Changes in the population of forest and dendrophilous birds of the clay semidesert in the Volga–Ural interfluve over sixty years

The modern situation of the vertebrate population in the clay semidesert of the interfluve of the Volga and Ural rivers differs significantly from that observed 50–60 years ago. This is due to the fact that reduction of ravine forests and steppe shrubs (which began in the 18th century) has extremely affected the forest and dendrophilous animals. The artificial afforestation, especially intense since the middle of the 20th century, provided surrogate “forest” sites in the region by the end of the 1970s. This helped to restore the missing species and raise the abundance and dispersal of forest and dendrophilous animals. By the beginning of the 21st century, afforestation had stopped in the region and the plantation areas had begun to shrink. Some trends in the populations of mammals and birds can be already noticed.     

First records of the brown marmorated stink bug <Emphasis Type="Italic">Halyomorpha halys</Emphasis> (Stål, 1855) (Heteroptera,Pentatomidae) in Russia,Abkhazia, and Georgia

The brown marmorated stink bug Halyomorpha halys (Stål, 1855) is recorded for the first time from Russia (Khosta and Adler districts of the city of Sochi), Abkhazia (Pitsunda), and Georgia (Khobi Municipality). Outbreaks of H. halys populations were detected in all of these regions in October 2016. More than a hundred specimens congregated for overwintering were collected in Sochi during two days. According to the personal communications of the local people, the species appeared in Sochi not later than in 2013, and in Georgia not later than in 2015. It must have been brought to Sochi from Europe (from Italy) with planting material of ornamental plants for landscaping the XXII Olympic Winter Games. Thereafter it spread to Abkhazia and Georgia. Additional steps to identification of H. halys are provided for the keys to the true bugs of the European part of the former USSR (Kerzhner and Jaczewski, 1964).     

The history of ranges of the great tit (<Emphasis Type="Italic">Parus major</Emphasis>) and Japanese tit (<Emphasis Type="Italic">Parus minor</Emphasis>) in the Amur Region

The history of ranges of the great tit (Parus major) and Japanese tit (P. minor) in the Amur River basin is described on the basis of original data collected between 1970 and 2010 and published data. The main factor accounting for the expansion of the great and Japanese tits to the Amur basin and neighboring territories in the 19th to 21st centuries is economic activity, primarily agriculture and timber harvesting. The approximate range boundaries and the sympatry zone of these two species have been determined for the second half of the 19th century; the beginning, middle, and third quarter of the 20th century; and the turn of the 21st century. Three different ecological channels consecutively played the main role in the eastward expansion of the great tit: the Amur River valley (from the mid-19th to the early 20th century), the Trans-Siberian Railroad (since the early 20th century), and the Baikal-Amur Railroad (since the 1970s). It is shown that the concept concerning the finding of great tits in Udskii Ostrog by Middendorff’s expedition is erroneous: according to dates on the labels, the corresponding two specimens were in fact collected in a different geographic locality. It has been found that Komsomolsk-on-Amur is a new locality jointly inhabited by both species, independent of the main zone of their sympatry. It has appeared very recently, at the turn of the 21st century.     

Past, current, and future of the central European corridor for aquatic invasions in Belarus

We analyzed the role of the waterways of Belarus in the spread of aquatic exotic invertebrates through the central European invasion corridor. Present day Belarus became critically important when in the end of the 18th—beginning of the 19th century three interbasin canals connecting rivers from the Black and Baltic seas basins were constructed for international trade. These canals became important pathways facilitating the spread of aquatic alien species. For more than a hundred years, only Ponto-Caspian species colonized Belarus using ships and especially timber in rafts exported by Russia into Western Europe. In the second half of the 20th century, new vectors of spread appeared in Belarus, such as stocking of economically important invertebrates and accidental introductions. This paper is the first comprehensive review of aquatic exotic invertebrates in Belarus. Currently, 19 exotic aquatic invertebrates are known in Belarus, including 14 species of Ponto-Caspian origin. The rate of spread of aquatic invasive species in the second half of the 20th century increased 7-fold compared to the 19th—beginning of the 20th century. We found a significant positive correlation between the time since initial invasion and number of waterbodies colonized. We predict a further increase in the rate of colonization of Belarus by exotic invertebrates as well as an increase in the diversity of vectors of spread and donor areas of alien species, especially when the ongoing reconstruction of the interbasin canals will be completed and the hydrological connection between Black Sea and Baltic Sea basins will be reestablished after an interruption that has lasted for almost a century.     

Recent advance of white spruce (Picea glauca) in the coastal tundra of the eastern shore of Hudson Bay (Québec, Canada)

Aim The species‐specific response of tree‐line species to climatic forcing is a crucial topic in modelling climate‐driven ecosystem dynamics. In northern Québec, Canada, black spruce (Picea mariana) is the dominant species at the tree line, but white spruce (Picea glauca) also occurs along the maritime coast of Hudson Bay, and is expanding along the coast and on lands that have recently emerged because of isostatic uplift. Here we outline the present distribution, structure, dynamics and recent spread of white spruce from the tree line up to its northernmost position in the shrub tundra along the Hudson Bay coast. We aimed to obtain a minimum date of the arrival of the species in the area and to evaluate its dynamics relative to recent climate changes. Location White spruce populations and individuals were sampled along a latitudinal transect from the tree line to the northernmost individual in the shrub tundra along the Hudson Bay coast and in the Nastapoka archipelago in northern Québec and Nunavut, Canada (56°06′–56°32′ N). Methods White spruce populations were mapped, and the position, dimension, growth form and origin (seed or layering) of every individual recorded. Tree‐ring analyses of living and dead trees allowed an estimation of the population structure, past recruitment, growth trends and growth rate of the species. A macrofossil analysis was performed of the organic horizon of the northernmost white spruce stands and individuals. Radiocarbon dates of white spruce remains and organic matter were obtained. The rate of isostatic uplift was assessed by radiocarbon dating of drifted wood fragments. Results The first recorded establishment of white spruce was almost synchronous at all sites and occurred around ad 1660. Spruce recruitment was rather continuous at the tree line, while it showed a gap in the northern shrub tundra during the first decades of the 19th century. A vigorous, recent establishment of seedlings was observed in the shrub tundra; only wind‐exposed, low krummholz (stunted individuals) did not show any sexual regeneration. A period of suppressed growth occurred from the 1810s to the 1850s in most sites. A growth increase was evident from the second half of the 19th century and peaked in the 1880s and the 20th century. A shift from stunted to tree growth form has occurred since the mid‐19th century. No sample associated with white spruce remains gave a date older than 300 ¹⁴C years bp [calibrated age (cal.) ad 1430–1690]. Main conclusions White spruce probably arrived recently in the coastal tundra of Hudson Bay due to a delayed post‐glacial spread. The arrival of the species probably occurred during the Little Ice Age. The established individuals survived by layering during unfavourable periods, but acted as nuclei for sexual recruitment almost continuously, except in the northernmost and most exposed sites. Warmer periods were marked by strong seedling recruitment and a shift to tree growth form. Unlike white spruce, black spruce showed no evidence of an ongoing change in growth form and sexual recruitment. Ecological requirements and recent history of tree‐line species should be taken into account in order to understand the present dynamics of high‐latitude ecosystems.     

Half a century of succession in a temperate oakwood: from species‐rich community to mesic forest

Aim Lowland woodlands in Europe went through dramatic changes in management in the past century. This article investigates the influence of two key factors, abandonment of coppicing and increased pressure of ungulates, in thermophilous oakwoods. We focused on three interconnected topics: (1) Has the assumed successional trend lead to impoverishment of the vegetation assemblages? (2) Has it resulted in vegetation homogenization? (3) Are the thermophilous oakwoods loosing their original character? Location Czech Republic, Central Europe. Methods The vegetation in 46 semi‐permanent plots was recorded three times: firstly, shortly after the abandonment of coppicing (1953) and then, after four to six decades of secondary succession and strong game impact (1992 and 2006). Overall trends and changes in species spectra were analysed. Results There is a marked successional shift towards species‐poorer communities growing in cooler, moister and nutrient‐richer conditions. The change was significantly different in parts affected and unaffected by high numbers of ungulates yet only for herbs, not the woody species. However, observed change in species composition was not accompanied by significant homogenization process that is the general process reported from elsewhere. A sharp decline in plant species typical for thermophilous woodland communities and in endangered species indicates that the original character of the woodland has been gradually lost. Main conclusions Thermophilous oakwoods have been largely replaced by mesic forests. Lowland oakwoods in continental parts of Europe historically depended on active management, which kept the understorey conditions light and warm. Successional processes in the 20th century caused a critical loss of species diversity at various spatial levels. However, artificially high numbers of ungulates, which otherwise have a negative impact, probably held up succession, so that the changes may still be reversible.     

On the altitudinal limits of birds on BasilC Peak (Bioko Island; Equatorial Guinea)

Pérez del Val, J. 2000. On the altitudinal limits of birds on Basile Peak (Bioko Island; Equatorial Guinea). Ostrich 71(1 & 2): 342.

The lower altitudinal limit of the montane avifauna in Africa has generally been set at 1 500- 800 m, corresponding to vegetation belts of the main mountain ranges of East Africa. However, much lower limits have been reported from the East Usambaras (Tanzania), Mount Cameroon, and Bioko Island. Basilé Peak is a volcano of 3 011 m which constitutes the northern half of Bioko Island. Below 400–900 m the forest has been logged and largely replaced by cocoa plantations, but the vegetation is relatively undisturbed at higher altitudes. Annual rainfall ranges between 2 000 mm and 3 500 mm. From January 1990 to July 1992 mist-nets were set at 13 standardised stations on Basilé Peak; 1 427 birds of 71 species were captured. Previous data from non-standardised mist-netting at 6 other localities, together with sight and sound records, published data, and 1 047 skins in the collections of Museo Naçional de Ciençias Naturales (Madrid), Estacion Biologica de Donaiia (Sevilla) and the Natural History Museum (Tring) were also used to compile distribution lists. From published botanical surveys, I recognised four vegetation zones: Lowland Rain Forest up to 800 m; Mountain Rain Forest at 80CL1 800 m; Araliaceus Forest 1 800–2 500 m; and Ericaceus Stands above 2 500 m. An analysis of similarity (using the index of Czechanowski) grouped 68 bird species into altitudinal classes at 200 m intervals. This suggests a division between lowland and montane birds at 800–1 000 m, broadly coinciding with the change between Lowland and Mountain Rain Forest. There does not seem to be a discrete bird community restricted to either of the upper zones (Araliaceus Forest or Ericaeus Stands), with only the Yellow Bishop Euplectes capensis restricted to the upper 500 m of the mountain. Most species which reach the summit are found in all vegetation zones, notably the endemic subspecies of the African Goshawk Accipiter tachiro lopezi. It is suggested that low temperatures, high rainfall, and in particular the seasonal distribution of rainfall, may explain the lower altitudinal limits of the montane avifauna on Bioko and on Mount Cameroon.     

Evaluation of the growth response of six invasive species to past,present and future atmospheric carbon dioxide

The response of plant species to future atmospheric carbon dioxide concentrations [CO(2)] has been determined for hundreds of crop and tree species. However, no data are currently available regarding the response of invasive weedy species to past or future atmospheric [CO(2)]. In the current study, the growth of six species which are widely recognized as among the most invasive weeds in the continental United States, Canada thistle (Cirsium arvense (L.) Scop.), field bindweed (Convolvulus arvensis L.), leafy spurge (Euphorbia esula L.), perennial sowthistle (Sonchus arvensis L.), spotted knapweed (Centaurea maculosa Lam.), and yellow star thistle (Centaurea solstitialis L.) were grown from seed at either 284, 380 or 719 micromol mol(-1) [CO(2)] until the onset of sexual reproduction (i.e. the vegetative period). The CO(2) concentrations corresponded roughly to the CO(2) concentrations which existed at the beginning of the 20th century, the current [CO(2)], and the future [CO(2)] projected for the end of the 21st century, respectively. The average stimulation of plant biomass among invasive species from current to future [CO(2)] averaged 46%, with the largest response (+72%) observed for Canada thistle. However, the growth response among these species to the recent [CO(2)] increase during the 20th century was significantly higher, averaging 110%, with Canada thistle again (+180%) showing the largest response. Overall, the CO(2)-induced stimulation of growth for these species during the 20th century (285-382 micromol mol(-1)) was about 3x greater than for any species examined previously. Although additional data are needed, the current study suggests the possibility that recent increases in atmospheric CO(2) during the 20th century may have been a factor in the selection of these species.     

The death of birds on the sea coast of northeastern Sakhalin Island

The taxonomical composition of dead birds found on the northeastern coast of Sakhalin Island and the causes of their death were studied. Sites with high, average, and low concentration of dead birds were identified. The period of highest mortality of birds (July–August) coincided with the beginning of massive migrations of birds and large numbers of young birds after termination of the nesting season. Collection of bird remains in periods of bird migrations and breeding, in addition to other methods of ornithological research (visual observations, fowling, shooting), can provide useful information on the avifauna and ecological state of the investigated region.     

Radial growth response of Populus xjrtyschensis to environmental factors and a century-long reconstruction of summer streamflow for the Tuoshigan River,northwestern China

Broad-leaved tree species have rarely been used in dendroclimatology and dendrohydrology in arid Central Asia. Core samples of Populus xjrtyschensis Ch. Y. Yang were collected along the Tuoshigan River in 2015. Correlation and response analyses indicate that the radial growth of P. xjrtyschensis shows a strong relationship to streamflow and a weak response to climate. We suggest that summer streamflow is a limiting factor for the radial growth of P. xjrtyschensis along the Tuoshigan River. Using tree-ring data from P. xjrtyschensis, we reconstructed the historical summer streamflow of the Tuoshigan River back to 1900. The reconstruction has an adjusted r² of 0.407 (1957–2006). Statistical verification methods and historical documents indicate that the reconstructed series is stable and reliable. The results reveal that the beginning of the 20th century and the end of the 20th century to the present experienced above average streamflow, while the mid-20th century was characterized by a long dry period. The reconstructed streamflow data series revealed 6-yr (99%), 11-yr (95%) and 17–25-yr (99%) cycles. We suggest that variability in summer streamflow of the Tuoshigan River may be related to solar activity and large-scale oscillations in the climate system.     

Global Patterns and Drivers of Avian Extinctions at the Species and Subspecies Level

Birds have long fascinated scientists and travellers, so their distribution and abundance through time have been better documented than those of other organisms. Many bird species are known to have gone extinct, but information on subspecies extinctions has never been synthesised comprehensively. We reviewed the timing, spatial patterns, trends and causes of avian extinctions on a global scale, identifying 279 ultrataxa (141 monotypic species and 138 subspecies of polytypic species) that have gone extinct since 1500. Species extinctions peaked in the early 20^th century, then fell until the mid 20^th century, and have subsequently accelerated. However, extinctions of ultrataxa peaked in the second half of the 20^th century. This trend reflects a consistent decline in the rate of extinctions on islands since the beginning of the 20^th century, but an acceleration in the extinction rate on continents. Most losses (78.7% of species and 63.0% of subspecies) occurred on oceanic islands. Geographic foci of extinctions include the Hawaiian Islands (36 taxa), mainland Australia and islands (29 taxa), the Mascarene Islands (27 taxa), New Zealand (22 taxa) and French Polynesia (19 taxa). The major proximate drivers of extinction for both species and subspecies are invasive alien species (58.2% and 50.7% of species and subspecies, respectively), hunting (52.4% and 18.8%) and agriculture, including non-timber crops and livestock farming (14.9% and 31.9%). In general, the distribution and drivers of subspecific extinctions are similar to those for species extinctions. However, our finding that, when subspecies are considered, the extinction rate has accelerated in recent decades is both novel and alarming.     

Invasive brown marmorated stink bug <Emphasis Type="Italic">Halyomorpha halys</Emphasis> (Stål) (Heteroptera: Pentatomidae) in Russia,Abkhazia, and Serbia: history of invasion,range expansion,early stages of establishment,and first records of damage to local crops

Halyomorpha halys is native to Asia, but was recently accidentally introduced to North America and Europe. This species was recorded for the first time in Russia in 2013 (2014) and in both Serbia and Abkhazia in 2015. In 2015–2017, we conducted surveys in Russia, Serbia, and Abkhazia and found that H. halys had not only successfully survived its first winters in new regions, but also started to establish locally, spread, increase populations, and damage local crops. In Sochi (Russia) and Abkhazia, H. halys was recorded to feed on 32 species and cultivars from 16 plants families. In Serbia, it has so far been observed on only four species from four plant families. H. halys is already widely spread in Abkhazia and causes serious damage to many crops: in 2016, the yield of peach, mandarin orange, persimmon and other crops fell down by 13.2–87.4% if compared to the long-term means of yield. The losses are likely to be mostly caused by feeding of H. halys. We conclude that H. halys was accidentally introduced to Russia in 2012–2013 most likely with woody plants imported to Sochi from Italy or Greece for urban landscaping before the 2014 Winter Olympics. The species established in Sochi and quickly moved to Krasnodar (Russia), Abkhazia, and beyond—to Georgia. Populations in Serbia most likely arrived in 2015 traveling on railway cars or in commodities on the Bucharest–Belgrade railway line. We discuss phenology and prospects of further expansion of H. halys in Europe.     

Taxonomic and functional homogenization of an endemic desert fish fauna

Aim The highly endemic fishes of the arid Southwest USA have been heavily impacted by human activities resulting in one of the most threatened fish faunas in the world. The aim of this study was to examine the patterns and drivers of taxonomic and functional beta diversity of freshwater fish in the Lower Colorado River Basin across the 20th century. Location Lower Colorado River Basin (LCRB). Methods The taxonomic and functional similarities of watersheds were quantified to identify patterns of biotic homogenization or differentiation over the period 1900–1999. Path analysis was used to identify the relative influence of dam density, urban land use, precipitation regimes and non‐native species richness on observed changes in fish faunal composition. Results The fish fauna of the LCRB has become increasingly homogenized, both taxonomically (1.1% based on β_sim index) and functionally (6.2% based on Bray–Curtis index), over the 20th century. The rate of homogenization varied substantially; range declines of native species initially caused taxonomic differentiation (?7.9% in the 1960s), followed by marginal homogenization (observed in the 1990s) in response to an influx of non‐native species introductions. By contrast, functional homogenization of the basin was evident considerably earlier (in the 1950s) because of the widespread introduction of non‐native species sharing similar suites of biological traits. Path analysis revealed that both taxonomic and functional homogenization were positively related to the direct and indirect (facilitation by dams and urbanization) effects of non‐native species richness. Main conclusions Our study simultaneously examines rates of change in multiple dimensions of the homogenization process. For the endemic fish fauna of the LCRB, we found that the processes of taxonomic and functional homogenization are highly dynamic over time, varying both in terms of the magnitude and rate of change over the 20th century.     

Medieval and Early Modern Whaling in Portugal

ABSTRACT

Mainland Portugal is not renowned for having been a whaling nation of significance. However, preliminary studies have brought to light enough historical references to suggest that whaling occurred from at least the 13th century, and the present work identifies 38 historical sources documenting whale use or whaling on the Portuguese coast between 1201 and 1728. A peak of whale-related sources occurred during the 13th and 14th centuries, and almost all Portuguese accounts are contemporary to those found from the French and Spanish Basque countries, such that the beginning of the whaling activity seems to be coeval. No geographical cluster of whaling activities can be established—they seem to have been unevenly scattered along the entire coastline. Nor can a chronological north–south movement of coastal whaling activities be discerned. The geographical and chronological patterns give support to the assumption that whaling was not introduced to Portugal by the Basques, who are known to have spread westward from the French Labourd (11th century), via Golf of Biscay, to Asturias, and southward to Galicia (14th century). Rather, Portuguese whale use seems to have originated independently of Basque influence. Several of the sources specify “black whales” as the target species. This is consistent with modern knowledge about the distribution and migration patterns of North Atlantic right whales during Basque medieval and early modern whaling. The Portuguese sources are not clear as to numbers of whales taken, nor to the whaling technology used, but the activity was sufficiently well organized and developed to warrant the levying of tithes in the feudal system of 13th-century Portugal.     

Subfossil diatoms from Hann Park pond,Dakar, Senegal: floristic inventory and palaeoenvironmental reconstruction

Diatoms in a 100 cm-long core from a pond in Hann Forest Park, western Senegal, were studied with the aim of reconstituting this interdune depression’s history, particularly the human influence, during the last century. Sixty-three species and varieties of diatoms belonging to 32 genera were identified, of which twelve are reported for the first time in Senegambia. The genera most represented were Nitzschia (10 species), Eunotia (9 species) and Pinnularia (6 species). The microflora was characterised by a dominance of epipelic, epiphytic and aerophilic species. Diatom assemblage analyses, combined with lithological core data, showed that the pond has remained very shallow throughout its evolution. The disappearance of acidophilic species and the development of mesosaprobes and mesoeutrophic alkaliphilic species in the upper part of the core can be attributed to organic pollution caused by human activities, which resulted in eutrophication of the pond waters since the beginning of the 20th century.     

Digger wasps (Hymenoptera,Apoidea: Ampulicidae,Sphecidae, Crabronidae) of the Black Sea coast of Krasnodar Territory,Abkhazia, and adjacent areas

A list of 208 digger-wasp species (Hymenoptera, Apoidea: Ampulicidae, Sphecidae, Crabronidae) from the Black Sea coast and adjacent areas within Krasnodar Territory, Abkhazia, and Adygea is given. Gorytes schmiedeknechti Handlirsch, 1888, Miscophus albufeirae Andrade, 1952, Psenulus fulvicornis (Schenck, 1857), and Passaloecus pictus Ribaut, 1952) are new to the Russian fauna, and 47 species are recorded for the first time from Abkhazia. Ectemnius guttatus (Vander Linden, 1829) does not occur in the Western Caucasus; the record of the species from this region was based on a misidentified female of E. lituratus Pz. Tachysphex gibbus Kohl, 1885, stat. n. is considered a distinct species based on its ecological and morphological features.     

Some data on the distribution,occurrence, and biology of rockfish of the genus <Emphasis Type="Italic">Sebastes</Emphasis> (Sebastidae) off the western coast of Sakhalin

Results of trawl surveys performed by SakhNIRO in Tatar Strait in the end of the 1970s and 1990s, as well as in the beginning of the current century, made it possible to clarify former concepts of rockfish species of the genus Sebastes dwelling off the western coast of Sakhalin, specific features of their distribution, and some aspects of biology. According to specified data, the number of rockfish species in the area of western Sakhalin attains ten.     

Latest developments of dendro-archaeology in the French Alps: Assessing changes in mountain forests exploitation over the last millennium

Dendrochronological studies are carried out on rural buildings in the French Alps for twenty years. In this contribution, we examine an extensive dataset of larch timbers (n = 1294) that were dendrochronologicaly dated at 139 buildings. This material yielded felling dates spanning the 11th century to the 20th century and contributed to improve our knowledge of human occupation and exploitation of mountain forests during the second millennium CE. From the 11th to the 14th century, rural populations increasingly exploited older forests. The crises of the 14th century led to a significant decrease in construction and by extension in tree cutting. The beginning of the 15th century marks a resumption of construction and felling which is continuous until the beginning of the 20th century. There is a relationship between the age of harvested trees, the number of dates and population fluctuations, which corroborates findings at the European scale. Regional trade probably influenced the stem diameters used in constructions in the immediate vicinity of the forests. Logging regulations can be perceived through variations in the age of harvested trees. The 14th century gap in felling dates would also mark a transition period in the exploitation of mountain forests and by extension a transformation of the economy.     

Coastal erosion due to long-term human impact on mangrove forests

A coast in southern Vietnam, which is located in a wide and flat alluvial fan and neighbors tidal rivers fringed by wide mangrove swamps, has been eroded continuously by approximately 50 m/year since the early 20th century. Based on field observations and numerical experiments, it is inferred that this large scale erosion is caused by the transition of mangrove vegetation resulting from the long-term impact of humans since the late 19th century. This eroded coast is not in direct contact with mangrove swamps, but is strongly affected by the existence of mangrove forests through the intermediation of neighboring tidal rivers. Thus, with a view to coastal protection, it is argued that the mangrove vegetation in adjacent areas should be managed more sensitively.     

Natural and human-mediated factors in the recovery and subsequent expansion of the Purple swamphen Porphyrio porphyrio L. (Rallidae) in the Iberian Peninsula

Instances of range contraction and population decline in bird species in Europe are more common than cases of recovery following decline. Here we report on the recovery and expansion processes of an endangered bird species in Europe, the purple swamphen (Porphyrio porphyrio L., Rallidae), with special reference to the Iberian Peninsula, its main distribution area in Western Europe. After a drastic decline during the first half of the 20th century, which restricted its range to a few areas in southern Spain, the Iberian population has recovered. Currently, the species occurs in a range similar to the one it had at the beginning of the 20th century, and has even colonized new areas. These processes seem to be the result of both human-mediated (effective protection of the species and suitable habitats; success of reintroduction programs as expansion focuses of birds colonizing nearby and distant regions [>300 km] wetlands) and natural factors (inter- and intra-seasonal cycles of wet and dry years). Thus, we found a significant relationship between rainfall and bird abundance and productivity, suggesting that such inter- and intra-seasonal cycles may have significant effects on demographic parameters that could be related to the expansion process. Finally the species shows remarkable adaptability, as proven by data on breeding success in recently colonized areas and the ability to breed shortly after reintroduction. We hypothesize that saturation of breeding habitats in established areas, a reasonable habitat continuity and favorable environmental conditions, and protection have facilitated the dispersion of birds.