The use of metal and colour‐rings or bands as a means of measuring survival, movements and behaviour in birds is universal and fundamental to testing ecological and evolutionary theories. The ...practice rests on the largely untested assumption that the rings do not affect survival. However this assumption may not hold for several reasons, for example because the ‘oddity effect’ predicts predators select prey that appear different to their neighbours in order to avoid the ‘confusion effect’. We compared the foraging behaviour and the death rates of redshanks Tringa totanus conspicuously marked with six colour rings and one metal ring each to unmarked birds in a study system, where routinely up to 50% of the total population are killed by avian predators during a winter. If avian predators selectively target and/or have a higher capture success of ringed birds then we would predict the proportion of colour‐ringed birds in the population to decline through a winter. The proportion of colour‐ringed birds in the population did not change over the course of three separate winters, and in one winter the ratio of marked:unmarked birds found killed by sparrowhawks Accipiter nisus was the same as the ratio of marked birds alive in the population. In the year with largest sample size, power was sufficient to detect a greater than 2.2% difference in predation rate between ringed and unringed groups. The average kill rate difference between ringed and unringed birds across the three winters was less than 1% (0.73±2.2%) suggesting that even if there were differences in predation rate that were not detected because of low statistical power they were extremely small. There were no differences in any foraging measures comparing ringed and unringed birds, suggesting that the rings did not affect the ability of birds to meet their daily energy budgets. The results showed that colour‐ringed birds were not preferentially targeted or killed by avian predators, and suggest that the presence of a metal and even several large colour‐rings is unlikely to affect behaviour and predation mortality even under extreme selection.
Shorebirds (Charadriiformes) undergo rapid migrations with potential for long‐distance dispersal (LDD) of plants. We studied the frequency of endozoochory by shorebirds in different parts of Europe ...covering a broad latitudinal range and different seasons. We assessed whether plants dispersed conformed to morphological dispersal syndromes. A total of 409 excreta samples (271 faeces and 138 pellets) were collected from redshank Tringa totanus, black‐winged stilt Himantopus himantopus, pied avocet Recurvirostra avosetta, northern lapwing Vanellus vanellus, Eurasian curlew Numenius arquata and black‐tailed godwit Limosa limosa in south‐west Spain, north‐west England, southern Ireland and Iceland in 2005 and 2016, and intact seeds were extracted and identified. Godwits were sampled just before or after migratory movements between England and Iceland. The germinability of seeds was tested. Intact diaspores were recovered from all bird species and study areas, and were present in 13% of samples overall. Thirteen plant families were represented, including Charophyceae and 26 angiosperm taxa. Only four species had an ‘endozoochory syndrome’. Four alien species were recorded. Ellenberg values classified three species as aquatic and 20 as terrestrial. Overall, 89% of seeds were from terrestrial plants, and 11% from aquatic plants. Average seed length was higher in redshank pellets than in their faeces. Six species were germinated, none of which had an endozoochory syndrome. Seeds were recorded during spring and autumn migration. Plant species recorded have broad latitudinal ranges consistent with LDD via shorebirds. Crucially, morphological syndromes do not adequately predict LDD potential, and more empirical work is required to identify which plants are dispersed by shorebirds. Incorporating endozoochory by shorebirds and other migratory waterbirds into plant distribution models would allow us to better understand the natural processes that facilitated colonization of oceanic islands, or to improve predictions of how plants will respond to climate change, or how alien species spread.
The study is intended to deliver the incidence of heavy metals in the feathers of shorebirds from two important Central Asian Flyway (CAF) migratory shorebirds wintering sites such as the Point ...Calimere Wildlife Sanctuary (PWLS) and Pichavaram Mangrove Forest (PMF), India. Feathers of fifteen species of shorebirds and seven different metals viz., Cu, Cr, Co, Pb, Hg, Ni and Zn were analyzed. Zn was highest in Dunlin, Little-ringed Plover, Marsh Sandpiper, and Common sandpiper, Ni showed highest in Little ringed plover, and Common sandpiper, Co, Cr, and Cu were maximum in Little stint, Marsh sandpiper, and Dunlin, respectively. The Hg was higher in Black-winged stilt, Common redshank, Curlew Sandpiper, Eurasian curlew, Lesser Sand-plover, Temminck's stint, Kentish plover, Spotted redshank, and Wood sandpiper, the Pb found highest in Kentish plover, Painted stork, Spotted redshank, Wood sandpiper, Eurasian Curlew, and Lesser sand-plover. The concentration of metals showed significant variations among the species of shorebirds studied (P < 0.001). The mercury negatively correlated with the other metals than the other six metals studied in both the wetlands. The order of metal concentration in the feathers of shorebirds was Zn > Ni > Co > Cr > Cu > Pb > Hg. Nevertheless, the current study revealed that the level of metals in the shorebirds is alarming; since the PWLS and PMF are located along the CAF routes, it needs intensive studies on various pollutions to manage both the resident as well as migratory shorebirds.
Wet grassland populations of wading birds in the United Kingdom have declined severely since 1990. To help mitigate these declines, the Royal Society for the Protection of Birds has restored and ...managed lowland wet grassland nature reserves to benefit these and other species. However, the impact of these reserves on bird population trends has not been evaluated experimentally due to a lack of control populations. We compared population trends from 1994 to 2018 among 5 bird species of conservation concern that breed on these nature reserves with counterfactual trends created from matched breeding bird survey observations. We compared reserve trends with 3 different counterfactuals based on different scenarios of how reserve populations could have developed in the absence of conservation. Effects of conservation interventions were positive for all 4 targeted wading bird species: Lapwing (Vanellus vanellus), Redshank (Tringa totanus), Curlew (Numenius arquata), and Snipe (Gallinago gallinago). There was no positive effect of conservation interventions on reserves for the passerine, Yellow Wagtail (Motacilla flava). Our approach using monitoring data to produce valid counterfactual controls is a broadly applicable method allowing large‐scale evaluation of conservation impact.
Un Enfoque Hipotético para Medir el Impacto de la Conservación de Pastizales Húmedos sobre Poblaciones Reproductoras de Aves en el Reino Unido
Resumen
Las poblaciones de aves zancudas en los pastizales húmedos del Reino Unido han declinado gravemente desde 1990. Para ayudar con la mitigación de estas declinaciones, la Real Sociedad para la Protección de las Aves ha restaurado y manejado las reservas naturales en pastizales húmedos de tierras bajas para beneficiar a estas y otras especies. Sin embargo, el impacto de estas reservas sobre las tendencias poblacionales de las aves no ha sido evaluado experimentalmente debido a la falta de poblaciones control. Comparamos las tendencias poblacionales entre 1994 y 2018 de cinco especies de aves de importancia para la conservación, que se reproducen dentro de estas reservas naturales, mediante tendencias hipotéticas creadas a partir de los censos de observación de aves reproductoras emparejadas. Comparamos las tendencias de las reservas con tres casos hipotéticos diferentes basados en diferentes escenarios de cómo las poblaciones de la reserva podrían haberse desarrollado en ausencia de la conservación. Los efectos de las intervenciones de conservación fueron positivos para las cuatro especies focales de aves zancudas: Vanellus vanellus, Tringa totanus, Numenius arquata y Gallinago gallinago. No hubo un efecto positivo de las intervenciones de conservación para la especie paserina Motacilla flava. Nuestra estrategia utilizando datos de monitoreos para producir controles hipotéticos válidos es un método ampliamente aplicable que permite ka evaluación del impacto de la conservación a gran escala
摘要
自1990 年以来, 英国湿草地涉禽的数量急剧下降。为了缓解这些鸟类种群丧失, 英国皇家鸟类保护协会通过恢复和管理低地湿草地自然保护区来帮助保护这些鸟类及其它物种。然而, 由于缺乏对照种群, 保护区对鸟类种群动态的影响还没有得到实验评估。本研究将在这些保护区繁殖的五种受保护鸟类 1994–2018 年的种群动态与配对的鸟类繁殖调查获得的反事实动态进行了比较。我们比较了保护区鸟类种群动态与三种反事实动态, 这些反事实动态是基于保护区种群在没有保护的情况下如何发展的不同情景假设。结果表明, 研究关注的四种涉禽:凤头麦鸡 (Vanellus vanellus) 、红脚鹬 (Tringa totanus) 、白腰杓鹬 (Numenius arquata) 和扇尾沙锥 (Gallinago gallinago) 的保护措施均取得了积极成效, 而对保护区中雀形目鸟类黄鹡鸰 (Motacilla flava) 的保护干预没有积极作用。我们的方法利用监测数据产生了可靠的反事实对照, 是一种可用于大规模评估保护影响的广适性方法。【翻译: 胡怡思; 审校: 聂永刚】
Article impact statement: Post hoc quasi‐experimental analysis shows that wet grassland conservation has positively affected targeted breeding bird populations.
Edge effects occur when the matrix has adverse impacts on the patches of remnant habitat. A widely explored example of this is the hypothesis of a higher predation pressure on bird nests closer to ...the habitat edge. In parallel with the recent loss of open habitats through afforestation as a climate change mitigation measure, an interest in the impact of forest on species dependent on open habitats has re‐emerged. We follow wader nest survival to study the issue of an edge effect in a system of wet grasslands fragmented by forests in a region where it has not been tested before, focussing mainly on northern lapwing (Vanellus vanellus), common ringed plover (Charadrius hiaticula), common redshank (Tringa totanus) and southern dunlin (Calidris alpina schinzii). To record nest survival, we monitored 753 nests of 10 wader species on coastal grasslands in Estonia for 3 consecutive years. A subset (n = 85) of these nests was equipped with camera traps to record nest predation events and predator association with forest edge. The distance to nearest trees and forest and a forest cover within a 1‐km buffer around each nest was measured. We recorded extremely low daily nest survival rates (0.903–0.922 for different species), with most nests lost to predation. We showed that nest survival is lower closer to the forest edge and negatively affected by the proportion of forest within a 1‐km buffer around each nest. Based on camera trap recordings, we suggest that the edge effect is caused by elevated nest predation rates by the most common predator, the red fox (Vulpes vulpes), closer to the forest edge. Future afforestation plans of open habitats need to acknowledge that the resulting fragmentation has a negative impact on nest survival of ground‐breeding birds. On the other hand, our results imply that restoration efforts aimed at removal of most damaging forest plantations could benefit breeding waders.
In parallel with the recent loss of open habitats through afforestation as a climate change mitigation measure, an interest in the impact of forest on species dependent on open habitats has re‐emerged. We follow wader nest survival to study the issue of an edge effect in a system of wet grasslands fragmented by forests and demonstrate lower survival of nests closer to the forest edge. Based on camera trap recordings, we suggest that the edge effect is caused by elevated nest predation rates by the most common predator, the red fox (Vulpes vulpes), closer to the forest edge.
There has been an increasing number of coastal restoration projects to eradicate Smooth cordgrass (
Spartina alterniflora
) and restore bare tidal flats to conserve waterbirds. However, the evidence ...for the assumed benefits to waterbirds and benthic organisms after such restoration efforts remains limited. We evaluated the impact of
S. alterniflora
eradication on waterbirds and benthic organisms in southern China. We deployed time‐lapse cameras and satellite trackers to quantify and compare the occurrence frequency and habitat use of birds in different habitats. We compared the density and biomass of benthic organisms collected in bare tidal flats and areas where
S. alterniflora
had been eradicated. We found that almost all waterbirds, except gulls, avoided areas where
S. alterniflora
was present. Once
S. alterniflora
was eradicated, the species richness and species‐level diversity of shorebirds and waterbirds did not differ significantly from those of the bare tidal flats. At least 9 out of 14 tracked individual shorebirds used areas where
S. alterniflora
had been eradicated, with Common Redshank (
Tringa totanus
) demonstrating a clear preference for such habitat. The density and biomass of benthos in deeper sediments (5–20 cm below the surface) were significantly lower in areas where
S. alterniflora
had been eradicated than in bare tidal flats, indicating that the food resources for birds may take longer than 1 year to recover. This research demonstrates that the eradication of
S. alterniflora
is important for the restoration of waterbird habitats, and such efforts should be made in areas that are important to waterbirds.
Planting forests is a commonly suggested measure to mitigate climate change. The resulting changes in habitat structure can greatly influence the diversity and abundance of pre‐existing wildlife. ...Understanding these consequences is key for avoiding unintended impacts of afforestation on habitats and populations of conservation concern.
Afforestation in lowland Iceland has been gaining momentum in recent years and further increases are planned. Iceland supports internationally important breeding populations of several ground‐nesting, migratory bird species that mostly breed in open habitats. If afforestation impacts the distribution and abundance of these species, the consequences may be apparent throughout their non‐breeding ranges across Europe and Africa.
To quantify the effects of plantation forests on the abundance and distribution of ground‐nesting birds (in particular waders, Charadriiformes), surveys were conducted on 161 transects (surrounding 118 plantations) perpendicular to forest edges throughout Iceland. The resulting variation in density with distance from plantation was used to estimate the likely changes in bird numbers resulting from future afforestation plans, and to explore the potential effects of different planting configuration (size and number of forest patches) scenarios.
Of seven wader species, densities of five (golden plover Pluvialis apricaria, whimbrel Numenius phaeopus, oystercatcher Haematopus ostralegus, dunlin Calidris alpina and black‐tailed godwit Limosa limosa) in the 200 m surrounding plantations were just under half of those further away (up to 700 m). Redshank Tringa totanus densities were lowest ≤150 m from the plantation edge while snipe Gallinago gallinago densities were 50% higher close to plantations (0–50 m) than further away (51–700 m), and no consistent effects of plantation height, diameter, density or type were identified. Plantations are typically small and widespread, and simulated scenarios indicated that total declines in bird abundance resulting from planting trees in one large block (1,000 ha) could result in only ~11% of the declines predicted from planting multiple small blocks (1 ha) in similar habitats.
Synthesis and application. Planting forests in open landscapes can have severe impacts on populations of ground‐nesting birds, which emphasizes the need for strategic planning of tree‐planting schemes. Given Iceland's statutory commitments to species protection and the huge contribution of Iceland to global migratory bird flyways, these are challenges that must be addressed quickly, before population‐level impacts are observed across migratory ranges.
Útdráttur
Skógrækt er mikilvæg í baráttunni við hnattræna hlýnun en umfangsmiklar breytingar í gróðurfari geta haft mikil áhrif á fjölbreytileika og þéttleika dýra. Mikilvægt er að greina slík áhrif til að komast hjá því að valda óafturkræfum breytingum á dýrastofnum sem hafa hátt verndargildi.
Skógrækt á Íslandi hefur aukist til muna síðustu ár og stefnt er að því að auka hana enn frekar. Á Íslandi eru stórir hlutar heimsstofna ýmissa farfugla sem verpa á jörðu niðri í opnum búsvæðum. Ef aukin skógrækt hefur áhrif á dreifingu og stofnstærðir þessara tegunda, getur áhrifanna gætt á vetrarstöðvum þeirra í Evrópu og Afríku.
Áhrif skóga á þéttleika og dreifingu fugla sem verpa á jörðu niðri (einkum vaðfugla Charadriiformes), voru metin með talningum á 161 sniðum (umhverfis 118 skógarreiti) út frá skógarjöðrum á Íslandi. Tengsl fuglafjölda við fjarlægð frá skógarjöðrum voru notuð til að meta hvernig fjöldi fugla getur breyst með áframhaldandi skógrækt á láglendi Íslands og hvernig þær breytingar eru háðar skipulagi skóga (stærð og fjölda bletta).
Af sjö vaðfuglum var þéttleiki fimm þeirra, heiðlóu Pluvialis apricaria, spóa Numenius phaeopus, tjalds Haematopus ostralegus, lóuþræls Calidris alpina og jaðrakans Limosa limosa, meira en helmingi lægri næstu 200 m við skógarjaðar samanborið við svæði lengra frá skóginum (upp að 700 m). Stelkur Tringa totanus var í lægstum þéttleika næstu 150 m umhverfis skóginn en hrossagaukur Gallinago gallinago fannst hins vegar í hærri þéttleika nálægt skógarjaðrinum (0–50 m) en lengra frá (51–700 m). Engin áhrif fundust af hæð trjáa, stærð og þéttleika skógarreita, eða hvort um barr‐ eða laufskóga var að ræða. Skógarreitir á Íslandi eru almennt litlir og dreifðir, en útreikningar benda til þess að fækkun fugla vegna skógræktar yrði nánast tífalt minni ef 1000 ha skógi yrði plantað í einu lagi miðað við að honum væri plantað í 1 ha reitum.
Samantekt og notagildi. Skógrækt í opnum búsvæðum getur haft mikil áhrif á stofna fugla sem verpa á jörðu niðri og mikilvægt er að hafa það í huga þegar skógrækt er skipulögð. Mikill fjöldi farfugla verpir hér á landi og Ísland hefur skrifað undir alþjóðlega samninga og skuldbundið sig til að vernda þessa fuglastofna. Það er því mikilvægt að huga að áhrifum skógræktar á þessar tegundir og bregðast við þeim áður en áhrifin koma fram á farleiðum íslenskra fugla í Evrópu og Afríku.
Planting forests in open landscapes can have severe impacts on populations of ground‐nesting birds, which emphasizes the need for strategic planning of tree‐planting schemes. Given Iceland's statutory commitments to species protection and the huge contribution of Iceland to global migratory bird flyways, these are challenges that must be addressed quickly, before population‐level impacts are observed across migratory ranges.
Yearly electricity production has increased steadily worlwide in recent decades and the associated overhead power lines are widespread and occur across urban and natural habitats, and often in remote ...areas where there is little other anthropogenic influence. Here we assessed the effects of overhead power lines on the density of ground‐nesting birds in the Icelandic lowlands, which host several populations of international importance. The combined breeding density of the eight study species increased significantly from ~ 112 birds/km2 close (< 50 m) to the power lines to ~ 177 birds/km2 away (450–500 m) from the power lines, with two of these species (Eurasian Whimbrel Numenius phaeopus and Common Redshank Tringa totanus) increasing significantly with distance from power lines and six species (European Golden Plover Pluvialis apricaria, Common Snipe Gallinago gallinago, Meadow Pipit Anthus pratensis, Black‐tailed Godwit Limosa limosa, Dunlin Calidris alpina and Redwing Turdus iliacus) showing no changes. These findings suggest that power lines can influence the breeding density of ground‐nesting bird species in their vicinity and that accounting for such effects when planning future infrastructure will be imperative.
Many birds wintering in the Indian subcontinent fly across the Himalayas during migration, including Bar-headed Geese (Anser indicus), Demoiselle Cranes (Anthropoides virgo) and Ruddy Shelducks ...(Tadorna ferruginea). However, little is known about whether shorebirds migrate across the Himalayas from wintering grounds beyond the Indian subcontinent. Using geolocators and satellite tracking devices, we demonstrate for the first time that Common Redshanks (Tringa totanus) and Whimbrels (Numenius phaeopus) wintering in Singapore can directly fly over the Himalayas to reach breeding grounds in the Qinghai-Tibet Plateau and north-central Russia respectively. The results also show that migratory shorebirds wintering in Southeast Asia can use both the Central Asian Flyway and the East Asian-Australasian Flyway. For Redshanks, westerly-breeding birds crossed the Himalayas while more easterly breeders on the Plateau migrated east of the Himalayas. For Whimbrels, an individual that crossed the Himalayas was probably from a breeding population that was different from the others that migrated along the coast up the East Asian-Australasian Flyway. The minimum required altitude of routes of trans-Himalayan Redshanks were no higher on average than those of eastern migrants, but geolocator temperature data indicate that birds departing Singapore flew at high elevations even when not required to by topography, suggesting that the Himalayan mountain range may be less of a barrier than assumed.
Breeding populations of many wading birds have declined globally, primarily caused by habitat degradation and loss. In the UK, population declines have been particularly notable on lowland wet ...grasslands. In response, some areas of lowland wet grassland have been restored and are under ongoing management to improve the breeding conditions of target species. Here, we assess the efficacy of management measures using a Bayesian framework and controlling for confounding factors. We focus on four wader species, Northern Lapwing Vanellus vanellus, Eurasian Curlew Numenius arquata, Common Snipe Gallinago gallinago and Common Redshank Tringa totanus, that breed in numbers on wet grassland reserve sites in the UK. We collated annual site‐specific climate variables, management information (e.g. the creation of wet features and predator control measures) and bird counts between 1994 and 2018. We found the effects of conservation actions varied between intervention types and species. For Lapwing and Redshank, excluding predators by predator‐exclusion fencing, especially in combination with fox control, was generally associated with higher breeding counts. For all study species, sites with longer histories of management were associated with higher breeding numbers, with the effect of site age being particularly notable for management on former arable land. Our findings support the effectiveness of targeted conservation actions to achieve high numbers of breeding waders on lowland wet grassland reserves, and also highlight the value of consistent and reliable monitoring data.
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