The little auk <i>Alle alle</i> in Belgium = De Kleine Alk in België

Little Auks Alle alle winter in the central en northern North Sea and visit the southern North Sea only in small numbers (Stone el al. 1995). The species is rare in Belgium (Commissie voor de Belgische Avifauna 1967, Lippens & Wille 1972, Raes & Van Compel 1989). Over the past 20 years, in fact since winter 1977/78, Little Auks have been recorded more frequently along the Belgian coast (Lust & Vanloo 1991, Van Compel 1990). An unprecedented influx was witnessed in the autumn of 1995. In this paper, we give an overview of all Little Auk observations in the autumn of 1995, and compare the present invasion with previous ones

Kleine mantelmeeuwen <i>Larus fuscus</i> in de zuidelijke Noordzee in augustus en september 1995 = Lesser Black-backed Gulls in the southern North Sea in August and September 1995

The Institute of Nature Conservation conducted seabird counts onboard of the 'R.V. Belgica' between 28 August and 8 September, intended to estimate the stock of Lesser Black-backed Gulls in the southern North Sea, In total 1182 km were surveyed in the area situated between 51° and 54°30' latitude, using the standard strip-transect method. In order to compensate for underestimation caused by congregation of gulls around fishing vessels, the density of the fishing vessels was estimated by using a line transect method. In total 9193 Lesser Black-backed Gulls were recorded, of which 612 were located 'in transect' during the strip-transect counts (353.9 km²). It was appraised that the average density of birds was 1.73/km². The overall density of vessels was approximately 0,0053/km² in a selected area of 57 000 km², with an mean flocksize of 96.6 Lesser Black-backed Gulls per ship. Summing up these two figures, it can be estimated that 100 000 - 150 000 Lesser Black-backed Gulls occurred in the southern North Sea in this period. The highest densities were found off the Belgian and Dutch coast, between Zeebrugge and Katwijk. Another patch with high density was located off NE Norfolk. The majority was associated with fishing vessels (74%, n=9193), although a group of self-feeding birds was seen off the English coast

Pitfalls in the design and analysis of paediatric clinical trials: a case of a ‘failed’ multi-centre study, and potential solutions

Aim: To increase awareness of possible pitfalls in the design and analysis of a multi-centre randomized clinical trial and to give an overview of alternative study designs and their consequences for power analyses in case of limited availability of trial participants

Beach bird surveys in Belgium (poster)

Oil contamination is still a major cause of mortality in many coastal and seabird species around Europe. In a comparison with other North Sea areas, oil rates of most Belgian beached bird species are significantly higher than in northern areas such as the Shetlands and Norway, and more or less in line with oil rates at other European continental coasts. Wrecks of starved unoiled guillemots (and other species) became an almost annual event at the North Sea coasts from the first half of the ‘80s onwards, also in Belgium.Oil rates of beached bird corpses are an appropriate condition indicator of oil pollution at sea. Oil rate of most bird species/taxa in Belgium indicate a decline in oil pollution for the period 1962-99, though only Laridae, guillemot and razorbill show significant reductions. For the other taxa no significant decrease in proportion of oiled birds could be demonstrated, often due to the relatively small study area and hence insufficient number of birds collected. Assuming that a sample of at least ten complete corpses is required to calculate reliable oil rates, only the guillemot (as species) and auks (as taxon) can provide the necessary data in Belgium these days.Long-term oil pollution monitoring in Belgium should be continued with a major focus on a set of abundant bird taxa, sensitive to oil pollution and occurring in various marine habitats and the collection of additional data during the rest of the winter. Most appropriate for this set of limited bird taxa to focus on are grebes (inshore), Laridae, guillemot and razorbill (midshore) and kittiwake and fulmar (offshore).Birds dying at sea may eventually wash ashore. As such, beached bird surveys can be an important source of information concerning mortality of seabirds in the marine environment. However, there has been a lot of debate on the question how numbers of casualties on beaches relate to the actual mortality at sea and which factors affect this relationship. The temporal patterns of beached birds usually follow those of seabirds at sea with a time lag of at least one month. Considering the short Belgian shoreline and the prevailing frequency distribution of winds, probably only 10% of all birds washing ashore died in Belgian marine waters. With a dominant SSW circulation and a net residual current in northeastern direction, many birds must end up on Dutch, German or Scandinavian beaches. Accordingly, there is a higher probability that Belgian beaches receive birds that died in northern France or south England than from other North Sea border states. Based on the number of birds found on the beach and brought in at the MEC, and taking into account that 50-80 % of the corpses have disappeared already within the first 9 days (the mean interval between succeeding weekly surveys), we estimate that the total number of bird corpses beaching on the Belgian coast each winter might be as high as 5,000-10,000 birds

Seabirds in Belgian marine waters: implications for policy and management (poster)

In 1992, the Institute of Nature Conservation (INC) started ship-based surveys on the Belgian Continental Shelf (BCS) to study the spatial and temporal distribution of seabirds. Among other things, the study showed that the Belgian marine waters hold internationally important numbers (> 1% of the biogeographical populations) of several coastal and marine bird species. Also the area proved to be of major importance for several species of migratory birds. Out of the 121 bird species encountered at sea during the period 1992-98, 23 were selected as being true marine species that occur in relatively high densities within the Belgian waters. Of these 23 species six were so-called ‘focal species’, being seabirds which are included in the highest priority lists of international conservation instruments (EC-Birds Directive, Bern Convention or Bonn Convention) and which attain at least 1% of the flyway population in Belgian marine waters in a particular season. Based on the distribution patterns, conservation value, and sensitivity for disturbance or oil pollution of the six focal seabirds several areas of high ornithological importance as well as areas sensitive for disturbance or pollution could be distinguished at the BCS. The avian hotspots at the Westkustbanken and Vlaamse Banken turned out to be the most sensitive areas for disturbance and oil pollution throughout the year, while the sensitivity of other areas varies with the seasons