The Seasonal Dynamics of Artificial Nest Predation Rates along Edges in a Mosaic Managed Reedbed

Boundaries between different habitats can be responsible for changes in species interactions, including modified rates of encounter between predators and prey. Such ‘edge effects’ have been reported in nesting birds, where nest predation rates can be increased at habitat edges. The literature concerning edge effects on nest predation rates reveals a wide variation in results, even within single habitats, suggesting edge effects are not fixed, but dynamic throughout space and time. This study demonstrates the importance of considering dynamic mechanisms underlying edge effects and their relevance when undertaking habitat management. In reedbed habitats, management in the form of mosaic winter reed cutting can create extensive edges which change rapidly with reed regrowth during spring. We investigate the seasonal dynamics of reedbed edges using an artificial nest experiment based on the breeding biology of a reedbed specialist. We first demonstrate that nest predation decreases with increasing distance from the edge of cut reed blocks, suggesting edge effects have a pivotal role in this system. Using repeats throughout the breeding season we then confirm that nest predation rates are temporally dynamic and decline with the regrowth of reed. However, effects of edges on nest predation were consistent throughout the season. These results are of practical importance when considering appropriate habitat management, suggesting that reed cutting may heighten nest predation, especially before new growth matures. They also contribute directly to an overall understanding of the dynamic processes underlying edge effects and their potential role as drivers of time-dependent habitat use.     

Reedbed selection and colony size of breeding Purple Herons Ardea purpurea in southern France

Reedbeds of Phragmites australis have declined in Europe in recent decades. Moreover, in some European countries the remaining reedbeds are intensively managed for industrial reed cutting, hunting or grazing. Several species of conservation concern, such as herons and pelicans, use reedbeds as their principal breeding habitat. At the same time, data on habitat use and colony size of these species in relation to reedbed management practices are scarce. We investigated habitat characteristics of 71 reedbeds occupied or unoccupied by breeding Purple Herons Ardea purpurea in the Rhône delta (Camargue) and in other Mediterranean coastal marshes in southern France. In addition, data on colony size in occupied reedbeds were collected from aerial surveys. Reedbeds occupied by breeding Purple Herons were unharvested, or only partially harvested, in winter and had higher water levels in spring compared with unoccupied reedbeds. A logistic regression model with reed harvesting intensity and water levels in mid‐April as independent variables correctly classified reedbed use for 94.7% of the reedbeds in the study. A model with water levels in mid‐April alone was only 90.9% accurate, suggesting that low water level in spring is the most important factor limiting reedbed occupation by breeding Purple Herons. A general linear model indicated significant effects of harvesting intensity and reedbed surface area on colony size. Within occupied reedbeds there was a strong tendency for colony size to increase with increasing reedbed surface area. Given the recent developments in reed harvesting and wetland management in southern France and elsewhere in Europe, these results provide the first information on potential effects of these practices on reed nesting herons, and suggest that Purple Heron conservation is likely to be favoured by maintaining large uncut reedbeds with relatively high water levels in spring. The possible effect of changes in habitat on the Purple Heron population in southern France is discussed.     

Management of reedbeds: mosaic reed cutting does not affect prey abundance and nest predation rate of reed passerine birds

Reed passerine birds are strict habitat specialists inhabiting reedbed habitats. In Europe, many of these species are threatened due to loss and degradation of natural reedbeds. Another important factor that can negatively affect the abundance of reed passerines is commercial reed harvesting. Previous studies have shown negative impacts of large-scale winter reed cutting on passerine breeding assemblages and arthropod communities. The effect of reed cutting on a small scale, however, has not been studied experimentally to date. The aim of this study was to investigate whether and how small-scale, mosaic reed cutting influences prey abundance and nest predation rate of reed passerines. In June, after the reed had reached maturity, we conducted nest predation experiments with artificial nests and arthropod sampling using pan traps in cut reed patches, adjacent uncut reed patches and unmanaged reedbed. We found no differences in the risk of egg predation between three types of reedbeds. In contrast, the abundance of arthropods in cut and adjacent uncut reed patches was significantly higher than that in unmanaged reedbed. We assume this was caused by habitat heterogeneity, small size of cut patches and their rapid recolonization by arthropods from adjacent uncut patches. Our results suggest that in contrast to large-scale reed cutting, small-scale, mosaic reed cutting has no negative effect on nest survival and food abundance of reed passerine birds. However, given that we performed all experiments in June, i.e., when the reed was mature, our findings cannot be generalized to whole breeding period of all reed passerine birds. Therefore, temporal variation in nest predation rate and arthropod abundance in managed and unmanaged reedbeds during the entire breeding season should be examined in future studies.     

The importance of temporal dynamics of edge effect in reedbed design: a 12-year study on five bird species

Although edge effect is a key topic of conservation biology, we have no data on the temporal dynamics of it. I investigated the distribution of five passerine bird species across reedbed (Phragmites australis) edges during large-scale construction work in the Kis-Balaton marshland, Hungary. The construction provided an experimental approach to study the effects of large timescale changes within a shorter period, because neither the locality nor the vegetation type changed. The water level was increased in the study area, which homogenised the internal structure of reedbed by declining the scattered small willow bushes (Salix) and the grass/sedge layer. The sedge (Acrocephalus schoenobaenus) and reed warblers (Acrocephalus scirpaceus) preferred edges. The sedge warbler, however, declined after inundation, while the reed warbler did not respond. Savis warbler (Locustella luscinioides) sharply declined during the study with changing edge effect. The number of great reed warblers (Acrocephalus arundinaceus) increased during the study, mainly in the reedbed interior, where the stands became patchy with open water. Reed bunting (Emberiza schoeniclus) avoided interiors, and declined over the study. Therefore, there were significant changes in the distribution of reedbed birds across the edge, although the location of edges and the basic habitat, reedbed, did not change. The results highlight the need to incorporate edge effect as a dynamic process in wetland planning.     

Bird species numbers in an archipelago of reeds at Lake Velence, Hungary

1 Bird species numbers were studied on 109 reed islands at Lake Velence, Hungary, in the 1993 and 1994 breeding seasons. The aim was to describe and account for the abundance and distribution patterns of the bird species. 2 It was expected that an exponential model would fit the calculated species–area curves. However, for the 1993 data, both the power function (LogS ~ LogArea) and the exponential (S ~ LogArea) models did so, while the power function, exponential and linear (S ~ A) models fitted the curves for the 1994 data. 3 The results showed that the pattern was not random: a collection of small islands held more species than a few large islands with the same total area. 4 The relative species richness of small islands is a result of the preference of most common passerine bird species for the edges of reed islands. Most individuals were found in the first 5 m of the reedbed, and no edge avoidance was detected on a local spatial scale. Large, rarer species (e.g. Great White Egret), however, were found to be dependent on large reed islands. 5 Comparison of results with two other studies on bird communities of reed islands revealed that the type of landscape matrix (e.g. deep water, shallow water or agricultural lands) among reed patches significantly influences bird communities. Deep water was dominated by grebes and coot, shallow water by reed‐nesting passerines, and farmed areas by reed‐ and bush‐nesting passerines.     

Colonisation by Dreissena of Great Lakes coastal ecosystems: how suitable are wetlands?

1.  Invasive zebra ( Dreissena polymorpha ) and quagga mussels ( Dreissena bugensis ) have become widespread throughout the Great Lakes basin. However, some types of Great Lakes coastal wetlands may be unsuitable for Dreissena invasion.
2.  To test this observation, artificial substrata were placed in wetlands (with emergent vegetation) and in adjacent open water (without emergent vegetation) habitats in two types of Great Lakes coastal ecosystems: drowned river mouth (DRM) and coastal fringing systems. Wetlands in DRM systems generally have deep organic sediment and limited water movement, whereas coastal fringing wetlands generally have low to moderate amounts of organic sediment and intense wind and wave action.
3.  We did not find a significant difference in Dreissena colonisation between wetlands and adjacent open water habitat in fringing systems. However, Dreissena colonisation was significantly lower in DRM wetlands than in the adjacent open water. We also found significantly lower survival in DRM wetlands than adjacent open water habitats, whereas survival did not differ significantly in coastal fringing wetlands and the adjacent open water.
4.  Our results suggest that vulnerability to Dreissena invasion varied among wetland types with DRM wetlands being less suitable than fringing wetlands. We suggest that colonisation and survival of Dreissena is lower in wetlands with deep organic sediment and less turbulent water.     

Seasonal Abundance and Species Richness of Birds in Common Reed Habitats in Lake Erie

Abstract: Common reed (Phragmites australis) forms dense stands with deep layers of residual organic matter that negatively affects plant diversity and possibly habitat use by wetland birds. We sought to determine whether seasonal relative abundance and species richness of birds varied among 3 habitat types in Great Lakes coastal wetland complexes recently invaded by common reed. We used fixed-distance point counts to determine species relative abundances and species richness in edge and interior locales within common reed, cattail (Typha spp.), and meadow marsh habitats of various sizes during 2 summers (2001 and 2002) and 1 autumn (2001) at Long Point, Lake Erie, Ontario, Canada. We found that total relative abundance and species richness of birds were greater in common reed habitat compared to cattail or meadow marsh habitats. However, we also found that relative abundance of marsh-nesting birds was greater in meadow marsh habitat than in cattail and common reed during summer. Lastly, we found that, irrespective of habitat type, habitat edges had higher total relative abundance and species richness of birds than did habitat interiors. Our results show that common reed provides suitable habitat for a diversity of landbirds during summer and autumn but only limited habitat for many marsh-nesting birds during summer. Based on these results, we recommend restoration of meadow marsh habitat through reduction of common reed in Great Lakes wetlands where providing habitat for breeding marsh-nesting birds is an objective. Managers also might consider reducing the size of nonnative common reed stands to increase edge effect and use by birds, possibly including wetland birds.     

Microclimate and vegetation edge effects in a reedbed in Hungary

The aim of the study was to describe microclimate (surface and air temperature, humidity, light and wind intensity) and vegetation structure (density and height of reeds, and reed shoot structure) across the first 20m of a sharp reedbed edge at Lake Velence, Hungary, in June 1996. There was a significant edge effect, although different variables contributed differently to the pattern. The reedbed edge had three bands: the first is characterised by very dense stand, where the shoots were thin and short; in the second band density declined, but reed shoots were thick and very high, and in the third band both density and height declined, but not shoot diameter. Microclimate variables showed similar pattern: reedbed edges were warm, dry, bright and windy, further inside temperature, light and wind intensity declined, humidity increased, and still further temperature and light intensity increased, and humidity decreased. I estimated that the edge effect penetrates into the reedbed up to ca. 15m. The great variation of variables across the edge inevitable has significant impact on the occurrence of animals species; our knowledge, however, is too limited to predict the expected extinction of species owing to edge effect.     

Reedbed structure and habitat preference of reed passerines during the post-breeding period

Post-breeding habitats of nine passerine species were studied in the permanently flooded reed beds of ponds near the village Pusté úlany (SW Slovakia) in 2002. Structural features of reed beds and the abundance of all birds studied were sampled at two sites and eight study plots. The reed bed structure and abundance of four passerines differed considerably between the individual study plots. The variations in vegetation structure were also caused by winter reed burning in the SE part of study area. Stems in burnt reed beds were smaller and thinner than unburnt. Abundance of the reed warbler and to a lesser extent sedge warbler was higher in tall reed beds, while the bearded tit preferred thick reed stems. Position of reed beds along the shore — open water gradient was an important factor in terms of abundance at the study plots in the case of the reed bunting. This species showed a strong preference for the reed bed edge with open water. Horizontal distribution of other species seems to be random, however, the birds with the exception of Savi’s warbler preferred the upper stratum of reed bed in vertical distribution. Our field data corroborate with those found in experimental studies concerning with ecomorphological characteristics of birds. Some inconsistencies, however, could also be caused by other factors (e.g. foraging preferences). Comparison of breeding and post-breeding habitat requirements of the studied bird species confirmed a more or less random distribution of the majority of species in the post-breeding period. Some variation was found in the cases of only the reed warbler and bearded tit.     

Genetic diversity of riverine reed stands indicating the water regime of the habitat

Although genetic diversity of reed stands developing in habitats with unchanged water levels have been frequently investigated, little is known about reed propagation along rivers, where fluctuating water levels may provide various conditions for germination and seedling development.The present paper evaluates genetic diversity of reed stands grown in (i) an oxbow with significant water level fluctuations related to the flood events in the main river; (ii) a separated oxbow which has lost connection to the main channel; and (iii) artificially controlled running water with low water level fluctuation. At each site, reed stands were investigated along transects parallel to the shore and multilocus phenotypes were determined by microsatellite analysis.The results demonstrated that genetic diversity of riverine reed stands can indicate the water regime of the habitat. Reed colonizes mostly by vegetative propagation where regular inundation can impede germination and seedling development and, therefore, genetic diversity is low in the whole stand. If a former oxbow becomes practically a lake, the clonal diversity and colonization processes are similar to those observed in regular lakes; clone number decreases toward the open water. When reed forms floating mats (i.e. the effect of water level fluctuation is excluded), generative reproduction prevails in the entire stand, resulting in high genetic diversity even at the open water edge of the stand.     

Effects of longitudinal variations in stream habitat structure on fish abundance: an analysis based on subunit-scale habitat classification

SUMMARY 1. Stream reaches contain assortments of various habitat types that can be defined at different spatial scales, such as channel unit (e.g. pools, riffles) and subunit (patches within channel units). We described longitudinal (upstream–downstream) patterns of stream habitat structure by considering subunits as structural elements, and examined their effects on the abundance of masu salmon ( Oncorhynchus masou ) and rosyface dace ( Leuciscus ezoe ) in a third-order tributary of the Teshio River in northern Hokkaido, Japan.
2. Nine subunit types were determined on the basis of water depth, current velocity and substrate, using 0.5 × 0.5 m grids. Although both masu salmon and rosyface dace used pools as a major habitat, the former preferred a subunit type occurring at pool heads (PH subunit) while the latter preferred a slow-current edge type (SE-2 subunit).
3. Along the course of the stream, slow-edge subunits (SE-1, 2 and 3) increased in frequency downstream while fast-edge subunits (FE-1 and 2) decreased, suggesting a downstream development of slow-current edges. Regression analyses indicated that longitudinal variation in masu salmon abundance was explained by the area of PH, rather than pools. Masu salmon density increased with the area of PH. Rosyface dace abundance was explained by a combination of water depth and the area of SE-2, both effects being positive.
4. Longitudinal variations in the abundance of both species were related to the abundance of their preferred habitat at the subunit scale, rather than channel-unit scale. The results emphasise the importance of fine-scale patchiness when examining stream fish habitats.     

震旦鸦雀在镶嵌型芦苇收割生境中的巢址选择

大规模的芦苇收割会对在该生境中繁殖的鸟类产生严重影响。为降低芦苇收割对鸟类繁殖的负面影响,许多地区的湿地管理者逐渐采用了镶嵌型的芦苇收割方式。但是,这种新的芦苇管理方式对鸟类繁殖期生境选择的作用机理尚不清楚。震旦鸦雀是一种主要分布在我国东部、完全依赖芦苇生境而生存的珍稀鸟类,已被IUCN定为全球性近危物种。大规模的芦苇收割导致其适宜生境丧失,被认为是该物种面临的一个主要威胁。选择山东黄河三角洲国家级自然保护区为研究地区,采用AIC信息准则法,从巢址微生境、巢域斑块和全模型3个水平上对可能影响震旦鸦雀巢址选择的生境因子进行了逻辑斯蒂回归分析,并重点探讨芦苇镶嵌收割对其巢址选择的影响以及不同水平的相互效应。结果发现,震旦鸦雀的巢址选择受巢址微生境和巢域斑块尺度双重水平的影响,但巢址微生境因子的影响要大于巢域斑块因子。在巢址微生境水平上,影响震旦鸦雀巢址选择的因素有:1.5—2.5 m旧芦苇的密度、2.5 m以上新芦苇的密度、香蒲密度和巢的可见度;在巢域斑块水平上,影响因素包括芦苇生境类型、旧芦苇斑块面积的比例和植被盖度;在综合模型中,影响因素有1.5—2.5 m旧芦苇的密度、2.5 m以上新芦苇的密度、香蒲密度、巢的可见度和植被盖度。综上,震旦鸦雀倾向于在植被盖度较高、具有一定比例(18.3%)旧芦苇面积、1.5—2.5 m旧芦苇密度较高、可见度较低的生境斑块中筑巢。研究中,78.7%(n=141)的震旦鸦雀将巢筑在新旧芦苇混合的微生境中,其中36.9%的巢址附近旧芦苇的比例在一半以上;53.2%(n=111)的巢筑于新、旧两种芦苇茎秆之上,22.3%的巢的支撑芦苇中旧芦苇所占比例在一半以上。研究结果表明,旧芦苇在震旦鸦雀巢址选择和筑巢过程中发挥了重要作用。由于大范围的芦苇收割在微生境水平上可降低1.5—2.5 m旧芦苇的密度,在巢域斑块尺度上可降低旧芦苇斑块面积的比例,因此建议,在震旦鸦雀的繁殖地,未来的芦苇收割应采用镶嵌收割的形式,并至少应保留面积在20%以上的结构较好的旧芦苇斑块,以供震旦鸦雀选择巢址和繁衍后代。     

芦苇收割对震旦鸦雀觅食活动的影响

芦苇(Phragmites australis)湿地具有重要的社会经济价值和特殊的自然保育意义,芦苇收割是芦苇湿地管理的主要手段,往往对栖息于芦苇湿地中的动物群落产生影响,尤其对专食芦苇昆虫的鸟类影响较大。2007年1～4月,在长江口崇明岛崇西湿地科学实验站研究基地芦苇收割前后通过样方法研究了芦苇收割对震旦鸦雀(Paradoxornis heudei)觅食的影响。研究表明,芦苇收割显著减少了震旦鸦雀潜在食物资源,改变了震旦鸦雀觅食分布并使震旦鸦雀提前转移到新生芦苇枝上取食,芦苇收割后残留老芦苇枝对震旦鸦雀取食具有重要影响。芦苇收割时保留一定的斑块状和条带状老芦苇有利于震旦鸦雀利用新芦苇枝上潜在食物资源,可以在一定程度上缓解芦苇收割引起的震旦鸦雀食物短缺。     

Top-down and bottom-up impacts of juvenile fish in a littoral reed stand

1. Research has often focused on pelagic food chains and processes of lakes; less is known about the contribution of benthic energy flows to whole‐lake ecosystem energetics. This stems from the fact that the shoreline and littoral habitats, which provide a key linkage between sediment and water column, have only recently become a significant focus for study. 2. This study aimed to quantify the feeding and phosphorus allocation of a juvenile fish community in a littoral zone of a shallow lake in response to the biomass succession of the invertebrate prey community. Habitats comprising reed and adjacent open water were sampled over two consecutive years during day and night. 3. Although there were substantial year‐to‐year differences in the biomass of invertebrates, the fish community composition, diet consumption rates and phosphorus allocations were very similar in both study years. Biomasses and predation impacts by juvenile fish on prey groups were substantially higher within the reeds than in the adjacent open water habitat. This may be explained by the refuge‐seeking behaviour of the fish. 4. In general, invertebrates were negligibly influenced by fish feeding, with the exception for a strong top‐down control of large cladocerans. In response to the resulting low Daphnia biomass, fish were forced to switch to a higher degree of benthivory. Consequently, juvenile fish in littoral reed stands may shift benthic‐derived energy and phosphorus via the excretion of soluble reactive phosphorus into the open water.     

向海自然保护区丹顶鹤生境结构空间特征

丹顶鹤为国家一级保护珍稀禽类,是向海自然保护区重点保护对象。在我国乃至世界范围的丹顶鹤保护中占有重要的地位。近年来,由于自然条件和人类活动的干扰,丹顶鹤的天然家园．沼泽湿地发生退化,其生存受到威胁,丹顶鹤的数量波动变化较大。为了有效地保护丹顶鹤有必要详细了解和掌握其生境结构的空间特征和变化特点,以了解丹顶鹤的生境动态。在RS、GIS技术和统计分析方法的支持下,运用景观生态学方法对向海自然保护区丹顶鹤生境空间结构特征从景观特征、生境斑块空间关系和生境破碎化3个方面进行分析。选择景观斑块面积、周长、斑块大小以及斑块密度等描述保护区景观格局基本特征。利用斑块的邻接边界长度和斑块间隙指数分析丹顶鹤生境——沼泽斑块的空间邻接关系和聚集程度,数据表明沼泽斑块与人类活动频繁的耕地邻接较为紧密,而自身的间隙指数自20世纪70年代以来有明显增大趋势。分析了由于自然原因和人为活动影响所造成的丹顶鹤生境斑块的空间破碎化程度。计算结果表明,由于沼泽生境自身条件的限制,研究区内物理性破碎化减少的生境面积为2039．6hm^2,人为破碎化（居民地和道路）减少的生境面积为3845．1hm^2,这样研究区内丹顶鹤适宜生境面积为13680．1hm^2,可见人类活动对丹顶鹤生境影响很大。研究为保护区内丹顶鹤物种的保护和生境管理提供重要的科学依据。     

Nest predation in Reed Buntings Emberiza schoeniclus: an experimental study

Predation is a major cause of nest failure in many bird species. High levels of nest loss may be a consequence of habitat fragmentation, leading to increased amounts of edge habitat. Yet the evidence for generally high nest predation rates along edges in fragmented landscapes is ambiguous. Using real nests of Reed Buntings Emberiza schoeniclus in which artificial Reed Bunting and real Japanese Quail Coturnix japonica eggs were placed, we experimentally tested for edge effects on nest predation in highly fragmented reed Phragmites sp. habitats in the Swiss lowlands. We also examined seasonal patterns of predation and the impacts of nest visits by observers. We found evidence for an edge effect at the water-sided reed edge, with nests located closer to the water being more likely to be predated than those further away. Predation probability increased from early to late season, suggesting that nest predation may be density dependent. Probability of nest predation was only weakly influenced by whether or not a nest was visited. Our results suggest that the intensive reed management currently applied in Swiss nature reserves may result in unnaturally high levels of nest losses in the Reed Bunting, because reed bands are not wide enough to allow nest placement at a safe distance from reed edges.     

Response of ground-dwelling beetles across logging coupe edges into streamside reserves

Streamside reserves can provide important habitat reservation in forest landscapes subject to logging. Depending on the width of streamside reserves, edge effects have the potential to compromise their effectiveness for terrestrial conservation, yet edge effects into riparian environments have rarely been assessed. It would be unwise to assume that edge effects act in the same way at streamside reserves as at the non-riparian edges of logging coupes, as interactions with riparian influences on beetles along the stream-upslope gradient might create unique edge conditions. In this study, we assess edge effects on ground dwelling beetles at four sites, using transects of pitfall traps across logging coupe edges into streamside reserves that have only been affected by logging on one side of the stream. Edge effects were found to extend further into streamside reserves in this study than into upslope habitat at the same sites from a concurrent study. Edge effects were site specific and appeared to extend as far as the stream in most cases (23–65 m). Comparison of beetle assemblage composition with adjacent unlogged streams supported the conclusion that beetles within 10 m of streams in streamside reserves were still responding to edge effects. These results suggest that streamside reserves might not contain habitat comparable with riparian areas away from the influences of nearby clearfelling, and wider reserves are recommended to maintain core habitat not compromised by edge effects.     

Experiments with artificial nests on predation in reed habitats

We performed nest predation experiments with artificial nests in reedbeds investigating whether nest predation pressure is different at the water-reed edge and the grassland-reed edge compared with the reed interior. Furthermore, we tested the effects of vegetation structure (reed density, height and thickness) and the effect of other nest site characteristics (distance from edge, water depth) on the success of artificial nests. The experiments were completed 3 times during the breeding season in 2001 at Lake Neusiedl, Austria. Each artificial nest resembled Great Reed Warbler (Acrocephalus arundinaceus) nests and contained one plasticine and one Quail (Coturnix coturnix) egg and the predators were identified by marks left on the eggs. The potential predators were birds, probably the Marsh Harrier (Circus aeruginosus), gulls (Larus spp.) and reed warblers (Acrocephalus spp.). Nest survival data were analysed using the Mayfield method, and we performed a discriminant analysis for the data of vegetation and nest site characteristics. The nest predation was higher at the edges than in the reed interior, and was most pronounced in April, before the new reed sprouted. The reason for this finding was probably that after May the new reed contributed to greater concealment of the nests through the higher reed density and height.     

Long-term trends in the breeding populations of waterbirds (1951–1985) at a sewage treatment plant

Long-term (1951–1985) data on the breeding waterbird populations and habitat modifications at Cape Flats sewage treatment works (Strandfontein) and Rondevlei Bird Sanctuary (Rondevlei) were assessed to establish the main factors affecting the breeding species richness and nest abundance. Fifty-two 'water-associated' breeding species were recorded in the Zeekoe River catchment waterbodies, 46 (88.5%) at Strandfontein, 38 (73.1%) at Rondevlei Bird Sanctuary (Rondevlei), 33 (63.5%) at Zeekoevlei and ten (19.2%) at Princess Vlei. Thirteen (25.5%) of the species were unique to Strandfontein and five (9.8%) to Rondevlei. Sorenson's similarity indices indicated high similarity (C_s = 0.81) in species richness and low similarity in nest abundance pattern (C_N = 0.10) for the paired sites Strandfontein-Rondevlei. The lowest breeding species richness (11 species) was in winter (June) and the peak (42 species) was in spring (October). Twenty-four species joined the breeding population of Strandfontein during 1959–1976 (during which time pond water surface area increased 2372%). The mean breeding species richness increased significantly (χ ² ₂ = 14.42, P <0.001) at Strandfontein during three distinctive periods: 1951–1958 (pre-construction), 1959–1976 (construction) and 1977–1985 (stabilization). At Rondevlei there were no significant differences in breeding species richness during the same periods. However, there were significant differences in the nest abundance pattern between these grouped years, both at Strandfontein (χ ² ₂ = 1472.2, P <0.001) and at Rondevlei (χ ² ₂ = 60.28, P <0.001). It is suggested that the same pool of species use the heterogeneous habitats at all the sites in the catchment according to their availability. The remarkable increase in species richness and nest abundance at Strandfontein after the late 1970s is attributed to higher habitat structural complexity, broad habitat types, stabilization and maturation of pond water and the subsequent increase in food diversity and availability. The decrease in Rondevlei nesting populations after the 1960s is probably related to fluctuations in water levels, cover of mudbanks with vegetation and high density of alien fish. A multipurpose management concept for conservation is proposed for the Zeekoe River catchment area. Strandfontein provides the greatest diversity of aquatic habitats not available elsewhere in the catchment (habitats for rare breeders such as Avocet, Black-winged Stilt, Red-billed Teal and some plovers) Rondevlei has a complementary habitat spectrum (suitable for Great Crested Grebe, Podiceps cristatus, Little Bittern, Ixobrychus minutus, and reedbed species). Zeekoevlei provides a large area of reedbed habitat for colonial breeding species (African Spoonbill and herons) and Princess Vlei is suggested for attracting Laridae.     

Restoring a rainforest habitat linkage in north Queensland: Donaghy's Corridor

Summary  Donaghy's Corridor is a 1.2 km × 100 m planting of rain forest species on the Atherton Tableland, Queensland, designed to link an isolated fragment (498 ha) to adjacent continuous forest (80 000 ha). Vegetation and fauna monitoring commenced immediately after the linkage was completed. Vegetation surveys showed 119 plant species established in the linkage in 3 years, and 35 of these were not known to occur within the extant linkage either as planted stock or as natural individuals existing prior to project commencement. There were differences between the fauna trapped within the restoration, adjacent open pasture habitats, forest interior sites and forest edge sites. Differences likely reflect variation in species habitat preferences and the habitat suitability of the planted vegetation. Now over 10 years old, Donaghy's Corridor has developed a complex forest structure, with the tallest planted stems exceeding 20 m in height. This feature article provides information about the planning, implementation and monitoring of the linkage, and shows how restoring landscape and ecological connectivity can be a locally effective strategy to counter forest fragmentation.