Long-Term Changes of a Coastal Bird Breeding Community on a Small Island – Does Natural Succession Compromise Conservation Values?

Limited spatial resources available for conservation lead to controversy about whether to apply single-species management or ecosystemary approaches in order to maintain biodiversity. In this study I analyse changes in a community of breeding coastal birds over a 90-year period, in order to examine whether natural processes on an unmanaged island are in accordance with requirements to save endangered species. Both diversity and species richness of the community increased significantly over time, and evenness increased after having been severely reduced by human impact. Diversity, evenness and species richness seemed to approach an equilibrium in the past decade, but number of breeding pairs declined as a consequence of altered natural disturbance regime. Species identity changed over time, with two initially very common species recently becoming locally extinct. These species are of high conservation concern, and their disappearance causes a problem for the concept of naturalness on islands. I conclude that natural processes need to be applied to the entire landscape in order to maintain dynamic processes that are essential for the survival of these species. The natural changes on the island should not be interrupted, but rather demonstrated to the public in order to increase conservation mindedness and gain support for changes in anthropogenic influences on a larger spatial scale.     

Impact of wind turbines on birds in Zeebrugge (Belgium)

We studied the impact of a wind farm (line of 25 small to medium sized turbines) on birds at the eastern port breakwater in Zeebrugge, Belgium, with special attention to the nearby breeding colony of Common Tern Sterna hirundo, Sandwich Tern Sterna sandvicensis and Little Tern Sterna albifrons. With the data of found collision fatalities under the wind turbines, and the correction factors for available search area, search efficiency and scavenging, we calculated that during the breeding seasons in 2004 and 2005, about 168 resp. 161 terns collided with the wind turbines located on the eastern port breakwater close to the breeding colony, mainly Common Terns and Sandwich Terns. The mean number of terns killed in 2004 and 2005 was 6.7 per turbine per year for the whole wind farm, and 11.2 resp. 10.8 per turbine per year for the line of 14 turbines on the sea-directed breakwater close to the breeding colony. The mean number of collision fatalities when including other species (mainly gulls) in 2004 and 2005 was 20.9 resp. 19.1 per turbine per year for the whole wind farm and 34.3 resp. 27.6 per turbine per year for 14 turbines on the sea-directed breakwater. The collision probability for Common Terns crossing the line of wind turbines amounted 0.110–0.118% for flights at rotor height and 0.007–0.030% for all flights. For Sandwich Tern this probability was 0.046–0.088% for flights at rotor height and 0.005–0.006% for all flights. The breeding terns were almost not disturbed by the wind turbines, but the relative large number of tern fatalities was determined as a significant negative impact on the breeding colony at the eastern port breakwater (additional mortality of 3.0–4.4% for Common Tern, 1.8–6.7% for Little Tern and 0.6–0.7% for Sandwich Tern). We recommend that there should be precautionary avoidance of constructing wind turbines close to any important breeding colony of terns or gulls, nor should artificial breeding sites be constructed near wind turbines, especially not within the frequent foraging flight paths.     

Use of sandbanks by terns in Queensland,Australia: a priority for conservation in a popular recreational waterway

Many terns (Laridae) from the northern hemisphere overwinter in Australia, but they are rarely covered comprehensively in bird counts in Australian coastal waterways. We conducted censuses over 3 years on terns in an increasingly popular recreational waterway at the northern end of Moreton Bay, known as Caloundra sandbanks, to provide the first overview of the relative abundance of non-breeding tern species on estuary-type sandbanks in Australia. The maximum number of birds counted was > 43,000, of which over 90% belonged to six species of terns. The most abundant tern species was the common tern Sterna hirundo longipennis which reached > 38,000 in one Austral summer. Other northern-breeding migrant terns were the white-winged black tern Chlidonias leucopterus ( > 17,000) and the little tern S. albifrons sinensis ( >11,000), which also breeds in Australia. These migrant terns arrived at Caloundra sandbanks at around late-October and a vast majority had departed by mid-April. Numbers were generally highest from late-December through to early-April. An additional three Australian-breeding terns of smaller population sizes frequented the sandbanks. Density of terns using the habitats could reach a peak of 600 ha⁻¹ during the warmer months of the year, coinciding with peak human recreational activities. In light of the results, Caloundra sandbanks should be regarded as an Area of International Importance based on criteria contained in the Ramsar Convention. The situation at Caloundra sandbanks presents challenges to recreational and tourism issues, requiring review of traditional government priorities in the conservation of wetlands based primarily on waders.     

中澳之间迁徙■鹬类和燕鸥类的环志介绍

From Australia to Asia (China)，the main species of the migratory bird are the waders and terns. In Oct. 1999，an invitation was extended by Dr. Clive Minton of the chairman of the Victorian Wader Study Group (VWSG) to catch and band waders and terns at Sandy Point，Swan Bay，Swan Island，Anderson Inlet/Inverloch，Phillip Island，Mud Islands，Geelong and Werribee and so on. The paper summarizes the methods (catch，bio-metric data，banding，recoveries，flagging，satellite tracking，data analysis on computer，fox control et al.)and results (species of wader and tern，number of banding from 1975 to 1999，calculate the minimum age，breeding success，age of first breeding，levels of fat deposits，molt，the distance of moved) and discuss. The total 141 787 waders，about 35 species (from 1975 to 1999) and 6 057 chicks and adults of terns，about 7-9 species (1998-1999) were captured and banded by the Victorian Wader Study Group.