1,204 research outputs found
A Waterbird Inventory of the Darkhad Depression, Kbovsgol, Mongolia
The Darkhad Depression, Khövsgöl aimag, Mongolia has an abundance of rivers, lakes, and pothole wetlands, providing one of the most extensive concentrations of waterbird habitat in Mongolia. Waterbirds use the wetlands of the Darkhad Depression for breeding, molting, and as stopover sites during migration. As far as we are aware, our survey of waterbirds in this region is the first to provide broad wetland coverage of the Darkhad Depression. We conducted a survey of waterbirds in the Darkhad Depression in Tsagaannuur and Renchinlhumbe soums and compared densities of waterbirds between two lakes with subsistence fishing and those without. We surveyed 60 lakes (5867.26 ha) and a 5.4 ha portion of a river for waterbirds. We observed 39 species and calculated their frequency of occurrence among lakes and densities among occupied lakes (birds/ha). Common goldeneyes (Bucephala clangula) and tufted ducks (Aythya fuligula) had the greatest estimated densities for the Darkhad Depression (0.3 birds/ha), whereas common greenshank (Tringa nebularia), Eurasian curlew (Numenius arquata), smew (Mergellus albellus), and black stork (Ciconia nigra) had the least (\u3c 0.0001 birds/ha). Tufted ducks had the highest mean density on used lakes (6.66 ± 5.69 birds/ha), and common goldeneye used the highest percentage of wetlands (57.38% of surveyed wetlands). We detected that piscivorous waterbird densities on two lakes that were historically overfished were 79% less than those on lakes of similar size, suggesting that overfishing could be a threat to these birds in the Darkhad Depression. We recommend that future studies conduct more extensive surveys of waterbirds over a longer surveying period and earlier in the breeding season, so that more species can be counted with their young and a more complete inventory of waterbirds can be created
The Kloo Wetland: A reconnaissance of its ecological diversity 1988-93
The Kloo Wetland is an area of approximately 100 sq. km. of just over 340 small to medium sized ponds and lakes associated with the floodplain of the Jarvis River in the South Western Yukon. It includes two larger lakes, Kloo and Sulphur, and is about 30 km NW of the village of Haines Junction, YT. In 1980, an area of 447 sq. km. including the wetland was identified as ‘critical’ wildlife habitat by map notation for Land Use decision purpose (Yukon Waterfowl Management Plan, 1985, 1990). This designation was based simply on the obvious concentration of waterbodies and the area’s known value to wildlife species and to local people.Peer reviewe
Predation on the angulate tortoise Chersina angulata by the kelp gull Larus dominicanus on Dassen Island, Western Cape
The kelp gull (Larus dominicanus) is an important predator on the angulate tortoise (Chersina angulata) on Dassen Island, Western Cape, South Africa. Tortoise shell fragments (n= 142) were collected and measured. Using regression curves based on 184 live tortoises measured on the island, the size class of tortoises eaten by kelp gulls was determined to include tortoises from 38-124 mm (mean 84 mm) total length (mass 25-350 g; mean 130 g). It is probable that very small tortoises were also eaten, but totally consumed. It is suggested that predation on tortoises occurs during the autumn-winter by the small population of resident gulls (approximately 50 individuals)
Restoration of the tidal lagoon of the Zwin
The tidal tloodplain of the Zwin between Knokke (Belgium,Flanders) and Cadzand(Netherlands) is a border-crossing relic of the sound that once connected the medieval ports of Damme and Sluis with the North Sea and gave Bruges its golden age. Historic land reclaim, that only ended in 1872, reduced the Zwin to a tidal lagoon with a superficies of only 200 hectares, comprising salt marshes, mudtlats, tidal gullies and coastal dunes. Once an important sanctuary for coastal bird-species, the Zwin is in both concerned European Union member states included in the European Natura 2000 network. Since the years 1980, accelerated silting up of the lagoon and gullies and encroachment of the salt marshes with Elymus athericus have resulted into a significant loss of biodiversity. The accelerated silting up is caused by the lack of dynamics in relation to the too small scale of the remaining sea-inlet. After the necessary hydrodynamic modelling and an Environmental Impact Assessment were carried out, it was decided that the tloodplain of the Zwin should be enlarged with 120 hectares by moving the searetaining dike inland. The Agency for Nature and Forest (Flanders) has, together with the Province of Zeeland (Netherlands), also elaborated an arrangement-plan for the presently existing tidal site. This arrangement-plan prescribes rejuvenation of the salt marshes by cutting off sods and grazing by cattle and livestock as well as restoration of a tidal lagoon and expansion of the main sea-inlet by excavations
Understanding the Visitation Aspect of Black-headed Gull (Larus ridibundus) in the Long Period at Nakdong Estuary, Busan, Republic of Korea
AbstractThis study analyzes data in the first half of 1990 (May, 1989 - April, 1993) and mid-2000 (May, 2002 - April, 2006) to understand long-term status of black-headed gulls (Larus ridibundus) in the estuary of the Nakdong River under rapid changes. During the period (May, 1989 - April, 1993 and May, 2002 - April, 2003 for a total of 8 years), a total of 201,519 individuals of Laridae were discovered at the estuary and the number of the black-headed gulls (Larus ridibundus) was 32,538 (16.15%). Monthly average of the black-headed gulls showed that there were just a small number of individuals arrived in July and August, but the number increased from September, reached the highest in April for the first term (1989 - 1993). The second term showed that some individuals were discovered in summer (June - August), then the number increased from October and reached the peak in April. Monthly average in the latter period marked 5.7 times higher than that of the former. In the aspect of individuals, there is a significant difference between the two period (P<0.05) and it is discovered that the number of individuals in 2000s (Mean= 6923.50) was higher than that of 1990s (Mean=1211.00). Comparing individuals of gulls, herring gulls (Larus argentatus) and black-headed gulls for 8 years, it was found out that the herring gulls (Larus argentatus) showed the largest number (average=5313.13), followed by the black-headed gulls (average=4067.25) and gulls (average= 1207.63). The fluctuation on individuals of black-headed gulls in the mid-2000s (May, 2005 - April, 2006) recorded the average number of 472.75, then 113.50 in DMD, 244.00 in JJ and SJD, 635.25 in SJ and DY, 727.50 in LUD and 643.50 in USD, showing significant differences among regions (P<0.05)
UPDATED GEOGRAPHIC DISTRIBUTIONS OF MICHIGAN HERPETOFAUNA:: A SYNTHESIS OF OLD AND NEW SOURCES
Recently a comprehensive overview of reptiles and amphibians in Michigan was published. Unfortunately, the distributions of the species represented were compiled before widespread accessibility to technological tools providing greater access to museum and historical records as well as citizen science efforts. To update the known ranges of Michigan herpetofauna, published literature, museum collections, and photographic vouchers submitted to an online database were examined and 339 new county and island records were added, updating the maps for 48 of Michigan’s 55 known species of reptiles and amphibians. I also present the first published list of Michigan amphibians that includes two new plethodontid salamanders, the Northern Dusky Salamander (Desmognathus fuscus) and Southern Two-lined Salamander (Eurycea cirrigera). This paper serves as an example of the wealth of information available to scientists that may have previously been unobtainable, and can be used for the distribution of herpetofauna elsewhere
Coastal Geology and Geomorphology of Cape Cod - An Aerial and Ground View
Guidebook for field trips to the Boston area and vicinity : 68th annual meeting, New England Intercollegiate Geological Conference, October 8-10, 1976: Trip A-10; B-1
MRC B0319-454: Probing the large-scale structure with a giant radio galaxy
We present an investigation of the relationships between the radio properties
of a giant radio galaxy MRC B0319-454 and the surrounding galaxy distribution
with the aim of examining the influence of intergalactic gas and gravity
associated with the large-scale structure on the evolution in the radio
morphology. Our new radio continuum observations of the radio source, with high
surface brightness sensitivity, images the asymmetries in the megaparsec-scale
radio structure in total intensity and polarization. We compare these with the
3-D galaxy distribution derived from galaxy redshift surveys. Galaxy density
gradients are observed along and perpendicular to the radio axis: the
large-scale structure is consistent with a model wherein the galaxies trace the
ambient intergalactic gas and the evolution of the radio structures are
ram-pressure limited by this associated gas. Additionally, we have modeled the
off-axis evolution of the south-west radio lobe as deflection of a buoyant jet
backflow by a transverse gravitational field: the model is plausible if
entrainment is small. The case study presented here is a demonstration that
giant radio galaxies may be useful probes of the warm-hot intergalactic medium
believed to be associated with moderately over dense galaxy distributions.Comment: 27 pages, 15 figures, accepted for publication in MNRA
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