Human-altered Habitats Research Articles

Status of Appalachian Jacob's-Ladder in Vermont

abstract Nine Element Occurrences (EOs) of Appalachian Jacob's-ladder Polemonium van-bruntiae in Vermont were recognized in 2002. Presently there are 15 EOs comprising 79 Sub-Element Occurrences (subEOs). The author monitored all 79 subEOs at least once and 31 of them twice between 2004 and 2017. The total number of sexually reproductive stems was 32,300, averaging 2153 per EO and 409 per subEO. Six subEOs had fewer than 10 plants each. More than half the subEOs occurred in wooded seeps; the remainder occurred in wet meadows, alder thickets, northern white cedar swamps or human-altered patchy habitats that mimic seeps. In Vermont the species is currently known only from southeast Addison County. The species is now more populous but only slightly more widely distributed in Vermont than in Deller's account. Increase in numbers is due to discovery of new EOs and subEOs, as well as to population growth of the EOs known since 2002. It remains at risk to the same variety of threats that it was believed subject ...

Habitat use, but not gene flow, is influenced by human activities in two ecotypes of Egyptian fruit bat (Rousettus aegyptiacus).

Understanding the ecological, behavioural and evolutionary response of organisms to changing environments is of primary importance in a human-altered world. It is crucial to elucidate how human activities alter gene flow and what are the consequences for the genetic structure of a species. We studied two lineages of the Egyptian fruit bat (Rousettus aegyptiacus) throughout the contact zone between mesic and arid Ecozones in the Middle East to evaluate the species' response to the growing proportion of human-altered habitats in the desert. We integrated population genetics, morphometrics and movement ecology to analyse population structure, morphological variation and habitat use from GPS- or radio-tagged individuals from both desert and Mediterranean areas. We classified the spatial distribution and environmental stratification by describing physical-geographical conditions and land cover. We analysed this information to estimate patch occupancy and used an isolation-by-resistance approach to model gene flow patterns. Our results suggest that lineages from desert and Mediterranean habitats, despite their admixture, are isolated by environment and by adaptation supporting their classification as ecotypes. We found a positive effect of human-altered habitats on patch occupancy and habitat use of fruit bats by increasing the availability of roosting and foraging areas. While this commensalism promotes the distribution of fruit bats throughout the Middle East, gene flow between colonies has not been altered by human activities. This discrepancy between habitat use and gene flow patterns may, therefore, be explained by the breeding system of the species and modifications of natal dispersal patterns.

Assisting seed dispersers to restore oldfields: An individual‐based model of the interactions among badgers, foxes and Iberian pear trees

Abstract Increasing land abandonment in many areas of the world presents an opportunity for ecosystem recovery, which is often driven by seed dispersal by vertebrate frugivores. However, we are far from understanding the most effective way of using common management actions (i.e. planting fruiting trees) to stimulate animal seed dispersal and thus the restoration of human‐altered abandoned habitats. To investigate how to stimulate animal seed dispersal, we combined long‐term field data with individual‐based, spatially explicit simulation models. We used our approach to assess the effectiveness of contrasting Iberian pear Pyrus bourgaeana planting strategies in enhancing restoration of abandoned lands through seed dispersal by red foxes Vulpes vulpes and Eurasian badgers Meles meles in the Doñana World Biosphere Reserve (South West Spain). Our simulation results indicate that planting trees in an aggregated fashion is less efficient in terms of seed arrival than planting them regularly or randomly. For aggregated planted trees, the increase in the area of the oldfield that received seeds was only 7%–9% compared to the baseline scenario of no intervention, whereas for regularly distributed planted trees the increment was up to 40%. Doubling the number of planted P. bourgaeana trees appeared cost‐effective for regular and random tree distributions, but not for the aggregated one. For example, while doubling the number of trees planted regularly leads up to 12% increase in the number of seeds arriving into the oldfield, no increment on the number of arrived seeds was detected when trees were planted aggregately. Synthesis and applications. Choosing the spatial distribution and density of planted trees in abandoned lands depends on a number of ecological and socio‐economical factors. Given our results, the strong seed dispersal limitation of the target tree population and that our study site was fully protected for conservation, planting Pyrus bourgaeana trees regularly appeared to be the most efficient strategy to enhance seed arrival into the target oldfield. Combining long‐term field data with individual‐based, spatially explicit simulation models have the potential to guide local restoration efforts in diverse human‐altered habitats and thus bridge the existing gap between basic and applied research on animal seed dispersal.

Diverse habitat use during two life stages of the critically endangered Bahama Oriole (Icterus northropi): community structure, foraging, and social interactions.

Our ability to prevent extinction in declining populations often depends on effective management of habitats that are disturbed through wildfire, logging, agriculture, or development. In these disturbed landscapes, the juxtaposition of multiple habitat types can be especially important to fledglings and young birds, which may leave breeding grounds in human-altered habitat for different habitats nearby that provide increased foraging opportunities, reduced competition, and higher protection from predators. In this study, we evaluated the importance of three habitat types to two life stages of the critically endangered Bahama Oriole (Icterus northropi), a synanthropic songbird endemic to Andros, The Bahamas. First, we determined the avian species composition and relative abundance of I. northropi among three major vegetation types on Andros: Caribbean pine (Pinus caribaea) forest, coppice (broadleaf dry forest), and anthropogenic areas, dominated by nonnative vegetation (farmland and developed land). We then compared the foraging strategies and social interactions of two age classes of adult Bahama Orioles in relation to differential habitat use. Bird surveys late in the Bahama Oriole’s breeding season indicated the number of avian species and Bahama Oriole density were highest in coppice. Some bird species occurring in the coppice and pine forest were never observed in agricultural or residential areas, and may be at risk if human disturbance of pine forest and coppice increases, as is occurring at a rapid pace on Andros. During the breeding season, second-year (SY) adult Bahama Orioles foraged in all vegetation types, whereas after-second-year (ASY) adults were observed foraging only in anthropogenic areas, where the species nested largely in introduced coconut palms (Cocos nucifera). Additionally, SY adults foraging in anthropogenic areas were often observed with an ASY adult, suggesting divergent habitat use for younger, unpaired birds. Other aspects of foraging (vegetation features, food-gleaning behavior, and food items) were similar for the two age classes. Older Bahama Orioles exhibited relatively higher rates of social interactions (intraspecific and interspecific pooled) in anthropogenic areas, and won more interaction outcomes compared to younger adults. Our findings concur with those of other studies indicating dry broadleaf forest is vitally important to migrating, wintering, and resident birds, including the critically endangered Bahama Oriole, which appears to depend heavily on this vegetation type during certain life stages.

Functional diversity in a fragmented landscape — Habitat alterations affect functional trait composition of frog assemblages in Madagascar

Anthropogenic habitat alterations cause biodiversity loss, which in turn negatively affects ecosystem functioning and services, and thus human well-being. To be able to consider ecosystem functioning in conservation actions, analyzing the effects of habitat alteration on functional diversity is essential. Some altered habitats can maintain a significant part of regional biodiversity, however, functional diversity information in altered habitats is so far mostly lacking. We compared functional richness and functional β-diversity based on resource-use traits of frogs between three land-use categories in a rainforest ecosystem in Madagascar. Land-use categories represent a habitat alteration gradient ranging from continuous forest over forest fragments to matrix habitats including different agricultures. Our study revealed distinct changes in resource-use trait composition and complex patterns in the relationship between species richness and functional richness. Thus, the functional structure of frog assemblages changed due to habitat alterations. However, altered habitats likely provide different, rather than fewer functions compared to intact forest. Streams in all land-use categories were the functionally richest habitats, and thus important for ecosystem functioning. Species richness was one, but not the only driver of functional richness in our system. Functional clustering, potentially due to environmental filters depending on resource availability, was caused by anthropogenic and natural drivers. Our study shows that, even in systems where fragmented landscapes still maintain high species diversity, functional diversity can be altered in human altered habitats, which may affect ecosystem processes like productivity, nutrient cycling, and energy flows.

Activity patterns and habitat preference of eastern Hermann’s tortoise(Testudo hermanni boettgeri) in Serbia

We analyzed variation in the distribution of eastern Hermann's tortoise (Testudo hermanni boettgeri) in a complex landscape consisting of both natural and human-altered habitats in a temperate climate region in Serbia. Our results indicated nonrandom distribution of tortoises within different habitat types with large and medium effect size for year and activity pattern, respectively. Additionally, the tortoises expressed relatively weak preference for habitats modified by human activity (e.g., vineyards, orchards, or gardens). The results suggested that these tortoises preferred some particular habitats more than others when performing specific activities. They also did not exhibit the same distribution pattern among habitats over consequent years. In other words, they were not randomly distributed among habitat types with regard to specific activity or year. The information on preferences in complex habitat systems is important for the conservation management of eastern Hermann's tortoise and should be considered when planning activities related to sustainable development within the region of study.

High levels of male diploidy but low levels of genetic structure characterize Bombus vosnesenskii populations across the Western US

Patterns of genetic structure for some bee species suggest that gene flow may be limited across natural and human-created barriers and that local dispersal or natal site fidelity may be common. Interestingly, this past work has primarily focused on female bees, despite the fact that males may differ substantially in their dispersal processes. By examining genetic structure and diploidy in males, it is possible to gain insight into potential barriers to gene flow and drivers of inbreeding. In this study, we examine diploidy as well as regional and local spatial genetic structure using males of Bombus vosnesenskii, a stable bumble bee species found across western North America. Specifically, we investigate patterns of genetic structure in both island and mainland populations, across spatial scales, and over a range of natural and human-altered habitats. We document high levels of male diploidy, with significantly higher levels in mainland populations compared to island populations and increasing diploidy in areas with poor nesting habitat. Interestingly, we also find evidence of significant spatial genetic structure from 0 to 10 km and 0 to 5 km on island and mainland populations, respectively. Finally, we document low but significant genetic differentiation across the region (ΦST = 0.049). Overall, this work reveals the unique potential for biogeographic context and local habitat composition to drive male diploidy patterns in bumble bees.

Temporal overlaps of feral cats with prey and competitors in primary and human-altered habitats on Bohol Island, Philippines.

The vertebrate fauna of the Philippines, known for its diversity and high proportion of endemic species, comprises mainly small- to medium-sized forms with a few large exceptions. As with other tropical ecosystems, the major threats to wildlife are habitat loss, hunting and invasive species, of which the feral cat (Felis catus) is considered the most damaging. Our camera-trapping study focused on a terrestrial vertebrate species inventory on Bohol Island and tempo-spatial co-occurrences of feral cats with their prey and competitors. The survey took place in the Rajah Sikatuna Protected Landscape, and we examined the primary rainforest, its border with agricultural land, and rural areas in the vicinity of villages. Altogether, over 2,885 trap days we captured 30 species of vertebrates–10 mammals (including Sus philippensis), 19 birds and one reptile, Varanus cumingi. We trapped 81.8% of expected vertebrates. Based on the number of events, the most frequent native species was the barred rail (Gallirallus torquatus). The highest overlap in diel activity between cats and potential prey was recorded with rodents in rural areas (Δ = 0.62); the lowest was in the same habitat with ground-dwelling birds (Δ = 0.40). Cat activity was not recorded inside the rainforest; in other habitats their diel activity pattern differed. The cats’ activity declined in daylight in the proximity of humans, while it peaked at the transition zone between rainforest and fields. Both rodents and ground-dwelling birds exhibited a shift in activity levels between sites where cats were present or absent. Rodents tend to become active by day in cat-free habitats. No cats’ temporal response to co-occurrences of civets (Paradoxurus hermaphroditus and Viverra tangalunga) was found but cats in diel activity avoided domestic dogs (Canis lupus familiaris). Our first insight into the ecology of this invasive predator in the Philippines revealed an avoidance of homogeneous primary rainforest and a tendency to forage close to human settlements in heterogeneous habitats. A detailed further investigation of the composition of the cat’s diet, as well as ranging pattern, is still needed.

Complementary Ecological Approaches to Understand Decreases in Frog Diversity in Altered Andean Ecosystems

Abstract. The Andes Mountains of South America are considered one of the most biologically diverse and threatened areas in the world. Habitat destruction in this area is among the most common causes of amphibian population declines and extinction, but few studies have used complementary approaches to understand the interplay between habitat transformation and microhabitat use by amphibians. We studied the anuran diversity in modified vegetation cover types in a cloud forest in the tropical Andes of Colombia in order to compare components of biological diversity and microhabitat preferences among forested and human-altered habitats. Secondary Forest and Riparian Forest were the vegetation cover type with the highest local diversity, whereas the highest turnover was between the forested and human-altered areas. The species in the assemblage showed specific microhabitat associations with the substrate and the vertical stratification, with lower mean values of niche overlap between species pairs in forested a...

Is supplementary feeding in gardens a driver of evolutionary change in a migratory bird species?

Human activities are causing rapid environmental change at a global scale. Urbanization is responsible for some of the most extreme human-altered habitats and is a known driver of evolutionary change, but evidence and understanding of these processes is limited. Here, we investigate the potential underlying mechanisms contributing to the contemporary evolution of migration behaviour in the Eurasian blackcap (Sylvia atricapilla). Blackcaps from central Europe have been wintering in urban areas of Britain with increasing frequency over the past 60years, rather than migrating south to the Mediterranean. It has been hypothesized that the popularization of providing supplementary foods for wild birds within Britain may have influenced this marked migratory change, but quantifying the selective forces shaping evolutionary changes remains challenging. Using a long-term national scale data set, we examine both the spatial distribution and interannual variation in blackcap wintering behaviour in Britain in relation to supplementary food availability and local climate. Over a 12-year period, we show that blackcaps are becoming increasingly associated with the provision of supplementary foods in British gardens, and that the reliability of bird food supplies is influencing their winter distribution at a national scale. In addition, local climatic temperatures and broader scale weather variation are also important determinants of blackcap wintering patterns once they arrive in Britain. Based on our findings, we conclude that a synergistic effect of increased availability of feeding resources, in the form of garden bird food, coupled with climatic amelioration, has enabled a successful new wintering population to become established in Britain. As global biodiversity is threatened by human-induced environmental change, this study presents new and timely evidence of the role human activities can play in shaping evolutionary trajectories.

Railway tracks can have great value for butterflies as a new alternative habitat

Natural and semi-natural habitats are declining. However, little is known of the value of artificial and human-altered habitats for biodiversity maintenance in fragmented landscapes. We hypothesized that railway tracks can have great value for butterflies as an alternative habitat. Using 200-m-long transects, we investigated species richness and two main types of β-diversity, i.e. nestedness and community dispersion, for both butterflies and their nectar plants in eight sites under an expected gradient of habitat quality – meadows, railway tracks, forest clearings and degraded meadows. Railway tracks and meadows had higher butterfly species richness than forest clearings and degraded meadow. Butterfly species distribution among sites was strongly related to the gradient of habitat quality that was measured as nectar plant composition. Railway tracks contained the widest pool of butterflies with species of various biotopes as well as a wide pool of nectar plants at a nested subset pattern of β-diversity. However, the pattern of community dispersion was opposite to what had been expected. Meadows and railway tracks, being more heterogeneous sites in terms of composition of nectar plants, supported slightly more homogeneous butterfly communities. This suggests that habitats of low quality, i.e. forest clearings and degraded meadows, have less-stable butterfly communities. We concluded that railway tracks located on sun-warmed embankments containing a reach pool of nectar plants could enable multi-species communities to persist in an environment of good suitability. Conservation managers should therefore focus on enhancing the quality of railway tracks and their vicinity through the preservation of a high abundance of various flowering plants.

Green roofs provide habitat for urban bats

Understanding bat use of human-altered habitat is critical for developing effective conservation plans for this ecologically important taxon. Green roofs, building rooftops covered in growing medium and vegetation, are increasingly important conservation tools that make use of underutilized space to provide breeding and foraging grounds for urban wildlife. Green roofs are especially important in highly urbanized areas such as New York City (NYC), which has more rooftops (34%) than green space (13%). To date, no studies have examined the extent to which North American bats utilize urban green roofs. To investigate the role of green roofs in supporting urban bats, we monitored bat activity using ultrasonic recorders on four green and four conventional roofs located in highly developed areas of NYC, which were paired to control for location, height, and local variability in surrounding habitat and species diversity. We then identified bat vocalizations on these recordings to the species level. We documented the presence of five of nine possible bat species over both roof types: Lasiurus borealis, L. cinereus, L. noctivagans, P. subflavus,andE. fuscus. Of the bat calls that could be identified to the species level, 66% were from L. borealis. Overall levels of bat activity were higher over green roofs than over conventional roofs. This study provides evidence that, in addition to well documented ecosystem benefits, urban green roofs contribute to urban habitat availability for several North American bat species.

Testing the relationship between human occupancy in the landscape and tadpole developmental stress.

Amphibian population declines are widespread; the main causal factors are human related and include habitat fragmentation due to agriculture, mining, fires, and urban development. Brazil is the richest country in species of amphibians, and the Brazilian regions with the greatest amphibian diversity are experiencing relatively high rates of habitat destruction, but there are presently relatively few reports of amphibian declines. It is thus important to develop research methods that will detect deterioration in population health before severe declines occur. We tested the use of measurements of fluctuating asymmetry (FA) taken on amphibian larvae to detect anthropogenic stress. We hypothesized that greater human occupancy in the landscape might result in more stressful conditions for amphibians. We conducted this study at the Espinhaço mountain range in southeastern Brazil, using as a model an endemic species (Bokermannohyla saxicola, Hylidae). We chose two tadpole denticle rows and eye-nostril distance as traits for FA measurement. We measured percent cover of human-altered habitats in the landscape around tadpole sampling points and measured FA levels in sampled tadpoles. We found FA levels to differ among localities but found no relationship between human modification of the landscape and tadpole FA levels. Levels of FA in the traits we examined may not be strongly affected by environmental conditions, or may be affected by local variables that were not captured by our landscape-scale measures. Alternatively, populations may be genetically differentiated, affecting how FA levels respond to stress and obscuring the effects of anthropogenic disturbance.

Fish Out of Water: Evolutionary and Ecological Issues in the Conservation of Fishes in Water-Altered Environments: Introduction to the Symposium: Eco-Evolutionary Change and the Conundrum of Darwinian Debt

Human impacts on aquatic systems are pervasive and often extreme worldwide, resulting in numerous fish species, as well as other aquatic organisms, being at risk of extinction. Until recently, however, species targeted in conservation efforts have been treated as static units, rather than as locally evolving populations. The intent of the ASIH 2013 symposium, Fish Out of Water: Evolutionary and Ecological Issues in the Conservation of Fishes in Water-Altered Environments, was to examine fish assemblage responses to anthropogenic impacts and the potential for altered evolutionary trajectories. The recent realization that feedback between ecology and evolution can occur on ecological time scales emphasizes that ecological studies cannot assume evolutionary stasis. The cyclical interaction of ecology and evolution, termed eco-evolution, suggests that both directions of effect, ecology to evolution and evolution to ecology, are substantial. Such interactions seem to be particularly likely in many impoundments. For instance, various species of fishes show shifts in morphology in reservoir compared to stream environments, although the changes are generally species-specific or system-specific. In general, conservation efforts to recover populations that have changed in response to human-altered habitats could be compromised if systems are returned to quasi-normal states because of Darwinian debt, the situation where evolutionary recovery from genetic changes caused by anthropogenic impacts can take longer than the time required to induce the changes, resulting in evolutionary costs for future generations.

Contemporary human-altered landscapes and oceanic barriers reduce bumble bee gene flow.

Much of the world's terrestrial landscapes are being altered by humans in the form of agriculture, urbanization and pastoral systems, with major implications for biodiversity. Bumble bees are one of the most effective pollinators in both natural and cultivated landscapes, but are often the first to be extirpated in human-altered habitats. Yet, little is known about the role of natural and human-altered habitats in promoting or limiting bumble bee gene flow. In this study, I closely examine the genetic structure of the yellow-faced bumble bee, Bombus vosnesenskii, across the southwestern US coast and find strong evidence that natural oceanic barriers, as well as contemporary human-altered habitats, limit bee gene flow. Heterozygosity and allelic richness were lower in island populations, while private allelic richness was higher in island populations compared to mainland populations. Genetic differentiation, measured for three indices across the 1000 km study region, was significantly greater than the null expectation (F(ST) = 0.041, F'(ST) = 0.044 and D(est) = 0.155) and correlated with geographic distance. Furthermore, genetic differentiation patterns were most strongly correlated with contemporary (2011) not past (2006, 2001) resistance maps calibrated for high dispersal limitation over oceans, impervious habitat and croplands. Despite the incorporation of dramatic elevation gradients, the analyses reveal that oceans and contemporary human land use, not mountains, are the primary dispersal barriers for B. vosnesenskii gene flow. These findings reinforce the importance of maintaining corridors of suitable habitat across the distribution range of native pollinators to promote their persistence and safeguard their ability to provide essential pollination services.

Assessment of interactive effects of elevated salinity and three pesticides on life history and behavior of southern toad (Anaxyrus terrestris) tadpoles.

Because habitats are increasingly exposed to multiple stressors simultaneously, assessing the interactive effects of stressors is crucial for understanding how populations respond to human-altered habitats. Salinization of freshwater habitats is increasing and has the potential to interact with other stressors. Chemical pollutants also contribute to habitat degradation in freshwater environments, and both salinity and various pesticides can harm amphibians. The present study used a factorial experiment to investigate the effect of elevated salinity alone and in combination with each of 3 pesticides-atrazine, carbaryl, and glyphosate-on life history and behavior of southern toad larvae (Anaxyrus terrestris). Tadpoles were negatively affected by elevated salinity and by exposure to the insecticide carbaryl, with the most deleterious outcomes associated with both stressors combined. Carbaryl exposure led to reduced survival as well as sublethal effects on growth, activity and feeding behavior, escape response swimming, and time to metamorphosis. Tadpoles reared at elevated salinity were also smaller and less active, and ultimately metamorphosed later and at smaller size. Together, carbaryl and elevated salinity had a synergistic effect, resulting in particularly poor growth, depressed activity and feeding, and sluggish escape swimming among tadpoles exposed to both stressors simultaneously. These results suggest that both elevated salinity and carbaryl represent threats for amphibian populations and that pesticide exposure in salinized habitats may pose a particularly high risk.

Factors influencing the distribution and abundance of endemic pigeons on São Tomé Island (Gulf of Guinea)

SummaryUnderstanding the factors that determine habitat use and abundance of exploited species is essential to develop effective conservation strategies. We studied the four forest pigeons on São Tomé Island to assess the species’ distribution and abundance patterns. We determined ecological factors likely to be associated with each species’ use of habitats and numbers, as well as the influence of hunting pressure. In total, 35 km of line transects were surveyed in the rainy season and at the start of the dry season. Pigeons differed in their use of habitats; there were also strong seasonality effects. The most abundant species was the Lemon Dove Columba simplex, the only non-hunted species. The São Tomé Green Pigeon Treron sanctithomae and Maroon Pigeon Columba thomensis were less abundant and had more restricted ranges. Both species were strongly associated with old-growth forests. In contrast, the Bronze-naped Pigeon Columba malherbii was relatively abundant and widespread; this species favours human-altered habitats such as shade forests and non-forested areas. Fruit availability measured within the different habitats was linked with the distribution and abundance of the three hunted species. Potential human predation pressure on all species was determined from hunting signs found along the surveyed transects. There was a significant negative correlation between the abundance of two of the hunted species and hunting pressure. Our results indicate the importance of adequately protecting old-growth and secondary forests as core habitats for the survival of viable populations of all pigeon species in the island. However, control of hunting is also crucial.

Behavioral responses of the Strawberry Poison Frog (Oophaga pumilio) to herbicide olfactory cues: possible implications for habitat selection and movement in altered landscapes

Recent research has focused on the importance of behavior in mediating the effects of landscape change on amphibian populations and communities. Factors such as chemical contaminants may affect habitat selection and movement of amphibians in human-altered habitats and contribute to landscape-level patterns of distribution and abundance. The objective of this study was to determine if the Strawberry Poison Frog (Oophaga pumilio (Schmidt, 1857)) can use olfactory cues to detect and avoid the glyphosate-based herbicide Roundup™. Fifty frogs were captured in the field in Costa Rica and tested in experimental arenas where they were given a choice between a control and an herbicide treatment. Analysis of time spent in treatment areas revealed a significant interaction between sex and treatment. Analyses of choice at the start and end of the trials indicated that sex and cardinal direction were important factors influencing orientation behavior. These results suggest that males and females differed in their behavioral responses, and that male O. pumilio may use olfactory cues to detect and avoid areas treated with glyphosate-based herbicide. However, the sampled population was male-biased, which resulted in a lower sample size and lower power to detect an effect for females. Further work is needed to better understand amphibian behavioral responses to herbicides, as well as the role of sex and individual variation in modifying these responses.

Changes in plant diversity along an urban–rural gradient in an expanding city in Kazakhstan, Western Siberia

Plant communities respond sensitively to urban expansion and therefore serve as indicators for human land use. An urban–rural gradient approach was used to examine changes in plant species composition and abundance related to human-altered habitats in the Western Siberian city of Pavlodar (Kazakhstan). This region is characterized by harsh continental environmental conditions and recent anthropogenic degradation of the original steppe grasslands as a result of enforced land-use changes (Virgin Land Campaign) and rapidly expanding urbanization. Plant diversity and abundance as well as the percentage of alien species were recorded in plots on four 20-km long transect lines running from the city centre to the rural surroundings. Various habitat and landscape characteristics were assessed along the transect lines to describe the urban–rural gradient. Based on the results of a principal component analysis considering these landscape characteristics the variable “distance to the city centre” was used as proxy for the urban–rural gradient. Plant diversity increased with increasing distance to the city centre and was also influenced by the type of land use (ornamentally managed, agricultural or unmanaged land) and the percentage cover of built-up area within a 500m radius. The percentage of alien species decreased from 45% in the city centre to 23% in the rural surroundings. The percentage of species belonging to different plant life forms and to different evolutionary strategies were affected by different landscape characteristics. The study showed that the combined effects of expanding urbanization and agricultural land-use changes altered the plant species composition.

Incremento en la distribución y primer registro de anidación de la paloma de collar (Streptopelia decaocto) en la península de Baja California, México

We report the presence of Eurasian collared-dove Streptopelia decaocto in many towns, villages and ranches of Baja California Peninsula. Our first record was in fall 2008 and since then, we have found an increase in number and distribution of this dove in several locations of the peninsula, with presence in 64% of the total human settlements we surveyed throughout the peninsula (N= 100). We also present information on the first 2 active nests in Baja California Sur. Eurasian collared-dove is breeding in the Baja California Peninsula at the present and is increasing its distribution into the peninsula tightly linked to human altered habitats.