Ringed Research Articles

Solving the challenges of monitoring mobile populations: insights from studies of waterbirds in southern Africa

Highly mobile species are difficult to monitor. It is often unclear from abundance estimates whether a population is genuinely declining or simply elsewhere. If the spatial and temporal scales of monitoring are inadequate, the data will only be useful if the signal is very strong (i.e. the change in population size is large). We explored the ability of three major databases – the Southern African Bird Atlas Project (SABAP), the Coordinated Waterbird Counts (CWAC) and the South African Bird Ringing Unit (SAFRING) – to reveal the movement patterns of a highly mobile African waterbird, the Red-billed Teal Anas erythrorhyncha. Only ring recovery data provided clear evidence of long-distance movement. All three data sets were compromised to varying degrees by methodological biases and spatial and/or temporal resolutions that prevented the detection of movement patterns. By incorporating abundance estimates, increasing and quantifying sampling effort, and extending coverage at the data collection stage, the potential for these data sets to contribute to our understanding of bird movements could be greatly improved. Monitoring programmes for mobile species must be tested at an early stage to assess their ability to explain spatial and temporal population variation at the scales at which such variation occurs.

Migratory connectivity of a Neotropical migratory songbird revealed by archival light-level geolocators.

Understanding migratory connectivity is critical for interpreting population dynamics, seasonal interactions, and for the implementation of conservation strategies of migratory species. We evaluated the migratory connectivity of a Neotropical migratory songbird, the Ovenbird (Seiurus aurocapilla) using archival light-level geolocators deployed at two breeding and four nonbreeding locations while incorporating Ovenbird abundance as prior information using Bayes' Rule. We also included band recoveries submitted to the United States Geological Survey's Bird Banding Laboratory to assess connectivity of areas where geolocators were not deployed. We created a probabilistic map of origin for each capture site and mapped spring migration routes between nonbreeding and breeding locations. We found a complete separation of eastern and western populations of Ovenbirds throughout the annual cycle. Breeding Ovenbirds from western Canada spent the nonbreeding season throughout Central America and migrated through central North America during spring migration. Birds breeding in the northeastern United States were distributed throughout the central Greater Antilles in the Caribbean and migrated through eastern North America during spring migration. Fall migration routes were not included because the timing of migration coincided with fall equinox when latitudinal estimates are unreliable. However, longitudinal estimates suggest no overlap between eastern and western populations during fall migration. Ovenbirds with geolocators attached in Jamaica bred in the northeastern United States with the highest posterior probability of origin found in Massachusetts, while Ovenbirds captured in Florida and Puerto Rico bred primarily in the mid-Atlantic. Incorporating Ovenbird abundance as a prior into geolocator estimates decreased the area of origin by 90.37% ± 1.05% (mean ± SE) for the breeding season and 62.30% ± 1.69% for the nonbreeding season, compared to geolocator estimates alone. Ovenbirds exhibited strong migratory connectivity between breeding and nonbreeding season, which has important implications for various aspects of the ecology, evolution, and conservation.

Disentangling the drivers of change in Common Teal migration phenology over 50 years: land use vs. climate change effects

A large body of research has accumulated on the impact of climate change on wildlife movements and distributions, especially for migratory birds. We used large ringing datasets for the Common Teal (Anas crecca) from the Camargue, southern France, to compare historic (from 1956–1975) spatiotemporal patterns of teal recovery with those seen in modern (2002–2012) years and assess whether the migration phenology of these ringed birds and their use of the Camargue as winter quarters has changed. Because teal are short-distance migrants (i.e., they breed in northern Europe and winter north of the Sahara), they would be predicted to delay their autumn migration in response to climate change. Conversely, ring recoveries showed that teal are now arriving much earlier: a stable 80 % of the recoveries were made locally in the Camargue each week between mid-November and late January in the modern dataset, whereas this percentage was only 53 % on average in the older data, and the proportion of recoveries made locally in the Camargue gradually increased through the autumn and winter until late January. This suggests that Camargue habitats have changed markedly and become more attractive to teal compared to other potential wintering areas, consistent with known changes in local habitat management practices and improvements in the body condition of the birds. Despite the fact that global climate change will likely be one of the main drivers of wildlife distribution over the long term and at large spatial scales, local habitat management should not be overlooked, as it can increase habitat attractivity to migratory birds.

Low incidence of leg and foot injuries in colour-ringed Marsh Tits Poecile palustris

Marking birds with individually identifiable metal leg-rings (bands) is a common research tool, and the additional use of plastic colour rings has facilitated numerous studies of bird ecology, yet there is limited information for the impact of these methods on individuals and populations. Despite generally being considered to have a negligible effect upon birds, recent literature shows that leg rings can cause injuries to some passerines. This creates an ethical problem and may also bias research results by influencing individual behaviour and survival. The incidence of leg injuries was monitored on colour-ringed and unringed Marsh Tits Poecile palustris over 12 years. The overall incidence of permanent injury did not differ between ringed and unringed birds, but six of 404 colour-ringed birds (1.5%) carried a leg or foot injury, which was significantly greater than the background rate (0.2%) among 515 unringed birds. Some injuries on ringed birds were temporary or may have been unrelated to the rings; however, one fatality and two serious injuries were recorded, probably resulting from colour rings becoming caught on thorns or other objects. Although ring-related injuries were very rare, it is recommended that ringers studying Marsh Tits try to minimise the number of rings on each leg.

Seasonal distributions of Caspian Terns Hydroprogne caspia from Swedish populations, revealed by recoveries and resightings of ringed birds

The aim of this study was, by analysing recoveries and resightings of Caspian Terns Hydroprogne caspia ringed in Sweden, (1) to identify areas of importance during their migration and wintering, (2) to investigate the annual routines of migration and wintering of different age categories, and (3) to investigate how human activities, especially shooting, have affected survival of Caspian Terns over the 80-year period. In total, 2,048 metal-ring recoveries and resightings from 1,420 birds and 101 colour-ring recoveries and resightings since 2011 from 85 Caspian Terns ringed in Sweden were analysed for spatio-temporal patterns, age-dependent differences and mortality due to human activities. Ring recoveries beyond the breeding areas were widely dispersed southward but concentrated in several locations, such as coastal areas in the Netherlands, Italy and Germany during migration seasons and in Mali and Tunisia during winter. Distances to their wintering areas of up to more than 6,000 km were longer than for other populations of this species. Age-dependent differences in seasonal distributions seemed to be due mainly to young Caspian Terns remaining in wintering areas or otherwise well south of the breeding areas during their first years of life. Although shooting appeared to have been an important cause of death in former years, it has declined and recently seems to have had less influence on survival of European Caspian Terns than in the 1940s–2000s. Other recent changes in the distribution of recoveries are also discussed from ecological and social perspectives.

Space–time trends in Spanish bird electrocution rates from alternative information sources

Interaction with man-made infrastructures is one of the main sources of non-natural bird mortality. Here, we use a long-term study (1980–2010) to analyse spatial and temporal patterns in avian electrocution in Spain, using ringed birds as well as published reports and articles as information sources. Electrocution rates of ringed birds differ from rates obtained in unringed species. Electrocution rates are likely seasonally asymmetrical and are not constant across study periods: between 1990 and 2005 an annual rising trend of 5% was observed, whereas between 2006 and 2010 this trend decreased (16% annually). From the literature, we confirmed this decreasing trend. However, when we consider large eagles (Aquila genus), which include several of the most threatened bird species in Spain, this decreasing trend is not evident. The results of the analysis of different environmental and socio-economic factors affecting bird electrocution rates are similar between ringed birds and traditional power line surveys. Our modelling suggests three common factors that influence mortality rates: number of hunted rabbits, tree coverage and length of the power line network. Thus, the use of alternative information sources to detect high mortality areas due to electrocution by power lines may be a useful tool to complement other methods.

PRODUCTION RATE OF NITROGEN COMPOUNDS AND OTHER WATER QUALITY VARIABLES IN Macrobrachium vollenhovenii CULTURED IN TANKS

Juvenile-size of African River prawns ( Macrobrachi­um vollenhovenii ) of an average length of 46.34 ±0.23mm were collected from Epe Lagoon and cul­tured in concrete tanks for 56 days. The production of Nitrogenous compounds was monitored and the anal­yses of the water quality variables were carried out weekly. The ra nge of the water quality variables were 6.74-7.90 (pH), 25.7-30.3°C (Temperature), 6.71-8.01mg/L (Dissolved Oxygen), 0.00-0.03% (Salinity), 0.199 and 0.725 mS/cm (Conductivity), 24-48 NTU (Turbidity). The result showed that Nitrite (NO 2 - ) ranged between 0.07-0.50mg/L, Nitrate (NO 3 - ) was between the range of 1.32-6.63mg/L and Ammonia (NH 3 - ) was between 0.32-1.65mg/L.

Movement and mortality of Australian pelicans (Pelecanus conspicillatus) banded at inland and coastal breeding sites in South Australia

Globally, pelican populations have decreased, with three species being of conservation concern. Australian pelicans (Pelecanus conspicillatus) are not regarded as endangered, but have declined across south-eastern Australia. Information on their movements and causes of mortality are required to interpret the importance of these regional declines to the species’ global population. We explored patterns of movement and causes of mortality by analysing recoveries from 14 615 Australian pelicans banded over 37 years between 1969 and 2006. Data from 243 leg band recoveries showed that Australian pelicans move distances of up to 3206 km, and travel across the species’ entire geographic range, within a year of fledging. We found little evidence for the popular notion that these birds move en masse from the coast to inland areas in response to flooding rains. Maximum recorded age of a banded Australian pelican was 15 years. The banding data suggest that the regional pelican declines could reflect long-distance movements rather than an overall population response. However, a concentration of band returns from south-eastern Australia where the declines have been recorded, and the high incidence of human-induced deaths (16.4%) suggest otherwise. Accurate assessment of population trends in long-lived, long-distance nomads such as Australian pelicans requires assessment at a continental scale. Our results emphasise the importance of knowledge about fundamental aspects of a species’ biology for accurate interpretation of regional population declines.

Increasing protandry in the spring migration of the Pied Flycatcher (Ficedula hypoleuca) in Central Europe

Sexual selection theory suggests that the degree of protandry in spring migration should increase when earlier males benefit from better mating opportunities. Western European studies failed to show differences in sex-specific arrival dates for the Pied Flycatcher. However, different climatic conditions and other constraints may affect its phenology in continental Europe. Here, we present evidence that sex-related phenological changes have occurred over the past 25 years (between 1989 and 2013) in Central Europe (Ocsa Bird Ringing Station, Hungary). The spring arrival of male flycatchers shifted to earlier dates whereas female arrival showed no change, implying an increasing degree of protandry.

Using bird banding and recovery to study the migration of Black-necked Cranes ( Grus nigricollis ) in China

In this present study, by reorganizing and classifying the bird banding and recovery records from 1985 to 2012, we discussed the current research status of the migrations of Black-necked Cranes (Grus nigricollis) in China. The results showed that 94 Black-necked Cranes in total were banded and 13 among them were also attached with satellite transmitters. Whereas, only 66 counts were recovered, i.e., 27 or 28 birds (same color ring combinations were used on two individuals repeatedly, but were recovered at different places), indicating a recovery rate of 28.72% or 29.79%, while, most of the recovery (63 counts, 95.45%) happened in wintering sites. Data of banding showed that Black-necked Cranes hit their sexual maturity at the age≥5 years, and the morphological indexes of the sub-adults are all smaller than those of the adults. After being banded, the average life span of banded individuals was 40±40 months (n=26, 1-161 months). Moreover, the recovery records indicate three migration routes of Black-necked Cranes: (1) the eastern flyway: from the Greater Ruoergai wetland area (breeding ground) of Sichuan and Gansu Provinces to northeastern Yunnan and northwestern Guizhou Provinces; (2) the central flyway: from the Longbaotan Nature Reserve of Qinghai Province (breeding ground, several other breeding sites along this route are located in northwest Sichuan Province) to the Napahai Natural Reserve, Yunnan Province (wintering ground); (3) from the vast area of northwestern Qinghai, Xinjiang, and northern Tibet (breeding ground) to the Yarlung Zangbo valley, southcentral Tibet and Bhutan. Our findings provide useful information to the relevant conservation and research facilities and institutes upon the banding, recovery and protection of the Black-necked Cranes. We recommend carrying out bird banding at breeding sites, while intensifying banding recovery and observation at wintering sites. Moreover, to establish long-term and stable information platforms and facilitate communication, it is urgent and necessary to standarize the banding and morphology measuring systems.

Bird Ringing Data and Field Notes from The Kelabit Highlands: 1993 to 2010

The initial bird surveys of Sarawak, from 1985 to 1992, covered a few National Parks, and several other lowland sites. From January 1993, until November 2010, a new survey began, to explore a wide expanse of the Kelabit Highlands, including parts of the Pulong Tau National Park. During this eighteen-year period, the sites selected ranged from lower montane areas of the Kelabit plateau close to its border with Kalimantan to the higher montane slopes of Mount Murud massif to the north. The duration of these surveys, largely self-funded, ranged from short-term ones, of ten to fourteen days each, to several extended ones that lasted as long as three continuous months at the same location. A large volume of data, on 227 species, was collected during this time. A small part of it has been analysed to support a series of short papers previously published in The Sarawak Museum Journal. Much of it, however, especially the ringing data, remains unpublished. It is now released into public domain for use by other workers. The data collected in the lowland surveys will be published in a separate paper.

Importance of Juvenile Mortality in Birds' Population: Early Post-Fledging Mortality and Causes of Death in White StorkCiconia ciconia

ABSTRACT: Early post-fledging mortality of White Stork during the period from the first flight to their autumn departure from natal area was described. Data from eight breeding seasons (2005–2012) about 56 cases of death of juvenile White Storks from a study area in Western Poland were collected. For a comparison the data of 55 cases of death from recoveries data deposited in Polish Bird Ringing Centre from entire Poland were included in analysis. Early post-fledgling mortality rate varied from 2 to 11% (mean 4.3%) of all fledglings per year. The main causes of death were collision with power lines and electrocution which in Western Poland constituted 60% and in entire Poland — 78% of death cases with known causes. Other anthropogenic causes constituted responsibly 25 and 13% and natural causes — 15 and 9%. Mean distance where dead storks were found was 183.3m from natal nests, while 73% were found closer than 100 m from their nests.

Contrasting population trends at seabirds colonies: is food limitation a factor in Norway?

Norwegian Northern Gannet Morus bassanus populations exhibit contrasting trends on a regional scale, with several colony extinctions having occurred in recent decades. In an attempt to understand the ecological drivers of such variability, we tested whether resource availability is a factor limiting the current development of gannetries in the Lofoten/Vesteralen area. Between 2007 and 2010, we recorded arrival and departure times of breeding Northern Gannets from two colonies from regions showing contrasting population growth rates during the past two decades. We also recorded the duration of joint attendances by Northern Gannet parents at the nest, performed opportunistic diet sampling and counted numbers of occupied nests. Finally, we compiled ring recoveries over a 30-year period to assess inter-colony movements. Norwegian Gannet parents spent more time together, attending their chick, and performed shorter foraging trips than those in British and French colonies of similar size. This suggests that, despite some annual variations, their foraging effort was relatively low. Diet samples from both colonies mainly constituted fish of high energetic value, such as large herring Clupea harengus, mackerel Scomber scombrus, and saithe Pollachius virens, prey that are relatively abundant within the study area. Data from ringed birds revealed a northward movement of adults ringed as breeding birds and chicks from extinct Lofoten colonies that established a growing colony close to the North Cape. Recorded foraging features (trip duration, joint attendance and prey quality) during our study does not indicate food availability as a limiting factor explaining successive extinctions and re-colonisations of breeding sites in Lofoten/Vesteralen. White-tailed Eagles Haliaeetus albicilla are known to predate opportunistically on Northern Gannet adults or chicks and their populations are growing in the Lofoten area. Their potential impact on the Norwegian Northern Gannet population dynamics should be further investigated.

Large‐scale spatial analysis of ringing and re‐encounter data to infer movement patterns: A review including methodological perspectives

Summary A major aim of bird ringing is to provide information about the migration and movements of bird populations. However, in comparison with demographic studies, little research has been devoted to improving quantitative inferences through large‐scale spatial analyses. This represents a serious knowledge gap because robust information on geographical linkages of migratory populations throughout the annual cycle is necessary to understand the ecology and evolution of migrants and for the conservation and management of populations. Here, we review recent developments and emerging opportunities for the quantitative study of movements of bird populations based on marked birds. Large‐scale spatial analyses of ringing data need to account for spatiotemporal variation in re‐encounter probability and the complexity of movement processes, including variability among individuals and populations in migration direction and distance. We identify seven recent studies that used quantitative methods for large‐scale spatial analyses of ringing and re‐encounter data gathered by national ringing centres. In most cases, numbers ringed and recovered in a series of source and destination areas were used to derive estimates of the proportion of each source population travelling to each destination area. Where recovery data were sparse, precision was improved by incorporating information on re‐encounter probabilities of similar species. When numbers ringed were not available, inferences could sometimes be drawn based on local recapture data from the source areas. Studies to date illustrate that analyses of these large‐scale ringing data sets can provide robust quantitative inferences. Further work is needed to develop these modelling approaches and to test their sensitivity to key assumptions using both real and simulated data. Data for all birds that were marked, not only those re‐encountered, are often inaccessible and should be computerised in parallel with analytical developments. Further, there is great potential for the formal combination of re‐encounter data with information from additional data sources such as counts and detailed movement data from radiotracking or data loggers. Because data from bird ringing operations cover long periods of time and exist in large quantities, they hold great promise for inferring spatiotemporal migration patterns, including changes in relation to climate, land use change and other environmental drivers.

Aspects of the ecology and morphology of the protea seedeater, Crithagra leucopterus, a little-known Fynbos endemic

The protea seedeater, Crithagra leucopterus, is one of six passerine birds endemic to the Fynbos Biome, South Africa. It is the least known of these, and there is very little information on breeding and habitat use. Through nest observations and a bird ringing scheme in the eastern sections of the Fynbos, we provide updated information on habitat use, breeding and population biometrics. We document changes in capture rates for a suite of birds in relation to a fire event and use of burnt and unburnt sites within Blue Hill Nature Reserve, South Africa. Protea seedeaters were recorded nesting in mature Fynbos, but feeding in recently burnt Fynbos on freshly released protea seeds, suggesting the species benefits from smallscale burns that create a landscape of mixed veld ages. Protea seedeaters weighed less and had shorter wings compared to those of the western Fynbos. Further habitat-use and life-history information on protea seedeaters is needed to help guide conservation management plans, especially in the light of changing fire regimes in the Fynbos.

Combining spatial modelling and radar to identify and protect avian migratory hot-spots

Abstract Migrating landbirds are known to follow coast lines and concentrate on peninsulas prior to crossing water bodies, especially during daylight but also at night, creating enhanced potential collision hazards with man-made objects. Knowing where these avian migration “hot-spots” occur in time and space is vital to improve flight safety and inform the spatial planning process (e.g. environmental assessments for offshore windfarms). We developed a simple spatial model to identify avian migration hot-spots in coastal areas based on prevailing migration orientation and coastline features known, from visual and radar observations, to concentrate migrating landbirds around land masses. Regional scale model validation was achieved by combining nocturnal passerine movement data gathered from two tier radar coverage (long-range dual-polarization Doppler weather radar and short-range marine surveillance radar) and standardised bird ringing. Applied on a national scale, the model correctly identified the ten most important Danish coastal hot-spots for spring migrants and predicted the relative numbers of birds that concentrated at each site. These bird numbers corresponded well with historical observational data. Here, we provide a potential framework for the establishment of the first three-dimensional avian airspace sanctuaries, which could contribute to more effective conservation of long-distance migratory birds.

Aspects of the Ecology and Morphology of the Protea Seedeater,Crithagra Leucopterus, a Little-Known Fynbos Endemic

The protea seedeater, Crithagra leucopterus, is one of six passerine birds endemic to the Fynbos Biome, South Africa. It is the least known of these, and there is very little information on breeding and habitat use. Through nest observations and a bird ringing scheme in the eastern sections of the Fynbos, we provide updated information on habitat use, breeding and population biometrics. We document changes in capture rates for a suite of birds in relation to a fire event and use of burnt and unburnt sites within Blue Hill Nature Reserve, South Africa. Protea seedeaters were recorded nesting in mature Fynbos, but feeding in recently burnt Fynbos on freshly released protea seeds, suggesting the species benefits from smallscale burns that create a landscape of mixed veld ages. Protea seedeaters weighed less and had shorter wings compared to those of the western Fynbos. Further habitat-use and life-history information on protea seedeaters is needed to help guide conservation management plans, especially in the light of changing fire regimes in the Fynbos.

Weighted likelihood recapture estimation of detection probabilities from an ice‐based survey of bowhead whales

Estimating visual detection probabilities of migrating western Arctic bowhead whales from independent observers on two ice‐based perches presents challenges that cannot be resolved using standard capture‐recapture methods. Distant visual sighting and resighting of intermittent whale surfacings is very unlike recapturing banded birds or tagged fish. We develop several bias correction strategies that are essential to confront difficulties introduced by sighting ambiguities, match uncertainty, group size inconsistencies, and the survey protocol. These are implemented using a weighted likelihood adaptation of a standard capture‐recapture model. This model estimates the relationship between detection probabilities and covariates associated with the sighting. We present a complete analysis of the bowhead example and discuss how the data configuration, weighting, and estimation methods presented here highlight issues that are confronted in the analysis of many other complex capture‐recapture datasets. Copyright © 2014 John Wiley & Sons, Ltd.

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.

Northern Saw-whet Owl: regional patterns for fall migration and demographics revealed by banding data

We describe attributes of Northern Saw-whet Owls (Aegolius acadicus) during fall migration using 167,774 records from the U.S. Bird Banding Laboratory for central and eastern North America from 1929–2010. We describe movement among 18 geographic regions using records of 1,444 birds captured and recaptured between 1 September and 31 December of the same year. These data show little exchange between western Lake Superior and eastern North America. The direction of movement within a region was strongly influenced by large water bodies, varied greatly among regions, and showed high dispersal in the absence of shorelines of large water bodies. We used recent banding data to analyze population demographics from northwestern Minnesota to the coast of Maine in the north, and from southern Minnesota and southern Wisconsin to southern Appalachia and the mid-Atlantic coastal region in eastern United States. The weighted mean proportion of Hatch Year (HY) birds declined significantly from 63% in northwestern Minnesota to 42% in southern Minnesota/southern Wisconsin and from 70% in northern Ontario to 48% in southern Appalachia. Annual variation in the proportion of HY birds showed little correlation between eastern and central origin sites but moderate correlation within each of these regions. We define irruptions as years when the proportion of HY birds is 15% or greater than the weighted mean for each site, a level that occurs once in 4 years on average but at irregular intervals. We determined a very high correlation between the proportion of HY birds banded in northeast of Lake Ontario and the abundance of small mammals, suggesting a close relationship between food supply and reproductive success.