Sedge Warbler Acrocephalus Schoenobaenus Research Articles

Interactive effects of arrival date, territory quality and male polyterritorial behaviour on the mating system of the sedge warbler Acrocephalus schoenobaenus: a path analysis

Classical models predict that male fitness is based on resources monopolized and invested in reproduction, and/or on individual quality providing offspring with sexually attractive traits or viable genes. However, these factors are frequently correlated, making their relative influence on male fitness difficult to describe and quantify. We analysed the relative influence of the main features of the sedge warbler's Acrocephalus schoenobaenus breeding system, i.e. age, arrival date, territory quality, male sexual activity (song and polyterritorial behaviour), on males' mating success, fledging success and local recruitment. Results show that this species' breeding system involves three main paths: 1) earlier‐arriving males have higher mating success, regardless of territory quality, 2) the quality of territories pre‐empted by earlier males directly influences recruitment and 3) mating success is influenced by male sexual activity (polyterritorial behaviour), but an additional territory also affects recruitment directly. As arrival date plays a significant role in all the paths, the whole system seems to depend on male quality; although the benefits accruing to male fitness are obtained not only through sexual selection but also through resource monopolization.

Diet Analysis of Wetland Passerine Nestlings Using Neck Collars or Faecal Sampling Produces Similar Results

Two methods are commonly used to study the diet of nestling passerines: the neck collar method and faecal sampling. Most studies apply either method, however, few methodological studies comparing both methods exist and are mainly limited to farmland birds. Furthermore, existing methodological studies only include high-level taxonomic diet categories. Here, we compared both methods using two wetland species, the Reed Bunting Emberiza schoeniclus and the Sedge Warbler Acrocephalus schoenobaenus, and included family level as a lower taxonomic prey level. We found no differences between the two methods in the dietary composition of high-level taxonomic categories (mainly orders) and only small differences in some orders at the family level. Hence, we recommend using the less invasive and easily accessible faecal sampling method rather than the use of neck collars in diet composition studies.

Age‐related parasite load and longevity patterns in the sedge warbler Acrocephalus schoenobaenus

We report the results from a nine‐year study on parasite infection in males of a small migrant passerine, the sedge warbler Acrocephalus schoenobaenus. Every year, for each male caught during territory establishment we estimated infection intensity of two lineages of Haemoproteus belopolskyi (SW1 and SW3), using molecular methods. We found a significant relationship between infection intensity and males’ longevity in both studied lineages. There was severe mortality of second‐year sedge warblers after their first breeding season, with lower parasite load in survivors. The lower infection intensity in older age classes was related to between‐individual change in both lineages, but was also a result of differences in infection intensity during the lifetime of individual males in the SW3. The relation between parasite load and longevity suggests that parasite load may be an age‐dependent factor influencing individual survival.

Bird ringing and nest recording in Britain and Ireland in 2014

This is the 78th annual report of the British Trust for Ornithology's Ringing Scheme, incorporating the report of the Nest Record Scheme and covering work carried out and data processed in 2014. Many species have shifted their range towards the Earth's poles in response to global temperature increases. Data from four European Constant Effort Sites (CES) ringing schemes were examined to determine the impact of large-scale temperature variations on productivity in a group of seven migratory bird species to determine the potential for future range changes. Increased productivity at northern sites was apparent only in Reed Warbler Acrocephalus scirpaceus, although there was evidence of local adaptation in six species, suggesting that the rate of northward range shift may be constrained by adaptation to local climatic conditions. A study on the role of carry-over effects in Redstart Phoenicurus phoenicurus, Spotted Flycatcher Muscicapa striata and Wood Warbler Phylloscopus sibilatrix found that carry-over effects from passage regions impacted on the timing of breeding more strongly than climate on the breeding grounds and that warmer conditions in the breeding area were not associated with reduced productivity. Work on the impact of environmental variables on annual population changes found that, over 40 years, the strongest impact on migrants was rainfall in the Sahel. Over 25 years, positive population changes in response to wetter winters were found for 12 of 16 species studied. Data were submitted for 132 CE sites in 2014. Long-term (1984–2013) population trends derived from the CES data have changed little in the past year. The abundance of five migrant species and five resident species decreased significantly in 2014 compared to the five-year mean (2009–13). The abundance of five of these species (Willow Warbler Phylloscopus trochilus, Sedge Warbler Acrocephalus schoenobaenus, Blackbird Turdus merula, Chaffinch Fringilla coelebs and Greenfinch Chloris chloris) was at its lowest since CES monitoring began. There were significant increases in abundance for three species. Productivity decreased significantly in Willow Tit Poecile montana compared to the five-year mean (2009–13), but there were significant increases for eleven species (seven residents and four migrants),with productivity for Reed Warbler, Blackbird and Bullfinch Pyrrhula pyrrhula at its highest since CES began. There were only two significant changes in survival in 2014. A total of 176 Retrapping Adults for Survival (RAS) projects were active in 2014, the highest total ever, with 22 new projects starting, 17 of which involved RAS target species. Projects were carried out on Tawny Owl Strix aluco and Swift Apus apus for the first time. The total number of birds ringed in 2014 exceeded one million for the third time (1,047,026) and comprised 520,477 first-year birds, 303,086 adults (birds in their second calendar year or older), 29,799 unaged birds and 193,664 nestlings. In addition, there were 226,303 recaptures of ringed birds at or near the ringing site. In total, 28,187 recoveries of BTO-ringed birds were reported for 2014. A selection of recoveries that have extended our knowledge of movements is presented, as well as longevity records established during the year. The numbers of birds recovered between 2010 and 2013 have been revised as data submitted as retraps have been examined and some have been reclassified as recoveries. For the fifth year running, annual totals of nest records surpassed 40,000, reaching 46,382. Mean laying dates for 55 species were significantly earlier than the five-year mean (2009–13) with 19 species laying significantly later than the five-year mean. Breeding success (fledglings per breeding attempt) increased significantly for 14 species, with none showing a decrease. Nearly 600 permits/licences to disturb breeding birds on Schedule 1 of the Wildlife and Countryside Act (1981), were prepared/issued in 2014, a small increase from 2013. The use of special methods was authorised for 398 marking projects and 47 trapping projects in 2014, 12% fewer than in 2013.

The influence of phenology on double-brooding and polygyny incidence in the Sedge Warbler Acrocephalus schoenobaenus

There is growing evidence that the fitness of birds in temperate zones depends strongly on the match between the timing of breeding and local phenology. We have analysed data collected from a 15-year study on a Sedge Warbler (Acrocephalus schoenobaenus) population in its natural habitat. The highly skewed distribution of arrival dates of males indicated that they competed intensely to be the earliest arrivals. The distribution of mating dates, unlike arrival dates, was not skewed, rather it formed a bell-shaped distribution. Because females arrived much later, they could not base their mating choices on the arrival dates of males. Females, however, could use male song repertoire, a trait we found to be correlated with male arrival date. Double-brooded females mated early in the season, exactly within the peak of mating date distribution. Polygynous females, on the other hand, mated later in the season, choosing high-quality older males which had arrived significantly earlier. Male territory quality did not differ between double-brooded and polygynous females, nor did the quality of the territories occupied by an individual female change during her lifetime. Although longer lifespan and double-brooding influenced a female’s fitness over the course of her lifetime, polygyny had no significant effect. We conclude that Sedge Warbler females do not compete for territorial resources, but they do prefer to mate with high-quality early-arriving males. Polygyny is an effective strategy used by females to compensate for their late arrival and breeding onset, since they pair with high-quality males.

Effects of overgrowing at Cerknica Polje (southern Slovenia) on breeding farmland birds/ Vpliv zaraščanja Cerkniškega polja (južna Slovenija) na gnezdilke kmetijske krajine

Abstract Agriculture has a great impact on biodiversity in Europe. Populations of farmland birds are declining due to both intensification and abandonment of agriculture. The purpose of this study was to determine the effects of overgrowing on the diversity of birds at Cerknica Polje. Six vegetation types were identified on eight survey plots (15.2-31.6 ha each): Short grass - regularly mown wet meadows; Tall herbs - stands of Common Reed Phragmites australis and Reed Canary Grass Phalaris arundinacea; Sparse bushes - stands of low woody plants; Dense bushes - dense stands of bushes; Meadows with trees - mown meadows with scattered trees; Bushes with trees - hedges, trees and dense stands of bushes. In total, 34 species were registered. The heterogeneity of vegetation types correlated positively with the heterogeneity of bird species. The highest density of breeding territories and species was established in Bushes with trees, the lowest in Short grass. No species were registered in all vegetation types, and only Tree Pipit was recorded in five out of six types. Twelve species were registered in only one vegetation type. Cerknica Polje is an important breeding locality for species with the highest breeding density at the national level (e.g. Corncrake Crex crex, Curlew Numenius arquata, Skylark Alauda arvensis, Whinchat Saxicola rubetra, Sedge Warbler Acrocephalus schoenobaenus). These species breed in specific habitats with different stages of succession. A managing plan for the area should therefore combine abandoned plots in different stages of succession and large regularly mown areas. Abandonment of agriculture at Cerknica Polje has led to the emergence of areas with bushes in different succession stages. Efforts should be directed at preserving large complexes of mown wet meadows.

Obročkovalna Dejavnost in Pregled Najdb Obročkanih Ptic V Sloveniji V Letu 2013 / An overview of bird ringing in Slovenia in 2013

Abstract In 2013, 73,529 birds of 161 species were ringed in Slovenia, with 114 finds from abroad, 73 finds of foreign-ringed birds and 1580 local finds. The most numerous ringed species were Blackcap Sylvia atricapilla and Barn Swallow Hirundo rustica, while among ringed nestlings Great Tits Parus major and Blue Tits Cyanistes caeruleus prevailed. The most numerous species among recoveries was the Mute Swan Cygnus olor with probably the oldest swan recorded in Slovenia so far, a 25-year-old female. The longest distance recovery concerned a Sedge Warbler Acrocephalus schoenobaenus from Norway (2,801 km). Of interest among local finds is the longest recovery distance (122 km) recorded for Ural Owl Strix uralensis in Slovenia so far. In 2013, two rare species for Slovenia were ringed, Yellow-browed Warbler Phylloscopus inornatus (2 individuals) and Siberian Rubythroat Calliope calliope, which was the first record for Slovenia. The first analysis of ringing sites in Slovenia is given as a baseline for establishing a network of Constant Effort Sites

Bird ringing and nest recording in Britain and Ireland in 2013

This is the 77th annual report of the British Trust for Ornithology's Ringing Scheme, incorporating the report of the Nest Record Scheme and covering work carried out and data processed in 2013. In recent years the schemes have focused on the collection of demographic data as part of our Integrated Population Monitoring programme. We expanded (from 10 to 17) the number of species for which we were able to construct integrated models and identified differences in the relative contributions of recruitment and adult survival to population change between increasing and decreasing species. Recruitment of young into the breeding population can be difficult to estimate. We investigated the use of proportions of birds in their second calendar year, or older, caught in the early summer using Blackbird Turdus merula as a model. Results showed that recruitment was a more important determinant of population change than survival. Changes in phenology are being documented widely and we carried out analyses looking at the timing of moult and reproduction in selected passerine species. Patterns in timing and duration of moult varied between resident species but were more aligned within migrant species, which also moulted faster. Temperature on spring breeding grounds accounts for more variation between years in breeding phenology than precipitation rates on the wintering grounds in 19 migrant species but neither climate variable affected clutch size. We continued to emphasise the value of targeted ringing and nest recording; increased participation in our structured ringing schemes has provided additional opportunities to improve the quality of demographic monitoring. Long-term (1984–2012) population trends derived from the Constant Effort Sites (CES) data have changed little in the past year. Three of the eight migrant species monitored by CES showed significant increases in productivity compared to the five-year average, although Sedge Warbler Acrocephalus schoenobaenus recorded its second-lowest productivity since CES began in 1983. Breeding performance of residents was mixed, with juvenile:adult ratios for some early breeders significantly lower than during the preceding five years, but significantly higher for some late breeders; one late-breeding resident species, Bullfinch Pyrrhula pyrrhula, had its highest productivity since CES began. Data were submitted for 124 sites. The number of active RAS projects in 2013 was 154, with 22 new projects, 13 of which involved RAS target species. The total number of birds ringed in 2013 decreased slightly (952,750) compared to 2012 and comprised 424,401 first-year birds, 355,278 adults (birds in their second calendar year or older), 19,776 unaged birds and 153,295 nestlings. In addition, there were 241,111 recaptures of ringed birds at or near the ringing site. The reduction in numbers ringed compared to 2012 was probably a result of weather events in 2013. In 2013, there were 465 colour-marking projects registered, covering a total of 110 species; 65 new projects were registered during the year. There were 21,275 recoveries of BTO-ringed birds: the highest total ever. A selection of recoveries that have extended our knowledge of movements is presented, as well as longevity records established during the year. In total, 40,384 nest records were submitted. Of these, 82% originated from England, 8% from Wales and 9% from Scotland, the remaining 1% divided between Northern Ireland and the Republic of Ireland. This was a reduction on the 2012 totals and probably reflected the poor start to the breeding season caused by the exceptionally cold weather in early spring. Long-term trends in nest productivity (fledglings per breeding attempt) were significant for 44 of the 72 species monitored. Of these, thirteen trends were negative, indicating a decline in breeding success over time.

The Role of Extrinsic and Intrinsic Factors on the Departure Decisions of a Long-Distance Migratory Passerine

Factors determining departure decisions of migrants from a stopover site can be extrinsic and/or intrinsic but the relative role of each of these factors on departure decisions is still poorly known. Date and wind should be the main factors determining departure decisions in a long-distance migrant, which is expected to minimise duration of migration. Date was considered as an intrinsic factor and wind as an extrinsic one. We analysed the capture-recapture data of a long-distance migrant European songbird, the sedge warbler Acrocephalus schoenobaenus, from a stopover site in northern Iberia during the autumn migration period to quantify the relative importance of several factors on emigration likelihood. Cormack-Jolly-Seber (CJS) models were used to estimate the emigration likelihood. From 107 models tested, only the model with an additive effect of date, tailwind assistance and population size substantially supported the data. As expected, sedge warblers were more likely to depart with high tailwind values and late in the season and, contrary to expectations, with decreasing sedge warbler abundance.

長崎県対馬におけるスゲヨシキリ<i>Acrocephalus schoenobaenus</i>の日本初記録

長崎県対馬におけるスゲヨシキリ<i>Acrocephalus schoenobaenus</i>の日本初記録

Bird ringing and nest recording in Britain and Ireland in 2011

This is the 75th annual report of the British Trust for Ornithology's Ringing Scheme, covering data received and work carried out in 2011. A review of priorities for the Scheme identified the need to increase submission of nest records through the Nest Record Scheme and to extend the network of Retrapping Adults for Survival (RAS) studies. Collection of different demographic parameters from the same site (eg nest records, numbers of breeding pairs, adult survival, etc) can provide a powerful tool to identify reasons for population change. Constant Effort Sites (CES) data showed long-term declines in abundance for four migrants (Willow Warbler Phylloscopus trochilus, Lesser Whitethroat Sylvia curruca, Sedge Warbler Acrocephalus schoenobaenus and Reed Warbler Acrocephalus scirpaceus) and three resident species (Willow Tit Poecile montana, Song Thrush Turdus philomelos and Reed Bunting Emberiza schoeniclus). Robin Erithacus rubecula and Reed Bunting had the lowest survival rates since CES began and survival-rate estimates were also significantly below average for Long-tailed Tit Aegithalos caudatus and Wren Troglodytes troglodytes, two small resident species that are particularly vulnerable to cold weather. Abundance of Blue Tit Cyanistes caeruleus, Great Tit Parus major, Goldfinch Carduelis carduelis and Bullfinch Pyrrhula pyrrhula recorded by CES increased. Nine of the 16 resident species covered by CES also had higher-than-average productivity, in particular the highest ever recorded for Dunnock Prunella modularis, Chaffinch Fringilla coelebs and Bullfinch. The number of Constant Effort Sites increased in 2011, with a higher percentage of reedbed habitat covered by the scheme, but fewer dry and wet scrub sites. In 2011 the number of RAS projects increased by 34 to 158. Survival trends were generated for 46 species and the use of colour marks has been promoted to increase the resighting probability of trap-shy species such as House Sparrow Passer domesticus and Starling Sturnus vulgaris, and for species with low recapture probability such as seabirds. As in 2010, the total number of birds ringed in 2011 (1,151,665) was the highest ever. It included 540,696 first-year birds, 383,136 adults (birds in their second calendar year or later) and 27,495 unaged birds. All ringing data for 2011 were computerised. In addition, there were 166,061 recaptures of ringed birds at or near the ringing site. The increased numbers of fully grown birds ringed is probably due to three main factors: high survival of some species, as suggested by CES results, combined with high productivity in 2011 and the increasing number of ringers in the Scheme catching higher numbers of birds. In total 20,702 BTO-ringed birds were recovered (found dead or recaptured away from the ringing site) in 2011, the highest ever as a result of the increased number of birds ringed in the past decade, combined with efforts to increase reports of ringed birds by the public, an increasing number of colour-ringing projects and associated resightings, and a change in the way recoveries are processed. Recoveries of 17 BTO- and 13 foreign-ringed birds that have extended our existing knowledge of movements of a species, are unusual movements, or are a new longevity record are also presented. In 2011 40,845 nest records were submitted (over 70% electronically), the highest total since 1998. Of these, 82% originated from England, 9% from Wales and 8% from Scotland, with the remaining 1% divided equally between Northern Ireland and the Republic of Ireland. Long-term nest productivity trends (1966–2010) were significant for 36 of the 71 species for which sufficient data were available, and seven of these (Nightjar Caprimulgus europaeus, Tree Pipit Anthus trivialis, Willow Warbler, Bullfinch, Coal Tit Periparus ater, Treecreeper Certhia familiaris and Chaffinch) showed a significant decline over time. The 2011 breeding season was characterised by an early start compared to the previous five years, possibly due to the warmest April on record.

Bird ringing in Britain and Ireland in 2010

This is the 74th annual report of the British Trust for Ornithology's Ringing Scheme, covering data received and work carried out in 2010. Analytical work in the year concentrated on considering how we can improve demographic monitoring, an increasing focus for the Scheme. A broad review of the availability of demographic and count data for terrestrial-breeding species was carried out. This work will be further extended in 2011. To inform conservation we need to build population models for species with a range of ecologies and occupying different habitats. Reports of ringed birds make a large contribution to our understanding of two key demographic parameters – survival and dispersal. An analysis of Chiffchaff Phylloscopus collybita recovery data from across Europe suggested they are tending to migrate south later and north earlier over time. There is also a suggestion that the migratory journey is shortening. Analysis of biometrics of birds wintering in Britain showed that they are largely from the breeding populations of the nominate race in Britain and the near Continent. Constant Effort Sites (CES) data showed that, for seven of the 24 species monitored, there was a significant decrease in adult abundance compared to the mean of the previous five years. As six of these species were residents, this may have been a result of the second severe winter in succession, although there was a short-term increase for Long-tailed Tit Aegithalos caudatus, which is usually affected by cold winters. The adult abundance of several long-distance migrants also increased. A long-term decline (1984–2000) is, however, still evident for five migrants and three residents, although for Willow Tit Poecile montana and Linnet Carduelis cannabina the sample sizes are low. The abundance of the short-distance migrants, Blackcap Sylvia atricapilla and Chiffchaff, has increased, possibly as a result of climate change. Productivity was higher than the mean of the previous five years for 12 species with the long-term trend increasing for eight species – four migrants and four residents. The only significant decreases were for Blackbird Turdus merula and Long-tailed Tit, possibly as these species breed early and were affected by the severe winter. Dry summer weather is also likely to have contributed to the low productivity of Blackbirds and increasingly dry summers may be implicated in the long-term declines in productivity for both Blackbird and Song Thrush Turdus philomelos. Long-term trends in survival rates were produced using CES data for the first time in 2010. These suggested that the cold winter weather in 2009–10 reduced the survival rate of resident ground-feeding insectivores such as Dunnock Prunella modularis, Blackbird, Wren Troglodytes troglodytes and Robin Erithacus rubecula. Survival rates of migrants were relatively high, particularly for Garden Warbler Sylvia borin and Sedge Warbler Acrocephalus schoenobaenus, possibly as a result of good conditions on the wintering grounds or passage sites. Data for 129 Retrapping Adults for Survival (RAS) studies covering 39 species were submitted. For the first time we were able to calculate good or moderate annual estimates of survival for 18 species. A list of priority species for RAS was developed and promoted to volunteers. The total number of birds ringed (1,096,533) was the highest ever recorded, as well as being the first time the annual total has surpassed 1 million. It was 28% higher than the mean of the previous five years and 17% higher than in 2009. However, the total number of pulli ringed in 2009 (193,554) was only 12% higher than the preceding five-year mean, while that of fully grown birds (902,979) was 32% higher. The recovery total (17,315) was also the highest ever. This is partly due to changes in the way that records of colour-ringed and other specially marked birds are stored, but also reflects the increasing number of birds being ringed by a growing number of ringers. The number of recoveries of foreign-ringed birds (2,427) was higher than the mean of the preceding five years; this figure was influenced by varying response times of different ringing schemes, but was also partly as a result of multiple sightings. Recovery details for 221 individual birds are given in the final section of the report. They include movements that confirm suspected or known migration patterns, unexpected movements and longevity records.

Migratory Birds: Ecology and Conservation. A report on the BOU’s Annual Conference held at the University of Leicester, 5–7 April 2011

In April 2011, the British Ornithologist’s Union’s annual conference took place at the University of Leicester. The theme of this year’s conference was the ecology and conservation of migratory birds, and talks ranged from those focussed on either breeding, migration or wintering ecology, to those linking two or more of these and trying to build a more complete picture of the complex problems faced by long distance migrants. Talks also covered recent technological advances, which are increasingly allowing us intriguing new insights, particularly into the seasonal movements and wintering areas of some of the most declining species. Finally, talks examined the policy challenges associated with protecting migratory species and how best to tackle flyway-scale conservation of migratory birds.

Fuel Load and Potential Flight Ranges of Passerine Birds Migrating through the Western Edge of the Pyrenees

The estimation of fuel load and the potential flight ranges of migrant birds are crucial to understanding the ecological and evolutionary significance of bird migration strategies. The movement of migrant birds between Iberia and the rest of Western Europe is thought to be shaped by the Pyrenees and nearby seas. Because of this area's unique geography, the routes of migrants that move to (autumn migration) or from (spring migration) Iberia tend to pass through the western and eastern edges of the Pyrenees. Fuel-load analyses and the assessment of potential flight ranges from these edges can provide insights about the extent of Iberia's use as a consistent stopover and fuelling area. Using data obtained over a period of six years (2004–2009), we calculated fuel load and potential flight ranges for ten common passerines (pre-Saharan, i.e. that overwinter mainly within the circum-Mediterranean region: Robin Erithacus rubecula, Bluethroat Luscinia svecica, Chiffchaff Phylloscopus collybita, Blackcap Sylvia atricapilla; sub-Saharan, i.e. that overwinter in tropical Africa: Sedge Warbler Acrocephalus schoenobaenus, Reed Warbler Acrocephalus scirpaceus, Melodious Warbler Hippolais polyglotta, Willow Warbler Phylloscopus trochilus, Garden Warbler Sylvia borin, Common Whitethroat Sylvia communis that stopover at Txingudi marshlands, at the western edge of the Pyrenees. The fuel load for the 25% heaviest fraction of caught birds ranged from 10.6% over lean body mass to 25.5% (mean: 18.3%) in spring and from 6.7% to 39.7% (mean: 25.2%) in autumn. Thus, potential flight ranges tended to be longer during autumn than during spring, particularly for the sub-Saharan species. All pre-Saharan species except one (Bluethroat) had sufficient fuel to arrive in southern Iberia or northern Africa, and three sub-Saharan species (Sedge Warbler, Garden Warbler, Common Whitethroat) had sufficient fuel to reach the north of the Sahara Desert but not its southern border. The potential flight ranges in spring were rather similar among species (ca. 1000 km from Txingudi).

Sex- and age-related differences in the timing and body condition of migrating Reed Warblers Acrocephalus scirpaceus and Sedge Warblers Acrocephalus schoenobaenus

The migration strategies of birds may vary strongly between species and also between age and/or sex groups. We studied the autumn migration and body condition of molecularly sexed Reed Warblers Acrocephalus scirpaceus and Sedge Warblers Acrocephalus schoenobaenus (211 and 208 ind., respectively) at a stopover site on Lake Druzno, Northern Poland, in 2008. Immature male Reed Warblers were caught significantly later than females (median dates 9 days later), but in the Sedge Warbler, both sexes of immatures migrated at about the same time. Adult males and females of both species did not differ in their time of migration. Adult and immature males of both species were larger (wing length and body mass) than females. In both species, fat reserves were similar in both sexes of both age classes. Adults of both sexes of Reed and Sedge Warbler were generally caught earlier than immatures. In both species, the body mass and fat reserves of immatures were generally less than in adults. The autumn protogyny of immature Reed Warblers may allow smaller females to limit competition with bigger males during migration and at the wintering grounds. In the Sedge Warbler, which tends to match its migration to peak of occurrence of superabundant food at stopover sites, both sexes gain an advantage from migrating at the same time. Since part of the measured wing length variation in both species was explained by sex differences, temporal trends in wing length recorded at stopover sites should be interpreted with caution.

An Integrated Population Model From Constant Effort Bird-Ringing Data

Data from annual bird-ringing programs, in which catch effort is standardized, are routinely used to index abundance, productivity, and adult survival. Efficient models have been developed for each. Such monitoring schemes, based on ringing across a number of sites, are perhaps unique in providing this combination of demographic information and make the data particularly amenable to an integrated approach to population modeling. We develop a Bayesian approach and a deterministic population model uniting abundance, productivity, and survival. The method is applied to sedge warbler Acrocephalus schoenobaenus data from the British Trust for Ornithology’s Constant Effort Sites scheme. The possibility of “transient” birds needs to be incorporated within this analysis. We demonstrate how current methodology can efficiently be extended to use additional data from multiple within year recaptures when controlling for transience. Supplemental materials for this article are available online.

Bird ringing in Britain and Ireland in 2009

This is the 73rd annual report of the British Trust for Ornithology's Ringing Scheme, covering data received and work carried out in 2009. Much of the research carried out during the year looked at ways to improve the analysis of ringing data to understand population change. This included producing survival rates from the Constant Effort Sites (CES) scheme for the first time and further developing methods of analysing our demographic data sets in an integrated manner. Research was also undertaken on the biometric data to investigate how individual condition responds to long‐term environmental change. CES data suggested that the low productivity in 2007 and 2008, combined with one of the coldest winters since 1995/96 for residents, contributed to reduced adult numbers in 2009 in many species. There were significant decreases in Wren Troglodytes troglodytes, Sedge Warbler Acrocephalus schoenobaenus, Reed Warbler A. scirpaceus, Blackcap Sylvia atricapilla, Lesser Whitethroat S. curruca, Willow Warbler Phylloscopus trochilus, Long‐tailed Tit Aegithalos caudatus, Blue Tit Cyanistes caeruleus, Great Tit Parus major, Treecreeper Certhia familiaris, Chaffinch Fringilla coelebs, Greenfinch Carduelis chloris and Reed Bunting Emberiza schoeniclus. However, a good breeding season, for both residents and migrants, resulted in significantly higher productivity for 15 species, but significantly lower for Willow Tit Poecile montana, compared to the long‐term mean (1983–2007). Data for 104 Retrapping Adults for Survival studies were submitted, covering 39 species, three quarters of which are Birds of Conservation Concern. The total number of birds ringed (935,867) was the highest ever recorded, and was over 10% higher than the mean of the previous five years. However, the total number of pulli ringed in 2009 (179,712) was only 5% higher than the preceding five‐year mean, while that of fully grown birds (756,155) was over 13% higher. The recovery total (14,643) was also high. However, this is partly due to changes in the way that records of colour‐ringed and other specially marked birds are stored. The number of recoveries of foreign‐ringed birds (1,314) was higher than the mean of the preceding five years, although this figure is influenced by varying response times of different ringing schemes. Recovery details for 250 individual birds are given in the final section of the report. They include movements that confirm suspected or known migration patterns, unexpected movements and longevity records.

An Integrated Population Model From Constant Effort Bird-Ringing Data

Data from annual bird-ringing programs, in which catch effort is standardized, are routinely used to index abundance, productivity, and adult survival. Efficient models have been developed for each. Such monitoring schemes, based on ringing across a number of sites, are perhaps unique in providing this combination of demographic information and make the data particularly amenable to an integrated approach to population modeling. We develop a Bayesian approach and a deterministic population model uniting abundance, productivity, and survival. The method is applied to sedge warbler Acrocephalus schoenobaenus data from the British Trust for Ornithology’s Constant Effort Sites scheme. The possibility of “transient” birds needs to be incorporated within this analysis. We demonstrate how current methodology can efficiently be extended to use additional data from multiple within year recaptures when controlling for transience. Supplemental materials for this article are available online.

Extra-pair paternity in the socially monogamous Sedge Warbler Actocephalus schoenobaenus as revealed by multilocus DNA fingerprinting

A marked population of Sedge Warblers Acrocephalus schoenobaenus was studied from 1993-95, the reproductive success of pairs was monitored and blood samples collected for DNA profiling. Measures of male physical and behavioural traits were also made, including song repertoire size, the amount of time spent singing and song-flighting, as well as territory quality. Although the Sedge Warbler is generally considered to be monogamous, social polygyny occurred in both 1994 and 1995, giving an overall rate for the two years of 7.7% of males. The overall rate of extra-pair paternity in the population was found to be 8.4% of offspring, with 34.4% of broods containing one or more extra-pair young. No incidences of intra-specific brood parasitism (egg dumping) were identified. Cuckolded males were compared with other males, but no significant differences were identified for any of the physical, behavioural or territorial measures. In particular, there was no evidence that previously detected mate choice cues are related d to patterns of paternity within the population, and hence no evidence that such cues indicate genetic benefits to females. It therefore seems likely that repertoire size reflects male phenotypic quality in this species.

Site-dependent population dynamics: the influence of spatial habitat heterogeneity on individual fitness in the sedge warbler Acrocephalus schoenobaenus

During nine years of study, we detected a mechanism corresponding to site dependence operating in a population of the sedge warbler Acrocephalus schoenobaenus inhabiting a natural wetland of high within-habitat heterogeneity. Sites with a larger share of cover by tall wetland vegetation were preempted during spring settlement; they were occupied in more breeding seasons and by more experienced males. The fitness of males occupying these sites was higher in terms of local recruit production. The total area occupied by the population expanded or contracted depending on its population size. This mechanism increased or decreased the mean site quality, influencing local recruitment of young, although mainly by changing the share of unproductive sites in the total pool of occupied sites. The results indicate that population demographic rates may depend on the spatial heterogeneity of resources at the level of individuals.