Paternal effects in the initiation of migratory behaviour in birds

What determines why some birds migrate and others do not? This question is fundamental to understanding how migratory systems are responding to environmental changes, but the causes of individual migratory behaviours have proven difficult to isolate. We show that, in a partially migratory population of Eurasian Oystercatchers (Haematopus ostralegus), the migratory behaviour of progeny follows paternal but not maternal behaviour, and is unrelated to timing of hatching or fledging. These findings highlight the key role of social interactions in shaping the migratory behaviour of new generations, and thus the spatio-temporal distribution of migratory population

Vegetation structure influences predation rates of early nests in subarctic breeding waders

Ground-nesting species are vulnerable to a wide range of predators and often experience very high levels of nest predation. Strategies to reduce nest vulnerability can include concealing nests in vegetation and/or nesting in locations in which nests and eggs are camouflaged and less easy for predators to locate. These strategies could have important implications for the distribution of ground-nesting species and the success rates of nests in areas with differing vegetation structure. However, the factors influencing the success of nest concealment and camouflage strategies in ground-nesting species are complex. Here we explore the effects of local vegetation structure and extent of nest concealment on nest predation rates in a range of ground-nesting, sympatric wader species with differing nest concealment strategies (open-nest species: Oystercatcher Haematopus ostralegus, Golden Plover Pluvialis apricaria and Whimbrel Numenius phaeopus; concealed-nest species: Black-tailed Godwit Limosa limosa, Redshank Tringa totanus and Snipe Gallinago gallinago) in south Iceland, in landscapes that comprise substantial variability in vegetation structure at a range of scales. We monitored 469 nests of these six wader species in 2015 and 2016 and ~40% of these nests were predated. Nest predation rates were similar for open-nest and concealed-nest species and did not vary with vegetation structure in the surrounding landscape, but nest-concealing species were ~10% more likely to have nests predated when they were poorly concealed, and the frequency of poorly concealed nests was higher in colder conditions at the start of the breeding season. For concealed-nest species, the reduced capacity to hide nests in colder conditions is likely to reflect low rates of vegetation growth in such conditions. The ongoing trend for warmer springs at subarctic latitudes could result in more rapid vegetation growth, with consequent increases in the success rates of early nests of concealed-nest species. Temperature-related effects on nest concealment from predators could thus be an important mechanism through which climate change affecting vegetation could have population-level impacts on breeding birds at higher latitudes

Individual variation in migratory behavior in a sub-arctic partial migrant shorebird

Migratory behavior can differ markedly amongst individuals within populations or species. Understanding the factors influencing this variation is key to understanding how current environmental changes might influence migratory propensity and the distribution and abundance of migratory species across their range. Here, we investigate variation in migratory behavior of the partially migratory Eurasian oystercatcher (Haematopus ostralegus) population breeding in Iceland. We use the resightings of color-ringed adults and stable isotopes to determine whether individuals migrate or remain in Iceland during winter and test whether individual migratory strategies vary in relation to sex, body size, and breeding location. We also explore individual consistency in migratory strategy and test whether assortative mating with respect to strategy occurs in this population. The proportion of migrants and residents varied greatly across breeding locations but not with respect to sex or body size. Individuals were consistent in migratory strategy between years and there was no evidence of assortative mating by migratory strategy. We use these findings to explore factors underlying the evolution and maintenance of partial migration at high latitudes

Effects of overhead power-lines on the density of groundnesting birds in open sub-arctic habitats

Yearly electricity production has increased steadily in the world 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

Effects of pair migratory behavior on breeding phenology and success in a partially migratory shorebird population

In migratory systems, variation in individual phenology can arise through differences in individual migratory behaviors, and this may be particularly apparent in partial migrant systems, where migrant and resident individuals are present within the same population. Links between breeding phenology and migratory behavior or success are generally investigated at the individual level. However, for breeding phenology in particular, the migratory behaviors of each member of the pair may need to be considered simultaneously, as breeding phenology will likely be constrained by timing of the pair member that arrives last, and carryover effects on breeding success may vary depending on whether pair members share the same migratory behavior or not. We used tracking of marked individuals and monitoring of breeding success from a partially migrant population of Eurasian oystercatchers (Haematopus ostralegus) breeding in Iceland to test whether (a) breeding phenology varied with pair migratory behavior; (b) within-pair consistency in timing of laying differed among pair migratory behaviors; and (c) reproductive performance varied with pair migratory behavior, timing of laying, and year. We found that annual variation in timing of laying differed among pair migratory behaviors, with resident pairs being more consistent than migrant and mixed pairs, and migrant/mixed pairs breeding earlier than residents in most years but later in one (unusually cold) year. Pairs that laid early were more likely to replace their clutch after nest loss, had higher productivity and higher fledging success, independent of pair migratory behavior. Our study suggests that the links between individual migratory behavior and reproductive success can vary over time and, to a much lesser extent, with mate migratory behavior and can be mediated by differences in laying dates. Understanding these cascading effects of pair phenology on breeding success is likely to be key to predicting the impact of changing environmental conditions on migratory species

Population size of Oystercatchers Haematopus ostralegus wintering in Iceland

The first ever survey of Oystercatchers wintering in Iceland found around 11 000 individuals. This is an estimated 30% of the Icelandic population, including juveniles, suggesting that approximately 26 000 Icelandic Oystercatchers migrate to western Europe in the autumn. More Oystercatchers winter in Iceland than at similar latitudes elsewhere in Europe, which may reflect the remoteness and milder winter temperatures on this oceanic island

A Migratory Divide Among Red-Necked Phalaropes in the Western Palearctic Reveals Contrasting Migration and Wintering Movement Strategies

Non-breeding movement strategies of migratory birds may be expected to be flexibly adjusted to the distribution and quality of habitat, but only few studies compare movement strategies between populations using distinct migration routes and wintering areas. In thisour study, individual movement strategies of Rred-necked pPhalaropes Phalaropus lobatus, a long-distance migratory wader using saline waters in the non-breeding period, were studied using light-level geolocators. Results revealed the existence of two populations with distinct migration routes and wintering areas: one breeding in the north-eastern North Atlantic and migrating ca. 10,000 km oversea to the tropical eastern Pacific Ocean and the other breeding in Fennoscandia and Russia migrating ca. 6,000 km – largely over land – to the Arabian Sea (Indian Ocean). In line with our expectations, the transoceanic migration between the North Atlantic and the Pacific was associated with proportionately longer wings, a more even spread of stopovers in autumn and a higher migration speed in spring compared to the migration between Fennoscandian-Russian breeding grounds and the Arabian Sea. In the wintering period, birds wintering in the Pacific were stationaryresided in roughly a singlethe same area, whereas individuals wintering in the Arabian Sea showed individually consistent movementsd extensively between different areas, reflecting differences in spatio-temporal variation in primary productivity between the two wintering areas. Our study is unique in showing how habitat distribution shapes movement strategies over the entire non-breeding period within a species.Peer reviewe

Farhættir og lýðfræði sandlóu Charadrius hiaticula

Farfuglar lifa tvöföldu lífi, annars vegar á varpstöðum og hins vegar á vetrarstöðvum og leggja oft á sig löng og hættuleg ferðalög á milli þessara svæða. Þættir sem verka á einstaklinga á einni árstíð geta haft keðjuverkandi áhrif á öðrum tímum árs. Komutími að vori sýnir gjarnan fylgni við gæði einstaklinga og varpárangur og getur tengst gæðum vetrarstöðva. Á Íslandi verpa stórir stofnar nokkurra vaðfuglategunda og eru það allt farfuglar sem flestir hafa vetursetu í V-Evrópu og/eða V-Afríku. Það er lítið vitað um afdrif þessara stofna utan varptíma og því erfitt að tengja ástand á vetrarstöðvum við atburði á varpstöðvum, þó endurheimtur hafi sýnt hvar megin vetrarstöðvar þeirra eru. Ef tengja á atburði á vetrarstöðvum og á fartíma við varpvistfræði er því helst að líta til breytileika í komutíma einstaklinga. Markmið þessara rannsókna var að skoða tengsl fars sandlóa (Charadrius hiaticula), einkum komutíma, við lýðfræði. Til að skoða þessa þætti þurfti að einstaklingsmerkja varpfugla og fylgjast með þeim, frá því að þeir komu að vori þar til varpi lauk. Aðal rannsóknarsvæðin voru í Önundarfirði og Bolungarvík á Vestfjörðum og við Stokkseyri á Suðurlandi og stóð rannsóknin yfir á árunum 2004-2011. Talsverður fjöldi litmerktra sandlóa sást utan Íslands og merkingarnar gáfu því einnig upplýsingar um dreifingu sandlóu utan varptímans í Evrópu og Afríku ásamt upplýsingum úr gagnagrunni Náttúrufræðistofnunar Íslands. Flestar endurheimtur erlendis voru á Bretlandseyjum og vesturströnd Frakklands á haust- og vorfari. Um vetur fengust flestar endurheimtur í Suður Evrópu og í Vestur Afríku. Vísbendingar fengust um að karlfuglar færu frekar til Afríku á veturna en kvenfuglar en sýnið var of lítið til að staðfesta það með vissu. Komutími til Íslands var þekktur fyrir 15 fugla sem vitað var hvar héldu sig á vetrum. Fuglar sem voru í Evrópu á veturna komu marktækt fyrr á varpstöðvar að vori en fuglar sem dvöldu í Afríku. Sandlóur komu almennt á rannsóknarsvæðin frá 15. apríl til 10. maí og þær allra fyrstu hófu varp í byrjun maí en flestar í lok maí. Einstaklingar voru almennt á sömu áætlun á milli ára, bæði í komutíma og í varpi. Jákvætt samband var á milli komutíma og varptíma en þeir sem komu snemma biðu almennt lengur með að hefja varp heldur en þeir sem komu síðar. Afkoma hreiðra var afar breytileg milli ára, staða og innan varptímans. Klakdagsetningar unga, sem síðar snéru aftur sem varpfuglar, dreifðust yfir allan varptímann. Einstaklingar sem komu snemma gátu reynt varp allt að þrisvar sinnum yfir varptímann þar sem þeir höfðu tæpa tvo mánuði til að reyna varp en þeir sem hófu varp síðast höfðu aðeins um mánuð. Þar sem varpárangur er mjög breytilegur í tíma og rúmi getur möguleiki á fleiri varptilraunum yfir ævina aukið hæfni (fitness) einstaklingsins.Migratory birds live a double life and have to negotiate very different conditions on the breeding and wintering grounds throughout the year. The conditions at the distant ends of the migration are limiting in migratory populations. To unravel seasonal interactions it is necessary to follow individuals through the annual cycle. This is rarely possible but timing of migration of individuals is often correlated, both with conditions on the wintering grounds and breeding success, and can give information about seasonal interactions. A few very large migratory populations of waders breed in Iceland and winter in W-Europe and/or W-Africa. Little is known about most of these populations on wintering sites apart from very basic knowledge of their winter distribution. This study explored migration patterns and demography of Common Ringed Plovers (Charadrius hiaticula) and potential links between the two. Populations of individually marked birds were established in NW- and S-Iceland and followed during spring arrival and the breeding season. Main study sites were in Bolungarvik and Onundarfjordur in NW-Iceland and in Stokkseyri in S-Iceland and these sites were monitored from 2004-2011. Several marked birds were reported from outside Iceland which gave more detailed information about the non-breeding distribution of Ringed Plovers than previously known. Most recoveries in autumn and spring were from Britain, Ireland and France. In winter most recoveries were from S-Europe and NW-Africa. Icelandic Ringed Plovers leap-frog the British population and probably a part of the S-Scandinavia population. Arrival time in Iceland in spring was known for 15 birds of known winter location and birds wintering in Europe arrived significantly earlier than birds wintering in Africa. Ringed Plovers generally arrived on breeding sites in late April and early May and the arrival dates of individuals in consecutive years were repeatable. Individual timing of nesting was also repeatable and earlier arrivals tended to lay earlier despite having a longer gap between arrival and laying than later arrivals. Nest survival was generally very low but variable and neither sites nor years had a significant effect on hatching success. The hatching dates of marked chicks that later recruited as adults on the study sites were not significantly different from the background hatching dates in the year of their hatching on their natal sites. When clutches failed, earlier arriving birds in spring seemed to have more time for re-nesting and were more likely to have three nesting attempts than later arriving birds. The scope for increasing breeding success, by arriving earlier to allow for more re-nesting attempts may have a significant effect on fitness during the lifespan of Ringed Plovers

Conservation beyond Boundaries: Using animal movement networks in Protected Area assessment

Protected areas (PAs) are a core component of conservation policy and practice. However, many species for which they are designated are highly mobile, and may move among sites within and beyond PA boundaries. Environmental impacts on sites beyond those boundaries could thus impact the PA’s protected populations, with the risk of adversely affecting its conservation objectives. Conservationists therefore urgently need tools to assess impacts on PAs and their populations of developments beyond their boundaries. We present a framework for using network analysis of observations of marked individuals to assess the protection footprint of PAs in the wider landscape and the impact footprint of developments within or neighbouring PAs. We illustrate the use of this framework by assessing the impact of a current airport development proposal on a partially protected wetland, the Tagus Estuary in Portugal, specifically by evaluating the extent of noise disturbance on the PA’s population of Black-tailed Godwits, a protected migratory wader species. By analysing individual movements between sites and across seasons, we find disturbance impacts on up to 68.3% of individual Black-tailed Godwits, greatly exceeding the estimates of 0.46-5.5% in the airport’s Environmental Impact Assessments which derived from count data. We then compared the pre-development network with simulated networks that represented two levels of site avoidance by removing sites predicted to receive noise in excess of two thresholds, 55 or 65 dB(A). Avoidance by godwits of the potentially-impacted sites is predicted to have a larger effect on network structure than removing the same number of sites at random, suggesting that an airport in the proposed location would operate as a barrier to connectivity in this wetland. We also highlight the role that network analyses of locations of marked individuals can play in assessing environmental impacts on protected sites and populations

Movement of juvenile migratory birds from settlement to adulthood across the non-breeding range.

Publication status: PublishedFunder: University of Iceland Research fundAmong migratory vertebrates, high levels of fidelity to non-breeding sites during adulthood are common. If occupied sites vary in quality, strong site fidelity can have profound consequences for individual fitness and population demography. Given the prevalence of adult site fidelity, the regions of the non-breeding range to which juveniles first migrate, and the scale of any subsequent movements, are likely to be pivotal in shaping distributions and demographic processes across population ranges. However, inherent difficulties in tracking migratory individuals through early life mean that opportunities to quantify juvenile settlement and movements across non-breeding ranges, and the mechanisms involved, are extremely rare. Through long-term, range-wide resightings of hundreds of colour-marked individuals from their first migration to adulthood and the application of state-space models, we quantify levels of juvenile and adult regional-scale movements and distances at different life stages across the whole non-breeding distribution range in a migratory shorebird, the Black-tailed Godwit (Limosa limosa islandica). We show that the probability of individuals changing non-breeding regions (seven historical wintering regions spanning the Western Europe range) at all ages is very low (mean movement probability = 10.9% from first to subsequent winter, and 8.3% from first adult winter to later winters). Movement between regions was also low between autumn and winter of the same year for both juveniles (mean movement probability = 17.0%) and adults (10.4%). The great majority of non-breeding movements from the first autumn to adulthood were within regions and less than 100 km. The scarcity of regional-scale non-breeding movements from the first autumn to adulthood means that the factors influencing where juveniles settle will be key determinants of non-breeding distributions and of the rate and direction of changes in distributions