At the border of ecological change: status and nest sites of the Lithuanian Black Stork Ciconia nigra population 2000–2006 versus 1976–1992

Recent trends in the European Black Stork Ciconia nigra population are geographically distinct: range expansion and adaptation to human activity dominate in western and central Europe, while declines—probably induced by landscape change—are reported in the east. We studied the large Lithuanian Black Stork population in the transition zone to explore whether, and how, the detrimental influences of recent Baltic landscape changes are balanced by the West European tendency of behavioural adaptation to human activity. Based on monitoring in sample plots, the current population was estimated at 650–950 pairs, indicating a significant decrease (possibly over 20%) during the last two decades. In comparison to the Latvian and Estonian populations, however, this decline is smaller, and the reproductive success remains at a high level [66% breeding success and 2.99 ± 0.97 (SD) fledglings per successful attempt, 2000–2006]; this north–south gradient suggests a climate-mediated impact of habitat degradation in the Baltic countries. The storks are also nesting closer to forest edges and in younger stands than 15–30 years ago, which has probably reduced the nest-tree limitation, as indicated by an increased use of large oaks. Thus, habitat degradation and adaptation seem to be taking place simultaneously in the Lithuanian Black Stork population, as was expected from its geographical location. In general, our study supports the view that, whenever possible, species conservation strategies and the use of indicator species should be geographically explicit.     

Discovery of a regular nesting area of loggerhead turtle <Emphasis Type="Italic">Caretta caretta</Emphasis> in southern Italy: a new perspective for national conservation

Loggerhead turtle Caretta caretta nesting in Italy had been reported to be limited to the Pelagian Islands and only sporadically elsewhere. As presence of loggerhead turtle nests had occasionally been reported (1988–1999) along about 200 km of the Ionian coast of Calabria, we carried out a project to assess the actual state of the nesting population between 2000 and 2004. We divided the coastline in two sectors (A: 52 km, and B: 146 km) that were monitored from mid-June to end of July for a total of n = 174 monitoring days and 1,813.6 km patrolled on foot with different intensities (extensive versus intensive). In sector B, through extensive monitoring we did not find any emergence tracks, but in sector A by intensive survey (2002–2004: one survey/3.64 days) we detected 3–8 nests/year. In total, 25 nests (both observed and reported), were recorded in our study area, and an assessment of a total of 15–16 nests/year was suggested. These figures, within the national scenario depicted from the review of known nesting events in the last 40 years (88 records concerning more than 143–144 nests), show that loggerhead turtle nesting has been underestimated in Italy, due to inadequate monitoring protocols, and that nesting is more frequent than expected (at least 30–40 nests/year). Conservation strategies in Italy should then focus not only on the reduction of mortality at sea, but also include large-scale actions to preserve scattered (but regular) nesting events.     

Plant-water regime management in a wetland: consequences for a floating vegetation-nesting bird, whiskered tern Chlidonias hybridus

In this study we investigated the interplay between water level management, floating macrophytic vegetation and nesting whiskered tern (Chlidonias hybridus) during 8 years (1995–2002) at a shallow macrophyte-dominated lake in western France. The specific question was to see if slight increases in the water regime of the lake (three scenarios), as part of a restoration programme, affect the timing of nesting and occupation of colonies by whiskered terns by way of changes in biomass of waterlily (Nymphaea alba) beds where colonies always establish. During the study period, egg-laying dates were progressively delayed up to 40–50 days (mid-May to early July) in relation to late appearance of suitable waterlily biomass (R ² = 0.67, p = 0.01) associated with high spring water levels (1.10–1.25 m vs. 0.95 m). Simultaneously some nesting attempts were observed in sub-optimal habitats (adjacent wet grasslands) in high flooding conditions leading either to poor breeding success or colony desertion. We concluded that there is a need for compromise between the experimental water levels used to control waterlily biomass and the nesting requirements of the whiskered tern population in this lake of international importance (260–510 pairs in 1995–2002, ≥ 1% Ramsar level).     

Sand and nest temperatures and an estimate of hatchling sex ratio from the Heron Island green turtle (Chelonia mydas) rookery, Southern Great Barrier Reef

Sand and nest temperatures were monitored during the 2002–2003 nesting season of the green turtle, Chelonia mydas, at Heron Island, Great Barrier Reef, Australia. Sand temperatures increased from ∼ 24°C early in the season to 27–29°C in the middle, before decreasing again. Beach orientation affected sand temperature at nest depth throughout the season; the north facing beach remained 0.7°C warmer than the east, which was 0.9°C warmer than the south, but monitored nest temperatures were similar across all beaches. Sand temperature at 100 cm depth was cooler than at 40 cm early in the season, but this reversed at the end. Nest temperatures increased 2–4°C above sand temperatures during the later half of incubation due to metabolic heating. Hatchling sex ratio inferred from nest temperature profiles indicated a strong female bias.     

Distribution and status of bustards in China

This article presents the distribution and status of bustards, which are listed as first-category protected animals according to the survey results during 1990–2002 in China. The Chinese populations of Otis tarda dybowskii are breeding in south-west of Heilongjiang Province, western Jilin Province, east and middle Inner Mongolia, north Ningxia Hui Autonomous Region, and Gansu Province. A few can winter in the south breeding-range. Its winter-range lies from the south to the Yellow River, as far as to Guizhou Province and Jiangxi Province. Its population number is about 200–300 or 500–800. The Chinese populations of O. t. tarda are breeding in the north and west of Xinjiang. It is unclear about its winter-range, which is presumed to be in south Asia. Recently we found individuals wintering in Chabuchaer and west Xinjiang. The population number is about 2000–3000. The habitat in breeding range includes steppe, grassland, desert grassland, and farmland. The habitat in winter range is the beach of rivers and lakes, meadows, meadow-grassland, and wheatland. The Chinese populations of Chlamydotis undulata macqueeni are breeding in the fringe of the Jungar Basin, the banks of the Ulungur River, Balikun and south Turpan Basin in Xinjiang, west Inner Mongolia, and west Gansu. NortheastMulei in eastern Jungar Basin of Xinjiang is the main breeding-range in the world. The bird uses desert and desert grassland as its habitat. Its winter-range is west Asia and south Asia. Its population number is about 2000. The Chinese populations of Tetrax tetrax are breeding in north Xinjiang, and China is located on the east border of its breeding-range. Its habitat is grassland and semi-desert, and its winter-range lies in south Asia. Its population in China is very scarce. In addition, we analyzed the causes of their endangerment and put forward protection tactics of Chinese Bustards. __________ Translated from Arid Zone Research, 2007, 24(2): 179–186 [译自: 干旱区研究]     

Demonstration of the Bzura River restoration using diatom indices

The quality of running waters is reflected in the composition of benthic diatom assemblages. The biological assessment of changes in the composition, and thus of changes in water quality, was carried out in the lowland mid-sized Bzura River, Central Poland, over the period of 30 years. The benthic diatom material consisted of samples collected in two investigation periods, in 1972 and in 2003–2004. The methods applied were three diatom indices, IPS — Specific Pollution Sensitivity Index, GDI — Genetic Diatom Index and TDI —Trophic Diatom Index, and the OMNIDIA computer program, which are commonly used in Europe. The aim of the study was demonstrating the process of restoration that occurred in the river. The Bzura was included to the most polluted ones in Poland till 1996. Since 1998 a gradual improvement in water quality has been observed, which is caused by a number of biological-technical measures, mostly a proper organization of sewage management in most cites located on the river. In 1972 the IPS classified Bzura water into Water Quality Class IV-V, while in 2003–2004 it reached much higher values, i.e. Class III–IV. On the basis of the GDI Class III was determined in the whole river in 2003–2004, while its values indicated Class III–IV in 1972. The trophic index, TDI attributed Bzura water to the eutrophic to hypereutrophic zone in 2003–2004, and to one degree better water, i.e. from the mesoeutrophic to eutrophic zone, in 1972.     

Spatial, seasonal and species variations of harmful algal blooms in the South Yellow Sea and East China Sea

The occurrences of harmful algal blooms (HABs), in terms of frequency and area in the Chinese coastal waters, have been increasing since 1980s and caused considerable economic losses. In the present study, we have analyzed spatial and seasonal characteristics of HAB events in the southern Yellow Sea and East China Sea along Chinese coast from 1933 to 2004. With a total 435 HAB records, the most frequent HAB occurrence area (FHA) is off the Yangtze River mouth and another two FHA areas are located south of the Yangtze River estuary along about isobaths of 30–60 m coastal water in the East China Sea. The time of HAB occurrence shifted during our study period: from autumn (August–October) before 1980s to July–August in 1980s, during May–July in 1990s, and May–June for the period of 2000–2004. Causative species were found to be different: Noctiluca scintillans and Skeletonema costatum were dominant causative species prior to 2000; and Prorocentrum donghaiense Lu was dominant from 2000 to 2004 and also caused large blooms in May. Trichodesmium sp. caused many HABs in autumn (August–October) prior to 1980s with only one HAB between 1980 and 2004. The changes of the dominant HAB species may have affected the timings of HAB occurrence, as well as the increasing HAB-affected areas in recent years.     

Water conditions influence nestling survival in a Hooded Crow Corvus cornix wetland population

This paper examines how flooded river valley conditions affect reproductive success of Hooded Crows Corvus cornix nesting in the biotope considered as primary for this species. The main goals of the present study were to determine the nesting period that most influences the breeding output and to investigate the factors influencing reproductive efficiency of the studied population. Mean survival rate of the whole nesting period (53 days––from egg laying to fledgling) was 0.371 (95% CL: 0.338–0.403), while mean survival for the incubation period (to day 21) was 0.850 (0.827–0.875) and mean survival rate for the nestling period was 0.499 (0.460–0.538). The study has shown that the most critical period in the breeding cycle is the first half of the nestling stage, especially from hatching to day 5. Furthermore, the study demonstrated how water conditions affect reproduction in untypical wetland species. Similarly to many other waterbirds, in the studied population of the Hooded Crow, water level positively influences its reproduction.     

Population structure of the sailfin sandfish, Arctoscopus japonicus (Trichodontidae), in the Sea of Japan

We analyzed patterns of genetic diversity in the sailfin sandfish (Arctoscopus japonicus), focusing on population subdivisions within the Sea of Japan. We observed 270 specimens from nine sampling sites in 1999–2000, i.e., seven sites in the Sea of Japan and two sites from the Pacific coast of Hokkaido. An additional site (30 specimens) was sampled from eastern Korea in the spawning season of 2004 for comparison. Forty haplotypes, compiled into three haplogroups (A–C), were detected based on the comparison of a 400-bp sequence of the anterior part of the mitochondrial control region. In accordance with previous hypotheses from morphological and molecular analyses, genetic discontinuity between the Sea of Japan and the Pacific coast of Hokkaido was conspicuous. Within the Sea of Japan, eight sampling sites were not genetically uniform, and most of the variations among sites were detected between eastern Korea [the “eastern Korea” (EK) population: distributed from the Korean Peninsula to Mishima, Yamaguchi Prefecture] and the other sites along the coast of Japan [the “western Japan” (WJ) population: from Oki Islands to western Hokkaido] (Φ _CT  = 0.096, P = 0.0183). The WJ population, having lower genetic variability, showed significant departure from neutrality, indicating influences through a recent population expansion. The period of the expansion can be estimated to have begun on the order of 10⁴ years ago. We consider that the present Japan Sea populations have been formed through the invasion of a small ancestral stock to the Sea of Japan and its population expansion during the last glacial period or later. On the other hand, we failed to detect distinct evidence of a population expansion in the EK population. Haplogroup C, detected in a high frequency in this population, was estimated to have mixed with haplogroup A after rapid differentiations of the latter. Therefore, the EK population, strongly influenced by such a mixture, might possess haplogroup C in a higher frequency and a different haplotype composition from the WJ population.