and mammals—in a 50 × 50 km grid (n=259 cells). We used five criteria for identifying areas of high-value diversity: species richness, rarity, vulnerability, a combined index of biodiversity, and a Standardized Biodiversity Index that measured all four taxa together. As far as we know, the combined index of biodiversity and the Standardized Biodiversity Index are original. Areas of high-value diversity were defined as those cells within the 15% top segment of ranked values for the different criteria. Congruence of areas of high-value diversity for taxa pairs was moderate to low, and averaged 38.5% for areas of high-value diversity based on the combined index of biodiversity. The performance based on the average proportion of threatened species excluded from areas of high-value diversity followed the rank combined index of biodiversity=rarity (0.3%) > vulnerability (9.9%) > species richness (13.8%). The areas of high-value diversity identified according to the Standardized Biodiversity Index included all amphibian and mammal species, all but one reptile species (categorized as rare) and all but six bird species (three of which were categorized as threatened). About 70% of the areas of high-value diversity identified based on the Standardized Biodiversity Index included natural protected areas. However, they average only 274.6 km², thus occupying a small fraction of the areas of high-value diversity, and there is no guarantee that the species found in an area of high-value diversity site will be present in its protected fraction. Consequently, we urge managers of natural protected areas to conduct diversity surveys. We also urge that additional natural protected areas be established to include the gap of 30% of areas of high-value diversity not currently protected. We took an step for biodiversity conservation planning in the studied region, and discuss the usefulness of maps of areas of high-value diversity for conservation, ecological restoration, and environmental impact assessment and mitigation.     

Estimated dates of recent extinctions for North American and Hawaiian birds

Series of sighting records - the years in which a species has been recorded - can be used to infer whether species have gone extinct, and when extinctions occurred. We compiled sighting records for 52 rare bird species, subspecies, and distinct island populations from North America and Hawaii, 38 of which proved adequate for such analyses. Using a data set that combines non-controversial sight records with those for which physical evidence exists, no populations were judged likely to be extant, including those that have not been declared extinct. The ‘alalā was the only species with a 95% confidence interval around the extinction date that extended beyond 2009, suggesting that this population is the least unlikely to be extinct. Although all are probably extinct, populations were ranked according to their likelihood of persistence, so that any future searches can be prioritized to minimize the risk that resources are spent on extinct species. Estimated extinction dates spanned the period from the 1840s-2000s, with evidence for a peak in the early 1900s. On average, only about 4 years passed between a species’ last sighting and its estimated extinction date, and the 95% confidence intervals around extinction dates extended 9-26 years after the last sighting. Long gaps between sightings were very rare. Mean and median gap sizes between consecutive sightings within sighting records were 2.5 and 0 years, respectively. Gaps between the last and penultimate sightings were smaller than average gap sizes earlier in sighting records. Finally, a non-parametric method that can be calculated with more limited data proved a weak substitute for using more complete sighting records.     

Birds and green lanes: Breeding season bird abundance, territories and species richness

This study examines bird occurrence on 20 green lanes (farmland tracks with un-sealed surfaces, bordered on each side by hedgerows) and on 20 paired single hedgerows during the 2002 breeding season in Cheshire, UK. Measures of bird abundance, territories and species richness were all found to be significantly greater on green lanes than on single hedgerows. Significantly more birds were also found to occur on the inside rather than on the outside of green lanes in terms of abundance and species richness. All measures of bird occurrence on green lanes were influenced by hedge width and surrounding land use. Bird abundance on single hedgerows was influenced by the number of trees and amount of hawthorn in the hedge. Seventeen of the 18 most abundant bird species recorded in this study were found to occur in greater numbers on green lanes rather than in single hedgerows; for half of these species the difference was significant. The importance of green lanes for birds, and other wildlife is discussed, as well as their possible future within the UK landscape.     

Do fences protect birds from human disturbance?

Outdoor recreation and ecotourism are becoming increasingly popular, but such human activities are not entirely benign to birds. One way to manage wildlife habitats is to restrict public access with a fence or some similar barrier, under the assumption that this provides wildlife with a refuge from human activities. We tested this assumption by measuring the responses of 10 species of birds at a site containing a fence with a relatively large number of visitors on only one side. We compared these responses to those at a less-visited, control site. Responses were measured by quantifying flight initiation distance (FID), the distance birds would allow a human to approach before fleeing. Overall, we found birds on the protected side of the fence responded similarly to birds at the low visitation control site, and significantly differently from birds at the high visitation site. Our results suggest that by reducing the number of humans and providing areas of refuge within highly visited habitats, protective barriers allow birds to behave as they would in an undisturbed environment.     

Impact of a Semi-experimental increase in recreation intensity on the densities of birds in groves and hedges on a lake shore in The Netherlands

The possibility of disturbance of birds by outdoor recreation is often mentioned, but has rarely been studied. This article presents the results of a disturbance field experiment which took place during three breeding seasons and was conducted along a 4·5 km long lake shore with hedges and groves. Parts of this area have probably undergone an increase in visitor numbers since 1979 as a result of the construction and opening of a car park nearby. The recreation intensity in other parts further away from the car park has probably not increased.Visitors and the breeding birds were counted during the breeding seasons in 1977 and 1978 (before the car park was opened) and in the breeding season in 1980 (after the car park had been opened). All but one (Phylloscopus trochilus) of the 12 (most abundant) species showed a negative difference between experimental units and control units, indicating a disturbance effect. However, no significance was reached with regard to the following bird species analysed: Columba palumbus, Troglodytes troglodytes, Prunella modularis, Turdus philomelos, Turdus merula, Hippolais icterina, Sylvia atricapilla, Sylvia borin, Sylvia communis, Sylvia curruca, Phylloscopus trochilis, Phylloscopus collybita.The number of 11 negative differences out of 12, on the contrary, is highly significant using a sign test (p = 0·003).Interpreting the results as a recreation effect is also supported by the fact that species show negative correlations between recreation intensity and density in 1980 (p = 0·033; sign test). These correlations were significant for Hippolais icterina and Sylvia borin.Such correlations were not found for 1977 or 1978.     

Six years of habitat modification in a tropical rainforest margin of Indonesia do not affect bird diversity but endemic forest species

Studies on temporal changes of tropical bird communities in response to habitat modification are rare. We quantified changes in bird assemblages at the rainforest margin of Lore Lindu National Park, Central Sulawesi, over an interval of 6 years. Standardized bird counts were conducted in the years 2001/2002 and 2008 at 15 census points representing natural forest, secondary forest, agroforest and openland sites. Although overall species richness remained nearly identical, different species groups were affected unequally by habitat modification within the forest margin landscape. The mostly endemic forest species declined in abundance (72.0% of forest species) and were detected at fewer census points in 2008 (56.0%). In contrast, 81.8% of the solely widespread openland birds became more abundant and 63.6% of the species were recorded at a larger number of census points. Hence, recent human activities in the forest margin ecotone negatively affected species of high conservation value. Species richness turned out to be a poor indicator of habitat change, and our results underline the importance of considering species identities. Biotic homogenization as result of habitat conversion is a global phenomenon. In our study, the winners were widespread openland species, while the losers were endemic forest birds. In conclusion, our study shows that 6 years of land-use change had negative impacts on bird community structure and endangered species, but not on overall bird species richness.     

Bayesian spatial modeling of data from avian point count surveys

We present a unified framework for modeling bird survey data collected at spatially replicated survey sites in the form of repeated counts or detection history counts, through which we model spatial dependence in bird density and variation in detection probabilities due to changes in covariates across the landscape. The models have a complex hierarchical structure that makes them suited to Bayesian analysis using Markov chain Monte Carlo (MCMC) algorithms. For computational efficiency, we use a form of conditional autogressive model for modeling spatial dependence. We apply the models to survey data for two bird species in the Great Smoky Mountains National Park. The algorithms converge well for the more abundant and easily detected of the two species, but some simplification of the spatial model is required for convergence for the second species. We show how these methods lead to maps of estimated relative density which are an improvement over those that would follow from past approaches that ignored spatial dependence. This work also highlights the importance of good survey design for bird species mapping studies.     

Patterns of rarity and taxonomic group size in plants

The objective of this research is to examine the extent to which phylogenetic and geographical drivers of rarity may interact to help us better predict distributions of rare taxa. This information is useful to conservation biologists when considering plans for the effective capture of biological diversity within reserve systems. We use 33 floras, distributed globally among five biomes, to assess pattern of rarity across taxonomic group size for plants. We show that small plant families (1-10 taxa) contain consistently fewer rare taxa than expected, while rare plants are proportionately over-represented in large plant families (>100 taxa). We also examine the distribution of species within families. The degree to which species are inequitably distributed among families varied systematically across floristic biomes. Mediterranean floras, in particular, are characterized by a greater than expected fraction of their species pool concentrated within large families, suggesting a high propensity for rarity simply by virtue of having a higher proportion of their constituent taxa within groups with a high likelihood of rarity. Finally, an analysis of a suite of floras using a common system of identifying rarity shows that the fraction of species within floras that are rare is predicted both by flora size and by a general metric (the Gini coefficient) of inequality among family sizes. Together, these patterns suggest a high degree of predictability in the distribution of rarity in plants that may reflect underlying natural speciation and extinction processes.     

Wildlife conservation value of derelict metalliferous mine workings in Wales

The effects of mineral exploitation on wildlife through physical and chemical modification of the environment are normally considered to be deleterious to nature conservation. However, the extraction of minerals frequently alters landform to provide new habitats for plants and animals. Groups of abandoned lead-zinc mines in north-east and central-west Wales have been examined and evaluated for their significance to wildlife conservation.The extraction of mineralsl has created cliffs, ledges and crevices together with adits and shafts, which provide relatively undisturbed breeding sites for several imporatant bird species. Similarly, toxic metalliferous spoils provide sites for colonisation by several plants which have evolved metal-tolerant populations, and many calcareous metalliferous spoils not grossly polluted by lead and zinc provide refugia for regionally rare plants of conservation interest, including several species of orchid. The significance of derelict land clearance and reclamation works on old metal mines and their integration with wildlife conservation are discussed and recommendations are made for avoidance of conflict between the objectives of redevelopment and conservation interests.     

Endemic species: Contribution to community uniqueness, effect of habitat alteration, and conservation priorities

The biodiversity crisis, particularly dramatic in freshwaters, has prompted further setting of global and regional conservation priorities. Species rarity and endemism are among the most fundamental criteria for establishing these priorities. We studied the patterns of rarity and the role of rare species in community uniqueness using data on freshwater bivalve molluscs (family Unionidae) in Texas. Due to the large size and gradients in landscape and climate, Texas has diverse and distinct unionid communities, including numerous regional and state endemic species. Analysis of the state-wide distribution and abundance of Unionidae allowed us to develop a non-arbitrary method to classify species rarity based on their range size and relative density. Of the 46 Unionidae species currently present in Texas, 65% were classified as rare and very rare, including all state and regional endemics. We found that endemic species were a critical component in defining the uniqueness of unionid communities. Almost all endemics were found exclusively in streams and rivers, where diversity was almost double that of lentic waters. Man’s ongoing alteration of lotic with lentic waterbodies favors common species, and dramatically reduces habitat for endemics, contributing to homogenization of unionid fauna. We identified hotspots of endemism, prioritized species in need of protection, estimated their population size, and recommended changes to their current conservation status.     

Evaluating citizen-based presence data for bird monitoring

Species monitoring is one key approach to assess human impact on nature. Four main approaches have been applied in bird monitoring: comparing distribution atlases from different times, repeated monitoring programmes, checklist programmes, and species-specific surveys. We evaluate the potential of another type of data for monitoring: presence-only data on species sightings reported voluntarily by the public to open-access internet platforms, here the Species Gateway (SG) in Sweden. We regressed data on the 242 bird species observed 2001–2009 in the Swedish Bird Survey (SBS) against the corresponding SG data. We also investigated the relationship for groups of species utilizing different habitats and displaying a significant inter-annual variation, a coefficient of variation >0.3 according to the SBS. We found support for a positive relationship in inter-annual variation in population level between the two datasets. However, the species subsets displayed variation from positive to negative correlations. Restricting the analysis to species with high inter-annual variation increased the positive correlation between the data sets. The reason for the mismatch between the two datasets may be explained by temporal changes in the willingness to report certain common species to the SG. Another reason may be an imbalance in the coverage of common versus uncommon species among the two datasets. The use of voluntary citizen-based data requires great care and good knowledge of the limitation of the data. If these requirements are fulfilled, we suggest that they may be a complement to standardised programmes, especially for assessing uncommon species of conservation concern.     

Bird communities, roads and development: prospects and constraints of applying empirical models

Our objectives were to explain the prospects and constraints of applying empirical models that relate bird community metrics to broad-scale characteristics of roads and development. We explored the practical value of regression models that were derived for a large protected area in the Chihuahuan Desert. These models related bird species richness, relative abundance, or probability of occurrence to 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. Empirical models can be used to inform conservation decisions, to parameterise simulation models for conservation planning, to identify threshold levels of road and development variables, and to determine the focus of management experiments for confirmatory hypothesis testing and improvement of model realism.     

Regional priority setting for rare species based on a method combining three criteria

We propose a method to establish regional-level priorities for plant species that is based on three criteria. These involve two main criteria associated with species rarity, (a) small range size and thus regional responsibility and (b) low population numbers and thus local rarity, and a third criteria associated with habitat vulnerability to distinguish species currently threatened by human activities. Application of the method shows how the three criteria can be objectively and readily quantified (using a system of equal numbers of ranks) and combined into a hierarchy of priorities. We show how this can be done by using regional responsibility as a first order priority followed successively by local rarity and habitat vulnerability. Since the criteria are closely associated with rarity, this method is easily understandable for decision makers. We illustrate the application of the method to plants (a species rich group) at two regional scales where the objectives are different. If adapted to the availability of different types of data, the three criteria could be used to produce comparable lists in different countries and regions.     

Grouping and prioritization of vascular plant species for conservation: combining natural rarity and management need

National and International Red Lists and Legal Acts specify species with conservation needs, mainly on the basis of personal experiences. For effective conservation we need scientifically justified prioritization and grouping of these species. We propose a new combined approach where species are grouped according to the similar activities needed for their conservation. We used the national list of vascular plant species with conservation need for Estonia (301 species), and linked these species to eight qualitative conservation characteristics, four reflecting natural causes of rarity (restricted global distribution; restricted local distribution within a country; always small populations; very rare habitat type), and four connected with nature management (species needing the management of semi-natural grasslands; species needing local disturbances like forest fires; species needing traditional extensive agriculture; species which may be threatened by collecting). Only one positive association occurred among the characteristics - between restricted local distribution and small size of populations. Thus, natural causes of rarity and management aspects are not overlapping, and both should be used in conservation activities. Species grouping by different conservation characteristics allows one to focus on species groups with similar conservation needs instead of individual species. Prioritization of species with conservation needs can be based on the number of conservation characteristics that are associated with a particular species. Our prioritization did not correlate with the categories of the national Red Data Book, but a positive association was found with legal protection categories. The legislation, however, covers only the natural causes of rarity. We propose a new combined approach for plant species’ conservation planning that starts by considering human induced rarity and progresses through to natural rarity causes.