Status and abundance of the African Black Oystercatcher Haematopus moquini at the eastern limit of its breeding range

From 1983 to 2004 the breeding population of African Black Oystercatchers along the East London coast has more than trebled. The population increase is probably due to immigration as local breeding success is low. There are three classes of birds: breeding pairs, tenants and visitors, and birds may change status during the breeding season. In the winter, birds aggregate into groups and some birds may disperse from the East London coast. The presence of African Black Oystercatchers in all months of the year shows that they are resident, but may only be resident in the general sense, and at a local level appear to be nomadic, wandering along the coast in search of resources and, in the summer, opportunities to breed. The birds remain at any locality only for as long as conditions are suitable, suggesting that the birds along the East London coast are mostly visitors that have dispersed from their natal areas in the south.     

Status of the endangered ivory gull, <Emphasis Type="Italic">Pagophila eburnea</Emphasis>, in Greenland

The ivory gull, a rare high-Arctic species whose main habitat throughout the year is sea ice, is currently listed in Greenland as ‘Vulnerable’, and as ‘Endangered’ in Canada, where the population declined by 80% in 20 years. Despite this great concern, the status of the species in Greenland has been largely unknown as it breeds in remote areas and in colonies for which population data has rarely, if at all, been collected. Combining bibliographical research, land surveys, aerial surveys and satellite tracking, we were able to identify 35 breeding sites, including 20 new ones, in North and East Greenland. Most colonies are found in North Greenland and the largest are located on islands and lowlands. The current best estimate for the size of the Greenland population is approx. 1,800 breeding birds, but the real figure is probably >4,000 adult birds (i.e. >2,000 pairs) since all colonies have not yet been discovered and since only 50% or less of the breeding birds are usually present in the colonies at the time the censuses take place. Although this estimate is four to eight times higher than that previously arrived at, the species seems to be declining in the south of its Greenland breeding range, while in North Greenland the trends are unclear and unpredictable, calling for increased monitoring efforts.     

The timing of breeding and moult of the Lesser Striped Swallow Hirundo abyssinica

The Lesser Striped Swallow seems to have two different breeding populations. The birds south of 10°s breed largely during the spring and summer (July to April) and moult from about April to August. Birds further north breed throughout the year, but mainly during the first seven months of the year. Moult in the birds north of 10°s is from July to February when few birds are breeding. There seem to be two clearly defined moulting populations, with the southern breeding population moulting largely south of 10°s and the east African breeding population moulting largely north of the equator. In both populationsmoult and breeding seem to be separated in time, at least at the individual level.     

The timing of breeding and moult of the Lesser Striped Swallow Hirundo abyssinica

The Lesser Striped Swallow seems to have two different breeding populations. The birds south of 10°S breed largely during the spring and summer (July to April) and moult from about April to August. Birds further north breed throughout the year, but mainly during the first seven months of the year. Moult in the birds north of 10°S is from July to February when few birds are breeding. There seem to be two clearly defined moulting populations, with the southern breeding population moulting largely south of 10°S and the east African breeding population moulting largely north of the equator. In both populations moult and breeding seem to be separated in time, at least at the individual level.     

Individual flexibility in habitat selection in the ortolan bunting Emberiza hortulana

In order to understand habitat selection in birds, it is important to know how individuals respond when encountering a variety of habitats during dispersal and must choose between them. However, very few field studies have addressed this question. We compared habitat selection of ortolan buntings Emberiza hortulana before and after dispersal events. In Norway, this species has a patchy distribution and breeds in different open habitats of which the two major ones are botanically distinct: raised peat bogs and forest clear‐cuts on dry, sandy soil. There was no evidence that habitat selection of males after natal dispersal was influenced by natal habitat, and 83% changed vegetation type. Habitat selection was random when taking the availability of each vegetation type into account, both at the landscape level and among habitats encountered along likely dispersal routes. Habitat selection after breeding dispersal was not influenced by the habitat of the patch of origin, and 62–71% changed habitat during successive dispersal events. Changing habitat did not seem to affect pairing or breeding success, but decreased with age. Lifetime patterns of habitat selection indicated that the majority (86%) changed habitat one or more times. However, the proportion never changing habitat (14%) was significantly higher than expected if settlement after dispersal was random (5%), suggesting that the majority of males were flexible whereas a minority was habitat conservative. These results provide some of the first systematic evidence based on settlement decisions of individuals that habitat selection of birds can be flexible with regard to vegetation type.     

Winter bird communities in the northern Negev: species dispersal patterns, habitat use and implications for habitat conservation

Bird habitat conservation may require different management strategies for different seasonal bird assemblages. We studied habitat use by winter birds in forest and scrubland habitat patches in the northern Negev, Israel. Our goal was to assess whether differences in responses to landscape and habitat structure between breeding and non-breeding seasons require changes in future conservation plans that have been suggested for the Negev breeding bird community. We evaluated habitat and area effects on bird abundance and distribution and tested whether species habitat use during winter involves niche shifts. Compared with breeding birds, a larger proportion of winter bird species occupied both scrubland and forest. As in summer, forest bird species responded to habitat structure, whereas scrubland species were associated with both habitat structure and area. Resident birds disperse into habitats in which they were not present during summer. Consequently, for several species, the correlation between bird densities and environmental factors showed a better fit at the landscape rather than at the habitat scale. In addition, rather than niche shift, birds actually extended their niche breadth. Nest site selection may constrain bird distribution into a realized niche, smaller than their fundamental niche. Despite the scale differences in habitat use, the similar species diversity patterns between seasons suggest that both winter and summer birds would benefit from conservation of scrub patches larger than 50 ha, and enrichment of foliage layers within the planted forests.     

Translocation of the Eastern Bristlebird 2: applying principles to two case studies

Summary The Eastern Bristlebird (Dasyornis brachypterus) is an endangered endemic passerine of south‐eastern Australia. The re‐establishment of extirpated populations through translocation was identified as a key action in New South Wales to address the threats to this species associated with habitat fragmentation and widespread and frequent fire. At Jervis Bay during 2003–2005, 50 birds were translocated from Bherwerre Peninsula to Beecroft Peninsula. In the Illawarra in 2008, 50 birds were translocated from Barren Grounds Nature Reserve to Cataract. At Jervis Bay, monitoring indicated that after 7 years, (i) there was no detectable impact on the source population from the removal of birds and (ii) the count at Beecroft Peninsula was 94 birds, with dispersal up to 6.3 km from the release point. In the Illawarra, (i) the source population was recovering 3 years post‐removal and (ii) the maximum count at Cataract was 15 birds after 3.5 years, including evidence of breeding, and after 3 years, the maximum dispersal was 7 km from the release point. Both translocations adhered to five key principles as follows. (i) Feasibility analysis prior to each project was favourable. (ii) For 17 pre‐stated criteria for success, 14 and 10, respectively, were met for Jervis Bay and Illawarra. (iii) Financial accountability was achieved with detailed statements showing budgets of $201k and $92k, respectively, for Jervis Bay and Illawarra. (iv) Ecological research was incorporated into both projects. (v) The results of each project are progressively being published. The re‐introduction at Jervis Bay has succeeded, and we are optimistic about the Illawarra re‐introduction.     

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.     

Multi-scale habitat models for reintroduced bird populations: a case study of South Island saddlebacks on Motuara Island

Understanding resource selection by animals is important when considering habitat suitability at proposed release sites within threatened species recovery programmes. Multi-scale investigatory approaches are increasingly encouraged, as the patchy distribution of suitable habitats in fragmented landscapes often determines species presence and survival. Habitat models applied to a threatened New Zealand forest passerine, the South Island saddleback (Philesturnus carunculatus carunculatus), reintroduced to Ulva Island (Stewart Island) found that at landscape scale breeding pairs? preferences for sites near the coast were driven by micro-scale vegetation structure. We tested these results by examining models of breeding site selection by a reintroduced saddleback population on Motuara Island (Marlborough Sounds) at two scales: (1) micro-scale, for habitat characteristics that may drive breeding site selection, and (2) landscape scale, for variations in micro-scale habitat characteristics that may influence site colonisation in breeding pairs. Results indicated that birds on Motuara Island responded similarly to those on Ulva Island, i.e. birds primarily settled at the margins of coastal scrub and forest and later cohorts moved into larger stands of coastal forest where they established breeding territories. Plant species composition was also important in providing breeding saddleback pairs with adequate food supply and nesting support. However, Motuara Island birds differed in their partitioning of habitat use: preferred habitats were used for nesting while birds were foraging outside territorial boundaries or in shared sites. These differences may be explained because Motuara has a more homogeneous distribution of microscale habitats throughout the landscape and a highly bird-populated environment. These results show that resource distribution and abundance across the landscape needs to be accounted for in the modelling of density?bird?habitat relationships. In the search for future release sites, food (invertebrates and fruiting tree species) should be abundant close to available nesting sites, or evenly spread and available throughout the landscape.     

Are salinas a suitable alternative breeding habitat for Little Terns Sterna albifrons?

This paper describes the breeding population, breeding habitats and reproductive variables of Little Terns Sterna albifrons in natural (sandy beaches) and alternative (salinas) habitats. Studies of nesting success conducted between 1998 and 2002 in these two types of habitat were combined with a literature review of census work from the past 30 years in order to assess whether salinas are suitable alternative breeding habitat for Little Terns. Most of the Portuguese Little Tern population now breeds in salinas. Census data from the last 30 years show that this is a recent breeding behaviour, because until the 1990s most colonies were located on sandy beaches. Destruction and disturbance of the natural habitat has caused this habitat shift. Despite this shift, the Portuguese Little Tern breeding population did not decline during this period and no significant differences were found in nesting success between natural and alternative habitats. This might indicate that salinas are a suitable alternative breeding habitat for Little Terns, but differences in laying period, clutch size and egg size were recorded between birds nesting on sandy beaches and in salinas in the same area. Birds nested earlier on sandy beaches and laid larger clutches and eggs than in salinas. These data suggest that, when both habitats are available, older and/or higher quality birds prefer sandy beaches for breeding, presumably trying to re-nest in salinas when first breeding attempts failed. We discuss conservation priorities and management actions for both habitats.     

The importance of traditional farmland areas for steppe birds: a case study of migrant female Great Bustards Otis tarda in Spain

A detailed knowledge of the habitat requirements of steppe birds living in farmland habitats is necessary to identify agricultural practices compatible with their conservation. The globally threatened Great Bustard Otis tarda is a partial migrant in central Iberia, but factors affecting its winter habitat use have not been identified. We assessed habitat differences between breeding and wintering areas and winter habitat selection of radiotagged migrant female Great Bustards in central Spain. Of 68 tagged females, 35% moved to wintering areas located 64.3 ± 24.0 km south of their breeding areas, and 80% wintered in a single area of c. 236 km². A census of the population in this area identified it as one of the most important wintering areas of this species in the world, holding c. 1500 individuals. There were significant differences between breeding and wintering habitats of individually marked migrant females. Compared with breeding areas, wintering areas of migrant females were located further from roads and urban nuclei, had lower human population densities and area of urban developments, and a higher diversity of land‐use types, with less cover of cereals and more vineyards and olive groves. Within this area, radiotracked migrant females preferred sites with more vineyards and a lower land‐use diversity. Our results highlight the importance of traditional Mediterranean dry farmland mosaics, and suggest that different conservation strategies are needed for migrant and resident populations in winter to secure the conservation of suitable wintering habitat for Great Bustards in the Iberian Peninsula.     

Is the range size of migratory birds constrained by their migratory program?

Aim Intuitively, species in which the individuals migrate long distances between summer and winter quarters should be more likely to disperse and colonize new breeding areas than resident species. However, it has repeatedly been noted that many bird species with large ranges are residents. This paradox was tested on land birds breeding in the boreal forest of the Palaearctic, the largest uninterrupted stretch of habitat on earth. Methods The longitudinal distribution of two land bird communities on each side of the Eurasian continent, in Scandinavia and eastern Siberia, were used to test whether migratory birds indeed have a lower colonization success than resident birds. Results The migratory species are significantly less likely than resident species to have a range including both regions. The pattern held true even after controlling for latitudinal effects and local abundance, and was also observed at the level of genus and family. Main conclusions The relatively low colonization success of migratory species into new breeding areas may be because these new areas require novel migratory programs (migratory distance, direction and timing) in order for the birds to reach suitable wintering grounds.     

COMMUNAL ROOSTING BEHAVIOUR OF THE AUSTRALASIAN HARRIER CIRCUS APPROXIMANS IN NEW ZEALAND

The Australasian Harrier Circus upproximans habitually roosts communally in New Zealand but not in Australia. As many as 100 birds can occupy a roost in a small area of swamp. They start to assemble about one hour before dark and communal aerial displays in the vicinity of the roost are an integral part of the roosting behaviour. Roosts may be occupied all the year round, non-breeding birds continuing to roost communally throughout the summer. In New Zealand the habit is neither connected with migration nor is it an anti-predator device. It is considered that the abundance of food caused by the spread of introduced mammals and the large increase of habitat created by European settlement has built the harrier population up to such a size that the number required to elicit the response of communal roosting occurs at all times of year in most districts. Numbers within individual roosts fluctuate throughout the year and it is suggested that communal displays before roosting may provide the necessary feed-back for the initiation of population adjustments.     

Non‐breeding range size predicts the magnitude of population trends in trans‐Saharan migratory passerine birds

Understanding why populations of some migratory species show a directional change over time, i.e. increase or decrease, while others do not, remains a challenge for ecological research. One possible explanation is that species with smaller non‐breeding ranges may have more pronounced directional population trends, and their populations are thus more sensitive to the variation in environmental conditions in their non‐breeding quarters. According to the serial residency hypothesis, this sensitivity should lead to higher magnitudes (i.e. absolute values) of population trends for species with smaller non‐breeding ranges, with the direction of trend being either positive or negative depending on the nature of the environmental change. We tested this hypothesis using population trends over 2001–2012 for 36 sub‐Saharan migratory passerine birds breeding in Europe. Namely, we related the magnitude of the species' population trends to the size of their sub‐Saharan non‐breeding grounds, whilst controlling for factors including number of migration routes, non‐breeding habitat niche and wetness, breeding habitat type and life‐history strategy. The magnitude of species' population trends grew with decreasing absolute size of sub‐Saharan non‐breeding ranges, and this result remained significant when non‐breeding range size was expressed relative to the size of the breeding range. After repeating the analysis with the trend direction, the relationship with the non‐breeding range size disappeared, indicating that both population decreases and increases are frequent amongst species with small non‐breeding range sizes. Therefore, species with small non‐breeding ranges are at a higher risk of population decline due to adverse factors such as habitat loss or climatic extremes, but their populations are also more likely to increase when suitable conditions appear. As non‐breeding ranges may originate from stochasticity of non‐breeding site selection in naive birds (‘serial‐residency’ hypothesis), it is crucial to maintain a network of stable and resilient habitats over large areas of birds’ non‐breeding quarters.     

Winter commingling of populations of migratory species can cause breeding range underpopulation

We build a model with large-scale demographic consequences for migratory species. The model operates where four elements co-occur, and we rely on empirical research using migratory birds to demonstrate them. First, breeding ranges have internal structure flowing from natal philopatry. Second, fecundity varies geographically. Third, populations of different breeding provenances commingle during winter. And fourth, a population-limiting carrying capacity operates during winter. In the absence of breeding season population-limitation, only the breeding population with maximum fecundity persists. Consequently, some potential breeding areas that offer suitable and productive habitat are bereft of breeding birds because of the interplay between the geographical fecundity gradient and the shared winter quarters. Where breeding season population-limitation also plays a role for at least one population, one (or more) breeding population becomes permanently depressed, resulting in a density well below the carrying capacity of the productive breeding habitat that is occupied. In either case, not all populations fare equally well, despite net positive breeding season productivity. Changes in winter carrying capacity, for example habitat degradation in winter quarters, can lead to uneven effects on geographically defined breeding populations, even though there has been no change in the circumstances of the breeding range.     

Spring migration strategies of two populations of bar-tailed godwits,Limosa lapponica,in the Wadden Sea: time minimizers or energy minimizers?

Birds can optimize their migration either by minimizing time of transport, energy expenditure, or predation risk during migration. For each of these optimization criteria different fattening and stopover strategies are predicted. The first two of these optimization criteria are examined here for the bar-tailed godwit ( Limosa lapponica ). In the European Wadden Sea two populations of bar-tailed godwits stop over during spring migration between their wintering and breeding areas. The European population winters mainly in Great Britain and the western part of the Wadden Sea and breeds in Fennoscandia. The Afro-Siberian population winters in West Africa and breeds in Siberia. The European wintering population migrates to the eastern parts of Wadden Sea in March where it stays until early May. During this time birds gain 1.9 g d⁻¹ in body mass for a 1500–2000-km non-stop flight to the breeding areas. Afro-Siberian birds stay only for one month in May in the Wadden Sea where they gain on average 9.4 g d⁻¹ in mass for a 4000-km non-stop flight. Intake rates in April/May did not differ between the two populations (1.5 kJ min⁻¹ and 1.8 kJ min⁻¹ for Siberian and European migrants, respectively) but total energy intake was higher for the Siberian migrants, since they spend 50% of the day foraging vs 30% in the European birds. In contrast to European migrants, Afro-Siberian birds start to moult into breeding plumage already in their winter quarters. During their stopover in the Wadden Sea thermostatic costs are lower than at times when European birds are present. Thus, the higher energy demands of the Afro-Siberian birds seem to be fulfilled by a combination of physiological adaptations and a high working level. European birds seem to adopt an energy-minimized migration strategy whereas Afro-Siberian birds appear to follow a time-minimized migration.     

广西大明山鸟类群落组成、区系成分和垂直分布

为了了解鸟类组成和海拔分布状况,利用样线法和固定调查点法于2007~2015年对广西大明山的鸟类进行了研究。在大明山共记录鸟类337种,隶属于17目56科。繁殖鸟类(包括留鸟和夏候鸟)共计234种,占大明山鸟类种数的69.4%,具有明显优势,构成了大明山鸟类区系组成的主体。大明山具有典型的华南区向华中区过渡的鸟类区系特征,67.1%的繁殖鸟类属于东洋型的种类。随着海拔的增加,东洋型的种类逐渐减少。依据海拔梯度和植被的不同,可以将大明山鸟类分成6个类群,鸟类总种数和繁殖鸟类种数均以海拔500~900 m的范围内最多,海拔200~500 m范围内鸟类次之。由于大明山地处热带南缘,本研究将为今后监测气候变暖对鸟类的影响提供依据。     

SOME NOTES ON BIRDS OF SOUTHERN RHODESIA

Cyrus, Digby P. 1986. Seasonal and spatial distribution of Redheaded Quelea (Quelea erythrops) in South Africa. Ostrich. 57: 162–169.

There are 48 records of Redheaded Quelea Quelea erythrops occurring in South Africa. Most are for the summer and early autumn months from October to April and all are restricted to the low lying eastern coastal areas. The pattern of occurrence in South Africa is similar to that in adjoining countries to the north; the species does not however occur as regularly in the south. Breeding or attempted breeding has been recorded on six occasions. This shows the typical pattern of occurrence of a species at the southern limit of its distribution.

There is some evidence to suggest that its occurrence may be associated with “wet” years when rainfall is above average. The Redheaded Quelea may be considered as a rare and irruptive summer vagrant to South Africa, which only breeds when conditions are suitable.     

Seasonal use by birds of stream-side riparian habitat in coniferous forest of northcentral British Columbia

To determine use of riparian habitats by birds in the northern coniferous forest of British Columbia, we censused birds and vegetation along 500 m transects placed parallel and perpendicular to three second-order streams. Censuses were conducted during spring, summer, autumn, and winter to investigate how use of riparian habitat changed seasonally. Stream-side riparian zones were characterized by a dense understorey of deciduous vegetation not found in the upslope forest. Nine bird species preferred the riparian understorey for breeding, six preferred it only during migration. Neotropical migrants (16 of 46 species) were more closely associated with stream-sides than year-round residents (11 species). Some breeding birds (five species) were significantly negatively associated with riparian habitats. The density of riparian birds declined with distance upstream but did not decline up to 250 m away from the stream. The more extensive riparian areas downstream supported a greater density of birds in all seasons compared to upstream areas, but more species only in spring and autumn. Species that nested in non-riparian areas in summer used riparian habitat in autumn, making riparian corridors in the northern coniferous forest important during migration. Maintaining both riparian and upslope habitats is necessary to preserve species diversity al the landscape level.     

American Exceptionalism: Population Trends and Flight Initiation Distances in Birds from Three Continents

Background

All organisms may be affected by humans'' increasing impact on Earth, but there are many potential drivers of population trends and the relative importance of each remains largely unknown. The causes of spatial patterns in population trends and their relationship with animal responses to human proximity are even less known.

Methodology/Principal Finding

We investigated the relationship between population trends of 193 species of bird in North America, Australia and Europe and flight initiation distance (FID); the distance at which birds take flight when approached by a human. While there is an expected negative relationship between population trend and FID in Australia and Europe, we found the inverse relationship for North American birds; thus FID cannot be used as a universal predictor of vulnerability of birds. However, the analysis of the joint explanatory ability of multiple drivers (farmland breeding habitat, pole-most breeding latitude, migratory habit, FID) effects on population status replicated previously reported strong effects of farmland breeding habitat (an effect apparently driven mostly by European birds), as well as strong effects of FID, body size, migratory habit and continent. Farmland birds are generally declining.

Conclusions/Significance

Flight initiation distance is related to population trends in a way that differs among continents opening new research possibilities concerning the causes of geographic differences in patterns of anti-predator behavior.